Ruixia Guo, Clara Deser, Laurent Terray, Flavio Lehner

Geophysical Research Letters

Published date March 4, 2019

Human Influence on Winter Precipitation Trends (1921–2015) over North America and Eurasia Revealed by Dynamical Adjustment

Our research demonstrates that human-caused climate change has clearly affected precipitation over the past 100 years.

Clara Deser, NCAR senior scientist and co-author of the study

  • States that detecting and attributing a human influence on observed rainfall trends is a major challenge due to the presence of large amplitude internal variability on all time scales and by limited temporal and spatial data coverage
  • Applies a “dynamical adjustment” methodology to a gridded archive of monthly precipitation to estimate an anthropogenic influence on long‐term (1920–2015) trends over North America and Eurasia during winter (November–March)
  • This empirical approach aims to remove atmospheric circulation influences from precipitation variability and trends, thereby revealing the thermodynamically induced component as a residual
  • The geographical pattern and amplitude of this observed thermodynamic residual precipitation trend are in good agreement with anthropogenically forced trends obtained from ensembles of historical climate model simulations
  • Such consistency helps to reconcile observations and models and provides compelling evidence for a human influence on century‐scale precipitation trends over North America and Eurasia during the cold season
  • Concludes that we are able to identify a human influence on observed century‐scale precipitation trends over North America and Eurasia