No Evidence That Climate Change Causes Weather Extremes: (1) Drought

Weather extremes are a commonly cited line of evidence for human-caused climate change. Despite the UN’s IPCC (Intergovernmental Panel on Climate Change) having found little to no evidence that global warming triggers extreme weather, the mainstream media and more than a few climate scientists don’t hesitate to trumpet their beliefs to the contrary at every opportunity.

In this and subsequent blog posts, I’ll show how the quasi-religious belief linking extreme weather events to climate change is badly mistaken and at odds with the actual scientific record. We’ll start with drought.

Droughts have been a continuing feature of the earth’s climate for millennia. Although generally caused by a severe fall-off in precipitation, droughts can be aggravated by other factors such as elevated temperatures, soil erosion and overuse of available groundwater. The consequences of drought, which can be catastrophic for human and animal life, include crop failure, starvation and mass migration. A major exodus of early humans out of Africa about 135,000 years ago is thought to have been driven by drought.

Getting a good handle on drought has only been possible since the end of the 19th century, when the instrumentation needed to measure extreme weather accurately was first developed. The most widely used gauge of dry conditions is the Palmer Drought Severity Index that measures both dryness and wetness and classifies them as “moderate”, “severe” or “extreme.” The figure below depicts the Palmer Index for the U.S. during the past century or so, for all three drought or wetness classifications combined.

US drought index 1900-2012 JPG.jpg

What jumps out immediately is the lack of any long-term trend in either dryness or wetness in the U.S. With the exception of the 1930s Dust Bowl years, the pattern of drought (upper graph) looks boringly similar over the entire 112-year period, as does the pattern of excessive rain (lower graph).

Much the same is true for the rest of the world.



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No Evidence That Extreme Weather on the Rise: A Look at the Past – (2) Tornadoes

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