A newly released international study debunks climate models on global warming that forecast extreme rainfall and drought tied to temperature swings, casting doubt on disaster scenarios promoted by the climate-change movement.
The study in the journal Nature published Thursday examining Northern Hemisphere rainfall data going back 1,200 years found that today’s climate models were frequently wrong on predicting extreme rain and drought.
In the 20th century, for example, higher-than-average temperatures failed to produce wet-dry extremes, which contradicts the United Nations’ Intergovernmental Panel on Climate Change’s consensus that global warming will make dry areas drier and wet areas wetter.
The scientists also found periods of extreme variability in centuries prior to the Industrial Revolution and the rise of greenhouse-gas emissions in the atmosphere. For example, the study found severe drought in the 12th century, which was warmer than average, as well as the 15th century, which was colder.
“It might be more difficult than often assumed to project into the future,” the study’s lead author, Fredrik Ljungqvist of Stockholm University, told AFP, adding, “The truth can be much, much more complicated.”
Anthony Watts, who runs the climate-science website Watt’s Up With That, posted the results under the headline, “Ooops! Another big failure of the climate models — rainfall did not increase.”
He pointed out that Lawrence Livermore National Laboratory researchers reached the same conclusion in a study released in December, finding that climate models “overestimate the increase in global precipitation due to climate change,” in part because they fail to take into account the increased absorption of sunlight by water vapor.
The Nature study, “Northern Hemisphere hydroclimate variability over the past twelve centuries,” saw scientists from Sweden, Germany and Switzerland create a rainfall history of Europe, North America and North Asia.
In a comment published by Nature, Matthew Kirby of California State University Fullerton’s Department of Geological Sciences agreed that the study “certainly adds fuel to the fiery debate,” but challenged the idea that the results render current climate models obsolete.
“Do their results invalidate current predictive models? Certainly not. But they do highlight a big challenge for climate modellers, and present major research opportunities both for modellers and climate scientists,” said Mr. Kirby, according to AFP.