Jun 16, 2020

Human influence has intensified extreme precipitation in North America

by
Kirchmeier-Young and Xuebin Zhang
,
Proceedings of the National Academy of Sciences

Study key findings and significance

  • External forcing, dominated by human influence, has contributed to the increase in frequency and intensity of regional precipitation extremes in North America.
  • Although previous work has identified an anthropogenic influence on extreme precipitation at hemispheric scales, this study finds robust results for a continental scale. 

Author quotes

We're finding that in North America, we have seen an increase in the frequency and severity of heavy rainfall events. And this is largely due to global warming.

Megan Kirchmeier-Young, lead-author and research scientist at Environment and Climate Change Canada


Abstract

Precipitation extremes have implications for many facets of both the human and natural systems, predominantly through flooding events. Observations have demonstrated increasing trends in extreme precipitation in North America, and models and theory consistently suggest continued increases with future warming. Here, we address the question of whether observed changes in annual maximum 1- and 5-d precipitation can be attributed to human influence on the climate. Although attribution has been demonstrated for global and hemispheric scales, there are few results for continental and subcontinental scales. We utilize three large ensembles, including simulations from both a fully coupled Earth system model and a regional climate model. We use two different attribution approaches and find many qualitatively consistent results across different methods, different models, and different regional scales. We conclude that external forcing, dominated by human influence, has contributed to the increase in frequency and intensity of regional precipitation extremes in North America. If human emissions continue to increase, North America will see further increases in these extremes.