Human Contributions to Extreme High Temperature Events in China
Sun Ying, National Climate Center, China Meteorological Administration
Many studies have reported an increasing trend of temperature in China in the past 60 years. Also, more and more extreme high temperature events have been observed in China. With the unusually high temperature events become more and more in recent decade, long-lasting and severe societal impacts are frequently reported. Since the warming in observed global temperature is extremely likely due to the increase of greenhouse gases since 1951, and a small change in mean temperature may result in very large change in the probability of extremes, it is important to understand the causes of increased extreme high temperature events.
At global scale, it is now very likely that human influence has contributed to observed changes in the frequency and intensity of daily temperature extremes since the mid-20th century, and likely that human influence has more than doubled the probability of occurrence of heat waves in some locations. In China, several studies have shown that the increases in mean and extreme temperature in China can be attributed to anthropogenic influence. Using an optimal detection method, earlier studies show that the observed warming of annual mean temperature in China has been attributed to anthropogenic influence at the national scale. Recently, a few studies show that anthropogenic influence is clearly detectable in annual extreme temperatures over China. The anthropogenic forcing can be separated from natural forcing in signal analyses, while the influence of natural forcings cannot be detected in any analysis. There are indications that the effects of greenhouse gases and/or land use change may be separated from other anthropogenic forcings in warm extreme events. These studies indicate clear influence of anthropogenic activities on the changes of extreme events in China. However, since the attribution of climate change at regional scale is still very challenging, more relevant work is still needed.
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