New paper shows climate models suck

A paper published today in the Journal of Climate utilized the world's most commonly used computer climate model to "document model bias, and to explore possible future changes in air temperature, precipitation and snow cover over North America." The authors find that "large biases still exist in all analyzed fields [temperature, precipitation, and snow cover]".  Bias is defined as "an inclination to present or hold a partial perspective at the expense of (possibly equally valid) alternatives." The paper notes that future climate projections by the model assume these biases are valid and persist into the future, a huge assumption for which there is no evidence to support. In addition, different model runs and assumptions result in "considerable differences" in the magnitude of climate change projected. Furthermore, the model predicts a decrease in snow cover with rising greenhouse gases, which is in direct opposition to the empirical data:

Journal of Climate 2012 ; e-View

doi: http://dx.doi.org/10.1175/JCLI-D-11-00214.1

Projected 21st century changes in temperature, precipitation and snow cover over North America in CCSM4

Synte Peacock

National Center for Atmospheric Research, 1850 Table Mesa Drive, Boulder CO 80305, USA, (303) 497-1774

Abstract

Results from a suite of ensembles of 21st century climate projections made using the Community Climate System Model Version 4 (CCSM4) are analyzed to document model bias, and to explore possible future changes in air temperature, precipitation and snow cover over North America. Large biases still exist in all analyzed fields in this version of the model, and the necessary assumption in future climate projections is therefore that the bias persists into the future, such that the differences in a field between two time periods are meaningful indications of potential changes. Projected temperature increases show strong regional patterns with spatial similarities for all the emissions scenarios considered, although there are considerable differences in the magnitude of the projected change. Projections indicate an increase in total precipitation over much of North America for all emissions scenarios, with the exception of the South-West US. All of North America except parts of Northern Canada show a projected decrease in snow cover over the 21st century.