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Dombry, Clément, Mathieu Ribatet, and Stilian Stoev. "Probabilities of Concurrent Extremes." Journal of the American Statistical Association 113, no. 524 (June 12, 2018): 1565–82. http://dx.doi.org/10.1080/01621459.2017.1356318.
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Bennett, Katrina E., Carl Talsma, and Riccardo Boero. "Concurrent Changes in Extreme Hydroclimate Events in the Colorado River Basin." Water 13, no. 7 (April 1, 2021): 978. http://dx.doi.org/10.3390/w13070978.
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Extreme events resulting in catastrophic damage have more than doubled in the last five years, costing hundreds of lives and thousands of homes, and heavily undermining regional economic stability. At present, most of these hydroclimatic extreme events are documented by the media as individual events; however, in scientific terms, many are better understood as concurrent events—concurrent extremes of both temperature and precipitation (e.g., drought, floods). This paper considers concurrent changes in hydroclimate extremes, including heatwaves, drought, flooding, and low flows, in six historical-to-future (1970–1999, 2070–2099) Earth System Model (ESM) climate scenarios for the Colorado River basin. Results indicate that temperature-driven Impacts (heatwaves, drought) have the strongest responses while precipitation-driven Impacts have weaker responses. All Impacts exhibit an increase in magnitude from synoptic to annual time scales, with heatwaves increasing in strength about three times at the annual time scale versus the synoptic, while low flows only increase slightly. Critical watersheds in the Colorado were identified, highlighting the Blue River basin, Uncompahgre, East Taylor, Salt/Verde watersheds, locations of important water infrastructures, water resources, and hydrological research. Our results indicate that concurrent extreme hydroclimate events are projected to increase in the future and intensify within critical regions of the Colorado River basin. Considering extreme hydroclimate events concurrently is an important step towards linking economic and social effects of these events and their associated instabilities on a regional scale.
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Batibeniz, Fulden, Mathias Hauser, and Sonia Isabelle Seneviratne. "Countries most exposed to individual and concurrent extremes and near-permanent extreme conditions at different global warming levels." Earth System Dynamics 14, no. 2 (April 26, 2023): 485–505. http://dx.doi.org/10.5194/esd-14-485-2023.
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Abstract. It is now certain that human-induced climate change is increasing the incidence of extreme temperature, precipitation and drought events globally. A critical aspect of these extremes is their potential concurrency that can result in substantial impacts on society and environmental systems. Therefore, quantifying concurrent extremes in current and projected climate is necessary to take measures and adapt to future challenges associated with such conditions. Here we investigate changes in individual and concurrent extremes in multi-model simulations of the sixth phase of the Coupled Model Intercomparison Project (CMIP6) for different global warming levels (GWLs). We focus on the individual and simultaneous occurrence of the extreme events, encompassing heatwaves, droughts, maximum 1 d precipitation (Rx1day), and extreme wind (wind), as well as the compound events heatwave–drought and Rx1day–wind in the pre-industrial period (1850–1900; reference period), for approximately present conditions (+1 ∘C of global warming), and at three higher global warming levels (GWLs of +1.5, +2 and +3 ∘C). We focus our analysis on 139 countries and three climatic macro-regions: northern mid- and high-latitude countries (MHC), subtropical countries (STC), and tropical countries (TRC). We find that, on a global scale, most individual extremes become more frequent and affect more land area for higher GWLs. Changes in frequency of individual heatwaves, droughts, Rx1day and extreme wind with higher GWLs cause shifts in timing and disproportionate increases in frequency of concurrent events across different months and different regions. As a result, concurrent occurrences of the investigated extremes become 2.0 to 9.6 times more frequent at +3 ∘C of global warming compared to the pre-industrial period. At +3 ∘C the most dramatic increase is identified for concurrent heatwave–drought events, with a 9.6-times increase for MHC, an 8.4-times increase for STC and a 6.8-times increase for TRC compared to the pre-industrial period. By contrast, Rx1day–wind events increased the most in TRC (5.3 times), followed by STC (2.3 times) and MHC (2.0 times) at +3 ∘C with respect to the pre-industrial period. Based on the 2015 population, these frequency changes imply an increase in the number of concurrent heatwave–drought (Rx1day–wind) events per capita for 82 % (41 %) of countries. Our results also suggest that there are almost no time periods (on average 0 or only 1 month per year) without heatwaves, droughts, Rx1day and extreme wind for 21 countries at +1.5 ∘C of global warming, 37 countries at +2 ∘C and 85 countries at +3 ∘C, compared to 2 countries at +1 ∘C of global warming. This shows that a large number of countries will shift to near-permanent extreme conditions even at global warming levels consistent with the limits of the Paris Agreement. Given the projected disproportionate frequency increases and decreasing non-event months across GWLs, our results strongly emphasize the risks of uncurbed greenhouse gas emissions.
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De Luca, Paolo, Gabriele Messori, Robert L. Wilby, Maurizio Mazzoleni, and Giuliano Di Baldassarre. "Concurrent wet and dry hydrological extremes at the global scale." Earth System Dynamics 11, no. 1 (March 10, 2020): 251–66. http://dx.doi.org/10.5194/esd-11-251-2020.
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Abstract. Multi-hazard events can be associated with larger socio-economic impacts than single-hazard events. Understanding the spatio-temporal interactions that characterize the former is therefore of relevance to disaster risk reduction measures. Here, we consider two high-impact hazards, namely wet and dry hydrological extremes, and quantify their global co-occurrence. We define these using the monthly self-calibrated Palmer Drought Severity Index based on the Penman–Monteith model (sc_PDSI_pm), covering the period 1950–2014, at 2.5∘ horizontal resolution. We find that the land areas affected by extreme wet, dry, and wet–dry events (i.e. geographically remote yet temporally co-occurring wet or dry extremes) are all increasing with time, the trends of which in dry and wet–dry episodes are significant (p value ≪ 0.01). The most geographically widespread wet–dry event was associated with the strong La Niña in 2010. This caused wet–dry anomalies across a land area of 21 million km2 with documented high-impact flooding and drought episodes spanning diverse regions. To further elucidate the interplay of wet and dry extremes at a grid cell scale, we introduce two new metrics: the wet–dry (WD) ratio and the extreme transition (ET) time intervals. The WD ratio measures the relative occurrence of wet or dry extremes, whereas ET quantifies the average separation time of hydrological extremes with opposite signs. The WD ratio shows that the incidence of wet extremes dominates over dry extremes in the USA, northern and southern South America, northern Europe, north Africa, western China, and most of Australia. Conversely, dry extremes are more prominent in most of the remaining regions. The median ET for wet to dry is ∼27 months, while the dry-to-wet median ET is 21 months. We also evaluate correlations between wet–dry hydrological extremes and leading modes of climate variability, namely the El Niño–Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and Atlantic Multi-decadal Oscillation (AMO). We find that ENSO and PDO have a similar influence globally, with the former significantly impacting (p value < 0.05) a larger area (18.1 % of total sc_PDSI_pm area) compared to the latter (12.0 %), whereas the AMO shows an almost inverse pattern and significantly impacts the largest area overall (18.9 %). ENSO and PDO show the most significant correlations over northern South America, the central and western USA, the Middle East, eastern Russia, and eastern Australia. On the other hand, the AMO shows significant associations over Mexico, Brazil, central Africa, the Arabian Peninsula, China, and eastern Russia. Our analysis brings new insights on hydrological multi-hazards that are of relevance to governments and organizations with globally distributed interests. Specifically, the multi-hazard maps may be used to evaluate worst-case disaster scenarios considering the potential co-occurrence of wet and dry hydrological extremes.
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Zhan, Wang, Xiaogang He, Justin Sheffield, and Eric F. Wood. "Projected Seasonal Changes in Large-Scale Global Precipitation and Temperature Extremes Based on the CMIP5 Ensemble." Journal of Climate 33, no. 13 (July 1, 2020): 5651–71. http://dx.doi.org/10.1175/jcli-d-19-0311.1.
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AbstractOver the past decades, significant changes in temperature and precipitation have been observed, including changes in the mean and extremes. It is critical to understand the trends in hydroclimatic extremes and how they may change in the future as they pose substantial threats to society through impacts on agricultural production, economic losses, and human casualties. In this study, we analyzed projected changes in the characteristics, including frequency, seasonal timing, and maximum spatial and temporal extent, as well as severity, of extreme temperature and precipitation events, using the severity–area–duration (SAD) method and based on a suite of 37 climate models archived in phase 5 of the Coupled Model Intercomparison Project (CMIP5). Comparison between the CMIP5 model estimated extreme events and an observation-based dataset [Princeton Global Forcing (PGF)] indicates that climate models have moderate success in reproducing historical statistics of extreme events. Results from the twenty-first-century projections suggest that, on top of the rapid warming indicated by a significant increase in mean temperature, there is an overall wetting trend in the Northern Hemisphere with increasing wet extremes and decreasing dry extremes, whereas the Southern Hemisphere will have more intense wet extremes. The timing of extreme precipitation events will change at different spatial scales, with the largest change occurring in southern Asia. The probability of concurrent dry/hot and wet/hot extremes is projected to increase under both RCP4.5 and RCP8.5 scenarios, whereas little change is detected in the probability of concurrent dry/cold events and only a slight decrease of the joint probability of wet/cold extremes is expected in the future.
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Huang, Whitney K., Adam H. Monahan, and Francis W. Zwiers. "Estimating concurrent climate extremes: A conditional approach." Weather and Climate Extremes 33 (September 2021): 100332. http://dx.doi.org/10.1016/j.wace.2021.100332.
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Liu, Lulu, Yuan Jiang, Jiangbo Gao, Aiqing Feng, Kewei Jiao, Shaohong Wu, Liyuan Zuo, Yuqing Li, and Rui Yan. "Concurrent Climate Extremes and Impacts on Ecosystems in Southwest China." Remote Sensing 14, no. 7 (March 31, 2022): 1678. http://dx.doi.org/10.3390/rs14071678.
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Global warming and its associated changes in temperature and precipitation have significantly affected the ecosystem in Southwest China, yet studies that integrate temperature and precipitation changes are inadequate for quantitatively assessing the impacts of extreme events on ecosystems. In this study, the return period of concurrent climate extremes characterized by precipitation deficit and extreme temperature and the spatial and temporal dynamic patterns of their impacts on ecosystems were assessed by using high-precision temperature and precipitation data, as well as NDVI and NPP data collected for the 1985–2015 period. The results show that the 2009 concurrent event had a return period of about 200 years. The return periods of individual climate factors are significantly overestimated or underestimated. Concurrent events significantly reduced the spring and annual Normalized Difference Vegetation Index (NDVI) and net primary productivity (NPP) in Southwest China. The magnitude of the reduction in vegetation greenness and productivity increased with the intensity of concurrent events. Concurrent events beginning in autumn 2009 reduced spring NDVI and NPP by 8.8% and 23%, and annual NDVI and NPP by 2.23% and 7.22%, respectively. Under future climate scenarios, the return period of concurrent events could be significantly shortened, which would have a more severe impact on regional ecosystems.
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Chatzopoulos, Thomas, Ignacio Pérez Domínguez, Andrea Toreti, Marcel Adenäuer, and Matteo Zampieri. "Potential impacts of concurrent and recurrent climate extremes on the global food system by 2030." Environmental Research Letters 16, no. 12 (November 22, 2021): 124021. http://dx.doi.org/10.1088/1748-9326/ac343b.
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Abstract The risk of food-supply instability is expected to increase along with the frequency and intensity of extreme agro-climatic events in many regions. Assessing the sensitivity of the global agricultural system to evolving extremes requires the probability of occurrence of such events to be estimated and their links with potential food supply and demand culminations to be established. From this perspective, in this article we implement a novel approach that can be used as a tool to inform decision-makers about the resilience of agricultural markets to climate extremes. By incorporating simulated climate-stress events into a partial-equilibrium model of interconnected agricultural commodity markets, we examine the complex manifestations of grain supply, demand and prices attributable to hazardous extremes. Market outcomes are further synthesized into coherently defined vulnerability and risk indicators. The proposed framework currently covers compound heat and water anomalies at the country level, potentially concurrent and recurrent, that impact annual crop yields and market balances in a recursive-dynamic manner until 2030. Our findings indicate that extreme-climate anomalies significantly distort expected market equilibria in the medium term. Moreover, extreme global prices may result either from climate anomalies in single key countries or from simultaneous events in many regions. Last but not least, trade and storage come forth as important alleviative mechanisms of the market uncertainty provoked by recurrent extremes.
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Contzen, Justus, Thorsten Dickhaus, and Gerrit Lohmann. "Variability and extremes: statistical validation of the Alfred Wegener Institute Earth System Model (AWI-ESM)." Geoscientific Model Development 15, no. 4 (March 3, 2022): 1803–20. http://dx.doi.org/10.5194/gmd-15-1803-2022.
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Abstract. Coupled general circulation models are of paramount importance to quantitatively assessing the magnitude of future climate change. Usual methods for validating climate models include the evaluation of mean values and covariances, but less attention is directed to the evaluation of extremal behaviour. This is a problem because many severe consequences of climate change are due to climate extremes. We present a method for model validation in terms of extreme values based on classical extreme value theory. We further discuss a clustering algorithm to detect spatial dependencies and tendencies for concurrent extremes. To illustrate these methods, we analyse precipitation extremes of the Alfred Wegener Institute Earth System Model (AWI-ESM) global climate model and from other models that take part in the Coupled Model Intercomparison Project CMIP6 and compare them to the reanalysis data set CRU TS4.04. The clustering algorithm presented here can be used to determine regions of the climate system that are then subjected to a further in-depth analysis, and there may also be applications in palaeoclimatology.
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Niggli, Laura, Christian Huggel, Veruska Muccione, Raphael Neukom, and Nadine Salzmann. "Towards improved understanding of cascading and interconnected risks from concurrent weather extremes: Analysis of historical heat and drought extreme events." PLOS Climate 1, no. 8 (August 10, 2022): e0000057. http://dx.doi.org/10.1371/journal.pclm.0000057.
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Weather extremes can affect many different assets, sectors and systems of the human environment, including human security, health and well-being. Weather extremes that compound, such as heat and drought, and their interconnected risks are complex, difficult to understand and thus a challenge for risk analysis and management, because (in intertwined systems) impacts can propagate through multiple sectors. In a warming climate, extreme concurrent heat and drought events are expected to increase in frequency, intensity and duration, posing growing risks to societies. To gain a better understanding of compound extremes and associated risks, we analyze eight historical heat and drought extreme events in Europe, Africa and Australia. We investigated and visualized the direct and indirect impact paths through different sectors and systems together with the impacts of response and adaptation measures. We found the most important cascading processes and interlinkages centered around the health, energy and agriculture and food production sectors. The key cascades result in impacts on the economy, the state and public services and ultimately also on society and culture. Our analysis shows that cascading impacts can propagate through numerous sectors with far reaching consequences, potentially being able to destabilize entire socio-economic systems. We emphasize that the future challenge in research on and adaptation to concurrent extreme events lies in the integration of assets, sectors and systems with strong interlinkages to other sectors and with a large potential for cascading impacts, but for which we cannot resort to historical experiences. Integrating approaches to deal with concurrent extreme events should furthermore consider the effects of possible response and adaptation mechanisms to increase system resilience.
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Alizadeh, Mohammad Reza, Jan Adamowski, Mohammad Reza Nikoo, Amir AghaKouchak, Philip Dennison, and Mojtaba Sadegh. "A century of observations reveals increasing likelihood of continental-scale compound dry-hot extremes." Science Advances 6, no. 39 (September 2020): eaaz4571. http://dx.doi.org/10.1126/sciadv.aaz4571.
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Using over a century of ground-based observations over the contiguous United States, we show that the frequency of compound dry and hot extremes has increased substantially in the past decades, with an alarming increase in very rare dry-hot extremes. Our results indicate that the area affected by concurrent extremes has also increased significantly. Further, we explore homogeneity (i.e., connectedness) of dry-hot extremes across space. We show that dry-hot extremes have homogeneously enlarged over the past 122 years, pointing to spatial propagation of extreme dryness and heat and increased probability of continental-scale compound extremes. Last, we show an interesting shift between the main driver of dry-hot extremes over time. While meteorological drought was the main driver of dry-hot events in the 1930s, the observed warming trend has become the dominant driver in recent decades. Our results provide a deeper understanding of spatiotemporal variation of compound dry-hot extremes.
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Hao, Zengchao, Amir AghaKouchak, and Thomas J. Phillips. "Changes in concurrent monthly precipitation and temperature extremes." Environmental Research Letters 8, no. 3 (August 1, 2013): 034014. http://dx.doi.org/10.1088/1748-9326/8/3/034014.
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Mazdiyasni, Omid, and Amir AghaKouchak. "Substantial increase in concurrent droughts and heatwaves in the United States." Proceedings of the National Academy of Sciences 112, no. 37 (August 31, 2015): 11484–89. http://dx.doi.org/10.1073/pnas.1422945112.
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A combination of climate events (e.g., low precipitation and high temperatures) may cause a significant impact on the ecosystem and society, although individual events involved may not be severe extremes themselves. Analyzing historical changes in concurrent climate extremes is critical to preparing for and mitigating the negative effects of climatic change and variability. This study focuses on the changes in concurrences of heatwaves and meteorological droughts from 1960 to 2010. Despite an apparent hiatus in rising temperature and no significant trend in droughts, we show a substantial increase in concurrent droughts and heatwaves across most parts of the United States, and a statistically significant shift in the distribution of concurrent extremes. Although commonly used trend analysis methods do not show any trend in concurrent droughts and heatwaves, a unique statistical approach discussed in this study exhibits a statistically significant change in the distribution of the data.
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White, Rachel H., Kai Kornhuber, Olivia Martius, and Volkmar Wirth. "From Atmospheric Waves to Heatwaves: A Waveguide Perspective for Understanding and Predicting Concurrent, Persistent, and Extreme Extratropical Weather." Bulletin of the American Meteorological Society 103, no. 3 (March 2022): E923—E935. http://dx.doi.org/10.1175/bams-d-21-0170.1.
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Abstract A notable number of high-impact weather extremes have occurred in recent years, often associated with persistent, strongly meandering atmospheric circulation patterns known as Rossby waves. Because of the high societal and ecosystem impacts, it is of great interest to be able to accurately project how such extreme events will change with climate change, and to predict these events on seasonal-to-subseasonal (S2S) time scales. There are multiple physical links connecting upper-atmosphere circulation patterns to surface weather extremes, and it is asking a lot of our dynamical models to accurately simulate all of these. Subsequently, our confidence in future projections and S2S forecasts of extreme events connected to Rossby waves remains relatively low. We also lack full fundamental theories for the growth and propagation of Rossby waves on the spatial and temporal scales relevant to extreme events, particularly under strongly nonlinear conditions. By focusing on one of the first links in the chain from upper-atmospheric conditions to surface extremes—the Rossby waveguide—it may be possible to circumvent some model biases in later links. To further our understanding of the nature of waveguides, links to persistent surface weather events and their representation in models, we recommend exploring these links in model hierarchies of increasing complexity, developing fundamental theory, exploiting novel large ensemble datasets, harnessing deep learning, and increased community collaboration. This would help increase understanding and confidence in both S2S predictions of extremes and of projections of the impact of climate change on extreme weather events.
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Zhou, Ping, and Zhiyong Liu. "Likelihood of concurrent climate extremes and variations over China." Environmental Research Letters 13, no. 9 (September 19, 2018): 094023. http://dx.doi.org/10.1088/1748-9326/aade9e.
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Yu, Jianjun, Anupam Kumar, Kanhu Charan Pattnayak, Jeff Obbard, and Aurel Florian Moise. "Characteristics of Compound Climate Extremes and Impacts in Singapore, 1985–2020." Climate 11, no. 3 (March 5, 2023): 58. http://dx.doi.org/10.3390/cli11030058.
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Compound weather and climate extremes have amplified impacts on natural and socioeconomic systems across the world, including Singapore. To better understand the spatial and temporal characteristics of compound climate extremes, including concurrent rainfall and wind speed, as well as dry and hot conditions, we analyzed long-term observations from 11 selected meteorological stations over the period 1985–2020. The results revealed that the north and northeastern parts of Singapore were focal points for both types of compound extremes, with a higher frequency of occurrence than the southwest of the island. Concurrent rainfall and wind speed extremes were the most prominent in December and January thanks to the northeast monsoon, while dry and hot extremes were distributed mainly in the inter-monsoon season, with peaks in March and April. A notable upward trend was also detected for mild and moderate levels of both compound climate extremes over time. According to our review of the impacts, Singapore has benefited from investments in enhanced water infrastructure; water resource availability was less affected; and flash floods were not proportionally related to the severity of climate extremes. The forests in the urban landscape of Singapore also exhibit resilience to drought.
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Zhang, Yuqing, Xiubao Sun, and Changchun Chen. "Characteristics of concurrent precipitation and wind speed extremes in China." Weather and Climate Extremes 32 (June 2021): 100322. http://dx.doi.org/10.1016/j.wace.2021.100322.
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Ye, Chongchong, Jian Sun, Miao Liu, Junnan Xiong, Ning Zong, Jian Hu, Yong Huang, Xingwu Duan, and Atsushi Tsunekawa. "Concurrent and Lagged Effects of Extreme Drought Induce Net Reduction in Vegetation Carbon Uptake on Tibetan Plateau." Remote Sensing 12, no. 15 (July 22, 2020): 2347. http://dx.doi.org/10.3390/rs12152347.
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Climatic extremes have adverse concurrent and lagged effects on terrestrial carbon cycles. Here, a concurrent effect refers to the occurrence of a latent impact during climate extremes, and a lagged effect appears sometime thereafter. Nevertheless, the uncertainties of these extreme drought effects on net carbon uptake and the recovery processes of vegetation in different Tibetan Plateau (TP) ecosystems are poorly understood. In this study, we calculated the Standardised Precipitation–Evapotranspiration Index (SPEI) based on meteorological datasets with an improved spatial resolution, and we adopted the Carnegie–Ames–Stanford approach model to develop a net primary production (NPP) dataset based on multiple datasets across the TP during 1982–2015. On this basis, we quantised the net reduction in vegetation carbon uptake (NRVCU) on the TP, investigated the spatiotemporal variability of the NPP, NRVCU and SPEI, and analysed the NRVCUs that are caused by the concurrent and lagged effects of extreme drought and the recovery times in different ecosystems. According to our results, the Qaidam Basin and most forest regions possessed a significant trend towards drought during 1982–2015 (with Slope of SPEI < 0, P < 0.05), and the highest frequency of extreme drought events was principally distributed in the Qaidam Basin, with three to six events. The annual total net reduction in vegetation carbon uptake on the TP experienced a significant downward trend from 1982 to 2015 (−0.0018 ± 0.0002 PgC year−1, P < 0.001), which was negatively correlated with annual total precipitation and annual mean temperature (P < 0.05). In spatial scale, the NRVCU decrement was widely spread (approximately 55% of grids) with 17.86% of the area displaying significant declining trends (P < 0.05), and the sharpest declining trend (Slope ≤ −2) was mainly concentrated in southeastern TP. For the alpine steppe and alpine meadow ecosystems, the concurrent and lagged effects of extreme drought induced a significant difference in NRVCU (P < 0.05), while forests presented the opposite results. The recovery time comparisons from extreme drought suggest that forests require more time (27.62% of grids ≥ 6 years) to recover their net carbon uptakes compared to grasslands. Therefore, our results emphasise that extreme drought events have stronger lagged effects on forests than on grasslands on the TP. The improved resilience of forests in coping with extreme drought should also be considered in future research.
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Loikith, Paul C., and Anthony J. Broccoli. "The Influence of Recurrent Modes of Climate Variability on the Occurrence of Winter and Summer Extreme Temperatures over North America." Journal of Climate 27, no. 4 (February 10, 2014): 1600–1618. http://dx.doi.org/10.1175/jcli-d-13-00068.1.
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Abstract The influence of the Pacific–North American (PNA) pattern, the northern annular mode (NAM), and the El Niño–Southern Oscillation (ENSO) on extreme temperature days and months over North America is examined. Associations between extreme temperature days and months are strongest with the PNA and NAM and weaker for ENSO. In general, the association with extremes tends to be stronger on monthly than daily time scales and for winter as compared to summer. Extreme temperatures are associated with the PNA and NAM in the vicinity of the centers of action of these circulation patterns; however, many extremes also occur on days when the amplitude and polarity of these patterns do not favor their occurrence. In winter, synoptic-scale, transient weather disturbances are important drivers of extreme temperature days; however, many of these smaller-scale events are concurrent with amplified PNA or NAM patterns. Associations are weaker in summer when other physical mechanisms affecting the surface energy balance, such as anomalous soil moisture content, also influence the occurrence of extreme temperatures.
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Gallant, Ailie J. E., and David J. Karoly. "A Combined Climate Extremes Index for the Australian Region." Journal of Climate 23, no. 23 (December 1, 2010): 6153–65. http://dx.doi.org/10.1175/2010jcli3791.1.
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Abstract Changes in the area of Australia experiencing concurrent temperature and rainfall extremes are investigated through the use of two combined indices. The indices describe variations between the fraction of land area experiencing extreme cold and dry or hot and wet conditions. There is a high level of agreement between the variations and trends of the indices from 1957 to 2008 when computed using (i) a spatially complete gridded dataset without rigorous quality control checks and (ii) spatially incomplete high-quality station datasets with rigorous quality control checks. Australian extremes are examined starting from 1911, which is the first time a broad-scale assessment of Australian temperature extremes has been performed prior to 1957. Over the whole country, the results show an increase in the extent of hot and wet extremes and a decrease in the extent of cold and dry extremes annually and during all seasons from 1911 to 2008 at a rate of between 1% and 2% decade−1. These trends mostly stem from changes in tropical regions during summer and spring. There are relationships between the extent of extreme maximum temperatures, precipitation, and soil moisture on interannual and decadal time scales that are similar to the relationships exhibited by variations of the means. However, the trends from 1911 to 2008 and from 1957 to 2008 are not consistent with these relationships, providing evidence that the processes causing the interannual variations and those causing the longer-term trends are different.
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An, Ning, and Zhiyan Zuo. "Changing structures of summertime heatwaves over China during 1961–2017." Science China Earth Sciences 64, no. 8 (July 20, 2021): 1242–53. http://dx.doi.org/10.1007/s11430-020-9776-3.
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AbstractDespite the prevalence of artificial separation of daytime and nighttime hot extremes, they may actually co-occur or occur sequentially. Considering their potential lead-lag configuration, this study identified an entire heatwave period as consecutive days with either daytime or nighttime hot extremes and investigated the changes of the prevalence and sequence of daytime and nighttime hot extremes during heatwaves over China from 1961 to 2017. It was found that the majority (82%) of heatwaves were compound heatwaves that had both daytime and nighttime hot extremes exceeding the 90th percentile-based thresholds, while only 7% (11%) were purely daytime (nighttime) heatwaves that contained only daytime (nighttime) hot extremes. During the entire periods of compound heatwaves, daytime hot extremes usually occurred one day or a few days before nighttime hot extremes, which was in accordance with the daily variations in radiation and meteorological conditions, such as the increasing surface humidity and cloud cover, and decreasing solar radiation during the entire heatwave periods. From 1961 to 2017, compound heatwave numbers exhibited the sharpest increase with a statistically significant trend of 0.44 times decade−1, in contrast to an insignificant trend of 0.00 times decade−1 for purely daytime heatwaves and a significant trend of 0.09 times decade−1 for purely nighttime heatwaves. Within the compound heatwave periods, hot nights were starting earlier and ending later, and numbers of concurrent daytime-nighttime hot extremes increased significantly at 0.20 days decade−1. In particular, urban area were not only subject to increasingly more frequent and longer compound heatwaves, but also to more occurrences of concurrent daytime-nighttime hot extremes with more serious impact. This study provides instructions for researchers to customize and select appropriate heatwave indices.
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Dr. Vivek Jaglan, Ms Swati, Dr Shalini Bhaskar Bajaj,. "A NOVEL MULTI GRANULARITY LOCKING SCHEME BASED ON CONCURRENT MULTI -VERSION HIERARCHICAL STRUCTURE." INFORMATION TECHNOLOGY IN INDUSTRY 9, no. 1 (March 15, 2021): 932–47. http://dx.doi.org/10.17762/itii.v9i1.221.
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We present an efficient locking scheme in a hierarchical data structure. The existing multi-granularity locking mechanism works on two extremes: fine-grained locking through which concurrency is being maximized, and coarse grained locking that is being applied to minimize the locking cost. Between the two extremes, there lies several pare to-optimal options that provide a trade-off between the concurrency that can be attained. In this work, we present a locking technique, Collaborative Granular Version Locking (CGVL) which selects an optimal locking combination to serve locking requests in a hierarchical structure. In CGVL a series of version is being maintained at each granular level which allows the simultaneous execution of read and write operation on the data item. Our study reveals that in order to achieve optimal performance the lock manager explore various locking options by converting certain non-supporting locking modes into supporting locking modes thereby improving the existing compatibility matrix of multiple granularity locking protocol. Our claim is being quantitatively validated by using a Java Sun JDK environment, which shows that our CGVL perform better compared to the state-of-the-art existing MGL methods. In particular, CGVL attains 20% reduction in execution time for the locking operation that are being carried out by considering, the following parameters: i) The number of threads ii) The number of locked object iii) The duration of critical section (CPU Cycles) which significantly supports the achievement of enhanced concurrency in terms of the number of concurrent read accesses.
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Till, Aaron, Andrew L. Rypel, Andrew Bray, and Samuel B. Fey. "Fish die-offs are concurrent with thermal extremes in north temperate lakes." Nature Climate Change 9, no. 8 (July 8, 2019): 637–41. http://dx.doi.org/10.1038/s41558-019-0520-y.
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Li, Xin, Qinglong You, Guoyu Ren, Suyan Wang, Yuqing Zhang, Jianling Yang, and Guangfen Zheng. "Concurrent droughts and hot extremes in northwest China from 1961 to 2017." International Journal of Climatology 39, no. 4 (December 13, 2018): 2186–96. http://dx.doi.org/10.1002/joc.5944.
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Zhou, Sha, A. Park Williams, Alexis M. Berg, Benjamin I. Cook, Yao Zhang, Stefan Hagemann, Ruth Lorenz, Sonia I. Seneviratne, and Pierre Gentine. "Land–atmosphere feedbacks exacerbate concurrent soil drought and atmospheric aridity." Proceedings of the National Academy of Sciences 116, no. 38 (September 3, 2019): 18848–53. http://dx.doi.org/10.1073/pnas.1904955116.
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Compound extremes such as cooccurring soil drought (low soil moisture) and atmospheric aridity (high vapor pressure deficit) can be disastrous for natural and societal systems. Soil drought and atmospheric aridity are 2 main physiological stressors driving widespread vegetation mortality and reduced terrestrial carbon uptake. Here, we empirically demonstrate that strong negative coupling between soil moisture and vapor pressure deficit occurs globally, indicating high probability of cooccurring soil drought and atmospheric aridity. Using the Global Land Atmosphere Coupling Experiment (GLACE)-CMIP5 experiment, we further show that concurrent soil drought and atmospheric aridity are greatly exacerbated by land–atmosphere feedbacks. The feedback of soil drought on the atmosphere is largely responsible for enabling atmospheric aridity extremes. In addition, the soil moisture–precipitation feedback acts to amplify precipitation and soil moisture deficits in most regions. CMIP5 models further show that the frequency of concurrent soil drought and atmospheric aridity enhanced by land–atmosphere feedbacks is projected to increase in the 21st century. Importantly, land–atmosphere feedbacks will greatly increase the intensity of both soil drought and atmospheric aridity beyond that expected from changes in mean climate alone.
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Boero, Riccardo, Carl James Talsma, Julia Andre Oliveto, and Katrina Eleanor Bennett. "Expectations of Future Natural Hazards in Human Adaptation to Concurrent Extreme Events in the Colorado River Basin." Climate 10, no. 2 (February 18, 2022): 27. http://dx.doi.org/10.3390/cli10020027.
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Human adaptation to climate change is the outcome of long-term decisions continuously made and revised by local communities. Adaptation choices can be represented by economic investment models in which the often large upfront cost of adaptation is offset by the future benefits of avoiding losses due to future natural hazards. In this context, we investigate the role that expectations of future natural hazards have on adaptation in the Colorado River basin of the USA. We apply an innovative approach that quantifies the impacts of changes in concurrent climate extremes, with a focus on flooding events. By including the expectation of future natural hazards in adaptation models, we examine how public policies can focus on this component to support local community adaptation efforts. Findings indicate that considering the concurrent distribution of several variables makes quantification and prediction of extremes easier, more realistic, and consequently improves our capability to model human systems adaptation. Hazard expectation is a leading force in adaptation. Even without assuming increases in exposure, the Colorado River basin is expected to face harsh increases in damage from flooding events unless local communities are able to incorporate climate change and expected increases in extremes in their adaptation planning and decision making.
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Tschumi, Elisabeth, Sebastian Lienert, Karin van der Wiel, Fortunat Joos, and Jakob Zscheischler. "The effects of varying drought-heat signatures on terrestrial carbon dynamics and vegetation composition." Biogeosciences 19, no. 7 (April 6, 2022): 1979–93. http://dx.doi.org/10.5194/bg-19-1979-2022.
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Abstract. The frequency and severity of droughts and heatwaves are projected to increase under global warming. However, the differential impacts of climate extremes on the terrestrial biosphere and anthropogenic CO2 sink remain poorly understood. In this study, we analyse the effects of six hypothetical climate scenarios with differing drought-heat signatures, sampled from a long stationary climate model simulation, on vegetation distribution and land carbon dynamics, as modelled by a dynamic global vegetation model (LPX-Bern v1.4). The six forcing scenarios consist of a Control scenario representing a natural climate, a Noextremes scenario featuring few droughts and heatwaves, a Nocompound scenario which allows univariate hot or dry extremes but no co-occurring extremes, a Hot scenario with frequent heatwaves, a Dry scenario with frequent droughts, and a Hotdry scenario featuring frequent concurrent hot and dry extremes. We find that a climate with no extreme events increases tree coverage by up to 10 % compared to the Control scenario and also increases ecosystem productivity as well as the terrestrial carbon pools. A climate with many heatwaves leads to an overall increase in tree coverage primarily in higher latitudes, while the ecosystem productivity remains similar to the Control scenario. In the Dry and even more so in the Hotdry scenario, tree cover and ecosystem productivity are reduced by up to −4 % compared to the Control scenario. Regionally, this value can be much larger, for example up to −80 % in mid-western USA or up to −50 % in mid-Eurasia for Hotdry tree ecosystem productivity. Depending on the vegetation type, the effects of the Hotdry scenario are stronger than the effects of the Hot and Dry scenarios combined, illustrating the importance of correctly simulating compound extremes for future impact assessment. Overall, our study illustrates how factorial model experiments can be employed to disentangle the effects of single and compound extremes.
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Vogel, M. M., J. Zscheischler, R. Wartenburger, D. Dee, and S. I. Seneviratne. "Concurrent 2018 Hot Extremes Across Northern Hemisphere Due to Human‐Induced Climate Change." Earth's Future 7, no. 7 (July 2019): 692–703. http://dx.doi.org/10.1029/2019ef001189.
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Knight, Christopher H. "Lactation and gestation in dairy cows: flexibility avoids nutritional extremes." Proceedings of the Nutrition Society 60, no. 4 (November 2001): 527–37. http://dx.doi.org/10.1079/pns2001115.
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The modern dairy cow has been selectively bred to produce large amounts of milk. Partly as a result, food consumption is considerably less than milk energy output in early lactation. It is only at 2 months or more postpartum that intake increases to the point where positive energy balance is regained, the initial production being achieved by a substantial mobilisation of body reserves. These reserves are laid down before parturition, but it is certainly not the case that the pregnant cow will accumulate adipose tissue recklessly; in the last third of pregnancy well-fed cows in good body condition exhibit reduced, not increased, appetite. There is a fine balancing act to perform. Excessive body condition at parturition quickly leads to metabolic problems such as ketosis, but cows who subsequently become too thin have increased risk of metabolic diseases such as mastitis and lameness. The biological mechanisms regulating output of milk are reasonably well understood, those controlling appetite less well so, and there has been little attempt at systematic integration of the two. The transition from pregnancy to lactation represents a major challenge to homeostasis, made more complicated in multiparous cows by the fact that much of gestation is concurrent with lactation. Herein lies the potential for nutritionally-entrained flexibility. In the wild, concurrent pregnancy and lactation only occur when nutritional conditions are favourable. If conditions are poor, rebreeding will be delayed and lactation will continue, at an energetically-sustainable level, for much longer than its ‘normal’ duration. In this way the twin energetic burdens of pregnancy and lactation are separated, and extremes are avoided. Given the increasing public concern about stresses suffered by intensively-managed dairy cows, this case may be one where commercial dairying could learn useful lessons from nature.
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Sun, Xuerong, Fei Ge, Yi Fan, Shoupeng Zhu, and Quanliang Chen. "Will population exposure to heat extremes intensify over Southeast Asia in a warmer world?" Environmental Research Letters 17, no. 4 (March 9, 2022): 044006. http://dx.doi.org/10.1088/1748-9326/ac48b6.
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Abstract Temperature extremes have increased during the past several decades and are expected to intensify under current rapid global warming over Southeast Asia (SEA). Exposure to rising temperatures in highly vulnerable regions affects populations, ecosystems, and other elements that may suffer potential losses. Here, we evaluate changes in temperature extremes and future population exposure over SEA at global warming levels (GWLs) of 2.0 °C and 3.0 °C using outputs from the Coupled Model Intercomparison Project Phase 6. Results indicate that temperature extreme indices are projected to increase over SEA at both GWLs, with more significant magnitudes at 3.0 °C. However, daily temperature ranges show a decrease. The substantial increase in total SEA population exposure to heat extremes from 730 million person–days at 2.0 °C GWL to 1200 million person–days at 3.0 °C GWL is mostly contributed by the climate change component, accounting for 48%. In addition, if global warming is restricted well below 2.0 °C, the avoided impacts in population exposure are prominent for most regions over SEA with the largest mitigation in the Philippines. Aggregate population exposure to impacts is decreased by approximately 39% at 2.0 °C GWL, while the interaction component effect, which is associated with increased population and climate change, would decrease by 53%. This indicates serious consequences for growing populations concurrent with global warming impacts if the current fossil-fueled development pathway is adhered to. The present study estimates the risks of increased temperature extremes and population exposure in a warmer future, and further emphasizes the necessity and urgency of implementing climate adaptation and mitigation strategies in SEA.
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Retief, Johan V. "Assessment of existing structures under climate change." Acta Polytechnica CTU Proceedings 36 (August 18, 2022): 6–14. http://dx.doi.org/10.14311/app.2022.36.0006.
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Assessment of the influence of human activities on recent, current, and future global and regional climate conditions and extremes has advanced sufficiently to provide a reasonable measure of its impact across the globe. The lack of concurrent adaptation of the design base for load bearing structures results mainly from the absence of a clear signal that climate change will have a significant effect on the climate actions that are accounted for in the structural design basis. The recent IPCC assessment of the physical science basis of climate change reports significant advances in observing and projecting changes in weather and climate extremes due to human influences. This provides an opportunity to reassess projections of future climate action conditions. Whilst the IPCC assessment confirms previous indications that, for example extreme wind will respond moderately globally, improvements in understanding and projecting changes show that trends will be overshadowed by uncertainties. The implication is that the design base will need to account for increasing uncertainties as climate actions are projected into the future, over the service life of existing structures, as well as those designed to current standards. The design base consequently in advance need to reflect continuous changes of existing structures.
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Titkova, T. B., E. A. Cherenkova, and V. A. Semenov. "Regional features of changes in winter extreme temperatures and precipitation in Russia in 1970–2015." Ice and Snow 58, no. 4 (December 11, 2018): 486–97. http://dx.doi.org/10.15356/2076-6734-2018-4-486-497.
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Te space-time dynamics of the occurrence of winter extreme events is investigated on the territory of Russia in 1970-2015 on the basis of daily observations at weather stations. It was found that a whole on the territory a noticeable increase in the occurrence of days with extremely high daily temperatures and daily precipitation and a decrease in the occurrence of extremely cold days was noted. Te most noticeable changes happened in the European part of Russia, where at the beginning of the XXI century occurrence of the extremes was greater than during the previous thirty years. Note also that at the beginning of XXI century in Southern Siberia increase of occurrences of both daily maximum and daily minimum temperature was concurrent. Tis combination appears to be caused by the increase in temperature variability in the region due to the alternation of winters with extreme frosts and warmer and wet winters. Te increase in the frequency of extremely high temperatures in the European part of Russia could have been caused by both general warming and the increased influence of AMO. An increase in the frequency of extreme high and low temperatures in the south of Siberia may be due to the formation of an anticyclonic circulation anomaly with a center near the coast of the Kara Sea, which is responsible for advection of cold air masses from the northeast. As well as cyclonic formation in southern Siberia, along the eastern periphery of which temperate latitudes can receive anomalously warm air from the subtropics.
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Feng, Yao, Hong Wang, Wenbin Liu, and Fubao Sun. "Global Soil Moisture–Climate Interactions during the Peak Growing Season." Journal of Climate 36, no. 4 (February 15, 2023): 1187–96. http://dx.doi.org/10.1175/jcli-d-22-0161.1.
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Abstract Soil moisture (SM) during the vegetation growing season largely affects plant transpiration and photosynthesis, and further alters the land energy and water balance through its impact on the energy partition into latent and sensible heat fluxes. To highlight the impact of strong vegetation activity, we investigate global SM–climate interactions over the peak growing season (PGS) during 1982–2015 based on multisource datasets. Results suggest widespread positive SM–precipitation (P), SM–evapotranspiration (ET), and negative SM–temperature (T) interactions with non-negligible negative SM–P, SM–ET, and positive SM–T interactions over PGS. Relative to the influence of individual climate factors on SM, the compounding effect of climate factors strengthens SM–climate interactions. Simultaneously, variations of SM are dominated by precipitation from 50°N toward the south, by evapotranspiration from 50°N toward the north, and by temperature over the Sahara, western and central Asia, and the Tibetan Plateau. Importantly, the higher probability of concurrent SM wetness and climate extremes indicates the instant response of SM wetness to extreme climate. In contrast, the resistance of vegetation partially contributes to a consequent slower response of SM dryness to extreme climate. We highlight the significance of the compounding effects of climate factors in understanding SM–climate interaction in the context of strong vegetation activity, and the response of SM wetness and dryness to climate extremes.
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Zscheischler, Jakob, Philippe Naveau, Olivia Martius, Sebastian Engelke, and Christoph C. Raible. "Evaluating the dependence structure of compound precipitation and wind speed extremes." Earth System Dynamics 12, no. 1 (January 6, 2021): 1–16. http://dx.doi.org/10.5194/esd-12-1-2021.
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Abstract. Estimating the likelihood of compound climate extremes such as concurrent drought and heatwaves or compound precipitation and wind speed extremes is important for assessing climate risks. Typically, simulations from climate models are used to assess future risks, but it is largely unknown how well the current generation of models represents compound extremes. Here, we introduce a new metric that measures whether the tails of bivariate distributions show a similar dependence structure across different datasets. We analyse compound precipitation and wind extremes in reanalysis data and different high-resolution simulations for central Europe. A state-of-the-art reanalysis dataset (ERA5) is compared to simulations with a weather model (Weather Research and Forecasting – WRF) either driven by observation-based boundary conditions or a global circulation model (Community Earth System Model – CESM) under present-day and future conditions with strong greenhouse gas forcing (Representative Concentration Pathway 8.5 – RCP8.5). Over the historical period, the high-resolution WRF simulations capture precipitation and wind extremes as well as their response to orographic effects more realistically than ERA5. Thus, WRF simulations driven by observation-based boundary conditions are used as a benchmark for evaluating the dependence structure of wind and precipitation extremes. Overall, boundary conditions in WRF appear to be the key factor in explaining differences in the dependence behaviour between strong wind and heavy precipitation between simulations. In comparison, external forcings (RCP8.5) are of second order. Our approach offers new methodological tools to evaluate climate model simulations with respect to compound extremes.
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Yoon, Jin-Ho, S.-Y. Simon Wang, Min-Hui Lo, and Wen-Ying Wu. "Concurrent increases in wet and dry extremes projected in Texas and combined effects on groundwater." Environmental Research Letters 13, no. 5 (April 20, 2018): 054002. http://dx.doi.org/10.1088/1748-9326/aab96b.
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Faranda, Davide, Gabriele Messori, and Pascal Yiou. "Diagnosing concurrent drivers of weather extremes: application to warm and cold days in North America." Climate Dynamics 54, no. 3-4 (January 21, 2020): 2187–201. http://dx.doi.org/10.1007/s00382-019-05106-3.
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Raymond, Colin, Laura Suarez-Gutierrez, Kai Kornhuber, Madeleine Pascolini-Campbell, Jana Sillmann, and Duane E. Waliser. "Increasing spatiotemporal proximity of heat and precipitation extremes in a warming world quantified by a large model ensemble." Environmental Research Letters 17, no. 3 (March 1, 2022): 035005. http://dx.doi.org/10.1088/1748-9326/ac5712.
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Abstract Increases in climate hazards and their impacts mark one of the major challenges of climate change. Situations in which hazards occur close enough to one another to result in amplified impacts, because systems are insufficiently resilient or because hazards themselves are made more severe, are of special concern. We consider projected changes in such compounding hazards using the Max Planck Institute Grand Ensemble under a moderate (RCP4.5) emissions scenario, which produces warming of about 2.25 °C between pre-industrial (1851–1880) and 2100. We find that extreme heat events occurring on three or more consecutive days increase in frequency by 100%–300%, and consecutive extreme precipitation events increase in most regions, nearly doubling for some. The chance of concurrent heat and drought leading to simultaneous maize failures in three or more breadbasket regions approximately doubles, while interannual wet-dry oscillations become at least 20% more likely across much of the subtropics. Our results highlight the importance of taking compounding climate extremes into account when looking at possible tipping points of socio-environmental systems.
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Liu, Wenbin, Fubao Sun, Yao Feng, Chao Li, Jie Chen, Yan-Fang Sang, and Qiang Zhang. "Increasing population exposure to global warm-season concurrent dry and hot extremes under different warming levels." Environmental Research Letters 16, no. 9 (August 12, 2021): 094002. http://dx.doi.org/10.1088/1748-9326/ac188f.
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AghaKouchak, Amir, Linyin Cheng, Omid Mazdiyasni, and Alireza Farahmand. "Global warming and changes in risk of concurrent climate extremes: Insights from the 2014 California drought." Geophysical Research Letters 41, no. 24 (December 18, 2014): 8847–52. http://dx.doi.org/10.1002/2014gl062308.
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Zhang, Haoyue, Chuanhao Wu, and Bill X. Hu. "Recent intensification of short‐term concurrent hot and dry extremes over the Pearl River basin, China." International Journal of Climatology 39, no. 13 (May 10, 2019): 4924–37. http://dx.doi.org/10.1002/joc.6116.
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Fedden, Sebastian, and Greville G. Corbett. "Extreme classification." Cognitive Linguistics 29, no. 4 (November 27, 2018): 633–75. http://dx.doi.org/10.1515/cog-2017-0109.
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AbstractCategorization retains its key importance in research on human cognition. It is an intellectual area where all disciplines devoted to human cognition – psychology, philosophy, anthropology, and linguistics – intersect. In language, categorization is not only a central part of lexical structure but is also salient in systems of nominal classification, notably gender and classifiers. Recent years have seen great progress in the description and analysis of nominal classification systems, so that we are now in a position to offer an account of such systems which brings cognition and typology together, providing the essential parameters for the calibration of experiments for investigating cognition. To this end, we establish the extremes of nominal classification systems, from the surprisingly simple to the surprisingly complex. We analyse the two essential components of nominal classification systems: (i) assignment, i.e. the principles (semantic or formal) which govern category assignment and (ii) exponence, i.e. the morphological means by which systems of nominal classification are expressed. We discuss extreme configurations of assignment and exponence in individual languages and extreme multiple pairings of assignment and exponence in languages with two or even more concurrent classification systems.
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Ayugi, Brian, Zhihong Jiang, Vedaste Iyakaremye, Hamida Ngoma, Hassen Babaousmail, Charles Onyutha, Victor Nnamdi Dike, Richard Mumo, and Victor Ongoma. "East African population exposure to precipitation extremes under 1.5 °C and 2.0 °C warming levels based on CMIP6 models." Environmental Research Letters 17, no. 4 (March 29, 2022): 044051. http://dx.doi.org/10.1088/1748-9326/ac5d9d.
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Abstract Understanding population exposure to precipitation-related extreme events is important for effective climate change adaptation and mitigation measures. We analyze extreme precipitation using indices (EPIs), including consecutive dry days (CDD), annual total precipitation, simple daily intensity, and the number of extremely wet days, under the past and future climatic conditions over East Africa. The exposure of the East African population to these extreme events at 1.5 °C and 2.0 °C global warming levels (GWLs) is analyzed based on Climate Model Intercomparison Project phase 6 models. Exposure is computed from extremely wet and dry days (R95p and CDD, respectively). Under both GWLs, EPIs (except CDD) averaged over East Africa are projected to increase under the Shared Socio-economic Pathways (SSP)2-4.5 and SSP5-8.5 scenarios. The largest increase in wet events will likely occur in eastern and northern Kenya. The results also reveal an intensification of precipitation extremes over Burundi, Rwanda, and some parts of Uganda. However, small changes are expected over most parts of Kenya and Tanzania. Examination of population exposure to EPIs shows that the most prominent and net intense occurrence is over Burundi, Rwanda, and some parts of Uganda. In contrast, less change is noted to occur over vast parts of Kenya and Tanzania. Meanwhile, limiting the warming target to less than 1.5 °C but not more than 2.0 °C has 37% (44.2%) and 92% (4%) less impact on the occurrence of EPIs for R95p (CDD) under SSP2-4.5 (SSP5-8.5) scenarios, respectively. The study establishes that future exposure is predominantly driven by changes in population compared to other factors such as climate or concurrent changes in climate and population (the nonlinear interaction effect). For instance, climate effects are anticipated to contribute ∼10.6% (12.6%) of the total change in population exposure under 1.5 °C (2.0 °C) warming levels, while population and interaction effects are expected to contribute ∼77.4% (71.9%) and 12% (15.5%), respectively, under 1.5 °C (2.0 °C) scenarios. Interestingly, the projected changes in regional exposure due to the interaction effects under SSP2-4.5 are greater than the climate effect, while the reverse pattern is observed under SSP5-8.5. For example, under SSP5-8.5, climate effects for 1.5 °C and 2.0 °C are larger (after population effect) with ∼3.8 × 105 (15.7%) and ∼6.1 × 105 (17.5%) billion person-mm, respectively. The high exposure noted over East Africa calls for a shift in policies to instate suitable adaptation measures to cushion the already vulnerable population.
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Zhang, Haoyue, Chuanhao Wu, Pat J. ‐F Yeh, and Bill X. Hu. "Global pattern of short‐term concurrent hot and dry extremes and its relationship to large‐scale climate indices." International Journal of Climatology 40, no. 14 (April 3, 2020): 5906–24. http://dx.doi.org/10.1002/joc.6555.
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Loikith, Paul C., and Anthony J. Broccoli. "Comparison between Observed and Model-Simulated Atmospheric Circulation Patterns Associated with Extreme Temperature Days over North America Using CMIP5 Historical Simulations." Journal of Climate 28, no. 5 (February 26, 2015): 2063–79. http://dx.doi.org/10.1175/jcli-d-13-00544.1.
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Abstract Circulation patterns associated with extreme temperature days over North America, as simulated by a suite of climate models, are compared with those obtained from observations. The authors analyze 17 coupled atmosphere–ocean general circulation models contributing to the fifth phase of the Coupled Model Intercomparison Project. Circulation patterns are defined as composites of anomalies in sea level pressure and 500-hPa geopotential height concurrent with days in the tails of temperature distribution. Several metrics used to systematically describe circulation patterns associated with extreme temperature days are applied to both the observed and model-simulated data. Additionally, self-organizing maps are employed as a means of comparing observed and model-simulated circulation patterns across the North American domain. In general, the multimodel ensemble resembles the observed patterns well, especially in areas removed from complex geographic features (e.g., mountains and coastlines). Individual model results vary; however, the majority of models capture the major features observed. The multimodel ensemble captures several key features, including regional variations in the strength and orientation of atmospheric circulation patterns associated with extreme temperatures, both near the surface and aloft, as well as variations with latitude and season. The results from this work suggest that these models can be used to comprehensively examine the role that changes in atmospheric circulation will play in projected changes in temperature extremes because of future anthropogenic climate warming.
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Cao, Qian, Alexander Gershunov, Tamara Shulgina, F. Martin Ralph, Ning Sun, and Dennis P. Lettenmaier. "Floods due to Atmospheric Rivers along the U.S. West Coast: The Role of Antecedent Soil Moisture in a Warming Climate." Journal of Hydrometeorology 21, no. 8 (August 1, 2020): 1827–45. http://dx.doi.org/10.1175/jhm-d-19-0242.1.
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AbstractPrecipitation extremes are projected to become more frequent along the U.S. West Coast due to increased atmospheric river (AR) activity, but the frequency of less intense precipitation events may decrease. Antecedent soil moisture (ASM) conditions can have a large impact on flood responses, especially if prestorm precipitation decreases. Taken together with increased antecedent evaporative demand due to warming, this would result in reduced soil moisture at the onset of extreme precipitation events. We examine the impact of ASM on AR-related floods in a warming climate in three basins that form a transect along the U.S. Pacific Coast: the Chehalis River basin in Washington, the Russian River basin in Northern California, and the Santa Margarita River basin in Southern California. We ran the Distributed Hydrology Soil Vegetation Model (DHSVM) over the three river basins using forcings downscaled from 10 global climate models (GCMs). We examined the dynamic role of ASM by comparing the changes in the largest 50, 100, and 150 extreme events in two periods, 1951–2000 and 2050–99. In the Chehalis basin, the projected fraction of AR-related extreme discharge events slightly decreases. In the Russian basin, this fraction increases, however, and more substantially so in the Santa Margarita basin. This is due to increases in AR-related extreme precipitation events, as well as the fact that the relationship of extreme precipitation to extreme discharge is strengthened by projected increases in year-to-year volatility of annual precipitation in California, which increases the likelihood of concurrent occurrence of large storms and wet ASM conditions.
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Vaghefi, Saeid Ashraf, Veruska Muccione, Raphael Neukom, Christian Huggel, and Nadine Salzmann. "Future trends in compound concurrent heat extremes in Swiss cities - An assessment considering deep uncertainty and climate adaptation options." Weather and Climate Extremes 38 (December 2022): 100501. http://dx.doi.org/10.1016/j.wace.2022.100501.
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Zhu, Ying, Xiaoli Liu, Yuqing Zhang, Changchun Chen, Liucheng Shen, Qin Ju, Ting Zhou, and Ping Xia. "The Proportional Characteristics of Daytime and Nighttime Precipitation Based on Daily Precipitation in Huai River Basin, China." Atmosphere 13, no. 8 (August 13, 2022): 1287. http://dx.doi.org/10.3390/atmos13081287.
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The daytime and nighttime precipitation proportions of daily total precipitation (especially extreme daily precipitation) are important indicators that help to understand the process of precipitation formation, which in turn helps to evaluate and improve models and reanalysis precipitation data. In this study, we used the Huai River Basin (HRB) as a case to explore the daytime and nighttime precipitation proportions of daily total precipitation based on 135 meteorological stations during 1961–2018. The total, daytime, and nighttime precipitation showed zonal distributions with high and low values in the southern and northern parts of the basin, respectively. The nighttime precipitation was slightly greater than the daytime precipitation. With the increase in precipitation intensity, the seasonal cycles of the total, daytime, and nighttime precipitation were more distinct, and precipitation mainly occurred in summer. The annual range of precipitation differences between daytime and nighttime in wet seasons showed a downward trend in 1961–2003 followed by an upward trend in 2003–2018. This reversal of annual range of precipitation around 2003 may be related to the changes in annual range of convective precipitation differences between daytime and nighttime in wet seasons. The decrease of light precipitation mainly depended on the decrease of nighttime precipitation. The contributions of nighttime precipitation events to torrential precipitation events were greater than those of daytime precipitation. The days of extreme precipitation events accounted for a very low proportion of total precipitation days, but their precipitation amount accounted for relatively high proportions of total precipitation amount. Annual extreme precipitation amount showed a slightly upward trend, which was caused by the increased nighttime precipitation. Under extreme precipitation conditions, large proportions of daytime precipitation were mainly concentrated in the southeastern parts of the HRB, whereas large proportions of nighttime precipitation were mainly concentrated in the northwestern parts of the basin. The concurrent daytime and nighttime precipitation showed slightly increasing trends, especially in the southeastern part of the basin. With the increase in daytime and nighttime precipitation, the risk of concurrent precipitation extremes in the southern part of the basin increased (shorter return period means higher risk).
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Resh, Vincent H., and David M. Rosenberg. "SPATIAL–TEMPORAL VARIABILITY AND THE STUDY OF AQUATIC INSECTS,." Canadian Entomologist 121, no. 11 (November 1989): 941–63. http://dx.doi.org/10.4039/ent121941-11.
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AbstractSpatial and temporal variability are essential considerations in the study of aquatic insects. Traditionally, these two sources of variability are treated separately; however, they should be considered together because they occur concurrently in natural systems. To illustrate this interaction, we constructed two-way variability tables in which spatial (habitat, reach or zone, system, intersystem) and temporal (within a day, within a season, within a year, year to year) scales were ordered on separate axes, and examples of concurrent spatial and temporal variability were entered at the intersects of the scales. We examined three aspects of aquatic insect life histories in lotic and lentic waters using such tables: emergence, feeding and growth, and movements and migrations. It proved easier to find examples for the stream tables than for the lake tables, perhaps because of greater spatial and temporal variability in lotic than lentic waters. Also, more papers have been published on stream than on lake insects over the last decade or so. Spatial and temporal scales at which lotic and lentic research is done were determined by examining the recent contents of five key aquatic journals (≈ 500 articles). Research on aquatic insects appears generally to be done at relatively long temporal scales, but at smaller spatial and shorter temporal scales in lotic than lentic systems. Perusal of the literature to find examples of concurrent spatial and temporal variability revealed the prevalence of a “mean-values” appproach to data analysis, in which investigators “homogenize” data to reduce spatial and temporal variability. However, it is this spatial and temporal variability that often provides an explanation of factors causing the patterns observed. A “variance” approach, in which data are disaggregated and fluctuations or extremes are considered, may be far more informative and may elucidate underlying mechanisms.
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Tombesi, Sergio, Paolo Sabbatini, Tommaso Frioni, Francesca Grisafi, Federico Barone, Paolo Zani, Alberto Palliotti, and Stefano Poni. "Grapevine Response to Stress Generated by Excessive Temperatures during the Budburst." Horticulturae 8, no. 3 (February 22, 2022): 187. http://dx.doi.org/10.3390/horticulturae8030187.
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At springtime, the formation of stem somatic traits (stem elongation and leaf growth) and reproductive activity (flowering and fruit set) occur simultaneously. They are all competing carbon sinks, with an extremely high demand for carbohydrates. The shoot growth rate is strongly related to environmental temperature, which, according to climate change scenarios, is expected to increase also in extremes. Our hypothesis was that the increase in temperature during budburst could increase the vegetative carbon sink strength reducing the carbon stock available for the reproductive activity jeopardizing flowering of the next year. In our experiment, we artificially conditioned grapevine budburst by exposing the growing shoots to different temperature regimes. Higher temperatures during the spring vegetative growth favored shoot stem extension at the detriment of shoot leaf area. This caused a reduction in vine CO2 assimilation, which, combined with the competition of the growing vegetative organs, affected the concurrent reproductive activity, with carry-over effects on the following year, resulting in a limited flower initiation in dormant buds. These results suggest that the increase in springtime temperature can alter canopy development and vine physiology, resulting in the reduction in reproductive activity with an economical negative impact on grapevine productivity.
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Donkor, Felix Kwabena, Stergios-Aristoteles Mitoulis, Sotirios Argyroudis, Hassan Aboelkhair, Juan Antonio Ballesteros Canovas, Ahmad Bashir, Ginbert Permejo Cuaton, et al. "SDG Final Decade of Action: Resilient Pathways to Build Back Better from High-Impact Low-Probability (HILP) Events." Sustainability 14, no. 22 (November 19, 2022): 15401. http://dx.doi.org/10.3390/su142215401.
Full textAbstract:
The 2030 Sustainable Development Goals (SDGs) offer a blueprint for global peace and prosperity, while conserving natural ecosystems and resources for the planet. However, factors such as climate-induced weather extremes and other High-Impact Low-Probability (HILP) events on their own can devastate lives and livelihoods. When a pandemic affects us, as COVID-19 has, any concurrent hazards interacting with it highlight additional challenges to disaster and emergency management worldwide. Such amplified effects contribute to greater societal and environmental risks, with cross-cutting impacts and exposing inequities. Hence, understanding how a pandemic affects the management of concurrent hazards and HILP is vital in disaster risk reduction practice. This study reviews the contemporary literature and utilizes data from the Emergency Events Database (EM-DAT) to unpack how multiple extreme events have interacted with the coronavirus pandemic and affected the progress in achieving the SDGs. This study is especially urgent, given the multidimensional societal impacts of the COVID-19 pandemic amidst climate change. Results indicate that mainstreaming risk management into development planning can mitigate the adverse effects of disasters. Successes in addressing compound risks have helped us understand the value of new technologies, such as the use of drones and robots to limit human exposure. Enhancing data collection efforts to enable inclusive sentinel systems can improve surveillance and effective response to future risk challenges. Stay-at-home policies put in place during the pandemic for virus containment have highlighted the need to holistically consider the built environment and socio-economic exigencies when addressing the pandemic’s physical and mental health impacts, and could also aid in the context of increasing climate-induced extreme events. As we have seen, such policies, services, and technologies, along with good nutrition, can significantly help safeguard health and well-being in pandemic times, especially when simultaneously faced with ubiquitous climate-induced extreme events. In the final decade of SDG actions, these measures may help in efforts to “Leave No One Behind”, enhance human–environment relations, and propel society to embrace sustainable policies and lifestyles that facilitate building back better in a post-pandemic world. Concerted actions that directly target the compounding effects of different interacting hazards should be a critical priority of the Sendai Framework by 2030.