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Proxy-based precipitation reconstruction is essential to study the inter-annual to decadal variability and underlying mechanisms beyond the instrumental period that is critically needed for climate modeling, prediction, and attribution. Based on 3014 annually resolved proxy series mainly derived from tree-ring and historical documents, we present a set of standard precipitation index (SPI) reconstructions for annual (Nov-Oct) covering entire Asia and for wet season (i.e., Nov-Apr for western Asia and May-Oct for the others) with the spatial resolution of 2.5° since 1700. To screen the optimal candidate proxies for SPI reconstruction in each grid from available proxies in its connected region with a homogeneous rainfall regime and similar precipitation variability, a new approach is develop by adopting the grid-location-dependent division derived from the instrumental SPI data. The validation shows that these reconstructions are effective for most of Asia. The assessment of data quality compared with gauge precipitation before calibration time indicates that our reconstruction has high quality to show the precipitation variability in most of the study areas except for few grids in western Russia, the coastal area of southeastern Asia and northern Japan. [ABSTRACT FROM AUTHOR]

A climate event at 7.5-7.0 cal ka BP (thousand calibrated years before present) has been recognized. This event is important for foreseeing the possible response of the climate system to global warming and for interpreting considerable societal change, but it has heretofore lacked a systematic review. Here, we summarize previously published paleoclimate records spanning this event from 47 sites around the world. The proxy evidence from a variety of paleo-archives, including lake sediments, speleothems, marine sediments, and ice cores, provides a clear picture of this climate change. The synthesis results show a weaker Asian summer monsoon, in contrast to a stronger South American summer monsoon during the event. The event also involves dramatic cooling and wetter conditions in north-central Europe and in western North America, widespread aridity across Africa, contrasting patterns of precipitation variability throughout the Mediterranean, and notable cooling over the polar region, suggesting that it is a worldwide climate event. Comparison of paleoclimate records with climate-forcing time series gives likely climate controls for the event. The close correspondence in time of solar irradiance minima, strong volcanic eruptions, the meltwater flux into the North Atlantic, an orbitally induced decrease in solar insolation, and climate changes indicated by proxy data suggest possible linkages. More quantitative reconstructions and higher resolution climate records are needed to fully capture the magnitude, timing, duration, and nature of this event, which will be of considerable relevance to modeling. [ABSTRACT FROM AUTHOR]

The Paris Agreement proposes a 1.5 °C target to limit the increase in global mean temperature (GMT). Studying the population exposure to droughts under this 1.5 °C target will be helpful in guiding new policies that mitigate and adapt to disaster risks under climate change. Based on simulations from the inter-Sectoral Impact Model Intercomparison Project (ISI-MIP), the standardized precipitation evapotranspiration index (SPEI) was used to calculate drought frequencies in the reference period and 1.5 °C global warming scenario. Then population exposure was evaluated by combining drought frequency with simulated population data from shared socioeconomic pathways (SSPs). In addition, the relative importance of climate and demographic change and the cumulative probability of exposure change were analyzed. Results revealed that population exposure to droughts on the east side of the Hu line is much more than on the west side; exposure in the middle and lower reaches of the Yangtze River region is the highest and lowest in the Qinghai-Tibet region. An additional 6.97 million people will be exposed to droughts under the 1.5 °C global warming scenario relative to the reference period. Demographic change is the primary contributor to exposure (79.95 %) in the 1.5 °C global warming scenario, more than climate change (29.93 %) or the interaction effect (-9.88 %). Of the three drought intensities, mild, moderate, and extreme, moderate droughts contribute the most to exposure (63.59 %). The frequency of extreme droughts is likely to decrease (71.83 % probability), while mild and moderate droughts may increase slightly (55.17 % and 51.71 % probability, respectively) in the 1.5 °C global warming scenario. [ABSTRACT FROM AUTHOR]