Comparing Climate Models with Reality

The models are looking pretty good, as shown by this graph from Real Climate. The colored lines are different measurements of change in global temperature average.  The black line is the average of the predictions from the models used by IPCC, and the gray band shows the 95% confidence level (only a 1/20 chance of being outside the band).  There’s obviously a some significant short-term bouncing-around, but the trend line looks quite good — better than one might expect given all the difficulties involved in modeling something as complex as the planet’s climate.  Even putting aside the models, the actual observations leave no doubt that there’s been an upward temperature trend for the past thirty years.





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One Reply to “Comparing Climate Models with Reality”

  1. It seems you are repeating misinformation from a biased source. Other, unbiased analyses show that the climate models are outside the 90% confidence level for relevance to the actual climate data.

    A paper published in Nature Climate Change finds climate models have greatly exaggerated global warming over the past 20 years, noting the observed warming is “less than half” of the modeled warming. The authors falsify the models at a confidence level of 90%, and also find that there has been no statistically significant global warming for the past 20 years. According to the authors, “The evidence, therefore, indicates that the current generation of climate models …do not reproduce the observed global warming over the past 20 years, or the slowdown in global warming over the past fifteen years.” The paper follows another recent paper falsifying climate models at a confidence level of greater than 98% for the past 15 years. This difference might be explained by some combination of errors in external forcing, model response and internal [natural] climate variability…

    Overestimated global warming over the past 20 years
    John C. Fyfe, Nathan P. Gillett & Francis W. Zwiers
    Nature Climate Change 3, 767–769 (2013) doi:10.1038/nclimate1972
    Published online 28 August 2013

    And this one says they are not relevant at the 98% confidence level:

    A new paper by prominent German climatologists Dr. Hans von Storch and Dr. Eduardo Zorita, et al, finds “that the continued [global] warming stagnation over fifteen years, from 1998 -2012, is no longer consistent with model projections even at the 2% confidence level.” In other words, there is a greater than 98% probability that climate models are unable to explain the stagnation in warming over the past 15+ years.

    Can climate models explain the recent stagnation in global warming?

    Hans von Storch, Armineh Barkhordarian, Klaus Hasselmann and Eduardo Zorita
    Institute for Coastal Research, Helmholtz-Zentrum Geesthacht, Geesthacht, Germany
    Max-Planck-Institute for Meteorology, Hamburg, Germany

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About Dan

Dan Farber has written and taught on environmental and constitutional law as well as about contracts, jurisprudence and legislation. Currently at Berkeley Law, he has al…

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