Global climate models cannot predict impacts for even large regions accurately; yet a new study uses them to forecast a 30% drop in winter precipitation for California alone due to Arctic ice melt.

Time and time again, researchers publish papers that use global climate model output at the regional scale to make august pronouncements about our dire future. Yet, as we recently pointed out, scientists were quoted in Nature as saying “privately” that regional climate models—those applied to areas as big as, say, the lower 48 states—were “oversold.”
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The prestigious science journal Nature concurrently runs an article promising total melting of Greenland’s ice (applying climate models to this region) and another on how it is “next to impossible” to do accurate regional modeling.

Without acknowledging the incongruity, Nature’s editors include in their April 8, 2004, edition an article that relies on climate models to forecast certain elimination of Greenland’s ice-sheet a thousand years from now and another in which climate scientists say climate models applied at the regional level are not yet able “to predict what will happen in the next 20 years.”
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Airplane contrails, the condensation trails formed in the wake of high-altitude jets, may be responsible for all warming observed in the United States during the past 25 years, a new study suggests.

Land-use change. The urban heat island effect. Local surface warming in industrialized regions. More and more observational evidence emerges indicating that local and regional processes such as these are important players in recent global temperature changes. As these other influences emerge, anthropogenic greenhouse gas concentrations resulting from fossil fuel combustion appear less important than previously stated in reports such as those by the Intergovernmental Panel for Climate Change (IPCC, 2001).
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Urging caution regarding “implausible” and “unduly pessimistic” IPCC climate scenarios, NASA’s Hansen opts for observations to guide his forecasts of a 0.75ºC temperature rise by the year 2050.

NASA’s James Hansen, who is widely credited as being the “father of global warming” recently wrote that the climate change scenarios put forth in the Intergovernmental Panel on Climate Change’s (IPCC) 2001 Third Assessment Report (TAR) “may be unduly pessimistic,” and that the IPCC extreme scenarios are “implausible.” In fact, he argues, the observed trends in atmospheric carbon dioxide and methane concentrations for the past several years fall below all IPCC scenarios, so consequently future temperature rise will most like be about 0.75ºC during the next 50 years.
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New research further demonstrates that the lower atmosphere during the past 25 years has not warmed at the rate predicted by global climate models.

Major systematic problems in general circulation models (GCMs) are apparent in the discrepancy between observed temperature trends in the lower atmosphere and the trend predicted by models. As long as these problems persist, GCMs cannot provide reliable estimates of future climate conditions.
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Should Michael Mann’s infamous 1,000-year temperature reconstruction look less like a hockey stick and more like a city skyline? New research on natural climate variability suggests that may in fact be the case.

New research casts doubt on paleoclimatologist Michael Mann’s influential “Hockey Stick,” a now-famous 1,000-year temperature reconstruction.
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