A new paper by Guo et al. (2019) has successfully teased out the influence of human-induced climate change from natural climate variability on wintertime precipitation over Eurasia and North America during the past century. The authors used an innovative statistical approach that relies on observed relationships between precipitation and large-scale atmospheric circulation patterns to distinguish between natural variability and anthropogenic effects. The results show that human emissions of greenhouse gases spurred a noticeable increase in wintertime precipitation across widespread regions of northern Eurasia and eastern North America since 1920, and had a drying influence on parts of central and southwestern North America and on much of southern Eurasia. Their conclusions are in good agreement with climate model simulations of human-induced changes in precipitation, providing an independent verification of the models.

Figure: This map shows the influence of human-caused climate change on wintertime precipitation in the Northern Hemisphere from 1921 to 2015. The warming climate has spurred significant increases in precipitation across much of northeastern North America and northern Eurasia. The stippled regions show precipitation trends that are statistically insignificant. (©UCAR. Image: Simmi Sinha, UCAR, redrawn from map by Ruixia Guo of Lanzhou University and NCAR.