Cities are particularly vulnerable to climate risks due to their agglomeration of people, buildings and infrastructure. Differences in methodology, hazards considered, and climate models used limit ...the utility and comparability of climate studies on individual cities. Here we assess, for the first time, future changes in flood, heat-waves (HW), and drought impacts for all 571 European cities in the Urban Audit database using a consistent approach. To capture the full range of uncertainties in natural variability and climate models, we use all climate model runs from the Coupled Model Inter-comparison Project Phase 5 (CMIP5) for the RCP8.5 emissions scenario to calculate Low, Medium and High Impact scenarios, which correspond to the 10th, 50th and 90th percentiles of each hazard for each city. We find that HW days increase across all cities, but especially in southern Europe, whilst the greatest HW temperature increases are expected in central European cities. For the low impact scenario, drought conditions intensify in southern European cities while river flooding worsens in northern European cities. However, the high impact scenario projects that most European cities will see increases in both drought and river flood risks. Over 100 cities are particularly vulnerable to two or more climate impacts. Moreover, the magnitude of impacts exceeds those previously reported highlighting the substantial challenge cities face to manage future climate risks.
It has been argued that climate change is the biggest global health threat of the 21st century. The extreme high temperatures of the summer of 2003 were associated with up to seventy thousand excess ...deaths across Europe. Previous studies have attributed the meteorological event to the human influence on climate, or examined the role of heat waves on human health. Here, for the first time, we explicitly quantify the role of human activity on climate and heat-related mortality in an event attribution framework, analysing both the Europe-wide temperature response in 2003, and localised responses over London and Paris. Using publicly-donated computing, we perform many thousands of climate simulations of a high-resolution regional climate model. This allows generation of a comprehensive statistical description of the 2003 event and the role of human influence within it, using the results as input to a health impact assessment model of human mortality. We find large-scale dynamical modes of atmospheric variability remain largely unchanged under anthropogenic climate change, and hence the direct thermodynamical response is mainly responsible for the increased mortality. In summer 2003, anthropogenic climate change increased the risk of heat-related mortality in Central Paris by ∼70% and by ∼20% in London, which experienced lower extreme heat. Out of the estimated ∼315 and ∼735 summer deaths attributed to the heatwave event in Greater London and Central Paris, respectively, 64 ( 3) deaths were attributable to anthropogenic climate change in London, and 506 ( 51) in Paris. Such an ability to robustly attribute specific damages to anthropogenic drivers of increased extreme heat can inform societal responses to, and responsibilities for, climate change.
Heat waves, droughts, and compound drought and heat waves (CDHWs) have received extensive attention because of their disastrous impacts on agriculture, ecosystems, human health, and society. Here, we ...computed the heat wave magnitude index (HWMI), drought magnitude index (DMI), and compound drought and heat wave magnitude index (CDHMI) for Yangtze River Valley (YRV) from July to August during 1961–2022. We compared the large-scale atmospheric circulation characteristics of different extreme events based on these indexes. The results show that the positive center with sink motion in East Asia provides a favorable circulation background for heat wave events. Drought events are mainly affected by the zonal wave train dominated by a significant negative anomaly in Siberia and a high-pressure anomaly upstream, and a anticyclonic water vapor with strong divergence over the Yangtze River basin. During CDHW events, both anomalous systems that affect heat waves and droughts appear and strengthen simultaneously. Specifically, in the middle and upper troposphere, the positive height anomaly center in YRV expands abnormally, and the “+–+” wave train over the northern 50° N region of East Asia becomes more obvious. Therefore, the positive anomaly and water vapor anomaly brought by the two circulation patterns at different latitudes are superimposed over the YRV, leading to severe CDHWs. At the same time, the warm positive eddy center and cold negative eddy center in high latitudes exhibit more stable positive pressure features, which are conducive to the persistent development and strengthening of CDHWs. In addition, the anomalous warm sea surface temperature in western Pacific moderating the favorable circulation patterns may also promote the occurrence of CDHWs in the YRV during the same period.
An analysis of observed trends in African annual-average near-surface temperatures over the last five decades reveals drastic increases, particularly over parts of the subtropics and central tropical ...Africa. Over these regions, temperatures have been rising at more than twice the global rate of temperature increase. An ensemble of high-resolution downscalings, obtained using a single regional climate model forced with the sea-surface temperatures and sea-ice fields of an ensemble of global circulation model (GCM) simulations, is shown to realistically represent the relatively strong temperature increases observed in subtropical southern and northern Africa. The amplitudes of warming are generally underestimated, however. Further warming is projected to occur during the 21st century, with plausible increases of 4-6 °C over the subtropics and 3-5 °C over the tropics by the end of the century relative to present-day climate under the A2 (a low mitigation) scenario of the Special Report on Emission Scenarios. High impact climate events such as heat-wave days and high fire-danger days are consistently projected to increase drastically in their frequency of occurrence. General decreases in soil-moisture availability are projected, even for regions where increases in rainfall are plausible, due to enhanced levels of evaporation. The regional dowscalings presented here, and recent GCM projections obtained for Africa, indicate that African annual-averaged temperatures may plausibly rise at about 1.5 times the global rate of temperature increase in the subtropics, and at a somewhat lower rate in the tropics. These projected increases although drastic, may be conservative given the model underestimations of observed temperature trends. The relatively strong rate of warming over Africa, in combination with the associated increases in extreme temperature events, may be key factors to consider when interpreting the suitability of global mitigation targets in terms of African climate change and climate change adaptation in Africa.
Heat Waves Straughan, Brian
2011, 20110624, 2011-07-23, Volume:
177
eBook
Open access
This book surveys significant modern contributions to the mathematical theories of generalized heat wave equations. The first three chapters form a comprehensive survey of most modern contributions ...also describing in detail the mathematical properties of each model. Acceleration waves and shock waves are the focus in the next two chapters. Numerical techniques, continuous data dependence, and spatial stability of the solution in a cylinder, feature prominently among other topics treated in the following two chapters. The final two chapters are devoted to a description of selected applications and the corresponding formation of mathematical models. Illustrations are taken from a broad range that includes nanofluids, porous media, thin films, nuclear reactors, traffic flow, biology, and medicine, all of contemporary active technological importance and interest. This book will be of value to applied mathematicians, theoretical engineers and other practitioners who wish to know both the theory and its relevance to diverse applications.
The objective of this paper is to review statistical methods, dynamics, modeling efforts, and trends related to temperature extremes, with a focus upon extreme events of short duration that affect ...parts of North America. These events are associated with large scale meteorological patterns (LSMPs). The statistics, dynamics, and modeling sections of this paper are written to be autonomous and so can be read separately. Methods to define extreme events statistics and to identify and connect LSMPs to extreme temperature events are presented. Recent advances in statistical techniques connect LSMPs to extreme temperatures through appropriately defined covariates that supplement more straightforward analyses. Various LSMPs, ranging from synoptic to planetary scale structures, are associated with extreme temperature events. Current knowledge about the synoptics and the dynamical mechanisms leading to the associated LSMPs is incomplete. Systematic studies of: the physics of LSMP life cycles, comprehensive model assessment of LSMP-extreme temperature event linkages, and LSMP properties are needed. Generally, climate models capture observed properties of heat waves and cold air outbreaks with some fidelity. However they overestimate warm wave frequency and underestimate cold air outbreak frequency, and underestimate the collective influence of low-frequency modes on temperature extremes. Modeling studies have identified the impact of large-scale circulation anomalies and land–atmosphere interactions on changes in extreme temperatures. However, few studies have examined changes in LSMPs to more specifically understand the role of LSMPs on past and future extreme temperature changes. Even though LSMPs are resolvable by global and regional climate models, they are not necessarily well simulated. The paper concludes with unresolved issues and research questions.
Heat wave (HW) and severe heat wave (SHW) events are the manifestations of extreme temperature causing an array of impacts on health, ecosystem, and economy. Since the mid‐20th century, an increasing ...trend in the characteristics of heat waves has been observed over India causing an increased rate in human mortality. Our study aimed to analyse monthly, seasonal, and decadal variations along with long‐term trends of HW and SHW events for pre‐monsoon (March–May) and early summer monsoon (June–July) season during 1951–2016. HW and SHW events were identified using revised criteria given by the India Meteorological Department (IMD) using daily gridded maximum temperature data at 0.5° × 0.5° resolution from IMD. The study found a Spatio‐temporal shift in the occurrence of HW events with a significantly increasing trend in three prominent heat wave prone regions that is northwestern, central, and south‐central India, the highest being in West Madhya Pradesh (0.80 events/year), while a significantly decreasing trend was observed over an eastern region that is Gangetic West Bengal (−0.13events/year). SHW events showed a southward expansion and a spatial surge during the decades of 2001–2010 and 2010–2016. Tri‐decadal comparative assessment shows a decadal increase of around 12 HW and 5 SHW events post the 1980s. State‐wise Pearson's correlation between HW/SHW events and observed mortality reveals that the eastern coastal states that are Odisha and Andhra Pradesh show a significant positive correlation of 0.62 and 0.73, respectively. This significantly increasing trend in HW and SHW events may pose a grave risk to human health, predominantly on the vulnerable sections of the society. Heat waves need to be recognized as a potential health risk and demand further study, robust preparedness, and policy intervention.
Long term increasing and decreasing trend of seasonal heat wave and severe heat wave events during 1951–2016 (March–July) over India.
More intense heat waves are expected to occur more frequently in the twenty-first century. During severe heat waves, cooling capacity shortfall and overheating are likely to occur in residential ...buildings, and this will adversely affect occupant's thermal comfort and productivity. We propose a strategy of pre-cooling the house during off-peak hours to mitigate overheating during heat waves. Simulation results of a prototype single-family house show that adopting the rule-based control (RBC) of pre-cooling thermostat setpoint schedule is effective in reducing thermal discomfort, and that the efficacy of pre-cooling depends upon several building characteristics. An optimized control (OC) of the thermostat setpoint schedule was developed based on the simulation of a prototype building. A simplified yet improved RBC (IRBC) pre-cooling schedule was then extracted from the OC schedule for practical implementation at a larger scale. The effects of the RBC schedule and IRBC schedule were evaluated in the King District of Fresno, which contains 814 residential buildings. Results show that both thermostat setpoint schedules can reduce overheating effectively and that IRBC is slightly better than RBC for most buildings. The findings support the California government's recommendation on pre-cooling to mitigate overheating, which can be further improved with an optimized thermostat setpoint schedule broadcast to residents through early alert messages before a heat wave.
•Pre-cooling mitigates overheating in residential buildings during heatwaves.•Factors influencing the effectiveness of pre-cooling are investigated.•An improved rule-based schedule is extracted from an optimized schedule.•The improved rule-based schedule is tested in the King district, Fresno, California.•Results inform governments on early warning messages to residents to reduce risk.
Warmer temperatures can significantly increase the intensity of cyanobacterial harmful algal blooms (CHABs) in eutrophic freshwater ecosystems. However, few studies have examined the effects of CO2 ...enrichment in tandem with elevated temperature and/or nutrients on cyanobacterial taxa in freshwater ecosystems. Here, we observed changes in the biomass of cyanobacteria, nutrients, pH, and carbonate chemistry over a two-year period in a shallow, eutrophic freshwater lake and performed experiments to examine the effects and co-effects of CO2, temperature, and nutrient enrichment on cyanobacterial and N2-fixing (diazotrophic) communities assessed via high throughput sequencing of the 16S rRNA and nifH genes, respectively. During both years, there were significant CHABs (50–500 μg cyanobacterial chlorophyll-a L−1) and lake CO2 levels were undersaturated (≤300 μatm pCO2). NH4+ significantly increased the net growth rates of cyanobacteria as well as the biomass of the diazotrophic cyanobacterial order Nostocales under elevated and ambient CO2 conditions. In a fall experiment, the N2 fixation rates of Nostocales were significantly higher when populations were enriched with CO2 and P, relative to CO2-enriched populations that were not amended with P. During a summer experiment, N2 fixation rates increased significantly under N and CO2 - enriched conditions relative to N-enriched and ambient CO2 conditions. Nostocales dominated the diazotrophic communities of both experiments, achieving the highest relative abundance under CO2-enriched conditions when N was added in the first experiment and when CO2 and temperature were elevated in the second experiment, when N2 fixation rates also increased significantly. Collectively, this study indicates that N promotes cyanobacterial blooms including those formed by Dolichospermum and that the biomass and N2 fixation rates of diazotrophic cyanobacterial taxa may benefit from enhanced CO2 levels in eutrophic lakes.
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•Cyanobacteria of order Nostocales dominate diazotrophic communities in a eutrophic lake•Nostocales grow best under CO2 and nitrogen - enriched conditions•The negative effects of temperature on Nostocales were mitigated by CO2 enrichment•Despite the availability of nitrogen, N2 fixation increases when CO2 levels are raised•N2 fixation rates were negatively correlated with cyanobacterial growth rates
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