Refuting refutations of the IPCC models of global warming

by Joe Archive on May 12, 2008

There are those who try to point out flaws in the global climate model results (or the models themselves) that predict global warming. These people have a whole spectrum of motivations for this (I imagine) – some wishing to keep up business as usual, some interested in keeping the science honest etc.br /br /Some apparent flaws in the IPCC’s projections have been pointed out, but Gavin @ realclimate hs put together a cogent counter argument to various complaints about the projections in comparison with observations of the recent past – that basically comes down to really understanding the statistics of the ensembles of models that make up the projections.br /br /blockquoteulblockquotelia href=”http://climatesci.org/2008/05/01/comments-on-the-new-york-times-article-decade-break-in-global-warming-may-01-2008/”/ablockquotea href=”http://climatesci.org/2008/05/01/comments-on-the-new-york-times-article-decade-break-in-global-warming-may-01-2008/”Claims/a that GCMs project monotonic rises in temperature with increasing greenhouse gases are not valid. Natural variability does not disappear because there is a long term trend. The ensemble mean emis/em monotonically increasing in the absence of large volcanoes, but this is the forced component of climate change, not a single realisation or anything that could happen in the real world./blockquote/liliblockquoteClaims that a negative observed trend over the last 8 years would be inconsistent with the models cannot be supported. Similar claims that the IPCC projection of about 0.2ºC/dec over the next few decades would be falsified with such an observation are equally bogus./blockquote/liliblockquoteOver a twenty year period, you would be on stronger ground in arguing that a negative trend would be outside the 95% confidence limits of the expected trend (the one model run in the above ensemble suggests that would only happen ~2% of the time)/blockquote/li/blockquote/ul/blockquotebr /a href=”http://www.realclimate.org/index.php/archives/2008/05/what-the-ipcc-models-really-say/”read more/a

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