Human-induced warming has driven increasing precipitation variability

Anthropogenic climate warming has led to increased precipitation variability over much of the globe, according to a new study, which points to several hotspots for this trend. This effect is particularly prominent over Europe, Australia, and eastern North America, say the study’s authors, and is largely driven by increasing atmospheric moistening and decadal-scale changes in atmospheric circulation. As the climate warms, the atmosphere becomes more capable of holding moisture, leading to greater fluctuations between extreme precipitation events and wider swings between wet and dry episodes. Such amplified precipitation variability can profoundly impact human society and ecosystems, posing challenges for weather and climate forecasting as well as for adaptation and resilience planning.  Although many global climate models project increasing precipitation variability – especially in wet regions – due to higher atmospheric moisture and weakened large-scale atmospheric circulation, the phenomenon is far easier to predict than to observe. As a result, it remains unclear whether increased precipitation variability has already emerged in observations. To address these uncertainties, Wenxia Zhang and colleagues leveraged five global-scale and eight regional-scale datasets of daily precipitation observations, which spanned 1900 to 2020. Zhang et al. report that precipitation variability has systematically amplified over the past century across various timescales and regions, driven primarily by increased atmospheric moisture from anthropogenic warming. According to the findings, roughly 75% of land area has experienced an amplification of precipitation variability, with daily variability increased by 1.2% per decade globally. The authors note these precipitation swings pose “threats to the climate resilience of infrastructures, risk management, agriculture, ecosystem functions, and economic development.”