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Amin, Ir Mohd Zaki bin Mat, Ali Ercan, Kei Ishida, M. Levent Kavvas, Z. Q. Chen i Su-Hyung Jang. "Impacts of Climate Change on the Hydro-Climate of Peninsular Malaysia". Water 11, nr 9 (29.08.2019): 1798. http://dx.doi.org/10.3390/w11091798.
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In this study, a regional climate model was used to dynamically downscale 15 future climate projections from three GCMs covering four emission scenarios (SRES B1, A1FI, A1B, A2) based on Coupled Model Intercomparison Project phase 3 (CMIP3) datasets to 6-km horizontal resolution over the whole Peninsular Malaysia. Impacts of climate change in the 21st century on the precipitation, air temperature, and soil water storage were assessed covering ten watersheds and twelve coastal regions. Then, by coupling a physical hydrology model with the regional climate model, the impacts of the climate change on river flows were assessed at the outlets of ten watersheds in Peninsular Malaysia. It was found that the increase in the 30-year mean annual precipitation from 1970–2000 to 2070–2100 will vary from 17.1 to 36.3 percent among the ten watersheds, and from 22.9 to 45.4 percent among twelve coastal regions. The ensemble average of the basin-average annual mean air temperature will increase about 2.52 °C to 2.95 °C from 2010 to 2100. In comparison to the historical period, the change in the 30-year mean basin-average annual mean soil water storage over the ten watersheds will vary from 0.7 to 10.9 percent at the end of 21st century, and that over the twelve coastal regions will vary from −1.7 to 15.8 percent. Ensemble averages of the annual mean flows of the 15 projections show increasing trends for the 10 watersheds, especially in the second half of the 21st century. In comparison to the historical period, the change in the 30-year average annual mean flows will vary from −2.1 to 14.3 percent in the early 21st century, 4.4 to 23.8 percent in the middle 21st century, and 19.1 to 45.8 percent in the end of 21st century.
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Almazroui, Mansour. "Temperature Changes over the CORDEX-MENA Domain in the 21st Century Using CMIP5 Data Downscaled with RegCM4: A Focus on the Arabian Peninsula". Advances in Meteorology 2019 (20.05.2019): 1–18. http://dx.doi.org/10.1155/2019/5395676.
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This paper examined the temperature changes from the COordinated Regional climate Downscaling Experiment (CORDEX) over the Middle East and North Africa (MENA) domain called CORDEX-MENA. The focus is on the Arabian Peninsula in the 21st century, using data from three Coupled Model Intercomparison Project Phase 5 (CMIP5) models downscaled by RegCM4, a regional climate model. The analysis includes surface observations along with RegCM4 simulations and changes in threshold based on extreme temperature at the end of the 21st century relative to the base period (1971–2000). Irrespective of the driving CMIP5 models, the RegCM4 simulations show enhanced future temperature changes for RCP8.5 as compared to RCP4.5. The Arabian Peninsula will warm at a faster rate (0.83°C per decade) as compared to the entire domain (0.79°C per decade) for RCP8.5 during the period 2071–2100. Moreover, the number of hot days (Tmax ≥ 50°C) (cold nights: Tmin ≤ 5°C) will increase (decrease) faster in the Arabian Peninsula as compared to the entire domain. This increase (decrease) of hot days (cold nights) will be more prominent in the far future (2071–2100) as compared to the near future (2021–2050) period. Moreover, the future changes in temperature over the main cities in Saudi Arabia are also projected. The RegCM4-based temperature simulation data from two suitable CMIP5 models are recommended as a useful database for further climate-change-related studies.
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Murray-Tortarolo, G., P. Friedlingstein, S. Sitch, V. J. Jaramillo, F. Murguía-Flores, A. Anav, Y. Liu i in. "The carbon cycle in Mexico: past, present and future of C stocks and fluxes". Biogeosciences 13, nr 1 (15.01.2016): 223–38. http://dx.doi.org/10.5194/bg-13-223-2016.
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Abstract. We modeled the carbon (C) cycle in Mexico with a process-based approach. We used different available products (satellite data, field measurements, models and flux towers) to estimate C stocks and fluxes in the country at three different time frames: present (defined as the period 2000–2005), the past century (1901–2000) and the remainder of this century (2010–2100). Our estimate of the gross primary productivity (GPP) for the country was 2137 ± 1023 TgC yr−1 and a total C stock of 34 506 ± 7483 TgC, with 20 347 ± 4622 TgC in vegetation and 14 159 ± 3861 in the soil.Contrary to other current estimates for recent decades, our results showed that Mexico was a C sink over the period 1990–2009 (+31 TgC yr−1) and that C accumulation over the last century amounted to 1210 ± 1040 TgC. We attributed this sink to the CO2 fertilization effect on GPP, which led to an increase of 3408 ± 1060 TgC, while both climate and land use reduced the country C stocks by −458 ± 1001 and −1740 ± 878 TgC, respectively. Under different future scenarios, the C sink will likely continue over the 21st century, with decreasing C uptake as the climate forcing becomes more extreme. Our work provides valuable insights on relevant driving processes of the C cycle such as the role of drought in drylands (e.g., grasslands and shrublands) and the impact of climate change on the mean residence time of soil C in tropical ecosystems.
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Murray-Tortarolo, G., P. Friedlingstein, S. Sitch, V. J. Jaramillo, F. Murguía-Flores, A. Anav, Y. Liu i in. "The carbon cycle in Mexico: past, present and future of C stocks and fluxes". Biogeosciences Discussions 12, nr 15 (10.08.2015): 12501–41. http://dx.doi.org/10.5194/bgd-12-12501-2015.
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Abstract. We modelled the carbon (C) cycle in Mexico with a process-based approach. We used different available products (satellite data, field measurements, models and flux towers) to estimate C stocks and fluxes in the country at three different time frames: present (defined as the period 2000–2005), the past century (1901–2000) and the remainder of this century (2010–2100). Our estimate of the gross primary productivity (GPP) for the country was 2137 ± 1023 Tg C yr−1 and a total C stock of 34 506 ± 7483 Tg C, with 20 347 ± 4622 Pg C in vegetation and 14 159 ± 3861 in the soil. Contrary to other current estimates for recent decades, our results showed that Mexico was a C sink over the period 1990–2009 (+31 Tg C yr−1) and that C accumulation over the last century amounted to 1210 ± 1040 Tg C. We attributed this sink to the CO2 fertilization effect on GPP, which led to an increase of 3408 ± 1060 Tg C, while both climate and land use reduced the country C stocks by −458 ± 1001 and −1740 ± 878 Tg C, respectively. Under different future scenarios the C sink will likely continue over 21st century, with decreasing C uptake as the climate forcing becomes more extreme. Our work provides valuable insights on relevant driving processes of the C-cycle such as the role of drought in marginal lands (e.g. grasslands and shrublands) and the impact of climate change on the mean residence time of C in tropical ecosystems.
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Tan, Z., L. L. Tieszen, E. Tachie-Obeng, S. Liu i A. M. Dieye. "Historical and simulated ecosystem carbon dynamics in Ghana: land use, management, and climate". Biogeosciences Discussions 5, nr 3 (2.06.2008): 2343–68. http://dx.doi.org/10.5194/bgd-5-2343-2008.
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Abstract. We used the General Ensemble biogeochemical Modeling System (GEMS) to simulate responses of natural and managed ecosystems to changes in land use, management, and climate for a forest/savanna transitional zone in central Ghana. Model results show that deforestation for crop production during the last century resulted in a substantial reduction in ecosystem carbon (C) stock from 135.4 Mg C ha−1 in 1900 to 77.0 Mg C ha−1 in 2000, and in soil organic C stock within the top 20 cm of soil from 26.6 Mg C ha−1 to 21.2 Mg C ha−1. If no land use change takes place from 2000 through 2100, low and high climate change scenarios (increase in temperature and decrease in precipitation over time) will result in losses of soil organic C stock by 19% and 25%, respectively. A low nitrogen (N) fertilization rate is the principal constraint on current crop production. An increase in N fertilization under the low climate change scenario would increase crop yield by 14% with 30 kg N ha−1 and by 38% with 60 kg N ha−1, leading to an increase in the average soil C stock by 12% and 29%, respectively, in all cropland by 2100. The results suggest that the climate changes in the future from current climate conditions will not necessarily become a determinant control on ecosystem C fluxes and crop production, while a reasonable N fertilization rate is critical to achieve food security and agricultural sustainability in the study area through the 21st century, and current cropping systems could be optimized to make full use of the rainfall resource.
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Tan, Z., L. L. Tieszen, E. Tachie-Obeng, S. Liu i A. M. Dieye. "Historical and simulated ecosystem carbon dynamics in Ghana: land use, management, and climate". Biogeosciences 6, nr 1 (8.01.2009): 45–58. http://dx.doi.org/10.5194/bg-6-45-2009.
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Abstract. We used the General Ensemble biogeochemical Modeling System (GEMS) to simulate responses of natural and managed ecosystems to changes in land use and land cover, management, and climate for a forest/savanna transitional zone in central Ghana. Model results show that deforestation for crop production during the 20th century resulted in a substantial reduction in ecosystem carbon (C) stock from 135.4 Mg C ha−1 in 1900 to 77.0 Mg C ha−1 in 2000, and in soil organic C stock within the top 20 cm of soil from 26.6 Mg C ha−1 to 21.2 Mg C ha−1. If no land use change takes place from 2000 through 2100, low and high climate change scenarios (increase in temperature and decrease in precipitation over time) will result in losses of soil organic C stock by 16% and 20%, respectively. A low nitrogen (N) fertilization rate is the principal constraint on current crop production. An increase in N fertilization under the low climate change scenario would lead to an increase in the average crop yield by 21% with 30 kg N ha−1 and by 42% with 60 kg N ha−1 (varying with crop species), accordingly, the average soil C stock would decrease by 2% and increase by 17%, in all cropping systems by 2100. The results suggest that a reasonable N fertilization rate is critical to achieve food security and agricultural sustainability in the study area through the 21st century. Adaptation strategies for climate change in this study area require national plans to support policies and practices that provide adequate N fertilizers to sustain soil C and crop yields and to consider high temperature tolerant crop species if these temperature projections are exceeded.
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Schleussner, C. F., K. Frieler, M. Meinshausen, J. Yin i A. Levermann. "Emulating Atlantic overturning strength for low emission scenarios: consequences for sea-level rise along the North American east coast". Earth System Dynamics Discussions 1, nr 1 (10.12.2010): 357–84. http://dx.doi.org/10.5194/esdd-1-357-2010.
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Abstract. In order to provide probabilistic projections of the future evolution of the Atlantic Meridional Overturning Circulation (AMOC), we calibrated a simple Stommel-type box model to emulate the output of fully coupled three-dimensional atmosphere-ocean general circulation models (AOGCMs) of the Coupled Model Intercomparison Project (CMIP). Based on this calibration to idealised global warming scenarios with and without interactive atmosphere-ocean fluxes and freshwater perturbation simulations, we project the future evolution of the AMOC within the covered calibration range for the lower two Representative Concentration Pathways (RCPs) until 2100 obtained from MAGICC6. For RCP3-PD with a global mean temperature median below 1.0 °C warming relative to the year 2000, we project an ensemble median weakening of up to 11% compared to 22% under RCP4.5 with a warming median up to 1.9 °C over the 21st century. Additional Greenland melt water of 10 and 20 cm of global sea-level rise equivalent further weakens the AMOC by about 4.5 and 10%, respectively. By combining our outcome with a multi-model sea-level rise study we project a dynamic sea-level rise along the New York City coastline of 4 cm for the RCP3-PD and of 8 cm for the RCP4.5 scenario over the 21st century. We estimate the total steric and dynamic sea-level rise for New York City to be about 24 cm till 2100 for the RCP3-PD scenario, which can hold as a lower bound for sea-level rise projections in this region.
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Mezghani, Abdelkader, Andreas Dobler, Jan Erik Haugen, Rasmus E. Benestad, Kajsa M. Parding, Mikołaj Piniewski, Ignacy Kardel i Zbigniew W. Kundzewicz. "CHASE-PL Climate Projection dataset over Poland – bias adjustment of EURO-CORDEX simulations". Earth System Science Data 9, nr 2 (28.11.2017): 905–25. http://dx.doi.org/10.5194/essd-9-905-2017.
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Abstract. The CHASE-PL (Climate change impact assessment for selected sectors in Poland) Climate Projections – Gridded Daily Precipitation and Temperature dataset 5 km (CPLCP-GDPT5) consists of projected daily minimum and maximum air temperatures and precipitation totals of nine EURO-CORDEX regional climate model outputs bias corrected and downscaled to a 5 km × 5 km grid. Simulations of one historical period (1971–2000) and two future horizons (2021–2050 and 2071–2100) assuming two representative concentration pathways (RCP4.5 and RCP8.5) were produced. We used the quantile mapping method and corrected any systematic seasonal bias in these simulations before assessing the changes in annual and seasonal means of precipitation and temperature over Poland. Projected changes estimated from the multi-model ensemble mean showed that annual means of temperature are expected to increase steadily by 1 °C until 2021–2050 and by 2 °C until 2071–2100 assuming the RCP4.5 emission scenario. Assuming the RCP8.5 emission scenario, this can reach up to almost 4 °C by 2071–2100. Similarly to temperature, projected changes in regional annual means of precipitation are expected to increase by 6 to 10 % and by 8 to 16 % for the two future horizons and RCPs, respectively. Similarly, individual model simulations also exhibited warmer and wetter conditions on an annual scale, showing an intensification of the magnitude of the change at the end of the 21st century. The same applied for projected changes in seasonal means of temperature showing a higher winter warming rate by up to 0.5 °C compared to the other seasons. However, projected changes in seasonal means of precipitation by the individual models largely differ and are sometimes inconsistent, exhibiting spatial variations which depend on the selected season, location, future horizon, and RCP. The overall range of the 90 % confidence interval predicted by the ensemble of multi-model simulations was found to likely vary between −7 % (projected for summer assuming the RCP4.5 emission scenario) and +40 % (projected for winter assuming the RCP8.5 emission scenario) by the end of the 21st century. Finally, this high-resolution bias-corrected product can serve as a basis for climate change impact and adaptation studies for many sectors over Poland. The CPLCP-GDPT5 dataset is publicly available at http://dx.doi.org/10.4121/uuid:e940ec1a-71a0-449e-bbe3-29217f2ba31d.
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Schleussner, C. F., K. Frieler, M. Meinshausen, J. Yin i A. Levermann. "Emulating Atlantic overturning strength for low emission scenarios: consequences for sea-level rise along the North American east coast". Earth System Dynamics 2, nr 2 (28.09.2011): 191–200. http://dx.doi.org/10.5194/esd-2-191-2011.
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Abstract. In order to provide probabilistic projections of the future evolution of the Atlantic Meridional Overturning Circulation (AMOC), we calibrated a simple Stommel-type box model to emulate the output of fully coupled three-dimensional atmosphere-ocean general circulation models (AOGCMs) of the Coupled Model Intercomparison Project (CMIP). Based on this calibration to idealised global warming scenarios with and without interactive atmosphere-ocean fluxes and freshwater perturbation simulations, we project the future evolution of the AMOC mean strength within the covered calibration range for the lower two Representative Concentration Pathways (RCPs) until 2100 obtained from the reduced complexity carbon cycle-climate model MAGICC 6. For RCP3-PD with a global mean temperature median below 1.0 °C warming relative to the year 2000, we project an ensemble median weakening of up to 11% compared to 22% under RCP4.5 with a warming median up to 1.9 °C over the 21st century. Additional Greenland meltwater of 10 and 20 cm of global sea-level rise equivalent further weakens the AMOC by about 4.5 and 10%, respectively. By combining our outcome with a multi-model sea-level rise study we project a dynamic sea-level rise along the New York City coastline of 4 cm for the RCP3-PD and of 8 cm for the RCP4.5 scenario over the 21st century. We estimate the total steric and dynamic sea-level rise for New York City to be about 24 cm until 2100 for the RCP3-PD scenario, which can hold as a lower bound for sea-level rise projections in this region, as it does not include ice sheet and mountain glacier contributions.
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Stefanidis, Stefanos, i Dimitrios Stathis. "Effect of Climate Change on Soil Erosion in a Mountainous Mediterranean Catchment (Central Pindus, Greece)". Water 10, nr 10 (18.10.2018): 1469. http://dx.doi.org/10.3390/w10101469.
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The aim of this study was to assess soil erosion changes in the mountainous catchment of the Portaikos torrent (Central Greece) under climate change. To this end, precipitation and temperature data were derived from a high-resolution (25 × 25 km) RegCM3 regional climate model for the baseline period 1974–2000 and future period 2074–2100. Additionally, three GIS layers were generated regarding land cover, geology, and slopes in the study area, whereas erosion state was recognized after field observations. Subsequently, the erosion potential model (EPM) was applied to quantify the effects of precipitation and temperature changes on soil erosion. The results showed a decrease (−21.2%) in annual precipitation (mm) and increase (+3.6 °C) in mean annual temperature until the end of the 21st century, and the above changes are likely to lead to a small decrease (−4.9%) in soil erosion potential.
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Hammoudy, Wahib, Rachid Ilmen i Mohamed Sinan. "High-resolution RCP scenario for the 21st century in the North-West region of Morocco, future projections for 2041-2060, 2061-2080 and 2081-2100". Brazilian Journal of Science 2, nr 10 (18.05.2023): 63–73. http://dx.doi.org/10.14295/bjs.v2i10.375.
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Climate model simulations of future climate are the basis for adaptation decisions, which the effectiveness will depend on the quality of the models. A set of climate models developed under the CMIP6 project and generated by the spatial bias correction disaggregation method (BCSD) using a statistical downscaling algorithm have been used. These models are used to evaluate the future changes in thermal extremes projected by the climate models over the different time horizons with comparison to the 1981-2000 reference period. These projections are made under the scenario RCP 4.5 (optimistic). The examination of future climate change projections could confirm the result of warming over the entire North West region of Morocco. The increase in temperature could reached an average of 1.8 °C to 2.5 °C just in 2060. In the same sense of warming, the number of hot days and hot nights could increase year by year while a decrease could be noticed in the number of cold days and cold nights. The simulations for the 2080 and 2100 horizons revealed a situation that worsens year by year. The temperature anomaly could reached about 3 °C and more. Thus, a climatic warming may be predicted in the future and generalized over the entire North West region.
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Polovina, Jeffrey J., John P. Dunne, Phoebe A. Woodworth i Evan A. Howell. "Projected expansion of the subtropical biome and contraction of the temperate and equatorial upwelling biomes in the North Pacific under global warming". ICES Journal of Marine Science 68, nr 6 (4.02.2011): 986–95. http://dx.doi.org/10.1093/icesjms/fsq198.
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Abstract Polovina, J. J., Dunne, J. P., Woodworth, P. A., and Howell, E. A. 2011. Projected expansion of the subtropical biome and contraction of the temperate and equatorial upwelling biomes in the North Pacific under global warming. – ICES Journal of Marine Science, 68: 986–995. A climate model that includes a coupled ocean biogeochemistry model is used to define large oceanic biomes in the North Pacific Ocean and describe their changes over the 21st century in response to the IPCC Special Report on Emission Scenario A2 future atmospheric CO2 emissions scenario. Driven by enhanced stratification and a northward shift in the mid-latitude westerlies under climate change, model projections demonstrated that between 2000 and 2100, the area of the subtropical biome expands by ∼30% by 2100, whereas the area of temperate and equatorial upwelling (EU) biomes decreases by ∼34 and 28%, respectively, by 2100. Over the century, the total biome primary production and fish catch is projected to increase by 26% in the subtropical biome and decrease by 38 and 15% in the temperate and the equatorial biomes, respectively. Although the primary production per unit area declines slightly in the subtropical and the temperate biomes, it increases 17% in the EU biome. Two areas where the subtropical biome boundary exhibits the greatest movement is in the northeast Pacific, where it moves northwards by as much as 1000 km per 100 years and at the equator in the central Pacific, where it moves eastwards by 2000 km per 100 years. Lastly, by the end of the century, there are projected to be more than 25 million km2 of water with a mean sea surface temperature of 31°C in the subtropical and EU biomes, representing a new thermal habitat. The projected trends in biome carrying capacity and fish catch suggest resource managers might have to address long-term trends in fishing capacity and quota levels.
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Gangstø, R., F. Joos i M. Gehlen. "Sensitivity of pelagic calcification to ocean acidification". Biogeosciences 8, nr 2 (16.02.2011): 433–58. http://dx.doi.org/10.5194/bg-8-433-2011.
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Abstract. Ocean acidification might reduce the ability of calcifying plankton to produce and maintain their shells of calcite, or of aragonite, the more soluble form of CaCO3. In addition to possibly large biological impacts, reduced CaCO3 production corresponds to a negative feedback on atmospheric CO2. In order to explore the sensitivity of the ocean carbon cycle to increasing concentrations of atmospheric CO2, we use the new biogeochemical Bern3D/PISCES model. The model reproduces the large scale distributions of biogeochemical tracers. With a range of sensitivity studies, we explore the effect of (i) using different parameterizations of CaCO3 production fitted to available laboratory and field experiments, of (ii) letting calcite and aragonite be produced by auto- and heterotrophic plankton groups, and of (iii) using carbon emissions from the range of the most recent IPCC Representative Concentration Pathways (RCP). Under a high-emission scenario, the CaCO3 production of all the model versions decreases from ~1 Pg C yr−1 to between 0.36 and 0.82 Pg C yr−1 by the year 2100. The changes in CaCO3 production and dissolution resulting from ocean acidification provide only a small feedback on atmospheric CO2 of −1 to −11 ppm by the year 2100, despite the wide range of parameterizations, model versions and scenarios included in our study. A potential upper limit of the CO2-calcification/dissolution feedback of −30 ppm by the year 2100 is computed by setting calcification to zero after 2000 in a high 21st century emission scenario. The similarity of feedback estimates yielded by the model version with calcite produced by nanophytoplankton and the one with calcite, respectively aragonite produced by mesozooplankton suggests that expending biogeochemical models to calcifying zooplankton might not be needed to simulate biogeochemical impacts on the marine carbonate cycle. The changes in saturation state confirm previous studies indicating that future anthropogenic CO2 emissions may lead to irreversible changes in ΩA for several centuries. Furthermore, due to the long-term changes in the deep ocean, the ratio of open water CaCO3 dissolution to production stabilizes by the year 2500 at a value that is 30–50% higher than at pre-industrial times when carbon emissions are set to zero after 2100.
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Mavromatis, Theodoros, Aristeidis K. Georgoulias, Dimitris Akritidis, Dimitris Melas i Prodromos Zanis. "Spatiotemporal Evolution of Seasonal Crop-Specific Climatic Indices under Climate Change in Greece Based on EURO-CORDEX RCM Simulations". Sustainability 14, nr 24 (19.12.2022): 17048. http://dx.doi.org/10.3390/su142417048.
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This study presents an updated assessment of the projected climate change over Greece in the near future (2021–2050) and at the end of the 21st century (2071–2100) (EOC), relative to the reference period 1971–2000, and focusing on seasonal crop-specific climatic indices. The indices include days (d) with: a maximum daily near-surface temperature (TASMAX) > 30 °C in Spring, a TASMAX > 35 °C in Summer (hot days), a minimum daily near-surface temperature (TASMIN) < 0 °C (frost days) in Spring, a TASMIN > 20 °C (tropical nights) in Spring–Summer and the daily precipitation (PR) > 1 mm (wet days) in Spring and Summer covering the critical periods in which wheat, tomatoes, cotton, potato, grapes, rice and olive are more sensitive to water and/or temperature stress. The analysis is based on an ensemble of 11 EURO-CORDEX regional climate model simulations under the influence of a strong, a moderate, and a no mitigation Representative Concentration Pathway (RCP2.6, RCP4.5 and RCP8.5, respectively). The indices related to TASMAX are expected to increase by up to 11 days in Spring and 40 days in Summer, tropical nights to rise by up to 50 days, frost days to decrease by up to 20 days, and wet days to decline by up to 9 days in Spring and Summer, at the EOC with an RCP8.5. The increased heat stress and water deficit are expected to have negative crop impacts, in contrast to the positive effects anticipated by the decrease in frost days. This study constitutes a further step towards identifying the commodities and/or regions in Greece which, under climate change, are or will be significantly impacted.
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Bán, Beatrix, Gabriella Szépszó, Gabriella Allaga-Zsebeházi i Samuel Somot. "ALADIN-Climate at the Hungarian Meteorological Service: from the beginnings to the present day’s results". Időjárás 125, nr 4 (2021): 647–73. http://dx.doi.org/10.28974/idojaras.2021.4.6.
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This study is focusing on the past and, in particular, the present of the ALADIN-Climate model used at the Hungarian Meteorological Service. The currently applied model version is 5.2 (HMS-ALADIN52). In the recent experiments, the CNRM-CM5 global model outputs were downscaled in two steps to 10 km horizontal resolution over Central and Southeast Europe using RCP4.5 and RCP8.5 scenarios. Temperature and precipitation projections are analyzed for 2021-2050 and 2071–2100 with respect to the reference period of 1971–2000 with focus on Hungary. The results are evaluated in comparison to 26 simulations selected from the 12 km horizontal resolution Euro-CORDEX projection ensemble (including two additional versions of ALADIN-Climate: CNRM-ALADIN53 and CNRM-ALADIN63) to get more information about the projection uncertainties over Hungary and to assess the representativeness of HMS-ALADIN52. The HMS-ALADIN52 simulations project a clear warming trend in Central and Southeast Europe, which is more remarkable in case of greater radiative forcing change (RCP8.5). From the 2040s, the Euro-CORDEX simulations start to diverge using different scenarios. The total range of the annual change over Hungary is 1.3–3.3 °C with RCP4.5 and 3.2–5.7 °C with RCP8.5 by the end of the 21st century. HMS-ALADIN52 results are approximately near to the median: 2.9 °C with RCP4.5 and 4 °C with RCP8.5. CNRM-ALADIN53 shows generally similar results to HMS-ALADIN52, but simulations with CNRM-ALADIN63 indicate higher changes compared to both. In terms of seasonal mean precipitation change, the HMS-ALADIN52 simulations assume an increase between 9% and 33% (less in spring, more in autumn) over Hungary in both periods and with both scenarios. Most of the selected Euro-CORDEX simulations show a precipitation increase, apart from summer, when growth and reduction can be equally expected in 2021–2050, and the drying tendency continues towards the end of the century. Increase projected by HMS-ALADIN52 is mostly confirmed by CNRM-ALADIN53, while CNRM-ALADIN63 predicts precipitation decrease in summer. Precipitation results do not show a significantly striking difference between the scenarios, likely due to the fact that internal variability and model uncertainty are more relevant sources of uncertainty in precipitation projections over our region.
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Parazoo, Nicholas C., Charles D. Koven, David M. Lawrence, Vladimir Romanovsky i Charles E. Miller. "Detecting the permafrost carbon feedback: talik formation and increased cold-season respiration as precursors to sink-to-source transitions". Cryosphere 12, nr 1 (12.01.2018): 123–44. http://dx.doi.org/10.5194/tc-12-123-2018.
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Abstract. Thaw and release of permafrost carbon (C) due to climate change is likely to offset increased vegetation C uptake in northern high-latitude (NHL) terrestrial ecosystems. Models project that this permafrost C feedback may act as a slow leak, in which case detection and attribution of the feedback may be difficult. The formation of talik, a subsurface layer of perennially thawed soil, can accelerate permafrost degradation and soil respiration, ultimately shifting the C balance of permafrost-affected ecosystems from long-term C sinks to long-term C sources. It is imperative to understand and characterize mechanistic links between talik, permafrost thaw, and respiration of deep soil C to detect and quantify the permafrost C feedback. Here, we use the Community Land Model (CLM) version 4.5, a permafrost and biogeochemistry model, in comparison to long-term deep borehole data along North American and Siberian transects, to investigate thaw-driven C sources in NHL (> 55∘ N) from 2000 to 2300. Widespread talik at depth is projected across most of the NHL permafrost region (14 million km2) by 2300, 6.2 million km2 of which is projected to become a long-term C source, emitting 10 Pg C by 2100, 50 Pg C by 2200, and 120 Pg C by 2300, with few signs of slowing. Roughly half of the projected C source region is in predominantly warm sub-Arctic permafrost following talik onset. This region emits only 20 Pg C by 2300, but the CLM4.5 estimate may be biased low by not accounting for deep C in yedoma. Accelerated decomposition of deep soil C following talik onset shifts the ecosystem C balance away from surface dominant processes (photosynthesis and litter respiration), but sink-to-source transition dates are delayed by 20–200 years by high ecosystem productivity, such that talik peaks early (∼ 2050s, although borehole data suggest sooner) and C source transition peaks late (∼ 2150–2200). The remaining C source region in cold northern Arctic permafrost, which shifts to a net source early (late 21st century), emits 5 times more C (95 Pg C) by 2300, and prior to talik formation due to the high decomposition rates of shallow, young C in organic-rich soils coupled with low productivity. Our results provide important clues signaling imminent talik onset and C source transition, including (1) late cold-season (January–February) soil warming at depth (∼ 2 m), (2) increasing cold-season emissions (November–April), and (3) enhanced respiration of deep, old C in warm permafrost and young, shallow C in organic-rich cold permafrost soils. Our results suggest a mosaic of processes that govern carbon source-to-sink transitions at high latitudes and emphasize the urgency of monitoring soil thermal profiles, organic C age and content, cold-season CO2 emissions, and atmospheric 14CO2 as key indicators of the permafrost C feedback.
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Nishina, K., A. Ito, P. Falloon, A. D. Friend, D. J. Beerling, P. Ciais, D. B. Clark i in. "Decomposing uncertainties in the future terrestrial carbon budget associated with emission scenarios, climate projections, and ecosystem simulations using the ISI-MIP results". Earth System Dynamics 6, nr 2 (13.07.2015): 435–45. http://dx.doi.org/10.5194/esd-6-435-2015.
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Abstract. We examined the changes to global net primary production (NPP), vegetation biomass carbon (VegC), and soil organic carbon (SOC) estimated by six global vegetation models (GVMs) obtained from the Inter-Sectoral Impact Model Intercomparison Project. Simulation results were obtained using five global climate models (GCMs) forced with four representative concentration pathway (RCP) scenarios. To clarify which component (i.e., emission scenarios, climate projections, or global vegetation models) contributes the most to uncertainties in projected global terrestrial C cycling by 2100, analysis of variance (ANOVA) and wavelet clustering were applied to 70 projected simulation sets. At the end of the simulation period, changes from the year 2000 in all three variables varied considerably from net negative to positive values. ANOVA revealed that the main sources of uncertainty are different among variables and depend on the projection period. We determined that in the global VegC and SOC projections, GVMs are the main influence on uncertainties (60 % and 90 %, respectively) rather than climate-driving scenarios (RCPs and GCMs). Moreover, the divergence of changes in vegetation carbon residence times is dominated by GVM uncertainty, particularly in the latter half of the 21st century. In addition, we found that the contribution of each uncertainty source is spatiotemporally heterogeneous and it differs among the GVM variables. The dominant uncertainty source for changes in NPP and VegC varies along the climatic gradient. The contribution of GVM to the uncertainty decreases as the climate division becomes cooler (from ca. 80 % in the equatorial division to 40 % in the snow division). Our results suggest that to assess climate change impacts on global ecosystem C cycling among each RCP scenario, the long-term C dynamics within the ecosystems (i.e., vegetation turnover and soil decomposition) are more critical factors than photosynthetic processes. The different trends in the contribution of uncertainty sources in each variable among climate divisions indicate that improvement of GVMs based on climate division or biome type will be effective. On the other hand, in dry regions, GCMs are the dominant uncertainty source in climate impact assessments of vegetation and soil C dynamics.
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Meinshausen, Malte, Zebedee R. J. Nicholls, Jared Lewis, Matthew J. Gidden, Elisabeth Vogel, Mandy Freund, Urs Beyerle i in. "The shared socio-economic pathway (SSP) greenhouse gas concentrations and their extensions to 2500". Geoscientific Model Development 13, nr 8 (13.08.2020): 3571–605. http://dx.doi.org/10.5194/gmd-13-3571-2020.
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Abstract. Anthropogenic increases in atmospheric greenhouse gas concentrations are the main driver of current and future climate change. The integrated assessment community has quantified anthropogenic emissions for the shared socio-economic pathway (SSP) scenarios, each of which represents a different future socio-economic projection and political environment. Here, we provide the greenhouse gas concentrations for these SSP scenarios – using the reduced-complexity climate–carbon-cycle model MAGICC7.0. We extend historical, observationally based concentration data with SSP concentration projections from 2015 to 2500 for 43 greenhouse gases with monthly and latitudinal resolution. CO2 concentrations by 2100 range from 393 to 1135 ppm for the lowest (SSP1-1.9) and highest (SSP5-8.5) emission scenarios, respectively. We also provide the concentration extensions beyond 2100 based on assumptions regarding the trajectories of fossil fuels and land use change emissions, net negative emissions, and the fraction of non-CO2 emissions. By 2150, CO2 concentrations in the lowest emission scenario are approximately 350 ppm and approximately plateau at that level until 2500, whereas the highest fossil-fuel-driven scenario projects CO2 concentrations of 1737 ppm and reaches concentrations beyond 2000 ppm by 2250. We estimate that the share of CO2 in the total radiative forcing contribution of all considered 43 long-lived greenhouse gases increases from 66 % for the present day to roughly 68 % to 85 % by the time of maximum forcing in the 21st century. For this estimation, we updated simple radiative forcing parameterizations that reflect the Oslo Line-By-Line model results. In comparison to the representative concentration pathways (RCPs), the five main SSPs (SSP1-1.9, SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5) are more evenly spaced and extend to lower 2100 radiative forcing and temperatures. Performing two pairs of six-member historical ensembles with CESM1.2.2, we estimate the effect on surface air temperatures of applying latitudinally and seasonally resolved GHG concentrations. We find that the ensemble differences in the March–April–May (MAM) season provide a regional warming in higher northern latitudes of up to 0.4 K over the historical period, latitudinally averaged of about 0.1 K, which we estimate to be comparable to the upper bound (∼5 % level) of natural variability. In comparison to the comparatively straight line of the last 2000 years, the greenhouse gas concentrations since the onset of the industrial period and this studies' projections over the next 100 to 500 years unequivocally depict a “hockey-stick” upwards shape. The SSP concentration time series derived in this study provide a harmonized set of input assumptions for long-term climate science analysis; they also provide an indication of the wide set of futures that societal developments and policy implementations can lead to – ranging from multiple degrees of future warming on the one side to approximately 1.5 ∘C warming on the other.
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Christensen, N. S., i D. P. Lettenmaier. "A multimodel ensemble approach to assessment of climate change impacts on the hydrology and water resources of the Colorado River Basin". Hydrology and Earth System Sciences 11, nr 4 (9.07.2007): 1417–34. http://dx.doi.org/10.5194/hess-11-1417-2007.
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Abstract. Implications of 21st century climate change on the hydrology and water resources of the Colorado River Basin were assessed using a multimodel ensemble approach in which downscaled and bias corrected output from 11 General Circulation Models (GCMs) was used to drive macroscale hydrology and water resources models. Downscaled climate scenarios (ensembles) were used as forcings to the Variable Infiltration Capacity (VIC) macroscale hydrology model, which in turn forced the Colorado River Reservoir Model (CRMM). Ensembles of downscaled precipitation and temperature, and derived streamflows and reservoir system performance were assessed through comparison with current climate simulations for the 1950–1999 historical period. For each of the 11 GCMs, two emissions scenarios (IPCC SRES A2 and B1, corresponding to relatively unconstrained growth in emissions, and elimination of global emissions increases by 2100) were represented. Results for the A2 and B1 climate scenarios were divided into three periods: 2010–2039, 2040–2069, and 2070–2099. The mean temperature change averaged over the 11 ensembles for the Colorado basin for the A2 emission scenario ranged from 1.2 to 4.4°C for periods 1–3, and for the B1 scenario from 1.3 to 2.7°C. Precipitation changes were modest, with ensemble mean changes ranging from −1 to −2% for the A2 scenario, and from +1 to −1% for the B1 scenario. An analysis of seasonal precipitation patterns showed that most GCMs had modest reductions in summer precipitation and increases in winter precipitation. Derived April 1 snow water equivalent declined for all ensemble members and time periods, with maximum (ensemble mean) reductions of 38% for the A2 scenario in period 3. Runoff changes were mostly the result of a dominance of increased evapotranspiration over the seasonal precipitation shifts, with ensemble mean runoff changes of −1, −6, and −11% for the A2 ensembles, and 0, −7, and −8% for the B1 ensembles. These hydrological changes were reflected in reservoir system performance. Average total basin reservoir storage and average hydropower production generally declined, however there was a large range across the ensembles. Releases from Glen Canyon Dam to the Lower Basin were reduced for all periods and both emissions scenarios in the ensemble mean. The fraction of years in which shortages occurred increased by approximately 20% by period 3 for both emissions scenarios.
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Christensen, N., i D. P. Lettenmaier. "A multimodel ensemble approach to assessment of climate change impacts on the hydrology and water resources of the Colorado River basin". Hydrology and Earth System Sciences Discussions 3, nr 6 (13.12.2006): 3727–70. http://dx.doi.org/10.5194/hessd-3-3727-2006.
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Abstract. Implications of 21st century climate change on the hydrology and water resources of the Colorado River basin were assessed using a multimodel ensemble approach in which downscaled and bias corrected output from 11 General Circulation Models (GCMs) was used to drive macroscale hydrology and water resources models. Downscaled climate scenarios (ensembles) were used as forcings to the Variable Infiltration Capacity (VIC) macroscale hydrology model, which in turn forced the Colorado River Reservoir Model (CRMM). Ensembles of downscaled precipitation and temperature, and derived streamflows and reservoir system performance were assessed through comparison with current climate simulations for the 1950–1999 historical period. For each of the 11 GCMs, two emissions scenarios (IPCC SRES A2 and B1, corresponding to relatively unconstrained growth in emissions, and elimination of global emissions increases by 2100) were represented. Results for the A2 and B1 climate scenarios were divided into period 1 (2010–2039), period 2 (2040–2069), and period 3 (2070–2099). The mean temperature change averaged over the 11 ensembles for the Colorado basin for the A2 emission scenario ranged from 1.2 to 4.4°C for periods 1–3, and for the B1 scenario from 1.3 to 2.7°C. Precipitation changes were modest, with ensemble mean changes ranging from −1 to −2 percent for the A2 scenario, and from +1 to −1 percent for the B1 scenario. An analysis of seasonal precipitation patterns showed that most GCMs had modest reductions in summer precipitation and increases in winter precipitation. Derived 1 April snow water equivalent declined for all ensemble members and time periods, with maximum (ensemble mean) reductions of 38 percent for the A2 scenario in period 3. Runoff changes were mostly the result of a dominance of increased evapotranspiration over the seasonal precipitation shifts, with ensemble mean runoff reductions of −1, −6, and −11 percent for the A2 ensembles, and 0, −7, and −8 percent for the B1 ensembles. These hydrological changes were reflected in reservoir system performance. Average total basin reservoir storage generally declined, however there was a large range across the ensembles. Releases from Glen Canyon Dam to the Lower Basin (mandated by the Colorado River Compact) were reduced for all periods and both emissions scenarios in the ensemble mean. The fraction of years in which shortages occurred increased by approximately 20% by period 3 in for both emissions scenarios, and the average shortage increased to a maximum of 3.7 BCM/yr for the period 3 A2 ensemble average. Hydropower output was reduced in the ensemble mean for all time periods and both emissions scenarios.
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Rounce, David R., Regine Hock, Fabien Maussion, Romain Hugonnet, William Kochtitzky, Matthias Huss, Etienne Berthier i in. "Global glacier change in the 21st century: Every increase in temperature matters". Science 379, nr 6627 (6.01.2023): 78–83. http://dx.doi.org/10.1126/science.abo1324.
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Glacier mass loss affects sea level rise, water resources, and natural hazards. We present global glacier projections, excluding the ice sheets, for shared socioeconomic pathways calibrated with data for each glacier. Glaciers are projected to lose 26 ± 6% (+1.5°C) to 41 ± 11% (+4°C) of their mass by 2100, relative to 2015, for global temperature change scenarios. This corresponds to 90 ± 26 to 154 ± 44 millimeters sea level equivalent and will cause 49 ± 9 to 83 ± 7% of glaciers to disappear. Mass loss is linearly related to temperature increase and thus reductions in temperature increase reduce mass loss. Based on climate pledges from the Conference of the Parties (COP26), global mean temperature is projected to increase by +2.7°C, which would lead to a sea level contribution of 115 ± 40 millimeters and cause widespread deglaciation in most mid-latitude regions by 2100.
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Xu, Y., D. Zaelke, G. J. M. Velders i V. Ramanathan. "The role of HFCs in mitigating 21st century climate change". Atmospheric Chemistry and Physics 13, nr 12 (26.06.2013): 6083–89. http://dx.doi.org/10.5194/acp-13-6083-2013.
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Abstract. There is growing international interest in mitigating climate change during the early part of this century by reducing emissions of short-lived climate pollutants (SLCPs), in addition to reducing emissions of CO2. The SLCPs include methane (CH4), black carbon aerosols (BC), tropospheric ozone (O3) and hydrofluorocarbons (HFCs). Recent studies have estimated that by mitigating emissions of CH4, BC, and O3 using available technologies, about 0.5 to 0.6 °C warming can be avoided by mid-21st century. Here we show that avoiding production and use of high-GWP (global warming potential) HFCs by using technologically feasible low-GWP substitutes to meet the increasing global demand can avoid as much as another 0.5 °C warming by the end of the century. This combined mitigation of SLCPs would cut the cumulative warming since 2005 by 50% at 2050 and by 60% at 2100 from the CO2-only mitigation scenarios, significantly reducing the rate of warming and lowering the probability of exceeding the 2 °C warming threshold during this century.
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Meinshausen, M., T. M. L. Wigley i S. C. B. Raper. "Emulating atmosphere-ocean and carbon cycle models with a simpler model, MAGICC6 – Part 2: Applications". Atmospheric Chemistry and Physics 11, nr 4 (16.02.2011): 1457–71. http://dx.doi.org/10.5194/acp-11-1457-2011.
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Abstract. Intercomparisons of coupled atmosphere-ocean general circulation models (AOGCMs) and carbon cycle models are important for galvanizing our current scientific knowledge to project future climate. Interpreting such intercomparisons faces major challenges, not least because different models have been forced with different sets of forcing agents. Here, we show how an emulation approach with MAGICC6 can address such problems. In a companion paper (Meinshausen et al., 2011a), we show how the lower complexity carbon cycle-climate model MAGICC6 can be calibrated to emulate, with considerable accuracy, globally aggregated characteristics of these more complex models. Building on that, we examine here the Coupled Model Intercomparison Project's Phase 3 results (CMIP3). If forcing agents missed by individual AOGCMs in CMIP3 are considered, this reduces ensemble average temperature change from pre-industrial times to 2100 under SRES A1B by 0.4 °C. Differences in the results from the 1980 to 1999 base period (as reported in IPCC AR4) to 2100 are negligible, however, although there are some differences in the trajectories over the 21st century. In a second part of this study, we consider the new RCP scenarios that are to be investigated under the forthcoming CMIP5 intercomparison for the IPCC Fifth Assessment Report. For the highest scenario, RCP8.5, relative to pre-industrial levels, we project a median warming of around 4.6 °C by 2100 and more than 7 °C by 2300. For the lowest RCP scenario, RCP3-PD, the corresponding warming is around 1.5 °C by 2100, decreasing to around 1.1 °C by 2300 based on our AOGCM and carbon cycle model emulations. Implied cumulative CO2 emissions over the 21st century for RCP8.5 and RCP3-PD are 1881 GtC (1697 to 2034 GtC, 80% uncertainty range) and 381 GtC (334 to 488 GtC), when prescribing CO2 concentrations and accounting for uncertainty in the carbon cycle. Lastly, we assess the reasons why a previous MAGICC version (4.2) used in IPCC AR4 gave roughly 10% larger warmings over the 21st century compared to the CMIP3 average. We find that forcing differences and the use of slightly too high climate sensitivities inferred from idealized high-forcing runs were the major reasons for this difference.
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Shirley, Ian A., Zelalem A. Mekonnen, Robert F. Grant, Baptiste Dafflon, Susan S. Hubbard i William J. Riley. "Rapidly changing high-latitude seasonality: implications for the 21st century carbon cycle in Alaska". Environmental Research Letters 17, nr 1 (1.01.2022): 014032. http://dx.doi.org/10.1088/1748-9326/ac4362.
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Abstract Seasonal variations in high-latitude terrestrial carbon (C) fluxes are predominantly driven by air temperature and radiation. At present, high-latitude net C uptake is largest during the summer. Recent observations and modeling studies have demonstrated that ongoing and projected climate change will increase plant productivity, microbial respiration, and growing season lengths at high-latitudes, but impacts on high-latitude C cycle seasonality (and potential feedbacks to the climate system) remain uncertain. Here we use ecosys, a well-tested and process-rich mechanistic ecosystem model that we evaluate further in this study, to explore how climate warming under an RCP8.5 scenario will shift C cycle seasonality in Alaska throughout the 21st century. The model successfully reproduced recently reported large high-latitude C losses during the fall and winter and yet still predicts a high-latitude C sink, pointing to a resolution of the current conflict between process-model and observation-based estimates of high-latitude C balance. We find that warming will result in surprisingly large changes in net ecosystem exchange (NEE; defined as negative for uptake) seasonality, with spring net C uptake overtaking summer net C uptake by year 2100. This shift is driven by a factor of 3 relaxation of spring temperature limitation to plant productivity that results in earlier C uptake and a corresponding increase in magnitude of spring NEE from −19 to −144 gC m−2 season−1 by the end of the century. Although a similar relaxation of temperature limitation will occur in the fall, radiation limitation during those months will limit increases in C fixation. Additionally, warmer soil temperatures and increased carbon inputs from plants lead to combined fall and winter C losses (163 gC m−2) that are larger than summer net uptake (123 gC m−2 season−1) by year 2100. However, this increase in microbial activity leads to more rapid N cycling and increased plant N uptake during the fall and winter months that supports large increases in spring NPP. Due to the large increases in spring net C uptake, the high-latitude atmospheric C sink is projected to sustain throughout this century. Our analysis disentangles the effects of key environmental drivers of high-latitude seasonal C balances as climate changes over the 21st century.
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Donald, Rapp. "Estimate of Temperature Rise in the 21st Century for Various Scenarios". IgMin Research 2, nr 7 (11.07.2024): 564–69. http://dx.doi.org/10.61927/igmin218.
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The International Panel on Climate Change (IPCC) published a lengthy report on climate change in early 2023. This report hypothesizes five potential scenarios of greenhouse gas emissions from 2015 to the end of the century (2100) and estimates the global average temperature gain in the year 2100 from the mid-1800s for each scenario. The method of calculation in the IPCC report is obscure. The results are merely stated. The present paper provides a clear method for estimating the temperature gain each year from 2015 until 2100, along with yearly estimates of ppm of CO2. To facilitate the calculations, a set of scenarios of future emissions was chosen that is analogous to the scenarios used by the IPCC but is more amenable to computation. The basic assumption in this paper is that most of the temperature gain from the mid-1800s to 2015 (1.15 C – as reported by the IPCC) was due to rising CO2 concentration in the atmosphere and a relationship is thereby derived between warming and gigatons of CO2 emitted for the period: 1800s to 2015. If it is assumed that the amount of warming per gigaton CO2 from the past persists into the 21st century, then future warming in the 21st century can be estimated for any assumed future scenario of CO2 emissions. This paper provides a simple and clear estimate of yearly CO2 ppm and temperature rise from 2015 to 2100 since the 1800s for a set of scenarios that cover the likely range of future emissions.
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Pielke Jr, Roger, Matthew G. Burgess i Justin Ritchie. "Plausible 2005–2050 emissions scenarios project between 2 °C and 3 °C of warming by 2100". Environmental Research Letters 17, nr 2 (1.02.2022): 024027. http://dx.doi.org/10.1088/1748-9326/ac4ebf.
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Abstract Emissions scenarios used by the Intergovernmental Panel on Climate Change (IPCC) are central to climate change research and policy. Here, we identify subsets of scenarios of the IPCC’s 5th (AR5) and forthcoming 6th (AR6) Assessment Reports, including the Shared Socioeconomic Pathway scenarios, that project 2005–2050 fossil-fuel-and-industry (FFI) CO2 emissions growth rates most consistent with observations from 2005 to 2020 and International Energy Agency (IEA) projections to 2050. These scenarios project between 2 °C and 3 °C of warming by 2100, with a median of 2.2 °C. The subset of plausible IPCC scenarios does not represent all possible trajectories of future emissions and warming. Collectively, they project continued mitigation progress and suggest the world is presently on a lower emissions trajectory than is often assumed. However, these scenarios also indicate that the world is still off track from limiting 21st-century warming to 1.5 °C or below 2 °C.
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Lemes, Murilo da Costa Ruv, Michelle Simões Reboita, Roger Rodrigues Torres i Gilberto F. Fisch. "Projeções da temperatura da superfície na bacia hidrográfica do rio Tietê – SP para o final do Século XXI". Revista Brasileira de Geografia Física 13, nr 07 (11.12.2020): 3206. http://dx.doi.org/10.26848/rbgf.v13.07.p3206-3218.
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A bacia hidrográfica do rio Tietê tem sido afetada por mudanças em seu uso e cobertura do solo, principalmente às margens do rio Tietê, que influenciam diretamente a temperatura da superfície (Ts). Nesse contexto, o objetivo do trabalho é caracterizar sazonalmente a Ts na referida bacia e apresentar projeções dessa variável obtidas com o modelo ETA em alta resolução (5 km) nos cenários RCP4.5 e RCP8.5 e considerando 3 intervalos temporais: 2006-2040, 2040-2070, 2070-2100. Até o final do século XXI algumas áreas da bacia do rio Tietê, bem como sua região de foz, poderão apresentar aumento de até 5º C (8º C) no período entre 2070 - 2100 do cenário RCP4.5 (8.5), o que pode impactar tanto as atividades econômicas quanto o cotidiano da população. Projections of surface temperature in the hydrographic basin of the Tietê river - SP for the end of the 21st century A B S T R A C TThe hydrographic basin of the Tietê river has been affected by changes in its use and land cover, mainly on its banks, which directly influence the surface temperature (Ts). In this context, the objective of the work is to seasonally characterize the Ts in the referred basin and present projections of this variable obtained with the ETA model in high resolution (5 km), under the scenarios RCP4.5 and RCP8.5, and considering 3-time slices: 2006-2040, 2040-2070, 2070-2100. Some calculations (such as climatological averages and bias) were necessary to understand the magnitude of the changes that have occurred and those that may occur. By the end of the 21st century, some areas of the Tietê river basin, as well as its mouth region, may show an increase of up to 5º C (8º C) in the period between 2070 - 2100 of the RCP4.5 (8.5) scenario, which may impact both economic activities and the daily lives of the population.Keywords: Climate Change; Hydrographic Basin; Sao Paulo
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Pereira, Susana C., David Carvalho i Alfredo Rocha. "Temperature and Precipitation Extremes over the Iberian Peninsula under Climate Change Scenarios: A Review". Climate 9, nr 9 (14.09.2021): 139. http://dx.doi.org/10.3390/cli9090139.
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This paper presents the results of a systematic review of temperature and precipitation extremes over the Iberian Peninsula, focusing on observed changes in temperature and precipitation during the past years and what are the projected changes by the end of the 21st century. The purpose of this review is to assess the current literature about extreme events and their change under global warming. Observational and climate modeling studies from the past decade were considered in this review. Based on observational evidence and in climate modeling experiments, mean and maximum temperatures are projected to increase about 2 °C around the mid-century and up to 4 °C by the end of the century. The more pronounced warming is expected in summer for the central-south region of IP, with temperatures reaching 6 °C to 8 °C around 2100. Days with maximum temperature exceeding 30 °C and 40 °C will become more common (20 to 50 days/year), and the heatwaves will be 7 to 10 times more frequent. Significative reduction in events related to cold extremes. The climate change signal for precipitation in IP shows a considerable decline in precipitation (10–15%) for all seasons except winter. It is predicted that heavy precipitation will increase by 7% to 15%. Extreme precipitation will increase slightly (5%) by mid-century, then decline to 0% by 2100. Significant reduction in wet days (40% to 60%) followed by a dryness trend more pronounced by the end of the century.
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Adhikari, Surendra, i Philippe Huybrechts. "Numerical modelling of historical front variations and the 21st-century evolution of glacier AX010, Nepal Himalaya". Annals of Glaciology 50, nr 52 (2009): 27–34. http://dx.doi.org/10.3189/172756409789624346.
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AbstractDue to the lack of measurements of ice velocity, mass balance, glacier geometry and other baseline data, model-based studies of glacial systems in the Nepal Himalaya are very limited. Here a numerical ice-flow model has been developed for glacier AX010 in order to study its relation to local climate and investigate the possible causes of its general retreat since the end of the Little Ice Age. First, an attempt is made to simulate the historical front variations, considering each climatic parameter separately. Good agreement between the observations and model projections can be obtained under the assumption that variations in glacier front position are a response to changes in temperature alone. The same assumption is made about future changes to explore the 21st-century evolution of the glacier. Under a no-change scenario, the glacier will retreat by another ∽600m by AD 2100, whereas it is projected to vanish completely during this century for all trends with a temperature rise larger than +2.5˚C by AD 2100 with respect to the 1980–99 mean. With constant precipitation at the 1980–99 mean, the model predicts that the glacier will cease to exist at AD 2083, 2056 or 2049 if the temperature rises linearly by 3˚C, 4.5˚C or 6˚C respectively by the end of this century. With an additional range of precipitation changes between –30% and +30%, the life expectancy of glacier AX010 varies by 18, 6 and 2 years for the respective temperature rises. Thus the role of precipitation becomes minimal for the higher trends of temperature rise.
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Hipp, T., B. Etzelmüller, H. Farbrot, T. V. Schuler i S. Westermann. "Modelling borehole temperatures in Southern Norway – insights into permafrost dynamics during the 20th and 21st century". Cryosphere 6, nr 3 (23.05.2012): 553–71. http://dx.doi.org/10.5194/tc-6-553-2012.
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Abstract. This study aims at quantifying the thermal response of mountain permafrost in southern Norway to changes in climate since 1860 and until 2100. A transient one-dimensional heat flow model was used to simulate ground temperatures and associated active layer thicknesses for nine borehole locations, which are located at different elevations and in substrates with different thermal properties. The model was forced by reconstructed air temperatures starting from 1860, which approximately coincides with the end of the Little Ice Age in the region. The impact of climate warming on mountain permafrost to 2100 is assessed by using downscaled air temperatures from a multi-model ensemble for the A1B scenario. Borehole records over three consecutive years of ground temperatures, air temperatures and snow cover data served for model calibration and validation. With an increase of air temperature of ~1.5 °C over 1860–2010 and an additional warming of ~2.8 °C until 2100, we simulate the evolution of ground temperatures for each borehole location. In 1860 the lower limit of permafrost was estimated to be ca. 200 m lower than observed today. According to the model, since the approximate end of the Little Ice Age, the active-layer thickness has increased by 0.5–5 m and >10 m for the sites Juvvasshøe and Tron, respectively. The most pronounced increases in active layer thickness were modelled for the last two decades since 1990 with increase rates of +2 cm yr−1 to +87 cm yr−1 (20–430%). According to the A1B climate scenario, degradation of mountain permafrost is suggested to occur throughout the 21st century at most of the sites below ca. 1800 m a.s.l. At the highest locations at 1900 m a.s.l., permafrost degradation is likely to occur with a probability of 55–75% by 2100. This implies that mountain permafrost in southern Norway is likely to be confined to the highest peaks in the western part of the country.
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Hipp, T., B. Etzelmüller, H. Farbrot, T. V. Schuler i S. Westermann. "Modelling borehole temperatures in Southern Norway – insights into permafrost dynamics during the 20th and 21st century". Cryosphere Discussions 6, nr 1 (27.01.2012): 341–85. http://dx.doi.org/10.5194/tcd-6-341-2012.
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Abstract. A transient heat flow model was used to simulate both past and future ground temperatures of mountain permafrost and associated active layer thickness in Southern Norway. The model was forced by reconstructed air temperature starting from 1860, approximately coinciding with the Little Ice Age in the region. The impact of climate warming on mountain permafrost until 2100 is assessed by using downscaled air temperatures from a multi-model ensemble for the A1B scenario. For 13 borehole locations, records over three consecutive years of ground temperatures, air temperatures and snow cover data are available for model calibration and validation. The boreholes are located at different elevations and in substrates with different thermal properties. With an increase of air temperature of ~+1.5 °C over 1860–2010 and an additional warming of +2.8 °C until 2100, we simulate the evolution of ground temperatures for the borehole locations. According to model results, the active-layer thickness has increased since 1860 by 0.5–5 m and >10 m for the sites Juvvasshøe and Tron, respectively. The simulations also suggest that at an elevation of about 1900 m a.s.l. permafrost will degrade until the end of this century with a probability of 55–75% given the chosen A1B scenario.
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Goll, D. S., V. Brovkin, B. R. Parida, C. H. Reick, J. Kattge, P. B. Reich, P. M. van Bodegom i Ü. Niinemets. "Nutrient limitation reduces land carbon uptake in simulations with a model of combined carbon, nitrogen and phosphorus cycling". Biogeosciences Discussions 9, nr 3 (16.03.2012): 3173–232. http://dx.doi.org/10.5194/bgd-9-3173-2012.
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Abstract. Terrestrial carbon (C) cycle models applied for climate projections simulate a strong increase in net primary productivity (NPP) due to elevated atmospheric CO2 concentration during the 21st century. These models usually neglect the limited availability of nitrogen (N) and phosphorus (P), nutrients that commonly limit plant growth and soil carbon turnover. To investigate how the projected C sequestration is altered when stoichiometric constraints on C cycling are considered, we incorporated a P cycle into the land surface model JSBACH, which already includes representations of coupled C and N cycles. The model reveals a distinct geographic pattern of P and N limitation. Under the SRES A1B scenario, the accumulated land C uptake between 1860 and 2100 is 13% (particularly at high latitudes) and 16% (particularly at low latitudes) lower in simulations with N and P cycling, respectively, than in simulations without nutrient cycles. The combined effect of both nutrients reduces land C uptake by 25% compared to simulations without N or P cycling. However, the quantification of P limitation remains challenging as the poorly constrained processes of soil P sorption and biochemical mineralization strongly influence the strength of P limitation. After 2100, increased temperatures (+5 K) and high CO2 (700 ppm) concentrations cause a shift from N to P limitation at high latitudes, while nutrient limitation in the tropics declines. The increase in P limitation at high-latitudes is induced by a strong increase in NPP and the low P sorption capacity of soils, while a decline in tropical NPP due to high autotrophic respiration rates alleviates N and P limitation. These findings indicate that global land C uptake in the 21st century is likely overestimated in models that neglect P and N limitation. In the long-term, insufficient P availability might become an important constraint on C cycling at high latitudes. Accordingly, we argue that the P cycle must be included in global models used for C cycle projections.
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Wang, Sirui, Qianlai Zhuang, Outi Lähteenoja, Frederick C. Draper i Hinsby Cadillo-Quiroz. "Potential shift from a carbon sink to a source in Amazonian peatlands under a changing climate". Proceedings of the National Academy of Sciences 115, nr 49 (19.11.2018): 12407–12. http://dx.doi.org/10.1073/pnas.1801317115.
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Amazonian peatlands store a large amount of soil organic carbon (SOC), and its fate under a future changing climate is unknown. Here, we use a process-based peatland biogeochemistry model to quantify the carbon accumulation for peatland and nonpeatland ecosystems in the Pastaza-Marañon foreland basin (PMFB) in the Peruvian Amazon from 12,000 y before present to AD 2100. Model simulations indicate that warming accelerates peat SOC loss, while increasing precipitation accelerates peat SOC accumulation at millennial time scales. The uncertain parameters and spatial variation of climate are significant sources of uncertainty to modeled peat carbon accumulation. Under warmer and presumably wetter conditions over the 21st century, SOC accumulation rate in the PMFB slows down to 7.9 (4.3–12.2) g⋅C⋅m−2⋅y−1 from the current rate of 16.1 (9.1–23.7) g⋅C⋅m−2⋅y−1, and the region may turn into a carbon source to the atmosphere at −53.3 (−66.8 to −41.2) g⋅C⋅m−2⋅y−1 (negative indicates source), depending on the level of warming. Peatland ecosystems show a higher vulnerability than nonpeatland ecosystems, as indicated by the ratio of their soil carbon density changes (ranging from 3.9 to 5.8). This is primarily due to larger peatlands carbon stocks and more dramatic responses of their aerobic and anaerobic decompositions in comparison with nonpeatland ecosystems under future climate conditions. Peatland and nonpeatland soils in the PMFB may lose up to 0.4 (0.32–0.52) Pg⋅C by AD 2100 with the largest loss from palm swamp. The carbon-dense Amazonian peatland may switch from a current carbon sink into a source in the 21st century.
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Linsbauer, Andreas, Frank Paul, Horst Machguth i Wilfried Haeberli. "Comparing three different methods to model scenarios of future glacier change in the Swiss Alps". Annals of Glaciology 54, nr 63 (2013): 241–53. http://dx.doi.org/10.3189/2013aog63a400.
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AbstractOngoing atmospheric warming causes rapid shrinking of glaciers in the European Alps, with a high chance of their near-complete disappearance by the end of the 21st century. Here we present a comparison of three independent approaches to model the possible evolution of the glaciers in the Swiss Alps over the 21st century. The models have different levels of complexity, work at a regional scale and are forced with three scenarios of temperature increase (low, moderate, high). The moderate climate scenario gives an increase in air temperature of ∼2°C and ∼4°C for the two scenario periods 2021-50 and 2070-99, respectively, resulting in an area loss of 60-80% by 2100. In reality, the shrinkage could be even faster, as the observed mean annual thickness loss is already stronger than the modelled one. The three approaches lead to rather similar results with respect to the overall long-term evolution. The choice of climate scenarios produces the largest spread (∼40%) in the final area loss, while the uncertainty in present-day ice-thickness estimation causes about half this spread.
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Bachelet, D., J. Lenihan, R. Neilson, R. Drapek i T. Kittel. "Simulating the response of natural ecosystems and their fire regimes to climatic variability in Alaska". Canadian Journal of Forest Research 35, nr 9 (1.09.2005): 2244–57. http://dx.doi.org/10.1139/x05-086.
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The dynamic global vegetation model MC1 was used to examine climate, fire, and ecosystems interactions in Alaska under historical (19221996) and future (19972100) climate conditions. Projections show that by the end of the 21st century, 75%90% of the area simulated as tundra in 1922 is replaced by boreal and temperate forest. From 1922 to 1996, simulation results show a loss of about 9 g C·m2·year1 from fire emissions and 360 000 ha burned each year. During the same period 61% of the C gained (1.7 Pg C) is lost to fires (1 Pg C). Under future climate change scenarios, fire emissions increase to 1112 g C·m2·year1 and the area burned increases to 411 000 481 000 ha·year1. The carbon gain between 2025 and 2099 is projected at 0.5 Pg C under the warmer CGCM1 climate change scenario and 3.2 Pg C under HADCM2SUL. The loss to fires under CGCM1 is thus greater than the carbon gained in those 75 years, while under HADCM2SUL it represents only about 40% of the carbon gained. Despite increases in fire losses, the model simulates an increase in carbon gains during the 21st century until its last decade, when, under both climate change scenarios, Alaska becomes a net carbon source.
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Hipp, T., B. Etzelmüller, H. Farbrot i T. V. Schuler. "Modelling the temperature evolution of permafrost and seasonal frost in southern Norway during the 20th and 21st century". Cryosphere Discussions 5, nr 2 (11.03.2011): 811–54. http://dx.doi.org/10.5194/tcd-5-811-2011.
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Abstract. A heat flow model was used to simulate both past and future ground temperatures of mountain permafrost in Southern Norway. A reconstructed air temperature series back to 1860 was used to evaluate the permafrost evolution since the end of the Little Ice Age in the region. The impact of a changing climate on discontinuous mountain permafrost until 2100 is predicted by using downscaled temperatures from an ensemble of downscaled climate models for the A1B scenario. From 13 borehole locations two consecutive years of ground temperature, air temperature and snow cover data are available for model calibration and validation. The boreholes are located at different elevations and in substrates having different thermal properties. With an increase of air temperature of ~+1.5 °C over 1860–2010 and an additional warming of +2.8 °C towards 2100 in air temperature, we simulate the evolution of ground temperatures for the borehole locations. According to model results, the active-layer thickness has increased since 1860 by about 0.5–5 m and >10 m for the sites Juvvass and Tron, respectively. The simulations also suggest that at an elevation of about 1900 m a.s.l. permafrost will degrade until the end of this century with a likelihood of 55–75% given the chosen A1B scenario.
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Melo, Marian, Milan Lapin i Ingrid Damborska. "Methods for the Design of Climate Change Scenario in Slovakia for the 21St Century". Bulletin of Geography. Physical Geography Series 1, nr 1 (1.06.2009): 77–90. http://dx.doi.org/10.2478/bgeo-2009-0005.
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Abstract In this paper methods of climate-change scenario projection in Slovakia for the 21st century are outlined. Temperature and precipitation time series of the Hurbanovo Observatory in 1871-2007 (Slovak Hydrometeorological Institute) and data from four global GCMs (GISS 1998, CGCM1, CGCM2, HadCM3) are utilized for the design of climate change scenarios. Selected results of different climate change scenarios (based on different methods) for the region of Slovakia (up to 2100) are presented. The increase in annual mean temperature is about 3°C, though the results are ambiguous in the case of precipitation. These scenarios are required by users in impact studies, mainly from the hydrology, agriculture and forestry sectors.
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Compagno, Loris, Sarah Eggs, Matthias Huss, Harry Zekollari i Daniel Farinotti. "Brief communication: Do 1.0, 1.5, or 2.0 °C matter for the future evolution of Alpine glaciers?" Cryosphere 15, nr 6 (15.06.2021): 2593–99. http://dx.doi.org/10.5194/tc-15-2593-2021.
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Abstract. With the Paris Agreement, the urgency of limiting ongoing anthropogenic climate change has been recognised. More recent discussions have focused on the difference of limiting the increase in global average temperatures below 1.0, 1.5, or 2.0 ∘C compared to preindustrial levels. Here, we assess the impacts that such different scenarios would have on both the future evolution of glaciers in the European Alps and the water resources they provide. Our results show that even half-degree differences in global temperature targets have important implications for the changes predicted until 2100, and that – for the most optimistic scenarios – glaciers might start to partially recover, owing to possibly decreasing temperatures after the end of the 21st century.
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Goll, D. S., V. Brovkin, B. R. Parida, C. H. Reick, J. Kattge, P. B. Reich, P. M. van Bodegom i Ü. Niinemets. "Nutrient limitation reduces land carbon uptake in simulations with a model of combined carbon, nitrogen and phosphorus cycling". Biogeosciences 9, nr 9 (6.09.2012): 3547–69. http://dx.doi.org/10.5194/bg-9-3547-2012.
Pełny tekst źródłaStreszczenie:
Abstract. Terrestrial carbon (C) cycle models applied for climate projections simulate a strong increase in net primary productivity (NPP) due to elevated atmospheric CO2 concentration during the 21st century. These models usually neglect the limited availability of nitrogen (N) and phosphorus (P), nutrients that commonly limit plant growth and soil carbon turnover. To investigate how the projected C sequestration is altered when stoichiometric constraints on C cycling are considered, we incorporated a P cycle into the land surface model JSBACH (Jena Scheme for Biosphere–Atmosphere Coupling in Hamburg), which already includes representations of coupled C and N cycles. The model reveals a distinct geographic pattern of P and N limitation. Under the SRES (Special Report on Emissions Scenarios) A1B scenario, the accumulated land C uptake between 1860 and 2100 is 13% (particularly at high latitudes) and 16% (particularly at low latitudes) lower in simulations with N and P cycling, respectively, than in simulations without nutrient cycles. The combined effect of both nutrients reduces land C uptake by 25% compared to simulations without N or P cycling. Nutrient limitation in general may be biased by the model simplicity, but the ranking of limitations is robust against the parameterization and the inflexibility of stoichiometry. After 2100, increased temperature and high CO2 concentration cause a shift from N to P limitation at high latitudes, while nutrient limitation in the tropics declines. The increase in P limitation at high-latitudes is induced by a strong increase in NPP and the low P sorption capacity of soils, while a decline in tropical NPP due to high autotrophic respiration rates alleviates N and P limitations. The quantification of P limitation remains challenging. The poorly constrained processes of soil P sorption and biochemical mineralization are identified as the main uncertainties in the strength of P limitation. Even so, our findings indicate that global land C uptake in the 21st century is likely overestimated in models that neglect P and N limitations. In the long term, insufficient P availability might become an important constraint on C cycling at high latitudes. Accordingly, we argue that the P cycle must be included in global models used for C cycle projections.
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Todd-Brown, K. E. O., J. T. Randerson, F. Hopkins, V. Arora, T. Hajima, C. Jones, E. Shevliakova i in. "Changes in soil organic carbon storage predicted by Earth system models during the 21st century". Biogeosciences 11, nr 8 (25.04.2014): 2341–56. http://dx.doi.org/10.5194/bg-11-2341-2014.
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Abstract. Soil is currently thought to be a sink for carbon; however, the response of this sink to increasing levels of atmospheric carbon dioxide and climate change is uncertain. In this study, we analyzed soil organic carbon (SOC) changes from 11 Earth system models (ESMs) contributing simulations to the Coupled Model Intercomparison Project Phase 5 (CMIP5). We used a reduced complexity model based on temperature and moisture sensitivities to analyze the drivers of SOC change for the historical and high radiative forcing (RCP 8.5) scenarios between 1850 and 2100. ESM estimates of SOC changed over the 21st century (2090–2099 minus 1997–2006) ranging from a loss of 72 Pg C to a gain of 253 Pg C with a multi-model mean gain of 65 Pg C. Many ESMs simulated large changes in high-latitude SOC that ranged from losses of 37 Pg C to gains of 146 Pg C with a multi-model mean gain of 39 Pg C across tundra and boreal biomes. All ESMs showed cumulative increases in global NPP (11 to 59%) and decreases in SOC turnover times (15 to 28%) over the 21st century. Most of the model-to-model variation in SOC change was explained by initial SOC stocks combined with the relative changes in soil inputs and decomposition rates (R2 = 0.89, p < 0.01). Between models, increases in decomposition rate were well explained by a combination of initial decomposition rate, ESM-specific Q10-factors, and changes in soil temperature (R2 = 0.80, p < 0.01). All SOC changes depended on sustained increases in NPP with global change (primarily driven by increasing CO2). Many ESMs simulated large accumulations of SOC in high-latitude biomes that are not consistent with empirical studies. Most ESMs poorly represented permafrost dynamics and omitted potential constraints on SOC storage, such as priming effects, nutrient availability, mineral surface stabilization, and aggregate formation. Future models that represent these constraints are likely to estimate smaller increases in SOC storage over the 21st century.
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Parandin, Farzad, Asadollah Khoorani i Ommolbanin Bazrafshan. "The Impacts of Climate Change on Maximum Daily Discharge in the Payab Jamash Watershed, Iran". Open Geosciences 11, nr 1 (31.12.2019): 1035–45. http://dx.doi.org/10.1515/geo-2019-0080.
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Abstract One of the most crucial consequences of climate change involves the alteration of the hydrologic cycle and river flow regime of watersheds. This study was an endeavor to investigate the contributions of climate change to maximum daily discharge (MDD). To this end, the MDD simulation was carried out through implementing the IHACRES precipitation-runoff model in the Payyab Jamash watershed for the 21st century (2016-2100). Subsequently, the observed precipitation and temperature data of the weather stations (1980-2011) as well as 4 multi-model outputs of Global Climate Models (GCMs) under the maximum and minimum Representative Concentration Pathways (RCPs) (2016-2100) were utilized. In order to downscale the output of GCMs, Bias Correction (BC) statistical method was applied. The projections for the 21st century indicated a reduction in Maximum Daily Precipitation (MDP) in comparison with the historic period in the study area. The average projected MDP for the future period was 9 mm/day and 5 mm/ day under 2.6 and 8.5 RCPs (4.6% and 2.6% decrease compared with the historical period), respectively. Moreover, the temperature increased in Jamash Watershed based on 2.6 and 8.5 RCPs by 1∘C and 2∘C(3.7% and 7.4% increase compared with the historical period), respectively. The findings of flow simulation for the future period indicated a decrease in MDD due to the diminished MDP in the study area. The amount of this decrease under RCP8.5 was not remarkable (0.75 m3/s), whereas its value for RCP2.6 was calculated as 40m3/s (respectively, 0.11% and 5.88% decrease compared with the historical period).
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DAR, HIMAYOUN, ROSHNI THENDIYATH i MOHSIN FAROOQ. "Spatio-temporal variations of land surface temperature and precipitation due to climate change in the Jhelum river basin, India". MAUSAM 71, nr 4 (4.08.2021): 661–74. http://dx.doi.org/10.54302/mausam.v71i4.54.
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The present study investigated the spatio-temporal variations of precipitation and temperature for the projected period (2011-2100) in the Jhelum basin, India. The precipitation and temperature variables are projected under RCP 8.5 scenario using statistical down scaling techniques such as Artificial Neural Network (ANN) and Wavelet Artificial Neural Network (WANN) models. Firstly, the screened predictors were downscaled to predictand using ANN and WANN models for all the study stations. On the basis of the performance criteria, the WANN model is selected as an efficient model for downscaling of precipitation and temperature. The future screened predictor data pertaining to RCP 8.5 of CanESM2 model were downscaled to monthly temperature and precipitation for future periods (2011-2100) using WANN models. The investigation of the future projections revealed an average increase of 17-25% in the mean annual precipitation and 20-25% average increase in the monthly mean precipitation for all the selected stations towards the end of 21st century. The monthly mean temperature also showed an increase of 2-3 °C for all the study stations towards the end of 21st century. The mean seasonal temperature of the projected period is found to be increasing for all the four seasons in most parts of the basin.
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Giesen, R. H., i J. Oerlemans. "Response of the ice cap Hardangerjøkulen in southern Norway to the 20th and 21st century climates". Cryosphere Discussions 3, nr 3 (13.11.2009): 947–93. http://dx.doi.org/10.5194/tcd-3-947-2009.
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Abstract. Glacier mass balance changes lead to geometry changes and vice versa. To include this interdependence in the response of glaciers to climate change, models should include an interactive scheme coupling mass balance and ice dynamics. In this study, we couple a spatially distributed mass balance model to a two-dimensional ice-flow model and apply this coupled model to the ice cap Hardangerjøkulen in southern Norway. The available glacio-meteorological records, mass balance and glacier length change measurements were utilized for model calibration and validation. Driven with meteorological data from nearby synoptic weather stations, the coupled model realistically simulated the observed mass balance and glacier length changes during the 20th century. The mean climate for the period 1961–1990, computed from local meteorological data, was used as a basis to prescribe climate projections for the 21st century at Hardangerjøkulen. For a projected temperature increase of 3°C from 1961–1990 to 2071–2100, the modelled net mass balance soon becomes negative at all altitudes and Hardangerjøkulen disappears around the year 2100. The projected changes in the other meteorological variables could at most partly compensate for the effect of the projected warming.
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Schneider von Deimling, T., G. Grosse, J. Strauss, L. Schirrmeister, A. Morgenstern, S. Schaphoff, M. Meinshausen i J. Boike. "Observation-based modelling of permafrost carbon fluxes with accounting for deep carbon deposits and thermokarst activity". Biogeosciences 12, nr 11 (5.06.2015): 3469–88. http://dx.doi.org/10.5194/bg-12-3469-2015.
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Abstract. High-latitude soils store vast amounts of perennially frozen and therefore inert organic matter. With rising global temperatures and consequent permafrost degradation, a part of this carbon stock will become available for microbial decay and eventual release to the atmosphere. We have developed a simplified, two-dimensional multi-pool model to estimate the strength and timing of future carbon dioxide (CO2) and methane (CH4) fluxes from newly thawed permafrost carbon (i.e. carbon thawed when temperatures rise above pre-industrial levels). We have especially simulated carbon release from deep deposits in Yedoma regions by describing abrupt thaw under newly formed thermokarst lakes. The computational efficiency of our model allowed us to run large, multi-centennial ensembles under various scenarios of future warming to express uncertainty inherent to simulations of the permafrost carbon feedback. Under moderate warming of the representative concentration pathway (RCP) 2.6 scenario, cumulated CO2 fluxes from newly thawed permafrost carbon amount to 20 to 58 petagrams of carbon (Pg-C) (68% range) by the year 2100 and reach 40 to 98 Pg-C in 2300. The much larger permafrost degradation under strong warming (RCP8.5) results in cumulated CO2 release of 42 to 141 Pg-C and 157 to 313 Pg-C (68% ranges) in the years 2100 and 2300, respectively. Our estimates only consider fluxes from newly thawed permafrost, not from soils already part of the seasonally thawed active layer under pre-industrial climate. Our simulated CH4 fluxes contribute a few percent to total permafrost carbon release yet they can cause up to 40% of total permafrost-affected radiative forcing in the 21st century (upper 68% range). We infer largest CH4 emission rates of about 50 Tg-CH4 per year around the middle of the 21st century when simulated thermokarst lake extent is at its maximum and when abrupt thaw under thermokarst lakes is taken into account. CH4 release from newly thawed carbon in wetland-affected deposits is only discernible in the 22nd and 23rd century because of the absence of abrupt thaw processes. We further show that release from organic matter stored in deep deposits of Yedoma regions crucially affects our simulated circumpolar CH4 fluxes. The additional warming through the release from newly thawed permafrost carbon proved only slightly dependent on the pathway of anthropogenic emission and amounts to about 0.03–0.14 °C (68% ranges) by end of the century. The warming increased further in the 22nd and 23rd century and was most pronounced under the RCP6.0 scenario, adding 0.16 to 0.39 °C (68% range) to simulated global mean surface air temperatures in the year 2300.
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De Smedt, Bert, i Frank Pattyn. "Numerical modelling of historical front variations and dynamic response of Sofiyskiy glacier, Altai mountains, Russia". Annals of Glaciology 37 (2003): 143–49. http://dx.doi.org/10.3189/172756403781815654.
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AbstractThe recent fluctuation of the central Asian climate, and its effect on the region’s glaciers, is poorly known, largely because of a lack of knowledge of the dynamic behaviour of so-called summer-accumulation-type glaciers. In this study, a one-dimensional numerical glacier model is used to simulate the dynamic response of Sofiyskiy glacier, Altai mountains, Russia, to climate forcing. A successful simulation of the observed historical front variations was accomplished by dynamic calibration. This resulted in a reconstruction of the recent mass-balance history of the glacier, showing a distinct decline in surface mass balance in the second half of the 19th century, a slightly higher mass balance at the beginning of the 20th century, followed by a steady decline towards present conditions. The future response of Sofiyskiy glacier was projected for six 21st-century climate scenarios. Under a “no-change” scenario, the glacier will retreat > 2 km by 2100. If air temperature gradually rises by > 5°C during this century, the glacier will vanish around 2100. Basic response characteristics of Sofiyskiy glacier were determined. These indicate rather low mass-balance sensitivity to temperature change, but a strong front reaction due to geometric conditions.
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Todd-Brown, K. E. O., J. T. Randerson, F. Hopkins, V. Arora, T. Hajima, C. Jones, E. Shevliakova i in. "Changes in soil organic carbon storage predicted by Earth system models during the 21st century". Biogeosciences Discussions 10, nr 12 (4.12.2013): 18969–9004. http://dx.doi.org/10.5194/bgd-10-18969-2013.
Pełny tekst źródłaStreszczenie:
Abstract. Soil is currently thought to be a sink for carbon; however, the response of this sink to increasing levels of atmospheric carbon dioxide and climate change is uncertain. In this study, we analyzed soil organic carbon (SOC) changes from 11 Earth system models (ESMs) under the historical and high radiative forcing (RCP 8.5) scenarios between 1850 and 2100. We used a reduced complexity model based on temperature and moisture sensitivities to analyze the drivers of SOC losses. ESM estimates of SOC change over the 21st century (2090–2099 minus 1997–2006) ranged from a loss of 72 Pg C to a gain 253 Pg C with a multi-model mean gain of 63 Pg C. All ESMs showed cumulative increases in both NPP (15% to 59%) and decreases in SOC turnover times (15% to 28%) over the 21st century. Most of the model-to-model variation in SOC change was explained by initial SOC stocks combined with the relative changes in soil inputs and decomposition rates (R2 = 0.88, p<0.01). Between models, increases in decomposition rate were well explained by a combination of initial decomposition rate, ESM-specific Q10-factors, and changes in soil temperature (R2 = 0.80, p<0.01). All SOC changes depended on sustained increases in NPP with global change (primarily driven by increasing CO2) and conversion of additional plant inputs into SOC. Most ESMs omit potential constraints on SOC storage, such as priming effects, nutrient availability, mineral surface stabilization and aggregate formation. Future models that represent these constraints are likely to estimate smaller increases in SOC storage during the 21st century.
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Spahni, R., F. Joos, B. D. Stocker, M. Steinacher i Z. C. Yu. "Transient simulations of the carbon and nitrogen dynamics in northern peatlands: from the Last Glacial Maximum to the 21st century". Climate of the Past 9, nr 3 (20.06.2013): 1287–308. http://dx.doi.org/10.5194/cp-9-1287-2013.
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Abstract. The development of northern high-latitude peatlands played an important role in the carbon (C) balance of the land biosphere since the Last Glacial Maximum (LGM). At present, carbon storage in northern peatlands is substantial and estimated to be 500 ± 100 Pg C (1 Pg C = 1015 g C). Here, we develop and apply a peatland module embedded in a dynamic global vegetation and land surface process model (LPX-Bern 1.0). The peatland module features a dynamic nitrogen cycle, a dynamic C transfer between peatland acrotelm (upper oxic layer) and catotelm (deep anoxic layer), hydrology- and temperature-dependent respiration rates, and peatland specific plant functional types. Nitrogen limitation down-regulates average modern net primary productivity over peatlands by about half. Decadal acrotelm-to-catotelm C fluxes vary between −20 and +50 g C m−2 yr−1 over the Holocene. Key model parameters are calibrated with reconstructed peat accumulation rates from peat-core data. The model reproduces the major features of the peat core data and of the observation-based modern circumpolar soil carbon distribution. Results from a set of simulations for possible evolutions of northern peat development and areal extent show that soil C stocks in modern peatlands increased by 365–550 Pg C since the LGM, of which 175–272 Pg C accumulated between 11 and 5 kyr BP. Furthermore, our simulations suggest a persistent C sequestration rate of 35–50 Pg C per 1000 yr in present-day peatlands under current climate conditions, and that this C sink could either sustain or turn towards a source by 2100 AD depending on climate trajectories as projected for different representative greenhouse gas concentration pathways.
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Spahni, R., F. Joos, B. D. Stocker, M. Steinacher i Z. C. Yu. "Transient simulations of the carbon and nitrogen dynamics in northern peatlands: from the Last Glacial Maximum to the 21st century". Climate of the Past Discussions 8, nr 6 (15.11.2012): 5633–85. http://dx.doi.org/10.5194/cpd-8-5633-2012.
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Abstract. The development of northern high-latitude peatlands played an important role in the carbon (C) balance of the land biosphere since the Last Glacial Maximum (LGM). At present, carbon storage in northern peatlands is substantial and estimated to be 500 ± 100 Pg C (1 Pg C = 1015 g C). Here, we develop and apply a peatland module embedded in a dynamic global vegetation model (LPX). The peatland module features a dynamic nitrogen cycle, a dynamic C transfer between peatland acrotelm (upper oxic layer) and catotelm (deep anoxic layer), hydrology- and temperature-dependent respiration rates, and peatland specific plant functional types. Nitrogen limitation down-regulates average modern net primary productivity over peatlands by almost a factor of two. Decadal acrotelm-to-catotelm C fluxes vary between −20 and +50 g C m−2 yr−1 over the Holocene. Key model parameters are calibrated with reconstructed peat accumulation rates from peat-core data. The model reproduces the major features of the peat core data and of the observation-based modern circumpolar soil carbon distribution. Results from a set of simulations for possible evolutions of northern peat development and areal extent show that soil C stocks in modern peatlands increased by 365–550 Pg C since the LGM, of which 175–272 Pg C accumulated between 11 and 5 kyr BP. Furthermore, our simulations suggest a persistent C sequestration rate of 35–50 Pg C per 1000 yr in peatlands under current climate conditions, and that this C sink could either vanish or turn into a small source by 2100 AD depending on climate trajectories as projected for different representative greenhouse gas concentration pathways.
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Weatherly, John W., i Julie M. Arblaster. "Sea ice and climate in 20th- and 21st-century simulations with a global atmosphere-ocean-ice model". Annals of Glaciology 33 (2001): 521–24. http://dx.doi.org/10.3189/172756401781818077.
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AbstractA global atmosphere-ocean-sea-ice general circulation model (GCM) is used in simulations of climate with greenhouse gas concentrations and sulfate aerosols prescribed from observational data (1870−1995) and future projections (1995−2100). Simulations that include the variability in solar flux from 1870 through 1995 are also performed. The variation in solar flux of ± 2 W m−2 produces a global temperature change of ± 0.2°C in the model. The more recent simulated warming trend produced by increasing greenhouse gases exceeds this solar-flux warming, although the solar flux contributes to some of the simulated present-day warm temperatures. The future increases in greenhouse gases produce an increase in global temperature of 1.2°C over 70 years, with significant decreases in Arctic ice thickness and area. The model exhibits an atmospheric pressure mode similar to the Arctic Oscillation, with different correlation indices between the North Atlantic and North Pacific pressure anomalies.
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Vukovic, Ana, Mirjam Vujadinovic, Sonja Rendulic, Vladimir Djurdjevic, Mirjana Ruml, Violeta Babic i Dunja Popovic. "Global warming impact on climate change in Serbia for the period 1961-2100". Thermal Science 22, nr 6 Part A (2018): 2267–80. http://dx.doi.org/10.2298/tsci180411168v.
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Serbia is situated at Balkan Peninsula, and currently majority of the territory is under warm temperate ? fully humid climate type with warm summers (Cfb type, according to Koppen-Geiger Climate Classification). Observed changes in climate conditions since 1961 until present time show significant increase in temperature change and change in precipitation patterns. Disturbances in heat conditions, which are recorded to affect human health, agricultural production and forest eco?system, are priority in climate change analysis and application in adaptation plan?ning. Future change analysis show accelerated increase of temperature by the end of the 21st century, which proves the needs for immediate measures for mitigation of negative impacts. Temperature increase averaged over the territory of Serbia is 1.2?C for the period 1996-2015 with respect to the period 1961-1980, with highest increase of maximum daily temperature during the summer season, 2.2?C. Using high resolution multi-model ensemble approach for analysis of the future changes with respect to the base period 1986-2005, in compliance with Intergovernmental Panel on Climate Change (IPCC) fifth assessment report (AR5), it is estimated that temperature may increase by 1.9?C according to Representative Concentration Pathway 4.5 (RCP4.5) scenario and by 4.4?C according to RCP8.5 by the end of the century. Spatial distribution of temperature increase, intensification of high pre?cipitation events and decrease of summer precipitation, show intrusion of subtropi?cal climate over the Serbia and increase of high temperature and high precipitation risks. Results presented in this paper, using high-resolution multi-model ensemble approach, provide climate change information for short term to long term planning in different sectors of economy and preservation of human health and environment.