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