Recent changes in hot and humid extreme over China

2020 ◽  
Author(s):  
Nicolas Freychet ◽  
Simon F. B. Tett ◽  
Zhongwei Yan ◽  
Zhen Li
Keyword(s):  
Heat Waves ◽  
Eastern China ◽  
Complex Interaction ◽  
Dense Network ◽  
Sharp Drop ◽  
Extreme Heat Events ◽  
Observation Network ◽  
Heat Events ◽  
Independent Model ◽  
Model Approach

<p><span>Extreme heat events are well identified as a climate threat for human health. Less studied but at least as important as heat waves, extreme hot and humid conditions can lead to conditions where human survivability is not possible because in such environments bodies cannot cool down (evaporation becomes impossible). Wet-bulb temperature (TW) is a combined measurement of dry-bulb temperature and relative humidity (RH) and can be used to study hot and humid conditions. TW summarizes the complex interaction between humidity and temperature and allows more easy analysis. Here we investigate how TW has changed in the recent decades over Eastern China, a region already identified as vulnerable to such conditions. <br></span></p><p><span>For any observational analysis, reliable datasets are needed. Temperature data have traditionally received a lot of attention from the community while humidity observation remains poorly evaluated. We used a dense network of Chinese observation and compared it with the new ERA5 reanalysis during the 1979-2017 period. A first analysis indicate a weak increase in TW in both dataset due to a sharp drop in RH around 2000s. However, a new homogenised RH data have revealed that this decrease was an artifact due to a change in Chinese observation network. Newly homogenised data show no drop in RH and consequently a much larger increase in TW. ERA5 has assimilated biased data over China and is not reliable to study TW without performing RH correction. We did so by using an independent model approach, and recalculated RH and TW in ERA5. After correction, increase in TW becomes much larger and we could identified several location with already dangerous TW levels. </span></p><p> </p>

scholarly journals Interdecadal Variations of Persistent Extreme Heat Events in Eastern China Under Global Warming

2021 ◽  
Author(s):  
Naihui Zang ◽  
Junhu Zhao ◽  
Pengcheng Yan ◽  
Han Zhang ◽  
Shankai Tang ◽  
...  
Keyword(s):  
Global Warming ◽  
21St Century ◽  
South China ◽  
North China ◽  
Eastern China ◽  
Extreme Heat ◽  
Maximum Temperature ◽  
Extreme Heat Events ◽  
June July ◽  
Heat Events

Abstract Persistent extreme heat events (PEHEs) exert a more negative impact on society, including agriculture, plant phenology, power production and human health, compared to general EHEs. The temporal and spatial characteristics of summer PEHEs in eastern China were analysed based on a daily maximum temperature dataset from 759 stations over the period of 1961–2018. The results show the following: Persistent distributions of PEHEs show that they are characterized by an exponential decay with a drop in the decay rate. In terms of spatial distribution, there is an apparent regional difference in the duration of PEHEs. North China is dominated by multi-frequency and short-duration EHEs, while South China is the opposite. PEHEs in North China and the Huanghuai region mainly occur in June-July but mostly in July and August in South China. Strongly responding to global warming, the frequency and duration of PEHEs in North China have increased since the 1990s. However, the frequency of PEHEs in North China and the Huanghuai region has shown opposite trends in June-July since the beginning of the 21st century. Affected by the atmospheric circulations, the regional differences in PEHE frequency are also apparent. Since the beginning of the 21st century, the PEHEs in North China and the Huanghuai area have shown an increasing trend in August. The short-term PEHEs in the middle and lower reaches of the Yangtze River and South China increased rapidly in the 2000s, while long-term PEHEs increased in the 2010s. This study implies that attention should be paid to not only the frequency of EH days but also to the persistence of EHE which is a key characteristic of damaging EH.

scholarly journals High-Resolution WRF Simulation of Extreme Heat Events in Eastern China: Large Sensitivity to Land Surface Schemes

2021 ◽  
Vol 9 ◽  
Author(s):  
Wenjian Hua ◽  
Xuan Dong ◽  
Qingyuan Liu ◽  
Liming Zhou ◽  
Haishan Chen ◽  
...  
Keyword(s):  
High Resolution ◽  
Land Surface ◽  
Eastern China ◽  
Extreme Heat ◽  
Surface Processes ◽  
Energy Fluxes ◽  
Land Surface Processes ◽  
Extreme Heat Events ◽  
The Relationship ◽  
Heat Events

Regional climate models with high-resolution simulation are particularly useful for providing a detailed representation of land surface processes, and for studying the relationship between land surface processes and heat events. However, large differences and uncertainties exist among different land surface schemes (LSSs). This study comprehensively assesses the sensitivity to different LSSs based on two extreme heat events in eastern China using the Weather Research and Forecasting (WRF) model. Among the five LSSs (i.e., 5TD, CLM4, Noah, Noah-MP and RUC), Noah is closest to observations in reproducing the temperatures and energy fluxes for both two heat events. The modeled warm biases result mainly from the underestimation of evapotranspirative cooling. Our results show that how each LSS partitions the evapotranspiration (ET) and sensible heat largely determines the relationship between the temperature and turbulent fluxes. Although the simulated two extreme heat events manifest similar biases in the temperatures and energy fluxes, the land surface responses (ET and soil moisture) are different.

scholarly journals The effect of forced change and unforced variability in heat waves, temperature extremes, and associated population risk in a CO<sub>2</sub>-warmed world

2021 ◽  
Vol 21 (15) ◽  
pp. 11889-11904
Author(s):  
Jangho Lee ◽  
Jeffrey C. Mast ◽  
Andrew E. Dessler
Keyword(s):  
Heat Waves ◽  
Southern Oscillation ◽  
Extreme Heat ◽  
Max Planck ◽  
Extreme Heat Events ◽  
Heat Extremes ◽  
The Impact ◽  
Global Population ◽  
Heat Events ◽  
Impacts Of Climate Change

Abstract. This study investigates the impact of global warming on heat and humidity extremes by analyzing 6 h output from 28 members of the Max Planck Institute Grand Ensemble driven by forcing from a 1 % yr−1 CO2 increase. We find that unforced variability drives large changes in regional exposure to extremes in different ensemble members, and these variations are mostly associated with El Niño–Southern Oscillation (ENSO) variability. However, while the unforced variability in the climate can alter the occurrence of extremes regionally, variability within the ensemble decreases significantly as one looks at larger regions or at a global population perspective. This means that, for metrics of extreme heat and humidity analyzed here, forced variability in the climate is more important than the unforced variability at global scales. Lastly, we found that most heat wave metrics will increase significantly between 1.5 and 2.0 ∘C, and that low gross domestic product (GDP) regions show significantly higher risks of facing extreme heat events compared to high GDP regions. Considering the limited economic adaptability of the population to heat extremes, this reinforces the idea that the most severe impacts of climate change may fall mostly on those least capable of adapting.

scholarly journals Human and natural drivers of the recent contrasting trends between daytime and nighttime hot extremes

2021 ◽  
Author(s):  
Sang-Wook Yeh ◽  
Eun-Hye Lee ◽  
Seung-Ki Min
Keyword(s):  
Climate Models ◽  
Heat Waves ◽  
Low Frequency ◽  
Extreme Heat ◽  
Boreal Summer ◽  
Human Society ◽  
Sudden Increase ◽  
Tropical Night ◽  
Extreme Heat Events ◽  
Heat Events

Abstract The frequency and duration of extreme heat events, including heat waves (HWs, daytime hot extremes) and tropical night (TNs), are increasing significantly as the climate warms, adversely affecting human health, agriculture, and energy consumption. Although many detection and attribution studies have examined extreme heat events, the underlying mechanisms associated with the recent increase in HWs and TNs remain unclear. In this study, we analyze the controlling factors behind the distinct increases in HW and TN events over the Northern Hemisphere during boreal summer (June to August). We found that the occurrence of HW events has been increasing gradually since 1980, mostly due to anthropogenic forcing. However, the occurrence of TN events increased abruptly during the late 1990s and has changed little since then. We demonstrate that this sudden increase in TN events is closely associated with low frequency variability in sea surface temperature, including the Pacific Decadal Oscillation, indicating its natural origin. We further found that CMIP5 climate models fail to capture the observed non-linear increases in TN events, implying potentially large uncertainty in future projections of nighttime heat events and its impacts on human society and ecosystem.

scholarly journals Interdecadal variations of persistent extreme heat events in eastern China under global warming

2021 ◽  
Author(s):  
Naihui Zang ◽  
Junhu Zhao ◽  
Pengcheng Yan ◽  
Han Zhang ◽  
Shankai Tang ◽  
...  
Keyword(s):  
Global Warming ◽  
Eastern China ◽  
Extreme Heat ◽  
Extreme Heat Events ◽  
Heat Events

scholarly journals Responses of tree species to heat waves and extreme heat events

2014 ◽  
Vol 38 (9) ◽  
pp. 1699-1712 ◽  
Author(s):  
ROBERT TESKEY ◽  
TIMOTHY WERTIN ◽  
INGVAR BAUWERAERTS ◽  
MAARTEN AMEYE ◽  
MARY ANNE MCGUIRE ◽  
...  
Keyword(s):  
Tree Species ◽  
Heat Waves ◽  
Extreme Heat ◽  
Extreme Heat Events ◽  
Heat Events

scholarly journals The Effect of Forced and Unforced Variability on Heat Waves, Temperature Extremes, and Associated Population Risk in a CO<sub>2</sub>-Warmed World

2021 ◽  
Author(s):  
Jangho Lee ◽  
Jeffery C. Mast ◽  
Andrew E. Dessler
Keyword(s):  
Heat Waves ◽  
Extreme Heat ◽  
Max Planck ◽  
Extreme Heat Events ◽  
Hourly Output ◽  
Heat Extremes ◽  
The Impact ◽  
Global Population ◽  
Heat Events ◽  
Impacts Of Climate Change

Abstract. This study investigates the impact of global warming on heat and humidity extremes by analyzing 6-hourly output from 28 members of the Max Planck Institute Grand Ensemble driven by forcing from a 1 %/year CO2 increase. We find that unforced variability drives large changes in regional exposure to extremes in different ensemble members, and these variations are mostly associated with ENSO variability. However, while the unforced variability of the climate can alter the occurrence of extremes regionally, variability within the ensemble decreases significantly as one looks at larger regions or at a global population perspective. This means that, for metrics of extreme heat and humidity analyzed here, forced variability of the climate is more important than the unforced variability at global scales. Lastly, we found that most heat wave metrics will increase significantly between 1.5 °C and 2.0 °C, and that low GDP regions shows significant higher risks of facing extreme heat events compared to high GDP regions. Considering the limited economic adaptability of population to heat extremes, this reinforces the idea that the most severe impacts of climate change may fall mostly on those least capable to adapt.

scholarly journals Heat waves in Hungarian plant production

2009 ◽  
Vol 15 (4) ◽  
Author(s):  
A. Révész ◽  
K. Szentteleki ◽  
L. Horváth
Keyword(s):  
Heat Waves ◽  
Economic Effect ◽  
Plant Production ◽  
Maximum Temperature ◽  
Climate Change Scenarios ◽  
Global Circulation ◽  
Global Circulation Models ◽  
Extreme Heat Events ◽  
Unconventional Methods ◽  
Heat Events

A momentous inference of heat waves is the economic effect. The main demage after the human problems will caused by theese extreme events in agriculture. For example a long hot peiod without any percipitation can exterminate not only the annual yield, but also it can demage or in extreme situation it can destroy the whole orchard. Especially endangered most of the fruits, because an extreme summer with high temperature which usually goes hand in hand with an arid period can modify growth of the plant. Our investigations show that according to the most widely accepted climate change scenarios heat waves are expected to be essentially longer and hotter than in the past. It might happen that events we now define as heat waves last through entire summer. Although it will not be general, the length and intensity of present heat waves could also multiply. Based on data provided by some global circulation models, we might be face an event that exceeds the hottest heat waves of the 20th century by as much as 12 °C. This study also offers a survey of the methodology of heat wave definition. Besides traditional calculations, we present two unconventional methods by introducing minimum and maximum temperature heat waves. We show in what points this approach is different from those usually adopted and what extra information it may offer.As an extension of the usual studies, with considering the length of events, we analyse the development of two variants – temperature and duration – and, as a result, classify the extreme heat events according to both length and intensity.

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