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1
Lelono, Eko Budi, e Robert J. Morley. "Oligocene Climate Changes of Java". Scientific Contributions Oil and Gas 34, n. 3 (14 marzo 2022): 169–76. http://dx.doi.org/10.29017/scog.34.3.803.
Testo completoAbstract (sommario):
The study of palynology performed on the Oligocene marine sediment of the East Java Sea provides excellent recovery which allows the construction of palynological succession which applies regionally (Lelono et. al., 2011). In fact, this succession is characterized by assemblages that suggest climatic changes. These assemblages are divided into two major groups including mangrove and hinterland. The hinterland pollen group shows the most interesting succession, with elements on the one hand suggesting everwet climates (Dacrydium and Casuarina), and seasonal elements on the other (Gramineae, Schoutenia and Malvacipollis diversus). Mangrove pollen however suggests strong environmental control since mangrove pollen shows different abundance variations in the two wells. The age of the studied succession is independently defined using combined marine micro-fossils of foraminifer and nannoplankton which indicate Early to Late Oligocene. Although for most of the Oligocene in Southeast Asia, seasonal climate assemblages are the rule, this study interpretes the appearence of everwet climates. The Early Oligocene is characterized by common rain forest elements, suggesting an everwet rain forest climate at that time. The early part of the Late Oligocene, however, contains much reduced rain forest elements, and the presence of regular Gramineae pollen, suggesting a more seasonal climate, whereas for the latest Late Oligocene, rain forest (and peat swamp) elements return in abundance, suggesting a very wet rain forest climate. In fact, Java region experienced the wettest climate during Oligocene which probably reflected a wet climate fringe to the eastern margin of Sundaland prior to the collision of the Australian and Asian plates at the Oligo-Miocene boundary.
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Zajch, Andrew, William A. Gough e Giacomo Chiesa. "Earth–Air Heat Exchanger Geo-Climatic Suitability for Projected Climate Change Scenarios in the Americas". Sustainability 12, n. 24 (18 dicembre 2020): 10613. http://dx.doi.org/10.3390/su122410613.
Testo completoAbstract (sommario):
Earth–air heat exchangers (EAHE) provide heating and cooling that is intrinsically tied to the climate of the surrounding environment. A climate-based approach was applied to 273 sites for both historical and projected climate conditions, with the latter being defined by three different Representative Concentration Pathways (RCPs) from the CMIP5 collection of Global Circulation Models (GCMs). Changes to heating and cooling degree hours as well as heating and cooling capacity were estimated and used to classify geo-climatic suitability. The analysis revealed cooler climates will retain their ability to provide cooling despite increasing cooling needs driven by warming temperatures. On the other hand, warmer, more tropical, climates will observe reduced suitability as cooling demand grows. The magnitude and variability of the changes in EAHE potential were greatest for the RCP8.5 scenario during the 2061–2090 time period, particularly for regions with a comparable mix of heating and cooling needs. Ultimately, the results demonstrate that future EAHE suitability is climate dependent, with cooler climates being relatively resistant to changes when compared to warmer climates. The results can be used by stakeholders to find useful climate analogs for their sites of interest to consider the potential impact of global climate change on EAHE usability.
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Dubois, Emmanuel, Marie Larocque, Sylvain Gagné e Marco Braun. "Climate Change Impacts on Groundwater Recharge in Cold and Humid Climates: Controlling Processes and Thresholds". Climate 10, n. 1 (12 gennaio 2022): 6. http://dx.doi.org/10.3390/cli10010006.
Testo completoAbstract (sommario):
Long-term changes in precipitation and temperature indirectly impact aquifers through groundwater recharge (GWR). Although estimates of future GWR are needed for water resource management, they are uncertain in cold and humid climates due to the wide range in possible future climatic conditions. This work aims to (1) simulate the impacts of climate change on regional GWR for a cold and humid climate and (2) identify precipitation and temperature changes leading to significant long-term changes in GWR. Spatially distributed GWR is simulated in a case study for the southern Province of Quebec (Canada, 36,000 km2) using a water budget model. Climate scenarios from global climate models indicate warming temperatures and wetter conditions (RCP4.5 and RCP8.5; 1951–2100). The results show that annual precipitation increases of >+150 mm/yr or winter precipitation increases of >+25 mm will lead to significantly higher GWR. GWR is expected to decrease if the precipitation changes are lower than these thresholds. Significant GWR changes are produced only when the temperature change exceeds +2 °C. Temperature changes of >+4.5 °C limit the GWR increase to +30 mm/yr. This work provides useful insights into the regional assessment of future GWR in cold and humid climates, thus helping in planning decisions as climate change unfolds. The results are expected to be comparable to those in other regions with similar climates in post-glacial geological environments and future climate change conditions.
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Harrison, Susan, Marko J. Spasojevic e Daijiang Li. "Climate and plant community diversity in space and time". Proceedings of the National Academy of Sciences 117, n. 9 (18 febbraio 2020): 4464–70. http://dx.doi.org/10.1073/pnas.1921724117.
Testo completoAbstract (sommario):
Climate strongly shapes plant diversity over large spatial scales, with relatively warm and wet (benign, productive) regions supporting greater numbers of species. Unresolved aspects of this relationship include what causes it, whether it permeates to community diversity at smaller spatial scales, whether it is accompanied by patterns in functional and phylogenetic diversity as some hypotheses predict, and whether it is paralleled by climate-driven changes in diversity over time. Here, studies of Californian plants are reviewed and new analyses are conducted to synthesize climate–diversity relationships in space and time. Across spatial scales and organizational levels, plant diversity is maximized in more productive (wetter) climates, and these consistent spatial relationships are mirrored in losses of taxonomic, functional, and phylogenetic diversity over time during a recent climatic drying trend. These results support the tolerance and climatic niche conservatism hypotheses for climate–diversity relationships, and suggest there is some predictability to future changes in diversity in water-limited climates.
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Kwon, Minsung, e Jang Hyun Sung. "Changes in Future Drought with HadGEM2-AO Projections". Water 11, n. 2 (12 febbraio 2019): 312. http://dx.doi.org/10.3390/w11020312.
Testo completoAbstract (sommario):
The standardized precipitation index (SPI)—a meteorological drought index—uses various reference precipitation periods. Generally, drought projections using future climate change scenarios compare reference SPIs between baseline and future climates. Here, future drought was projected based on reference precipitation under the baseline climate to quantitatively compare changes in the frequency and severity of future drought. High-resolution climate change scenarios were produced using HadGEM2-AO General Circulation Model (GCM) scenarios for Korean weather stations. Baseline and future 3-month cumulative precipitation data were fitted to gamma distribution; results showed that precipitation of future climate is more than the precipitation of the baseline climate. When future precipitation was set as that of the baseline climate instead of the future climate, results indicated that drought intensity and frequency will decrease because the non-exceedance probability for the same precipitation is larger in the baseline climate than in future climate. However, due to increases in regional precipitation variability over time, some regions with opposite trends were also identified. Therefore, it is necessary to understand baseline and future climates in a region to better design resilience strategies and mechanisms that can help cope with future drought.
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Bryson, Reid A. "Simulating Past and Forecasting Future Climates". Environmental Conservation 20, n. 4 (1993): 339–46. http://dx.doi.org/10.1017/s0376892900023547.
Testo completoAbstract (sommario):
Climatic change is not a new phenomenon, nor is it random, as most of the variation can be explained in terms of variations in the sunlight reaching the surface of the Earth. The solar energy reaching the surface is modified by the aerosols in the atmosphere, however, and that means primarily aerosols of volcanic origin.The climatic history of the Earth is divided up into episodes with abrupt beginnings and ends. Rapid changes from one climatic state to another are normal. The fluctuations within this century do not appear to be unusual in any respect.To the Author's knowledge there is no evidence that past climatic changes, including those of the last decades, are related to changes in carbon dioxide in the atmosphere—except perhaps for warmer nights in the North American mid-west. It is not possible to simulate past climates using carbon dioxide content as the main variable, but it is possible to do so using calculated solar radiation as modified by volcanic aerosols. This strongly suggests that forecasts of the climatic future based on carbon dioxide increases are suspect.Computerized models of the climate that can simulate decadal and century-long variations of climate as well as variations on the millennium scale, suggest that the climate will not warm dramatically in the next fifty years, but will, rather soon after that, begin a rather rapid change towards the next glacial climate.Changes in our global array of cultures, sufficient to affect the global climate in a way which we perceive as beneficial, probably are not possible within centuries without massive physical conflict. There are both winners and losers when the climate changes in a non-uniform pattern, as it always does. It is a well-known fact that a global change of 0.5°C in mean temperature, such as has happened in recent years, might produce some regions of 10°C change in either direction and some regions with no change at all, and additionally an array of rainfall changes of various magnitudes. Russians would welcome warming of their climate!The problems with attempting to modify the global climate in a particular direction are enormous and would be incredibly costly. This is compounded by our not knowing what the climate would do without intervention. Only one thing is truly clear, and it is that the present knowledge of the climatic effect of changing carbon dioxide content of the atmosphere is totally inadequate as a basis for initiating any global attempt to change the climate.The indicated action would appear to be to engage in some high-quality climatic research based on sound science before taking global risks greater than those that might arise from the putative ‘global warming’.
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McGee, David. "Glacial–Interglacial Precipitation Changes". Annual Review of Marine Science 12, n. 1 (3 gennaio 2020): 525–57. http://dx.doi.org/10.1146/annurev-marine-010419-010859.
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Glacial–interglacial cycles have constituted a primary mode of climate variability over the last 2.6 million years of Earth's history. While glacial periods cannot be seen simply as a reverse analogue of future warming, they offer an opportunity to test our understanding of the response of precipitation patterns to a much wider range of conditions than we have been able to directly observe. This review explores key features of precipitation patterns associated with glacial climates, which include drying in large regions of the tropics and wetter conditions in substantial parts of the subtropics and midlatitudes. I describe the evidence for these changes and examine the potential causes of hydrological changes during glacial periods. Central themes that emerge include the importance of atmospheric circulation changes in determining glacial–interglacial precipitation changes at the regional scale, the need to take into account climatic factors beyond local precipitation amount when interpreting proxy data, and the role of glacial conditions in suppressing the strength of Northern Hemisphere monsoon systems.
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Ruget, F., J. C. Moreau, M. Ferrand, S. Poisson, P. Gate, B. Lacroix, J. Lorgeou, E. Cloppet e F. Souverain. "Describing the possible climate changes in France and some examples of their effects on main crops used in livestock systems". Advances in Science and Research 4, n. 1 (2 agosto 2010): 99–104. http://dx.doi.org/10.5194/asr-4-99-2010.
Testo completoAbstract (sommario):
Abstract. The effects of climate change on forage and crop production are an important question for the farmers and more largely for the food security in the world. Estimating the effect of climate change on agricultural production needs the use of two types of tools: a model to estimate changes in national or local climates and an other model using climatic data to estimate the effects on vegetation. In this paper, we will mainly present the effects of climate change on climatic features, the variability of criteria influencing crop production in various regions of France and some possible effects on crops.
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Chiesa, Giacomo. "Climatic potential maps of ventilative cooling techniques in Italian climates including resilience to climate changes". IOP Conference Series: Materials Science and Engineering 609 (23 ottobre 2019): 032039. http://dx.doi.org/10.1088/1757-899x/609/3/032039.
Testo completo
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Barcellos, Afonso Lopes, Renata Da Silva Pereira Saccol, Nathalia Leal Carvalho e Luana Filippin Rosa. "A simple reflection on climate change". Revista Eletrônica em Gestão, Educação e Tecnologia Ambiental 23 (1 giugno 2019): 18. http://dx.doi.org/10.5902/2236117034387.
Testo completoAbstract (sommario):
In order to discuss climate change and our role, this literature review was developed. The term climate change, climate change or climate change refers to global-scale climate change or Earth's regional climates over time. These variations refer to changes in temperature, precipitation, cloudiness and other climatic phenomena in relation to historical averages. Such variations can alter climatic characteristics in a way to change their didactic classification. These changes can be caused by processes internal to the Earth-atmosphere system, by external forces, or by the result of human activity. Therefore, it is understood that climate change can be either an effect of natural processes or arising from human action and so one should keep in mind what kind of climate change is being referred to.
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Oriangi, George, Paul Isolo Mukwaya, Justine Kilama Luwa, Menya Emmanuel, Malinga Geoffrey Maxwell e Yazidhi Bamutaze. "Variability and Changes in Climate in Northern Uganda". African Journal of Climate Change and Resource Sustainability 3, n. 1 (18 marzo 2024): 81–97. http://dx.doi.org/10.37284/ajccrs.3.1.1830.
Testo completoAbstract (sommario):
Variability and changes in climate are generally expected to occur. However, there remain gaps on dynamics of expected regional variations in climatic changes. This study assessed historic and projected climatic conditions up to the year 2033. The study hypothesized that temperature rather than rainfall significantly increased for the period 1980-2010 and rainfall rather than temperature is likely to decrease significantly by 2033 for Gulu District in northern Uganda. To determine historic climatic trends, rainfall and temperature data were obtained from Uganda National Meteorological Authority (UNMA) while for future climate, the PRECIS (Providing Regional Climates for Impact Studies) modelled data based on projected conditions at a 50 km spatial resolution was used. These data sets were subjected to trend analysis and the differences in means were detected at a 95% confidence level. Contrary to the evidences from other empirical studies, results generally indicated decreasing rainfall for the period 1980-2010. However, the decrease was not significant (P > 0.05) while both historic mean annual maximum and minimum temperature trends showed a statistically significant increase (P<0.05). Projections for 2033 reveal a significant decrease in rainfall (P < 0.05) while both maximum and minimum temperature will remain quasi uniform
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Oriangi, George, Yazidhi Bamutaze, Paul Isolo Mukwaya e Edekebon Elaijah. "Medium Term Climate Change Effects on Millet Yields in Gulu District, Northern Uganda". African Journal of Climate Change and Resource Sustainability 3, n. 1 (12 maggio 2024): 150–64. http://dx.doi.org/10.37284/ajccrs.3.1.1919.
Testo completoAbstract (sommario):
Climate change is expected to adversely affect crop yields and livelihoods of agro-dependent societies, especially in Sub-Saharan Africa. However, there remain gaps on the effects of expected regional climatic changes on key food security crops. This study assessed the projected climatic conditions and expected changes in millet yields for Paicho Sub County (S/C) in Gulu District up to the year 2033 using a cross sectional study design. To determine future climatic conditions, PRECIS (Providing Regional Climates for Impact Studies) model was used based on projected conditions at a 50 km spatial resolution while millet yields were modelled using Penman Grindley soil moisture balance model. PRECIS projected changes for 2033 reveal a strong and significant decrease in rainfall (p< 0.05). This is likely to decrease millet yields by 2.6% below the average current yields of 1.8 tons per hectare per year under business-as-usual scenario. The finding indicates a need for improved millet varieties that can survive under changed climatic conditions
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Maes, Patrick W., Amy S. Floyd, Brendon M. Mott e Kirk E. Anderson. "Overwintering Honey Bee Colonies: Effect of Worker Age and Climate on the Hindgut Microbiota". Insects 12, n. 3 (5 marzo 2021): 224. http://dx.doi.org/10.3390/insects12030224.
Testo completoAbstract (sommario):
Honey bee overwintering health is essential to meet the demands of spring pollination. Managed honey bee colonies are overwintered in a variety of climates, and increasing rates of winter colony loss have prompted investigations into overwintering management, including indoor climate controlled overwintering. Central to colony health, the worker hindgut gut microbiota has been largely ignored in this context. We sequenced the hindgut microbiota of overwintering workers from both a warm southern climate and controlled indoor cold climate. Congruently, we sampled a cohort of known chronological age to estimate worker longevity in southern climates, and assess age-associated changes in the core hindgut microbiota. We found that worker longevity over winter in southern climates was much lower than that recorded for northern climates. Workers showed decreased bacterial and fungal load with age, but the relative structure of the core hindgut microbiome remained stable. Compared to cold indoor wintering, collective microbiota changes in the southern outdoor climate suggest compromised host physiology. Fungal abundance increased by two orders of magnitude in southern climate hindguts and was positively correlated with non-core, likely opportunistic bacteria. Our results contribute to understanding overwintering honey bee biology and microbial ecology and provide insight into overwintering strategies.
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Seager, Richard, Timothy J. Osborn, Yochanan Kushnir, Isla R. Simpson, Jennifer Nakamura e Haibo Liu. "Climate Variability and Change of Mediterranean-Type Climates". Journal of Climate 32, n. 10 (29 aprile 2019): 2887–915. http://dx.doi.org/10.1175/jcli-d-18-0472.1.
Testo completoAbstract (sommario):
Abstract Mediterranean-type climates are defined by temperate, wet winters, and hot or warm dry summers and exist at the western edges of five continents in locations determined by the geography of winter storm tracks and summer subtropical anticyclones. The climatology, variability, and long-term changes in winter precipitation in Mediterranean-type climates, and the mechanisms for model-projected near-term future change, are analyzed. Despite commonalities in terms of location in the context of planetary-scale dynamics, the causes of variability are distinct across the regions. Internal atmospheric variability is the dominant source of winter precipitation variability in all Mediterranean-type climate regions, but only in the Mediterranean is this clearly related to annular mode variability. Ocean forcing of variability is a notable influence only for California and Chile. As a consequence, potential predictability of winter precipitation variability in the regions is low. In all regions, the trend in winter precipitation since 1901 is similar to that which arises as a response to changes in external forcing in the models participating in phase 5 of the Coupled Model Intercomparison Project. All Mediterranean-type climate regions, except in North America, have dried and the models project further drying over coming decades. In the Northern Hemisphere, dynamical processes are responsible: development of a winter ridge over the Mediterranean that suppresses precipitation and of a trough west of the North American west coast that shifts the Pacific storm track equatorward. In the Southern Hemisphere, mixed dynamic–thermodynamic changes are important that place a minimum in vertically integrated water vapor change at the coast and enhance zonal dry advection into Mediterranean-type climate regions inland.
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Barani, Nader, Ayatollah Karami e Mahmoud Ahmadpour Borazjani. "The impact of climatic changes on total horticultural production and food security in agro-ecological zones of Iran". Journal of Water and Climate Change 11, n. 4 (25 ottobre 2019): 1712–23. http://dx.doi.org/10.2166/wcc.2019.139.
Testo completoAbstract (sommario):
Abstract Arid and semi-arid climates, including that of Iran, are more susceptible to environmental changes due to their special ecological structure than other climates. Therefore, climate change in these areas appears to have significant effects on agricultural and food production systems. The present study explores the effect of climatic changes on total horticultural production and food security in agro-ecological zones of Iran. The study was conducted in two steps. In the first step, the effects of climatic parameters on total horticultural production were investigated using time series data (1985–2017) and a regression model. In the second step, due to the important role of horticultural products in per capita food consumption in Iran, the effect of climate parameters on food security was also examined. Results revealed that total horticultural production was influenced by temperature, evapotranspiration, and wind speed at the 0.05 level. With the increase in temperature (at a rate of one unit), total horticultural production is reduced to 0.01 million tons. Evapotranspiration and wind speed have had a negative effect on total horticultural production, and with increasing evapotranspiration and wind speed, total horticultural production was 0.029 and 0.008 million, respectively, tons decreased. Also, food security was influenced by temperature, precipitation, and wind speed.
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Lewis, S. C., e A. N. LeGrande. "Stability of ENSO and its tropical Pacific teleconnections over the Last Millennium". Climate of the Past 11, n. 10 (13 ottobre 2015): 1347–60. http://dx.doi.org/10.5194/cp-11-1347-2015.
Testo completoAbstract (sommario):
Abstract. Determining past changes in the amplitude, frequency and teleconnections of the El Niño-Southern Oscillation (ENSO) is important for understanding its potential sensitivity to future anthropogenic climate change. Palaeo-reconstructions from proxy records can provide long-term information of ENSO interactions with the background climatic state through time. However, it remains unclear how ENSO characteristics have changed on long timescales, and precisely which signals proxies record. Proxy interpretations are typically underpinned by the assumption of stationarity in relationships between local and remote climates, and often utilise archives from single locations located in the Pacific Ocean to reconstruct ENSO histories. Here, we investigate the long-term characteristics of ENSO and its teleconnections using the Last Millennium experiment of CMIP5 (Coupled Model Intercomparison Project phase 5; Taylor et al., 2012). We show that the relationship between ENSO conditions (NINO3.4) and local climates across the Pacific basin differs significantly for 100-year epochs defining the Last Millennium and the historical period 1906–2005. Furthermore, models demonstrate decadal- to centennial-scale modulation of ENSO behaviour during the Last Millennium. Overall, results suggest that the stability of teleconnections may be regionally dependent and that proxy climate records may reveal complex changes in teleconnected patterns, rather than large-scale changes in base ENSO characteristics. As such, proxy insights into ENSO may require evidence to be considered over large spatial areas in order to deconvolve changes occurring in the NINO3.4 region from those relating to local climatic variables. To obtain robust histories of the ENSO and its remote impacts, we recommend interpretations of proxy records should be considered in conjunction with palaeo-reconstructions from within the central Pacific.
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V.P. PRAMOD, B. BAPUJI RAO, S.S.V.S. RAMAKRISHNA, M. MUNESHWAR SINGH, N.R. PATEL, V.M. SANDEEP, V.U.M. RAO, P. S. CHOWDARY, V. NARSIMHA RAO e P. VIJAYA KUMAR. "Impact of projected climate on wheat yield in India and its adaptation strategies". Journal of Agrometeorology 19, n. 3 (1 settembre 2017): 207–16. http://dx.doi.org/10.54386/jam.v19i3.627.
Testo completoAbstract (sommario):
Wheat is highly sensitive to climate change especially temperature changes experienced in the later phase of crop season. Hence, it is of immense importance to know how and to what extent climate change will affect wheat yields and to assess the adaptive strategies for mitigating possible negative consequences on wheat production. Wheat yield responses to three future climatic periods (2025, 2050 and 2075) were studied by driving DSSAT-Wheat (v4.5) model with daily weather from three CMIP-5 climate models’ (GFDL-ESM2M, MIROC5, and NorESM1-M) as the basic input at four sites (Ludhiana, Raipur, Akola and New Delhi) representing three major wheat growing zones of the country. Projected changes in growing season (November-March) day and night temperatures at four sites differed substantially both in direction and magnitude. Day temperatures are projected to rise conspicuously at Ludhiana, representing northwest parts of the country, and moderately over central parts of India (Akola and Raipur). Positive rainfall anomalies at Ludhiana (+76%) and negative anomalies at Raipur (-15%) are projected in future climates. With these anticipated changes, wheat is likely to experience warmer days (+1.1 °C) at Ludhiana and nights at Raipur (+2.8 °C) and more seasonal moisture availability at Ludhiana in future climates. Negative impacts of climatic change in these sites are found to be minimized by adapting one or a combination of management practices, which are site specific.
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Schneider, Tapio, Tobias Bischoff e Hanna Płotka. "Physics of Changes in Synoptic Midlatitude Temperature Variability". Journal of Climate 28, n. 6 (13 marzo 2015): 2312–31. http://dx.doi.org/10.1175/jcli-d-14-00632.1.
Testo completoAbstract (sommario):
Abstract This paper examines the physical processes controlling how synoptic midlatitude temperature variability near the surface changes with climate. Because synoptic temperature variability is primarily generated by advection, it can be related to mean potential temperature gradients and mixing lengths near the surface. Scaling arguments show that the reduction of meridional potential temperature gradients that accompanies polar amplification of global warming leads to a reduction of the synoptic temperature variance near the surface. This is confirmed in simulations of a wide range of climates with an idealized GCM. In comprehensive climate simulations (CMIP5), Arctic amplification of global warming similarly entails a large-scale reduction of the near-surface temperature variance in Northern Hemisphere midlatitudes, especially in winter. The probability density functions of synoptic near-surface temperature variations in midlatitudes are statistically indistinguishable from Gaussian, both in reanalysis data and in a range of climates simulated with idealized and comprehensive GCMs. This indicates that changes in mean values and variances suffice to account for changes even in extreme synoptic temperature variations. Taken together, the results indicate that Arctic amplification of global warming leads to even less frequent cold outbreaks in Northern Hemisphere winter than a shift toward a warmer mean climate implies by itself.
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Levine, Xavier J., e Tapio Schneider. "Response of the Hadley Circulation to Climate Change in an Aquaplanet GCM Coupled to a Simple Representation of Ocean Heat Transport". Journal of the Atmospheric Sciences 68, n. 4 (1 aprile 2011): 769–83. http://dx.doi.org/10.1175/2010jas3553.1.
Testo completoAbstract (sommario):
Abstract It is unclear how the width and strength of the Hadley circulation are controlled and how they respond to climate changes. Simulations of global warming scenarios with comprehensive climate models suggest the Hadley circulation may widen and weaken as the climate warms. But these changes are not quantitatively consistent among models, and how they come about is not understood. Here, a wide range of climates is simulated with an idealized moist general circulation model (GCM) coupled to a simple representation of ocean heat transport, in order to place past and possible future changes in the Hadley circulation into a broader context and to investigate the mechanisms responsible for them. By comparison of simulations with and without ocean heat transport, it is shown that it is essential to take low-latitude ocean heat transport and its coupling to wind stress into account to obtain Hadley circulations in a dynamical regime resembling Earth’s, particularly in climates resembling present-day Earth’s and colder. As the optical thickness of an idealized longwave absorber in the simulations is increased and the climate warms, the Hadley circulation strengthens in colder climates and weakens in warmer climates; it has maximum strength in a climate close to present-day Earth’s. In climates resembling present-day Earth’s and colder, the Hadley circulation strength is largely controlled by the divergence of angular momentum fluxes associated with eddies of midlatitude origin; the latter scale with the mean available potential energy in midlatitudes. The importance of these eddy momentum fluxes for the Hadley circulation strength gradually diminishes as the climate warms. The Hadley circulation generally widens as the climate warms, but at a modest rate that depends sensitively on how it is determined.
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Plecha, Sandra, Carina L. Lopes, Nicolas Bruneau, Nuno A. Ribeiro, Paulo A. Silva, André B. Fortunato e João M. Dias. "INFLUENCE OF THE WAVE REGIME IN COASTAL SEDIMENT BUDGET: PRESENT AND FUTURE SCENARIOS". Coastal Engineering Proceedings 1, n. 33 (25 ottobre 2012): 85. http://dx.doi.org/10.9753/icce.v33.sediment.85.
Testo completoAbstract (sommario):
The wave regime has a strong influence on the sediment transport in coastal systems. Modifications in wave regime induced by climate changes can influence the sediment dynamics of those coastal systems. To access wave regime changes it is crucial to analyse the future modifications in the wave height, period and direction. This work aims to analyse the influence of a future wave regime in the sediment budget of a coastal lagoon inlet and at the nearshore adjacent coast. To achieve this goal a morphodynamic modelling system was used, forced by present and future waves, corresponding to a typical year of present and future wave climates. A methodology to determine a typical year of each climate was developed based on the determination of correlation coefficients between each climate and corresponding year data. The comparison between present and future wave climates evidences that wave period and height are in general similar for both climates, and confirms the anticlockwise rotation of waves in the future. The morphodynamic simulations revealed analogous results for both wave climates, resulting in similar patterns for the residual sediment fluxes, but slightly more intense in the present. The consequent bathymetric changes show that the deposition trend presently observed offshore the inlet tends to increase for future waves climate. The transport budgets were also analysed for both wave regimes, evidencing that the alongshore transport slightly decreases (~1%) for future waves.
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Varzinczak, Luiz H., Mauricio O. Moura e Fernando C. Passos. "Shifts to multiple optima underlie climatic niche evolution in New World phyllostomid bats". Biological Journal of the Linnean Society 128, n. 4 (22 ottobre 2019): 1008–20. http://dx.doi.org/10.1093/biolinnean/blz123.
Testo completoAbstract (sommario):
Abstract Climate underlies species distribution patterns, especially in species where climate limits distributions, such as the phyllostomid bats, which are mostly restricted to the New World tropics. The evolutionary dynamics that shaped phyllostomid climatic niches remain unclear, and a broad phylogenetic perspective is required to uncover their patterns. We used geographical distributions and evolutionary relationships of 130 species, climate data and phylogenetic comparative methods to uncover dynamics of phyllostomid climatic niche evolution. Diversification of climatic niches began early in phyllostomid evolution (~34 Mya), with most changes taking place ~20 Mya. Although most of these bats were found in tropical regions, shifts towards different evolutionary optima were common. Shifts were mostly towards temperate climates, reflecting complexities in phyllostomid evolution highlighted by the probable role of species-specific adaptations to cope with these climates, the influence of palaeoclimatic events, and biogeographical effects related to the evolution and dispersal of clades in the New World. Our results broaden our understanding of the relationships between phyllostomid bats and climate, filling an important gap in knowledge and suggesting a complex evolution in their occupation of the climatic niche space.
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Merlis, Timothy M., e Tapio Schneider. "Changes in Zonal Surface Temperature Gradients and Walker Circulations in a Wide Range of Climates". Journal of Climate 24, n. 17 (settembre 2011): 4757–68. http://dx.doi.org/10.1175/2011jcli4042.1.
Testo completoAbstract (sommario):
Variations in zonal surface temperature gradients and zonally asymmetric tropical overturning circulations (Walker circulations) are examined over a wide range of climates simulated with an idealized atmospheric general circulation model (GCM). The asymmetry in the tropical climate is generated by an imposed ocean energy flux, which does not vary with climate. The range of climates is simulated by modifying the optical thickness of an idealized longwave absorber (representing greenhouse gases). The zonal surface temperature gradient in low latitudes generally decreases as the climate warms in the idealized GCM simulations. A scaling relationship based on a two-term balance in the surface energy budget accounts for the changes in the zonally asymmetric component of the GCM-simulated surface temperature. The Walker circulation weakens as the climate warms in the idealized simulations, as it does in comprehensive simulations of climate change. The wide range of climates allows a systematic test of energetic arguments that have been proposed to account for these changes in the tropical circulation. The analysis shows that a scaling estimate based on changes in the hydrological cycle (precipitation rate and saturation specific humidity) accounts for the simulated changes in the Walker circulation. However, it must be evaluated locally, with local precipitation rates. If global-mean quantities are used, the scaling estimate does not generally account for changes in the Walker circulation, and the extent to which it does is the result of compensating errors in changes in precipitation and saturation specific humidity that enter the scaling estimate.
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Kageyama, Masa, Pascale Braconnot, Sandy P. Harrison, Alan M. Haywood, Johann H. Jungclaus, Bette L. Otto-Bliesner, Jean-Yves Peterschmitt et al. "The PMIP4 contribution to CMIP6 – Part 1: Overview and over-arching analysis plan". Geoscientific Model Development 11, n. 3 (16 marzo 2018): 1033–57. http://dx.doi.org/10.5194/gmd-11-1033-2018.
Testo completoAbstract (sommario):
Abstract. This paper is the first of a series of four GMD papers on the PMIP4-CMIP6 experiments. Part 2 (Otto-Bliesner et al., 2017) gives details about the two PMIP4-CMIP6 interglacial experiments, Part 3 (Jungclaus et al., 2017) about the last millennium experiment, and Part 4 (Kageyama et al., 2017) about the Last Glacial Maximum experiment. The mid-Pliocene Warm Period experiment is part of the Pliocene Model Intercomparison Project (PlioMIP) – Phase 2, detailed in Haywood et al. (2016).The goal of the Paleoclimate Modelling Intercomparison Project (PMIP) is to understand the response of the climate system to different climate forcings for documented climatic states very different from the present and historical climates. Through comparison with observations of the environmental impact of these climate changes, or with climate reconstructions based on physical, chemical, or biological records, PMIP also addresses the issue of how well state-of-the-art numerical models simulate climate change. Climate models are usually developed using the present and historical climates as references, but climate projections show that future climates will lie well outside these conditions. Palaeoclimates very different from these reference states therefore provide stringent tests for state-of-the-art models and a way to assess whether their sensitivity to forcings is compatible with palaeoclimatic evidence. Simulations of five different periods have been designed to address the objectives of the sixth phase of the Coupled Model Intercomparison Project (CMIP6): the millennium prior to the industrial epoch (CMIP6 name: past1000); the mid-Holocene, 6000 years ago (midHolocene); the Last Glacial Maximum, 21 000 years ago (lgm); the Last Interglacial, 127 000 years ago (lig127k); and the mid-Pliocene Warm Period, 3.2 million years ago (midPliocene-eoi400). These climatic periods are well documented by palaeoclimatic and palaeoenvironmental records, with climate and environmental changes relevant for the study and projection of future climate changes. This paper describes the motivation for the choice of these periods and the design of the numerical experiments and database requests, with a focus on their novel features compared to the experiments performed in previous phases of PMIP and CMIP. It also outlines the analysis plan that takes advantage of the comparisons of the results across periods and across CMIP6 in collaboration with other MIPs.
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Byrne, Michael P., e Tapio Schneider. "Energetic Constraints on the Width of the Intertropical Convergence Zone". Journal of Climate 29, n. 13 (14 giugno 2016): 4709–21. http://dx.doi.org/10.1175/jcli-d-15-0767.1.
Testo completoAbstract (sommario):
Abstract The intertropical convergence zone (ITCZ) has been the focus of considerable research in recent years, with much of this work concerned with how the latitude of maximum tropical precipitation responds to natural climate variability and to radiative forcing. The width of the ITCZ, however, has received little attention despite its importance for regional climate and for understanding the general circulation of the atmosphere. This paper investigates the ITCZ width in simulations with an idealized general circulation model over a wide range of climates. The ITCZ, defined as the tropical region where there is time-mean ascent, displays rich behavior as the climate varies, widening with warming in cool climates, narrowing in temperate climates, and maintaining a relatively constant width in hot climates. The mass and energy budgets of the Hadley circulation are used to derive expressions for the area of the ITCZ relative to the area of the neighboring descent region, and for the sensitivity of the ITCZ area to changes in climate. The ITCZ width depends primarily on four quantities: the net energy input to the tropical atmosphere, the advection of moist static energy by the Hadley circulation, the transport of moist static energy by transient eddies, and the gross moist stability. Different processes are important for the ITCZ width in different climates, with changes in gross moist stability generally having a weak influence relative to the other processes. The results are likely to be useful for analyzing the ITCZ width in complex climate models and for understanding past and future climate change in the tropics.
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Lewis, S. C., e A. N. LeGrande. "Stability of ENSO and its tropical Pacific teleconnections over the Last Millennium". Climate of the Past Discussions 11, n. 3 (7 maggio 2015): 1579–613. http://dx.doi.org/10.5194/cpd-11-1579-2015.
Testo completoAbstract (sommario):
Abstract. Determining past changes in the amplitude, frequency and teleconnections of the El Niño–Southern Oscillation (ENSO) is important for understanding its potential sensitivity to future anthropogenic climate change. Palaeo-reconstructions from proxy records provide long-term information of ENSO interactions with the background climatic state through time. However, it remains unclear how ENSO characteristics have changed through time, and precisely which signals proxies record. Proxy interpretations are underpinned by the assumption of stationarity in relationships between local and remote climates, and often utilise archives from single locations located in the Pacific Ocean to reconstruct ENSO histories. Here, we investigate the stationarity of ENSO teleconnections using the Last Millennium experiment of CMIP5 (Coupled Model Intercomparison Project phase 5) (Taylor et al., 2012). We show that modelled ENSO characteristics vary on decadal- to centennial-scales, resulting from internal variability and external forcings, such as tropical volcanic eruptions. Furthermore, the relationship between ENSO conditions and local climates across the Pacific basin varies throughout the Last Millennium. Results show the stability of teleconnections is regionally dependent and proxies may reveal complex changes in teleconnected patterns, rather than large-scale changes in base ENSO characteristics. As such, proxy insights into ENSO likely require evidence to be synthesised over large spatial areas in order to deconvolve changes occurring in the NINO3.4 region from those pertaining to proxy-relevant local climatic variables. To obtain robust histories of the ENSO and its remote impacts, we recommend interpretations of proxy records should be considered in conjunction with palaeo-reconstructions from within the Central Pacific.
26
Bykovskaya, Natal'ya, e Evgeniy Barishevskiy. "ASSESSMENT OF THE SUSTAINABILITY OF AGRICULTURAL PRODUCTION, TAKING INTO ACCOUNT CHANGES IN THE ENVIRONMENT". Russian Journal of Management 9, n. 3 (11 dicembre 2021): 136–40. http://dx.doi.org/10.29039/2409-6024-2021-9-3-136-140.
Testo completoAbstract (sommario):
The article on the example of the Moscow region investigated the relationship between the increase in crop yields and changes in climates - temperature, rainfall. The obtained correlation coefficients showed an inverse relationship: an increase in temperature in the summer affects a decrease in crop yields. The dependence of yields on the amount of precipitation in the warm period is moderate, stronger for vegetable crops. To adapt agricultural production in the Moscow region to climatic changes, it was proposed to introduce the development of regenerative meadow farming as climate-saving land use. The concept of "Climatefields" has been successfully tested in Germany.
27
Smith, H. J. "Climates conspire together to make big changes". Science 345, n. 6195 (24 luglio 2014): 413–14. http://dx.doi.org/10.1126/science.345.6195.413-o.
Testo completo
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Cui, Diyang, Shunlin Liang, Dongdong Wang e Zheng Liu. "A 1 km global dataset of historical (1979–2013) and future (2020–2100) Köppen–Geiger climate classification and bioclimatic variables". Earth System Science Data 13, n. 11 (4 novembre 2021): 5087–114. http://dx.doi.org/10.5194/essd-13-5087-2021.
Testo completoAbstract (sommario):
Abstract. The Köppen–Geiger classification scheme provides an effective and ecologically meaningful way to characterize climatic conditions and has been widely applied in climate change studies. Significant changes in the Köppen climates have been observed and projected in the last 2 centuries. Current accuracy, temporal coverage and spatial and temporal resolution of historical and future climate classification maps cannot sufficiently fulfill the current needs of climate change research. Comprehensive assessment of climate change impacts requires a more accurate depiction of fine-grained climatic conditions and continuous long-term time coverage. Here, we present a series of improved 1 km Köppen–Geiger climate classification maps for six historical periods in 1979–2013 and four future periods in 2020–2099 under RCP2.6, 4.5, 6.0, and 8.5. The historical maps are derived from multiple downscaled observational datasets, and the future maps are derived from an ensemble of bias-corrected downscaled CMIP5 projections. In addition to climate classification maps, we calculate 12 bioclimatic variables at 1 km resolution, providing detailed descriptions of annual averages, seasonality, and stressful conditions of climates. The new maps offer higher classification accuracy than existing climate map products and demonstrate the ability to capture recent and future projected changes in spatial distributions of climate zones. On regional and continental scales, the new maps show accurate depictions of topographic features and correspond closely with vegetation distributions. We also provide a heuristic application example to detect long-term global-scale area changes of climate zones. This high-resolution dataset of the Köppen–Geiger climate classification and bioclimatic variables can be used in conjunction with species distribution models to promote biodiversity conservation and to analyze and identify recent and future interannual or interdecadal changes in climate zones on a global or regional scale. The dataset referred to as KGClim is publicly available via http://glass.umd.edu/KGClim (Cui et al., 2021d) and can also be downloaded at https://doi.org/10.5281/zenodo.5347837 (Cui et al., 2021c) for historical climate and https://doi.org/10.5281/zenodo.4542076 (Cui et al., 2021b) for future climate.
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Rehfeld, Kira, Raphaël Hébert, Juan M. Lora, Marcus Lofverstrom e Chris M. Brierley. "Variability of surface climate in simulations of past and future". Earth System Dynamics 11, n. 2 (25 maggio 2020): 447–68. http://dx.doi.org/10.5194/esd-11-447-2020.
Testo completoAbstract (sommario):
Abstract. It is virtually certain that the mean surface temperature of the Earth will continue to increase under realistic emission scenarios, yet comparatively little is known about future changes in climate variability. This study explores changes in climate variability over the large range of climates simulated by the Coupled Model Intercomparison Project Phase 5 and 6 (CMIP5/6) and the Paleoclimate Modeling Intercomparison Project Phase 3 (PMIP3), including time slices of the Last Glacial Maximum, the mid-Holocene, and idealized experiments (1 % CO2 and abrupt4×CO2). These states encompass climates within a range of 12 ∘C in global mean temperature change. We examine climate variability from the perspectives of local interannual change, coherent climate modes, and through compositing extremes. The change in the interannual variability of precipitation is strongly dependent upon the local change in the total amount of precipitation. At the global scale, temperature variability is inversely related to mean temperature change on intra-seasonal to multidecadal timescales. This decrease is stronger over the oceans, while there is increased temperature variability over subtropical land areas (40∘ S–40∘ N) in warmer simulations. We systematically investigate changes in the standard deviation of modes of climate variability, including the North Atlantic Oscillation, the El Niño–Southern Oscillation, and the Southern Annular Mode, with global mean temperature change. While several climate modes do show consistent relationships (most notably the Atlantic Zonal Mode), no generalizable pattern emerges. By compositing extreme precipitation years across the ensemble, we demonstrate that the same large-scale modes influencing rainfall variability in Mediterranean climates persist throughout paleoclimate and future simulations. The robust nature of the response of climate variability, between cold and warm climates as well as across multiple timescales, suggests that observations and proxy reconstructions could provide a meaningful constraint on climate variability in future projections.
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Davis, Nicholas A., Dian J. Seidel, Thomas Birner, Sean M. Davis e Simone Tilmes. "Changes in the width of the tropical belt due to simple radiative forcing changes in the GeoMIP simulations". Atmospheric Chemistry and Physics 16, n. 15 (11 agosto 2016): 10083–95. http://dx.doi.org/10.5194/acp-16-10083-2016.
Testo completoAbstract (sommario):
Abstract. Model simulations of future climates predict a poleward expansion of subtropical arid climates at the edges of Earth's tropical belt, which would have significant environmental and societal impacts. This expansion may be related to the poleward shift of the Hadley cell edges, where subsidence stabilizes the atmosphere and suppresses precipitation. Understanding the primary drivers of tropical expansion is hampered by the myriad forcing agents in most model projections of future climate. While many previous studies have examined the response of idealized models to simplified climate forcings and the response of comprehensive climate models to more complex climate forcings, few have examined how comprehensive climate models respond to simplified climate forcings. To shed light on robust processes associated with tropical expansion, here we examine how the tropical belt width, as measured by the Hadley cell edges, responds to simplified forcings in the Geoengineering Model Intercomparison Project (GeoMIP). The tropical belt expands in response to a quadrupling of atmospheric carbon dioxide concentrations and contracts in response to a reduction in the solar constant, with a range of a factor of 3 in the response among nine models. Models with more surface warming and an overall stronger temperature response to quadrupled carbon dioxide exhibit greater tropical expansion, a robust result in spite of inter-model differences in the mean Hadley cell width, parameterizations, and numerical schemes. Under a scenario where the solar constant is reduced to offset an instantaneous quadrupling of carbon dioxide, the Hadley cells remain at their preindustrial width, despite the residual stratospheric cooling associated with elevated carbon dioxide levels. Quadrupled carbon dioxide produces greater tropical belt expansion in the Southern Hemisphere than in the Northern Hemisphere. This expansion is strongest in austral summer and autumn. Ozone depletion has been argued to cause this pattern of changes in observations and model experiments, but the results here indicate that seasonally and hemispherically asymmetric tropical expansion can be a basic response of the general circulation to climate forcings.
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Kindt, Roeland. "AlleleShift: an R package to predict and visualize population-level changes in allele frequencies in response to climate change". PeerJ 9 (15 giugno 2021): e11534. http://dx.doi.org/10.7717/peerj.11534.
Testo completoAbstract (sommario):
Background At any particular location, frequencies of alleles that are associated with adaptive traits are expected to change in future climates through local adaption and migration, including assisted migration (human-implemented when climate change is more rapid than natural migration rates). Making the assumption that the baseline frequencies of alleles across environmental gradients can act as a predictor of patterns in changed climates (typically future but possibly paleo-climates), a methodology is provided by AlleleShift of predicting changes in allele frequencies at the population level. Methods The prediction procedure involves a first calibration and prediction step through redundancy analysis (RDA), and a second calibration and prediction step through a generalized additive model (GAM) with a binomial family. As such, the procedure is fundamentally different to an alternative approach recently proposed to predict changes in allele frequencies from canonical correspondence analysis (CCA). The RDA step is based on the Euclidean distance that is also the typical distance used in Analysis of Molecular Variance (AMOVA). Because the RDA step or CCA approach sometimes predict negative allele frequencies, the GAM step ensures that allele frequencies are in the range of 0 to 1. Results AlleleShift provides data sets with predicted frequencies and several visualization methods to depict the predicted shifts in allele frequencies from baseline to changed climates. These visualizations include ‘dot plot’ graphics (function shift.dot.ggplot), pie diagrams (shift.pie.ggplot), moon diagrams (shift.moon.ggplot), ‘waffle’ diagrams (shift.waffle.ggplot) and smoothed surface diagrams of allele frequencies of baseline or future patterns in geographical space (shift.surf.ggplot). As these visualizations were generated through the ggplot2 package, methods of generating animations for a climate change time series are straightforward, as shown in the documentation of AlleleShift and in the supplemental videos. Availability AlleleShift is available as an open-source R package from https://cran.r-project.org/package=AlleleShift and https://github.com/RoelandKindt/AlleleShift. Genetic input data is expected to be in the adegenet::genpop format, which can be generated from the adegenet::genind format. Climate data is available from various resources such as WorldClim and Envirem.
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Torres-Amaral, Calil, Luciano Jorge Serejo dos Anjos, Ima Célia Guimarães Vieira e Everaldo Barreiros de Souza. "The climatic risk of Amazonian protected areas is driven by climate velocity until 2050". PLOS ONE 18, n. 6 (22 giugno 2023): e0286457. http://dx.doi.org/10.1371/journal.pone.0286457.
Testo completoAbstract (sommario):
Changes in species distribution in response to climate change might challenge the territorial boundaries of protected areas. Amazonia is one of the global regions most at risk of developing long distances between current and future analogous climates and the emergence of climate conditions without analogs in the past. As a result, species present within the network of Protected Areas (PAs) of Amazonia may be threatened throughout the 21st century. In this study, we investigated climate velocity based on future and past climate-analogs using forward and backward directions in the network of PAs of Amazonia, in order to assess the climatic risk of these areas to climate change and verify their effectiveness in maintaining the current climate conditions. Using current (1970–2000) and future (2041–2060) average annual air temperature and precipitation data with a resolution of 10 km, climate velocities across the entire Amazon biome and average climate velocities of PAs and Indigenous Lands (ILs) were evaluated. The results show that the effects of backward velocity will be greater than that of forward velocity in the Amazon biome. However, the PA network will be less exposed to backward velocity impacts than unprotected areas (UAs)–emphasizing the importance of these areas as a conservation tool. In contrast, for the forward velocity impacts, the PA network will be slightly more exposed than UAs–indicating that the current spatial arrangement of the PA network is still not the most suitable to minimize impacts of a possible climate redistribution. In addition, a large extent of no-analog climates for backward velocities was found in central Amazonia, indicating that high temperatures and changes in precipitation patterns in this region will surpass the historical variability of the entire biome, making it a potentially isolated and unsuitable climatic envelope for species in the future. Most of the no-analog climates are in PAs, however the climate risks in ILs should also be highlighted since they presented higher climate velocities than PAs in both metrics. Our projections contrast with the median latitudinal migration rate of 2 km/year observed in most ecosystems and taxonomic groups studied so far and suggest the need for median migration rates of 7.6 km/year. Thus, despite the important role of PAs and ILs as conservation tools, they are not immune to the effects of climate change and new management strategies, specific to each area and that allow adaptation to global changes, will be necessary.
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Schultz, Hans R. "Global Climate Change, Sustainability, and Some Challenges for Grape and Wine Production". Journal of Wine Economics 11, n. 1 (maggio 2016): 181–200. http://dx.doi.org/10.1017/jwe.2015.31.
Testo completoAbstract (sommario):
AbstractGrapevines are cultivated on six out of seven continents, between latitudes 4° and 51° in the Northern Hemisphere and between latitudes 6° and 45° in the Southern Hemisphere across a large diversity of climates (oceanic, warm oceanic, transition temperate, continental, cold continental, Mediterranean, subtropical, attenuated tropical, and arid climates). Accordingly, the range and magnitude of environmental factors differ considerably from region to region and so do the principal environmental constraints for grape production. The type, number, and magnitude of environmental constraints are currently undergoing changes due to shifts in climate patterns already observed for the past and predicted for the future. These changes are already affecting grape composition with observed changes in sugar and acidity concentrations. As with other components such as polyphenols or aroma compounds, their relationships to environmental changes are more difficult to quantify. In general, one can divide the expected climatic changes during the grape-ripening period into two scenarios: warmer and dryer and warmer and moister, with different responses for red and white grape varieties. The production challenges within this broad separation are vastly different, and the strategies to ensure a sustainable product need to be adapted accordingly. The economic impact of these changes is difficult to assess. An in-depth analysis is necessary to construct relevant scenarios and risk analysis for individual regions and to quantify the costs and/or benefits of regional climate developments. (JEL Classifications: Q1, Q54)
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Haas, Olivia, Iain Colin Prentice e Sandy P. Harrison. "The response of wildfire regimes to Last Glacial Maximum carbon dioxide and climate". Biogeosciences 20, n. 18 (28 settembre 2023): 3981–95. http://dx.doi.org/10.5194/bg-20-3981-2023.
Testo completoAbstract (sommario):
Abstract. Climate and fuel availability jointly control the incidence of wildfires. The effects of atmospheric CO2 on plant growth influence fuel availability independently of climate, but the relative importance of each in driving large-scale changes in wildfire regimes cannot easily be quantified from observations alone. Here, we use previously developed empirical models to simulate the global spatial pattern of burnt area, fire size, and fire intensity for modern and Last Glacial Maximum (LGM; ∼ 21 000 ka) conditions using both realistic changes in climate and CO2 and sensitivity experiments to separate their effects. Three different LGM scenarios are used to represent the range of modelled LGM climates. We show large, modelled reductions in burnt area at the LGM compared to the recent period, consistent with the sedimentary charcoal record. This reduction was predominantly driven by the effect of low CO2 on vegetation productivity. The amplitude of the reduction under low-CO2 conditions was similar regardless of the LGM climate scenario and was not observed in any LGM scenario when only climate effects were considered, with one LGM climate scenario showing increased burning under these conditions. Fire intensity showed a similar sensitivity to CO2 across different climates but was also sensitive to changes in vapour pressure deficit (VPD). Modelled fire size was reduced under LGM CO2 in many regions but increased under LGM climates because of changes in wind strength, dry days (DDs), and diurnal temperature range (DTR). This increase was offset under the coldest LGM climate in the northern latitudes because of a large reduction in VPD. These results emphasize the fact that the relative magnitudes of changes in different climate variables influence the wildfire regime and that different aspects of climate change can have opposing effects. The importance of CO2 effects imply that future projections of wildfire must take rising CO2 into account.
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Jansen, Malte F. "Glacial ocean circulation and stratification explained by reduced atmospheric temperature". Proceedings of the National Academy of Sciences 114, n. 1 (19 dicembre 2016): 45–50. http://dx.doi.org/10.1073/pnas.1610438113.
Testo completoAbstract (sommario):
Earth’s climate has undergone dramatic shifts between glacial and interglacial time periods, with high-latitude temperature changes on the order of 5–10 °C. These climatic shifts have been associated with major rearrangements in the deep ocean circulation and stratification, which have likely played an important role in the observed atmospheric carbon dioxide swings by affecting the partitioning of carbon between the atmosphere and the ocean. The mechanisms by which the deep ocean circulation changed, however, are still unclear and represent a major challenge to our understanding of glacial climates. This study shows that various inferred changes in the deep ocean circulation and stratification between glacial and interglacial climates can be interpreted as a direct consequence of atmospheric temperature differences. Colder atmospheric temperatures lead to increased sea ice cover and formation rate around Antarctica. The associated enhanced brine rejection leads to a strongly increased deep ocean stratification, consistent with high abyssal salinities inferred for the last glacial maximum. The increased stratification goes together with a weakening and shoaling of the interhemispheric overturning circulation, again consistent with proxy evidence for the last glacial. The shallower interhemispheric overturning circulation makes room for slowly moving water of Antarctic origin, which explains the observed middepth radiocarbon age maximum and may play an important role in ocean carbon storage.
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Levine, Xavier J., e William R. Boos. "A Mechanism for the Response of the Zonally Asymmetric Subtropical Hydrologic Cycle to Global Warming". Journal of Climate 29, n. 21 (13 ottobre 2016): 7851–67. http://dx.doi.org/10.1175/jcli-d-15-0826.1.
Testo completoAbstract (sommario):
Abstract Time-mean, zonally asymmetric circulations (hereafter referred to as stationary circulations) maintain intense hydrologic contrasts in Earth’s subtropics in the present climate, especially between monsoon regions and deserts during local summer. Such zonal contrasts in hydrology generally increase in comprehensive GCM simulations of a warming climate, yet a full understanding of stationary circulations and their contribution to the hydrologic cycle in present and future climates is lacking. This study uses an idealized moist GCM to investigate the response of subtropical stationary circulations to global warming. Stationary circulations are forced by a prescribed subtropical surface heat source, and atmospheric infrared opacity is varied to produce a wide range of climates with global-mean surface temperatures between 267 and 319 K. The strength of stationary circulations varies nonmonotonically with global mean temperature in these simulations. Zonal asymmetries in precipitation increase with temperature in climates colder than or comparable to that of Earth but remain steady or weaken in warmer climates. A novel mechanism is proposed in which this behavior is caused by the changes in tropopause height and zonal SST gradients expected to occur with global warming. Casting this mechanism in terms of the first-baroclinic mode of the tropical troposphere produces a theory that quantitatively captures the nonmonotonic dependence of stationary circulation strength on global mean temperature. Zonally asymmetric changes in precipitation minus surface evaporation (P − E) are predicted by combining this dynamical theory with the tropospheric moisture changes expected if relative humidity remains constant.
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Mutz, Sebastian G., Todd A. Ehlers, Martin Werner, Gerrit Lohmann, Christian Stepanek e Jingmin Li. "Estimates of late Cenozoic climate change relevant to Earth surface processes in tectonically active orogens". Earth Surface Dynamics 6, n. 2 (6 aprile 2018): 271–301. http://dx.doi.org/10.5194/esurf-6-271-2018.
Testo completoAbstract (sommario):
Abstract. The denudation history of active orogens is often interpreted in the context of modern climate gradients. Here we address the validity of this approach and ask what are the spatial and temporal variations in palaeoclimate for a latitudinally diverse range of active orogens? We do this using high-resolution (T159, ca. 80 × 80 km at the Equator) palaeoclimate simulations from the ECHAM5 global atmospheric general circulation model and a statistical cluster analysis of climate over different orogens (Andes, Himalayas, SE Alaska, Pacific NW USA). Time periods and boundary conditions considered include the Pliocene (PLIO, ∼ 3 Ma), the Last Glacial Maximum (LGM, ∼ 21 ka), mid-Holocene (MH, ∼ 6 ka), and pre-industrial (PI, reference year 1850). The regional simulated climates of each orogen are described by means of cluster analyses based on the variability in precipitation, 2 m air temperature, the intra-annual amplitude of these values, and monsoonal wind speeds where appropriate. Results indicate the largest differences in the PI climate existed for the LGM and PLIO climates in the form of widespread cooling and reduced precipitation in the LGM and warming and enhanced precipitation during the PLIO. The LGM climate shows the largest deviation in annual precipitation from the PI climate and shows enhanced precipitation in the temperate Andes and coastal regions for both SE Alaska and the US Pacific Northwest. Furthermore, LGM precipitation is reduced in the western Himalayas and enhanced in the eastern Himalayas, resulting in a shift of the wettest regional climates eastward along the orogen. The cluster-analysis results also suggest more climatic variability across latitudes east of the Andes in the PLIO climate than in other time slice experiments conducted here. Taken together, these results highlight significant changes in late Cenozoic regional climatology over the last ∼ 3 Myr. Comparison of simulated climate with proxy-based reconstructions for the MH and LGM reveal satisfactory to good performance of the model in reproducing precipitation changes, although in some cases discrepancies between neighbouring proxy observations highlight contradictions between proxy observations themselves. Finally, we document regions where the largest magnitudes of late Cenozoic changes in precipitation and temperature occur and offer the highest potential for future observational studies that quantify the impact of climate change on denudation and weathering rates.
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Sharafi, Saeed. "Predicting Iran’s future agro-climate variability and coherence using zonation‑based PCA". Italian Journal of Agrometeorology, n. 2 (29 gennaio 2023): 17–30. http://dx.doi.org/10.36253/ijam-1557.
Testo completoAbstract (sommario):
The effects of climate changes on agroecosystems can cause relevant issues. Using principal component analysis (PCA) we determined the 67 agricultural climate indicators (ACI) at 44 of Iran’s synoptic stations under current (1990-2019) and future (2025, 2050, 2075, and 2100) conditions. Based on UNESCO aridity index, the agroecological zonation (AEZ) was used to classify Iran’s regions (very dry, dry, semidry and humid climates). Using the PCA method, the first 5 principal components were determined by including data sets for temperature (winter, spring, summer and autumn maximum and winter minimum temperature), precipitation (winter and summer precipitation), reference evapotranspiration (ETref), and the degree of growth days in spring and winter, which explained about 96 percent of the total variance. For each climate empirical equation for ETref was selected. In order to accurate evaluation of ETref were used The Penman-Monteith based on FAO56 (PM-FAO56) for the very dry climate, the Hargreaves equation for the semidry climate, and the Penman 1 and 2 equations for the dry and humid climates, respectively. According to the results, the first component alone, with an eigenvalue of 41.15, explained more than 74 percent of the total variance. Based on the results of zoning by the PCA outcomes, the stations for 1990-2019 were classified into 7 zones. While 2025, 2050, 2075, and 2100 were classified in 6, 7, 6, and 5 zones, respectively. Under the future climatic conditions of the country, in terms of climatic indicators, the similarity between the stations will increase and the climatic diversity of the country will decline compared to current conditions. The results demonstrated that the PCA method would be valuable for monitoring AEZ in semidry climates at reasonably long periods.
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Riveras-Muñoz, Nicolás, Steffen Seitz, Kristina Witzgall, Victoria Rodríguez, Peter Kühn, Carsten W. Mueller, Rómulo Oses, Oscar Seguel, Dirk Wagner e Thomas Scholten. "Biocrust-linked changes in soil aggregate stability along a climatic gradient in the Chilean Coastal Range". SOIL 8, n. 2 (7 dicembre 2022): 717–31. http://dx.doi.org/10.5194/soil-8-717-2022.
Testo completoAbstract (sommario):
Abstract. Biological soil crusts (biocrusts) composed of cyanobacteria, bacteria, algae, fungi, lichens, and bryophytes stabilize the soil surface. This effect has mainly been studied in arid climates, where biocrusts constitute the main biological agent to stabilize and connect soil aggregates. Besides, biocrusts are an integral part of the soil surface under Mediterranean and humid climate conditions, mainly covering open spaces in forests and on denuded lands. They often develop after vegetation disturbances, when their ability to compete with vascular plants increases, acting as pioneer communities and affecting the stability of soil aggregates. To better understand how biocrusts mediate changes in soil aggregate stability under different climate conditions, we analyzed soil aggregate samples collected under biocrust communities from four national parks in Chile along a large climatic gradient ranging from (north to south) arid (Pan de Azúcar, PA), semi-arid (Santa Gracia, SG), Mediterranean (La Campana, LC) to humid (Nahuelbuta, NA). Biocrust communities showed a stabilizing effect on the soil aggregates in dry fractions for the three northern sites and the wet aggregates for the southernmost site. Here, permanent vascular plants and higher contents of organic carbon and nitrogen in the soil control aggregate stability more than biocrusts, which are in intense competition with higher plant communities. Moreover, we found an increase in stability for aggregate size classes < 2.0 and 9.5–30.0 mm. The geometric mean diameter of the soil aggregates showed a clear effect due to the climatic gradient, indicating that the aggregate stability presents a log-normal instead of a normal distribution, with a trend of low change between aggregate size fractions. Based on our results, we assume that biocrusts affect the soil structure in all climates. Their role in aggregate stability is masked under humid conditions by higher vegetation and organic matter contents in the topsoil.
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Carey, Cynthia. "The impacts of climate change on the annual cycles of birds". Philosophical Transactions of the Royal Society B: Biological Sciences 364, n. 1534 (27 novembre 2009): 3321–30. http://dx.doi.org/10.1098/rstb.2009.0182.
Testo completoAbstract (sommario):
Organisms living today are descended from ancestors that experienced considerable climate change in the past. However, they are currently presented with many new, man-made challenges, including rapid climate change. Migration and reproduction of many avian species are controlled by endogenous mechanisms that have been under intense selection over time to ensure that arrival to and departure from breeding grounds is synchronized with moderate temperatures, peak food availability and availability of nesting sites. The timing of egg laying is determined, usually by both endogenous clocks and local factors, so that food availability is near optimal for raising young. Climate change is causing mismatches in food supplies, snow cover and other factors that could severely impact successful migration and reproduction of avian populations unless they are able to adjust to new conditions. Resident (non-migratory) birds also face challenges if precipitation and/or temperature patterns vary in ways that result in mismatches of food and breeding. Predictions that many existing climates will disappear and novel climates will appear in the future suggest that communities will be dramatically restructured by extinctions and changes in range distributions. Species that persist into future climates may be able to do so in part owing to the genetic heritage passed down from ancestors who survived climate changes in the past.
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KAUR, PRABHJYOT, NAVNEET KAUR e HARPREET SINGH. "PRECIS-model simulated changes in climatic parameters under various scenarios in different agro-climatic zones of Punjab". MAUSAM 68, n. 1 (30 novembre 2021): 139–48. http://dx.doi.org/10.54302/mausam.v68i1.443.
Testo completoAbstract (sommario):
In this study,the future simulated climatic data (temperature and rainfall) for the 21st century were downscaled using the regional climate model, viz., PRECIS model (Providing Regional Climates for Impact Studies) for different agro-climatic zones, i.e., Zone II (Ballowal Saunkhri), Zone III (Ludhiana, Amritsar, Patiala and Jalandhar) and Zone V (Bathinda) of Punjab. The corrected simulated data were then analyzed on the annual and seasonal basis to quantify the changes in maximum and minimum temperature and rainfall. The study showed that the maximum and minimum temperature and rainfall by the end of 21st century are likely to increase by 2.0 to 2.2 °C, 3.3 to 5.4 °C and 33 to 66% respectively in agro-climatic zone II; by 0.4 to 5.8 °C, 2.5 to 7.4 °C and 3 to 62% respectively in agro-climatic zone III and by 0.5 to 4.0 °C, 4.7 to 7.7 °C and 58 to 69% respectively in agro-climatic zone V at different locations of Punjab state under various scenarios of climate change. The trend analysis of these parameters revealed there is positive linear increasing trend under different scenarios in the Punjab state.
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RENTON, MICHAEL, NANCY SHACKELFORD e RACHEL J. STANDISH. "How will climate variability interact with long-term climate change to affect the persistence of plant species in fragmented landscapes?" Environmental Conservation 41, n. 2 (28 novembre 2013): 110–21. http://dx.doi.org/10.1017/s0376892913000490.
Testo completoAbstract (sommario):
SUMMARYAs climates change, some plant species will need to migrate across landscapes fragmented by unsuitable environments and human activities to colonize new areas with suitable climates as previously habited areas become uninhabitable. Previous modelling of plant's migration potential has generally assumed that climate changes at a constant rate, but this ignores many potentially important aspects of real climate variability. In this study, a spatially explicit simulation model was used to investigate how interannual climate variability, the occurrence of extreme events and step changes in climate might interact with gradual long-term climate change to affect plant species’ capacity to migrate across fragmented landscapes and persist. The considered types of climate variability generally exacerbated the negative effects of long-term climate change, with a few poignant exceptions where persistence of long-lived trees improved. Strategic habitat restoration ameliorated negative effects of climate variability. Plant functional characteristics strongly influenced most results. Any modelling of how climate change may affect species persistence, and how actions such as restoration may help species adapt, should account for both short-term climate variability and long-term change.
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Baudin, François, Nathalie Combourieu-Nebout e Rainer Zahn. "Signatures of rapid climatic changes in organic matter records in the western Mediterranean Sea during the last glacial period". Bulletin de la Société Géologique de France 178, n. 1 (1 gennaio 2007): 3–13. http://dx.doi.org/10.2113/gssgfbull.178.1.3.
Testo completoAbstract (sommario):
Abstract Records of calcium carbonate, organic matter (organic carbon content, palynology) and planktonic foraminiferal oxygen isotopes from ODP Site 976, Alboran Sea, are used to reconstruct the evolution of continental climates and oceanic productivity in the westernmost Mediterranean over the past 50,000 years. The records mimic the Greenland ice core records in that they display the Heinrich events and the rapid Dansgaard/Oeschger-type stadial-interstadial oscillations. Warm interstadials correlate with an expansion of deciduous forests on the adjacent continents and enhanced river runoff and organic matter flux from terrestrial sources. In contrast, cold stadials are characterized by an expansion of semi-desert vegetation, reduced river runoff and limited terrestrial organic matter flux. The organic carbon record displays a longer-term cyclicity that correlates with the North Atlantic ’Bond’ cooling cycles. The records enable the documentation of rapid changes of continental climates in the western Mediterranean borderlands that caused changes in river runoff and in oceanic productivity that were driven by rapid fluctuations of the Atlantic inflow into the Mediterranean Sea. The combined terrestrial-marine patterns demonstrate the close linking of western Mediterranean climate with the climatic evolution in the North Atlantic region.
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Doering, C., F. Carini, M. Sato, BJ Howard, AR Harbottle, J. Brown, J. Twining e H. Velasco. "Updated soil to fruit concentration ratios for radiocaesium compiled under the IAEA MODARIA II Programme". Journal of Radiological Protection 42, n. 2 (4 maggio 2022): 020511. http://dx.doi.org/10.1088/1361-6498/ac6046.
Testo completoAbstract (sommario):
Abstract Under the International Atomic Energy Agency (IAEA) Modelling and Data for Radiological Impact Assessments (MODARIA II) Programme, Working Group 4 activities included collating radionuclide transfer data from Japan following the Fukushima Daiichi Nuclear Power Plant accident and separately collating concentration ratio (CR) data for root uptake of radionuclides by crops grown in tropical and arid climates. In this paper, the newly compiled radiocaesium CR data for fruit from Japan, tropical and arid climates have been combined with the data originally compiled for the IAEA Technical Reports Series No. 472 (TRS 472) and additional data identified from the literature to produce an enhanced MODARIA II dataset of fruit radiocaesium CR values. Statistical analysis of the MODARIA II dataset by climate class (based on the Köppen–Geiger climate classification) indicated that the CR values for tropical climates were significantly higher (p < 0.05) than those for arid, temperate and cold climates. Statistical analysis of the MODARIA II dataset by soil group (based on soil texture) indicated that the CR values for coral sand soil (tropical climates only) and organic soil (temperate climates only) were significantly higher (p < 0.05) than those for the clay, loam and sand soil groups. Statistical analysis of the MODARIA II dataset by plant group (based on plant morphology) indicated that the CR values for non-woody trees (tropical climate bias) were significantly higher (p < 0.05) than those for herbaceous plants, shrubs and woody trees. Comparison of the MODARIA II dataset with original TRS 472 values showed only small changes in the fruit radiocaesium CR values for herbaceous plants and shrubs in temperate climates. There was a decrease in the CR values for woody trees in temperate climate across all soil groups. There was also a decrease in the CR values for tropical climates for all comparable soil groups.
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Fubelli, Giandomenico, e Francesco Dramis. "Calcareous Tufa: Deposition and Erosion during Geological Times". Applied Sciences 13, n. 7 (30 marzo 2023): 4410. http://dx.doi.org/10.3390/app13074410.
Testo completoAbstract (sommario):
There is a general agreement in referring the deposition of calcareous tufa to climatic causes. Warm climates are believed to favor calcareous tufa formation due to higher concentrations of biogenic CO2 in soils, enhancing the dissolution rates of CaCO3 and the broader development of aquatic plants that remove CO2 from spring waters. Conversely, cold climates are considered less favorable because of the reduced biological activity of soils and the lesser development of aquatic plants. Dry climates are also considered unfavorable to the deposition of calcareous tufa due to scarcity of rainwater and the consequent reduction of water circulating in the ground and spring discharge contrary to humid climates, which, besides allowing abundant water infiltration and emergence, favor the spreading of vegetation cover, the development of biogenic processes in the soils, and the growth of aquatic plants. An additional factor controlling calcareous tufa deposition may be the temperature difference between the ground surface and the aquifer in connection with major climatic changes due to the low thermal conductivity of the limestone bedrock. With climate warming, the infiltrating water, made highly acidic when crossing the soil due to the elevated partial pressure of biogenic CO2 present therein, percolating through the progressively colder levels of the aquifer, induces a relevant dissolution of CaCO3, definitely higher than in normal conditions. At emergence, because of the higher surface temperatures, running water turbulence, photosynthetic activity of mosses and algae, and evaporation of spray droplets, the groundwater loses CO2, becoming oversaturated with CaCO3 and causing tufa deposition, even at a great distance from the spring. Opposite effects, such as the deposition of dissolved carbonate in the upper bedrock layers and the emergence of spring waters undersaturated with CaCO3, capable of further dissolution, are expected to occur with major climatic changes to cold conditions. This model appears to be confirmed by the deposition/erosion stages of calcareous tufa, which repeatedly occurred during the Holocene and the late Pleistocene in different parts of the world.
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Yanagihara, Hayata, So Kazama, Tsuyoshi Tada e Yoshiya Touge. "Estimation of the effect of future changes in precipitation in Japan on pluvial flood damage and the damage reduction effect of mitigation/adaptation measures". PLOS Climate 1, n. 7 (11 luglio 2022): e0000039. http://dx.doi.org/10.1371/journal.pclm.0000039.
Testo completoAbstract (sommario):
This study estimated the effect of changes in the amount of precipitation associated with climate change on pluvial flood damage and the effectiveness of mitigation and adaptation measures throughout Japan. First, the cost of damage caused by pluvial flooding was calculated based on extreme rainfall, assuming a situation in which river levels are high, and rainwater does not drain into the rivers. Additionally, extreme rainfall in future climates was estimated from the output values of five general circulation models. Then, using these figures for extreme rainfall, the cost of pluvial flood damage in future climates was estimated. Improving the maintenance level of inland water drainage facilities and converting buildings to a piloti design were selected as adaptation measures. The results showed that in the Representative Concentration Pathway (RCP) 8.5 scenario, the expected annual damage cost (EADC) in the late 21st-century climate (2081–2100) scenario increases to approximately 2.3 times that of the baseline climate (1981–2000). If climate change is mitigated to RCP 2.6, the EADC in the late 21st-century climate scenario is estimated to be reduced by 28% compared to the EADC in the RCP 8.5 scenario. It is also estimated that the EADC in future climates could be kept lower than in the baseline climate by taking multiple rather than single measures. However, in the RCP 8.5 scenario for the late 21st-century climate, even if multiple adaptation measures are taken, the EADC was estimated to increase by 9% compared to the EADC in the baseline climate.
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Bestion, Elvire, Andrea Soriano-Redondo, Julien Cucherousset, Staffan Jacob, Joël White, Lucie Zinger, Lisa Fourtune, Lucie Di Gesu, Aimeric Teyssier e Julien Cote. "Altered trophic interactions in warming climates: consequences for predator diet breadth and fitness". Proceedings of the Royal Society B: Biological Sciences 286, n. 1914 (30 ottobre 2019): 20192227. http://dx.doi.org/10.1098/rspb.2019.2227.
Testo completoAbstract (sommario):
Species interactions are central in predicting the impairment of biodiversity with climate change. Trophic interactions may be altered through climate-dependent changes in either predator food preferences or prey communities. Yet, climate change impacts on predator diet remain surprisingly poorly understood. We experimentally studied the consequences of 2°C warmer climatic conditions on the trophic niche of a generalist lizard predator. We used a system of semi-natural mesocosms housing a variety of invertebrate species and in which climatic conditions were manipulated. Lizards in warmer climatic conditions ate at a greater predatory to phytophagous invertebrate ratio and had smaller individual dietary breadths. These shifts mainly arose from direct impacts of climate on lizard diets rather than from changes in prey communities. Dietary changes were associated with negative changes in fitness-related traits (body condition, gut microbiota) and survival. We demonstrate that climate change alters trophic interactions through top-predator dietary shifts, which might disrupt eco-evolutionary dynamics.
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Parfenova, Elena I., Elena V. Bazhina, Sergei R. Kuzmin, Nina A. Kuzmina, Galina V. Kuznetsova, Vera A. Senashova, Georgy I. Antonov, Susan G. Conard e Nadezhda M. Tchebakova. "Potential Changes in Distribution of Major Conifers and Their Seed Mass across Siberia by the Mid-Twenty-First Century in a Warming Climate". Forests 15, n. 10 (25 settembre 2024): 1691. http://dx.doi.org/10.3390/f15101691.
Testo completoAbstract (sommario):
Research highlights: At the turn of the 21st century, there were more forest territories found disturbed by both natural processes (climate change, wildfires, insect outbreaks, permafrost thawing, etc.) and anthropogenic interferences (air pollution, clearcuts, etc.). Seed collecting, then growing seedlings in forest nurseries, and then planting seedlings over lost forest areas are the forestry measures needed to restore the forest after disturbances. Goals were to construct bioclimatic models of ranges and seed mass of major Siberian conifers (Siberian pine (Pinus sibirica Du Tour), Siberian fir (Abies sibirica Ledeb.), Siberian spruce (Picea obovata Ledeb.), Siberian larches (Larix sibirica Ledeb., L. gmelini (Rupr) Rupr, and L. cajanderi Mayr.) and Pinus sylvestris L.) and predict their potential change in a warming climate by the mid-century. Methods: Multi-year seed mass data were derived from the literature, seed station data, and were collected in the field. Climate data (January and July data and annual precipitation) were derived from published Russian reference books and websites on climate. Bioclimatic indices (growing degree-days > 5 C, negative degree-days < 0 C, and annual moisture index) were calculated from January and July temperatures and annual precipitation for both contemporary and the 2050s (2040–2060) climates using the general circulation model INM-CM5-0 and two climate change scenarios, ssp126 and ssp585, from CMIP6. Our bioclimatic range models (envelope and MaxEnt models) and regression seed mass models for major conifers were built based on these bioclimatic indices. Additionally, their ranges were limited by the permafrost border, which divided the forest area into the permafrost-free zone, where five conifers are able to grow, and the permafrost zone, where only one conifer, Dahurian larch, is able to survive. Results: Under warmed climates, the ranges of all Siberian conifers would expand 1.5-fold due to the decrease in the permafrost zone, except Dahurian larch, which would lose 5–20% of its coverage due to permafrost retreat. Conifers shifting northward would be slower than predicted only by warmed climates because permafrost would thaw slower than climates would warm. Scots pine may expand by up to 60%, covering dryer lands in the south. Future climates were found to favor seed mass increase for major Siberian conifers and for heavier seed to shift northward. Our major conifers differ by the type of seed dispersal mode: zoochoric, animal (Siberian pine) and anemochoric, and wind-dispersed (other five trees). The seed masses of the five anemochoric conifers varied within the range of 1.5–15 g of 1000 seeds, which is about 40–50-fold less than that of zoochoric Siberian pine. Site climate explained about 28–65% of the seed mass variation for the five anemochoric trees and only 11% for Siberian pine (zoochoric tree). This finding needs additional research to explain the reasons. Conclusions: Warmed climates would favor the expansion of the ranges of major Siberian conifers and their seed mass to be heavier, which would support the high-quality seed production for forest well-being and its restoration in Siberia.
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Kjelgren, Roger, Yongyut Trisurat, Ladawan Puangchit, Nestor Baguinon e Puay Tan Yok. "Tropical Street Trees and Climate Uncertainty in Southeast Asia". HortScience 46, n. 2 (febbraio 2011): 167–72. http://dx.doi.org/10.21273/hortsci.46.2.167.
Testo completoAbstract (sommario):
Urban trees are a critical quality of life element in rapidly growing cities in tropical climates. Tropical trees are found in a wide variety of habitats governed largely by the presence and duration of monsoonal dry periods. Tropical cities can serve as a proxy for climate change impacts of elevated carbon dioxide (CO2), urban heat island, and drought-prone root zones on successful urban trees. Understanding the native habitats of species successful as tropical urban trees can yield insights into the potential climate impact on those habitats. Species from equatorial and montane wet forests where drought stress is not a limiting factor are not used as urban trees in cities with monsoonal dry climates such as Bangkok and Bangalore. Absence of trees from a wet habitat in tropical cities in monsoonal climates is consistent with model and empirical studies suggesting wet evergreen species are vulnerable to projected climates changes such as lower rainfall and increased temperatures. However, monsoonal dry forest species appear to have wider environmental tolerances and are successful urban trees in cities with equatorial wet climates such as Singapore as well as cities with monsoonal climates such as Bangkok and Bangalore. In cities with monsoonal dry climates, deciduous tree species are more common than dry evergreen species. Although dry deciduous species generally have better floral displays, their prevalence may in part be the result of greater tolerance of urban heat islands and drought in cities; this would be consistent with modeled habitat gains at the expense of dry evergreen species in native forest stands under projected higher temperatures from climate change. Ecological models may also point to selection of more heat- and drought-tolerant species for tropical cities under projected climate change.
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Zareiee, A. R. "Evaluation of changes in different climates of Iran, using De Martonne index and Mann–Kendall trend test". Natural Hazards and Earth System Sciences Discussions 2, n. 3 (31 marzo 2014): 2245–61. http://dx.doi.org/10.5194/nhessd-2-2245-2014.
Testo completoAbstract (sommario):
Abstract. In this paper, according to the data of 40 stations in Iran during 1967–2005, changes in different climates of Iran evaluated. The De Martonne index and Mann–Kendall trend test are indexes that by uses the precipitation and temperature provide the evaluate possibility of the climate condition and pattern of climate changes. The objective of this study is to evaluation of changes in different climates in Iran. The results of this research showed that, The surface percent of Iran in the hyper arid, semi arid, humid and hyper humid type 1 climate categories have had a ascending trend, but only the ascending trend of the hyper arid category has been significant and the surface percent of the humid, hyper humid type 1 and semi arid categories have had a insignificant trend. The surface percent of Iran in the arid, Mediterranean, semi humid and hyper humid type 2 climate categories have had a descending trend, but the descending trend of the hyper humid type 2, Mediterranean and semi humid categories have been significant and the surface percent of the arid categories have had an insignificant trend. So the total results showed that, Iran is going to be more arid.