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The Status of Antarctic Precipitation in CMIP5 Climate Models

Paper Reviewed
Palerme, C., Genthon, C., Claud, C., Kay, J.E., Wood, N.B. and L'Ecuyer, T. 2017. Evaluation of current and projected Antarctic precipitation in CMIP5 models. Climate Dynamics 48: 225-239.

The following is a list of the ability -- or better make that non-ability -- of CMIP5 climate models to adequately represent Antarctic precipitation, which was recently developed by a team of three French and three U.S. climate change researchers.

1. "Comparisons with CloudSat and ERA-Interim data show that almost all the models over-estimate current Antarctic precipitation, some by more than 100%."

2. "A common practice of averaging all models to evaluate climate projections leads to a significant underestimation of the contribution of Antarctic precipitation to future sea level."

3. "Models differ widely in their simulations of the current precipitation rate in Antarctica."

4. "The models ... tend to simulate higher snowfall rates than CloudSat or ERA Interim reanalysis."

5. "The mean snowfall rate from all the CMIP5 models is 363 mm/year over this part [marginal regions] of the ice sheet."

6. "In the interior of the ice sheet north of 82°S ... the mean snowfall rate from all the CMIP5 models is 74 mm/year, compared to 46 mm/year from ERA Interim and 36 mm/year from Cloud Sat."

7. "The mean snowfall rate from the CMIP5 models is 374 mm/year over West Antarctica, 21% larger than observed by CloudSat."

8. "No clear seasonal variability can be extracted from the CMIP5 models archive in the interior of the ice sheet."

9. "On average, the sea ice area simulated by the CMIP5 models during the period 1986-2005 is smaller than the observed sea ice area by remote sensing."

10. "The models that closely reproduce the CloudSat snowfall rate for the current period simulate, on average, a 22% larger sea ice area during the period 1986-2005 than observed."

11. "There is no agreement for the seasonality of Antarctic precipitation between CloudSat observations, ERA Interim reanalysis, and the CMIP5 models in the interior of the ice sheet."

12. "Between the periods 1986-2005 and 2080-2099, the CMIP5 models predict, on average, a precipitation increase from 5.5% to 24.5%," which "changes in Antarctic precipitation correspond to a negative contribution to sea level ... between 2006 and 2099."

And so the six scientists conclude that "the relative impact of sea ice cover and temperature changes on Antarctic precipitation is difficult to assess and is beyond the scope of this study."

Posted 19 April 2017