"This paper exposes flaws in the mathematical structure of the Global Warming Potential (GWP) concept. These lead to errors when emissions changes in different greenhouse gases are compared. The most fundamental problem is that the unit impulse response fuctions from which GWPs, and many of their proposed alternatives, are constructed provide an INCOMPLETE REPRESENTATION of the relationship between emissions and radiactive forcing. Additional errors occur when GWPs are used to compare finite-length emissions changes."
Smith SJ, T Wigley. 200. "Global warming potentials: 2. Accuracy." Climatic Change 44(4):459-469.
Global warming potentials: 2. Accuracy | Joint Global Change Research Institute | University of Maryland
GAO found that: (1) although GCM have improved their ability to predict
future climatic changes over the last decade, their estimates are still
limited by their incomplete or inaccurate representations of
climate-affecting processes and by insufficient computer power; (2)
scientists do not fully understand how the climate system responds to
potentially important physical, chemical, and biological processes; (3)
the lack of computer power requires scientists to use simplified
assumptions and structures that increase the uncertainty of the models'
predictions; (4) scientists are conducting research to overcome the
limitations of the computer models
Global Warming: Limitations of General Circulation Models and Costs of Modeling Efforts
Wentz's team analyzed satellite data from the past 20 years to show that as global temperatures have risen, precipitation has kept pace.
The results fly in the face of many of the world's most sophisticated climate models, which predict that worldwide rainfall will increase at a much slower rate than temperatures.
(See a map of predicted effects of global warming.)
The findings also cast doubt on the ability of climate models to accurately predict precipitation on regional scales.
Global Warming Models Underpredict Increase in Rainfall, Study Says
The earth's atmosphere has actually cooled by 0.13° Celsius since 1979 according to highly accurate satellite-based atmospheric temperature measurements. By contrast, computer climate models predicted that the globe should have warmed by an easily detectable 0.4° C over the last fifteen years...Current computer climate models are incapable of coupling the oceans and atmosphere; misrepresent the role of sea ice, snow caps, localized storms, and biological systems; and fail to account accurately for the effects of clouds.
Temperature records reveal that predictive models are off by a factor of two when applied retroactively in projecting the change in global temperature for this century.
The amount of warming from 1881 to 1993 is 0.54° C. Nearly 70 percent of the warming of the entire time period — 0.37° C —occurred in the first half of the record — before the period of the greatest build-up of greenhouse gases."
CEI on Global Warming: Messy Models, Decent Data, Pointless Policy
Two University of Rochester studies published in the latest issue of Geophysical Research Letters underline how uncertain and complex the understanding of global climate can be. Both reports emphasize some of the shortcomings in current weather models that scientists use to determine the effect of carbon dioxide on the Earth's average temperature.
Global Warming Models Come Under Physicist's Scrutiny
