Multiple possibilities for future precipitation changes in Asia under the Paris Agreement

摘要

Future precipitation changes impact the availability of water resources and related flood and drought events. Recent studies have focused on the variations in precipitation based on the Representative Concentration Pathways scenarios, which do not reflect the current mitigation commitments of the Paris Agreement to stabilize the global mean temperature below the 2.0 degrees C threshold. This paper analyzes the Asian precipitation response to emissions scenarios from warming. This response is a result of the Intended Nationally Determined Contributions (INDC) pledges (as of August 2018), which would satisfy the Paris Agreement target over the next few decades. Our results demonstrate that by the end of 21st century, mean precipitation in Asia will increase by 12.9% (11.7-14.7%) for a delayed action (No-policy) scenario, 8.0% (6.7-8.8%) for a continued mitigation action (continued INDC-pledge) scenario, and 2.4% (1.9-3.5%) and 4.4% (3.7-5.4%) for scenarios that stabilize the global mean temperature at the 1.5 and 2.0 degrees C levels, respectively. The spatial heterogeneity of precipitation changes, however, reflects the complexity of precipitation responses in future climate projections. Furthermore, heavy rainfall events will become stronger as warming increases; however, the trend of dry spell events varies depending on the region. Considering the impacts of precipitation-related extremes, we determined that the projected population exposure to heavy rainfall and dry spell events will significantly increase in most Asian regions. Limiting warming to lower levels (such as 1.5 or 2.0 degrees C) would reduce the population exposure to heavy rainfall, thereby avoiding impacts associated with precipitation extremes. These results contribute to an improved understanding of the risks related to future climate extremes. Such information is crucial for planning mitigation and adaptation activities in Asia, which is home to nearly 60% of the global population.