The Synthesis Report (SYR) is a stand-alone synthesis of the most policy-relevant evidence from the scientific, technical, and socio-economic literature assessed in the Sixth Assessment Report (AR6) of the Intergovernmental Panel on Climate Change (IPCC). The SYR distils and integrates the main findings of the three reports of the Working Groups of the IPCC during the AR6, and the three AR6 Special Reports into a concise document. It consists of a Summary for Policymakers and a longer report.
The Summary for Policymakers (SPM) of the Synthesis Report (SYR) of the Sixth Assessment Report (AR6) of the Intergovernmental Panel on Climate Change (IPCC), is a component of the SYR which provides a policy-relevant but policy-neutral summary of the SYR. It is consistent with the Sections of the SYR and is approved line by line by the Governments at a plenary session of the Intergovernmental Panel on Climate Change.
Compound drought and heat event (CDHE) causes severe impacts on agriculture, ecosystem, and human health. Based on daily maximum surface air temperature and meteorological drought composite index data in China, changing features of CDHEs in warm season from 1961 to 2018 is explored at a daily time scale based on a strict and objective definition in this study. Results reveal that CDHEs have occurred more frequently and widely in China, especially since the late 1990s. Notably, such changes are more obvious in Southwest China, eastern Northwest China, northern North China, and the coastal area of southeastern China. A prominent feature is that persistent CDHEs on a daily scale have increased significantly. To better understand climate change of compound extreme events, further studies on the physical mechanism, especially attribution analyses at a regional scale, are urgently needed.
Summer precipitation plays critical roles in the energy balance and the availability of fresh water over eastern China. However, little is known regarding the trend in local‐scale precipitation (LSP). Here we developed a novel method to determine LSP events in the summer afternoon throughout eastern China from 1970 to 2010 based on hourly gauge measurements. The LSP occurrence hours decrease at an annual rate of 0.25%, which varies considerably by region, ranging from 0.14% over the Yangtze River Delta to 0.56% over the Pearl River Delta. This declining frequency of LSP is generally accompanied by an increase in rain rate of LSP but a decrease in visibility, whose linkage to LSP events was investigated. In particular, more LSP events tended to form when the atmosphere was slightly polluted. Afterward, LSP was suppressed. These findings have important implications for improving our understanding of the climatology of daytime precipitation at local scales.