Matt McGrath Peddles US Megadrought Poppycock

By Paul Homewood

h/t Philip Bratby/Ian Magness

Today’s dose of nonsense from Matt McGrath:

A drought, equal to the worst to have hit the western US in recorded history, is already under way, say scientists.

Researchers say the megadrought is a naturally occurring event that started in the year 2000 and is still ongoing.

Climate change, though, is having a major impact with rising temperatures making the drought more severe.

Some researchers are more cautious, saying that it is too early to say if the region really is seeing a true megadrought.

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According to the authors of this new paper, a megadrought in North America refers to a multi-decade event, that contains periods of very high severity that last longer than anything observed during the 19th or 20th centuries.

The authors say there have been around 40 drought events over the period from 800-2018 in the western US.

Of these, only four meet the criteria for a megadrought.

These were in the late 800s, the mid-1100s, the 1200s and the late 1500s.

How do researchers know what drought conditions were like in the past?

The key to this new study is the use of tree ring records to reconstruct soil moisture data for the past 1200 years.

The team were also able to use supporting evidence such as medieval tree stumps growing in normally wet river beds, the abandonment of settlements by indigenous civilisations at the peak of the 13th century drought, plus evidence from lake deposits indicating wildfire activity was enhanced during these drought periods.

https://www.bbc.co.uk/news/science-environment-52312260

In reality there has been nothing unusual about the recent drought in the region:

https://www.ncdc.noaa.gov/cag/regional/time-series/109/pcp/60/3/1895-2020

As is often the case, comparisons are made with only the last few decades:

The authors say the two most important water reservoirs in the region, Lake Powell and Lake Mead have both shrunk dramatically during the drought. Wildfires across the region are growing in area.

"At any given year, there’s over ten times more forest area burns than we would have expected in a given year, 40 years ago," said Dr Williams.

What they are doing, of course, is to compare rainfall with unusually wet climate of the 1980s and 90s.

They also argue that global warming has supercharged the drought:

But climate change has super-charged the current drought.

The authors say that in the western US, temperatures have gone up by 1.2C since 2000. Hotter air holds more moisture and that moisture is being pulled out of the ground.

However this is to ignore the fact that it used to be much warmer than now in the American West, before it became much colder during the Little Ice Age:

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