Abstract
Precipitation is characterized by substantial natural variability, including on regional and decadal scales. This relatively large variability poses a grand challenge in assessing the significance of anthropogenically forced precipitation changes. Here we use multiple large ensembles of climate change experiments to evaluate whether, on regional scales, anthropogenic changes in decadal precipitation mean state are distinguishable. Here, distinguishable means the anthropogenic change is outside the range expected from natural variability. Relative to the 1950–1999 period, simulated anthropogenic shifts in precipitation mean state for the 2000–2009 period are already distinguishable over 36–41% of the globe—primarily in high latitudes, eastern subtropical oceans, and the tropics. Anthropogenic forcing in future medium-to-high emission scenarios is projected to cause distinguishable shifts over 68–75% of the globe by 2050 and 86–88% by 2100. Our findings imply anthropogenic shifts in decadal-mean precipitation will exceed the bounds of natural variability over most of the planet within several decades.
Highlights
Precipitation is characterized by substantial natural variability, including on regional and decadal scales
This analysis is enabled by a large set of simulations from two climate models, the National Center for Atmospheric Research (NCAR) Community Earth System Model version 1 (CESM1)[17] and the Geophysical Fluid Dynamics Laboratory (GFDL) Forecast-oriented Low Ocean Resolution (FLOR) flux-adjusted model[18]
In our simulations, anthropogenic shifts in precipitation mean state are already distinguishable from natural climate variability over about 36–41% of the globe during the 2000s relative to the 1950–1999 climate
Summary
Precipitation is characterized by substantial natural variability, including on regional and decadal scales This relatively large variability poses a grand challenge in assessing the significance of anthropogenically forced precipitation changes. We assess where and when regional-scale decadal shifts in precipitation mean state that arise from anthropogenic forcing can be robustly distinguished from the background of unpredictable low-frequency (longer than a decade) internal climate variability in future ensemble projections. We address the following question: On a decade by decade and grid box by grid box basis, which projected shifts in precipitation mean state relative to the 1950–1999 climate can be distinguished from low-frequency internal climate variability and attributed to anthropogenic forcing? On regional scales, the anthropogenically forced decadal shifts in precipitation mean state are becoming progressively more distinguishable from natural climate variability with each decade over more areas of the globe
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have