Total Precipitation Increase

Climate science at a glance

• The 12 months spanning July 2018 through June 2019 were the wettest year-long period in the United States in records dating back to 1895.

• Climate change has increased the likelihood of wet years across the US.[1][2]

• In the Midwest, significant increases in flooding are well-documented, and the change is likely due to increases in total precipitation linked to climate change.

US total precipitation trends and climate change

• In the Northeast, increases in total precipitation are expected during the winter and spring but with little change in the summer.[3]
• In the Southern Great Plains, total precipitation decreased over the past 30 years.[3] An increase in extreme precipitation, however, has led to an increase in record-breaking flooding over this same period of time.[3]

US studies attribute changes in total precipitation to climate change

• (Knutson and Zeng 2018): Climate change has increased the amount of annual precipitation in the Midwest.
• (Diffenbaugh et al. 2017): Climate change has increased the likelihood of wet years over the US.
• (Knutson et al. 2014): Extreme seasonal and annual mean precipitation during 2013 in the north-central and eastern US were due in part to human-caused climate change.

Global total precipitation trends and climate change

• Climate models robustly predict an increase in global-mean precipitation in response to CO2 doubling. They agree that the magnitude of this increase will be less than the increase of water vapor concentrations.[4]

Global studies attribute changes in total precipitation to climate change

• (Wan et al. 2014): Increases in high latitude precipitation has showed an increase in various datasets, and this is due in part to human caused climate change.
• (Sarojini et al. 2012): Human-caused climate change has likely increased total precipitation across the globe, with the largest effect in high-latitude regions.
• (Zhang et al. 2007): Models detect the effect of anthropogenic climate change on average precipitation across latitudinal bands.