Science Source
Model Assessment of Observed Precipitation Trends Over Land Regions: Detectable Human Influences and Possible Low Bias in Model Trends
- Assesses precipitation trends for 1901–2010, 1951–2010, and 1981–2010 over relatively well-observed global land regions for detectable anthropogenic influences and for consistency with historical simulations from phase 5 of the Coupled Model Intercomparison Project (CMIP5)
- Finds that the CMIP5 historical all-forcing runs are broadly consistent with the observed trend pattern (1901–2010), but with an apparent low trend bias tendency in the simulations
- Finds, despite this bias, that observed and modeled trends are statistically consistent over 59% of the analyzed area.
- Finds that over 20% (9%) of the analyzed area, increased (decreased) precipitation is partly attributable to anthropogenic forcing, including:
- Increases over regions of the north-central United States, southern Canada, Europe, and southern South America and
- Decreases over parts of the Mediterranean region and northern tropical Africa
- Trends for the shorter periods (1951–2010 and 1981–2010) do not indicate a prominent low trend bias in the models, as found for the 1901–2010 trends
