Additional Intensification of Seasonal Heat and Flooding Extreme Over China in a 2°C Warmer World Compared to 1.5°C

Abstract

The Paris Agreement commits to stabilizing global mean surface warming to below 2°C (above preindustrial levels) and strives to limit it to 1.5°C to mitigate the risks of anthropogenic climate change. This study explores the impacts of stabilized 1.5°C and 2°C warming in the late 21st century on seasonal climate extremes over China by using a set of coupled Earth system model simulations explicitly targeting these warming levels. Our results show that global warming levels of 1.5°C and 2°C will lead to increases in surface air temperature (precipitation) averaged over China of 1.3°C and 1.9°C (11.6% and 13.3%), respectively, compared to 1976-2005. Climate extremes over China will become more frequent in a warmer world. Relative to the 1976-2005, the frequency of events similar to the 2013 extreme hot summer in eastern China and extreme flooding during the summer of 2010 in southeastern China will increase by 16 or 33 times and 2 or 3 times, respectively, given a global temperature increase of 1.5°C or 2°C. In particular, events similar to the 2013 extreme hot summer will occur almost yearly in a 2°C warmer world. The likelihood of an event similar to the 2014 extreme hot spring in northeastern China will increase to 8% or 20% in a 1.5°C or 2°C warmer world, whereas such events were rare during 1976-2005. Given these dangerous consequences, we conclude that there are discernible benefits for China to contribute to the global decarbonization effort to limit global warming to below 1.5°C rather than 2°C. Key Points:• Global warming levels of 1.5°C and 2°C will lead to increases in surface air temperature and precipitation averaged over China • Seasonal heat and flooding extremes over China will become more frequent in a 1.5°C or 2°C warmer world • Limiting the global warming at 1.5°C rather than 2°C will substantially reduce the frequency of those seasonal climate extremes in China , W. (2018). Additional intensification of seasonal heat and flooding extreme over China in a 2°C warmer world compared to 1.5°C. Earth's Future, 6, 968-978. https://doi.

Increased population exposure to precipitation extremes under future warmer climates

“…Faced with these threats of ongoing climate change, the Paris Agreement in 2015 proposed a goal to limit the global warming to no more than 2.0°C and pursue efforts to limit the temperature increase to 1.5°C above preindustrial levels (United Nations Framework Convention on Climate Change 2015). However, the warming, even if limited to 1.5°C, would pose serious threats to the populations around the world (King and Karoly 2017, Lehner et al 2017, Jones et al 2018, Lin et al 2018. Thus, voices urging the mitigation of the risks and impacts of climate change have become loud within governmental bodies, scientific communities, and the general public in recent years.…”

Increased population exposure to extreme droughts in China due to 0.5 °C of additional warming

“…Most previous studies utilized the model outputs from the Coupled Model Intercomparison Program phase 5 (CMIP5) for periods in which the increase in GMST reaches 1.5°C and 2.0°C during the 21st century under Representative Concentration Pathway (RCP) scenarios. The substantial disadvantage of this approach is that the increases in GMST to 1.5°C and 2.0°C are only present transiently in the CMIP5 simulations, which is likely to account for the large difference in the results compared with models using the stabilized warming levels (James et al 2017, Lehner et al 2017, Lin et al 2018. Recently, the National Center for Atmospheric Research (NCAR) released a set of climate simulations specifically targeting the stabilized warming levels of 1.5°C and 2.0°C in the late 21st century using the Community Earth System Model (CESM; Sanderson et al 2017).…”

Distinctive Evolutions of Eurasian Warming and Extreme Events Before and After Global Warming Would Stabilize at 1.5 °C

“…Based on these specially designed experiments, some studies have shown that limiting global warming to 1.5°C would have weaker regional climate impacts and fewer extreme events compared to the warming of 2°C (e.g., Lehner et al, 2017;Li et al, 2018;Lin et al, 2018;Nangombe et al, 2018). Limiting the warming to 1.5°C provides substantial benefits in reducing the frequency and intensity of extreme events both seasonally Nangombe et al, 2018) and synoptically (Lehner et al, 2017;Li et al, 2018).…”

“…Based on these specially designed experiments, some studies have shown that limiting global warming to 1.5 °C would have weaker regional climate impacts and fewer extreme events compared to the warming of 2 °C (e.g., Lehner et al, ; Li et al, ; Lin et al, ; Nangombe et al, ). Limiting the warming to 1.5 °C provides substantial benefits in reducing the frequency and intensity of extreme events both seasonally (Lin et al, ; Nangombe et al, ) and synoptically (Lehner et al, ; Li et al, ). In particular, extreme temperature events (e.g., heat waves) are much more sensitive to the increase of global mean surface temperature (GMST) compared to hydrometeorological extreme events in many regions.…”