Look in the Past for Extreme Weather

Recently I posted X-Weathermen are Back on news stories claiming that extreme weather events can be tied to global warming.  As Mike Hulme explained, the methods do not support those attributions.

Now we have a study looking at extreme weather in the past and concluding: Climate data since Vikings cast doubt on more wet, dry extremes.  It seems that our weather today is quite tame by comparison. There are the usual comments assuring readers that this in no way contradicts global warming doctrine.  But the conclusions say otherwise:

Climate records back to Viking times show the 20th century was unexceptional for rainfall and droughts despite assumptions that global warming would trigger more wet and dry extremes, a study showed on Wednesday.

Stretching back 1,200 years, written accounts of climate and data from tree rings, ice cores and marine sediments in the northern hemisphere indicated that variations in the extremes in the 20th century were less than in some past centuries.

“Several other centuries show stronger and more widespread extremes,” lead author Fredrik Ljungqvist of Stockholm University told Reuters of findings published in the journal Nature. “We can’t say it’s more extreme now.”

Ljungqvist said many existing scientific models of climate change over-estimated assumptions that rising temperatures would make dry areas drier and wet areas wetter, with more extreme heatwaves, droughts, downpours and droughts.

The 10th century, when the Vikings were carrying out raids across Europe and the Song dynasty took power in China, was the wettest in the records ahead of the 20th, according to the researchers in Sweden, Germany, Greece and Switzerland.

And the warm 12th century and the cool 15th centuries, for instance, were the driest, according to the report, based on 196 climate records. Variations in the sun’s output were among factors driving natural shifts in the climate in past centuries.

“This paper adds to the growing evidence that the simple paradigm of ‘wet-gets-wetter, dry-gets-drier’ under a warming climate does not apply over land areas,” said Ted Shepherd, a professor at the University of Reading.

For more on how rainfall is distributed across the globe see Here Comes the Rain Again

Rainbow signifying the promise of safety from global flooding