• The same scientists who blamed global warming for prolonged cold spells in the eastern U.S. last winter are applying the same theory to extreme summer weather
• However, their theory that Arctic ice melt is weakening the jet stream is “poorly understood,” meaning many scientists disagree
• Al Gore and other environmentalists like to trot these scientists around every winter to make sure people don’t lose faith in global warming alarmism

When the eastern U.S. plunged into a deep freeze last winter, some scientists blamed Arctic ice melt from man-made global warming for the anomalously cold weather in the eastern part of the country.

Now, those same scientists are blaming Arctic warming for weakening the jet stream and exacerbating extreme summer weather across the northern hemisphere. Global warming makes cold spells and heat waves more extreme, they contend.

Penn State University climate scientist Michael Mann is out telling media the heat waves, wildfires, droughts and floods are made worse because global warming is making the jet stream less stable.

“Climate change is literally making the jet stream more wild,” Mann told PBS NewsHour on Monday. “It undulates more, so you get those weather extremes, and it’s causing the jet stream to slow down, so those extreme weather events stick around.”

“And that’s when you get unprecedented damage and threat,” Mann said. (RELATED: NBC Worries Environmentalists Are Not Focusing Enough On Crucifying Oil Companies)

The basic idea is that a fast-warming Arctic is causing the jet stream to become weaker and wobblier, creating blocking patterns that keep weather patterns in place. Cold spells and heat waves, for example, become more prolonged under this theory. It’s not a well-accepted theory.

Mann is not the only one perpetuating this theory. Rutgers University scientist Jennifer Francis, probably the theory’s greatest proponent, suggested there was a link between Arctic warming and wildfires and heat waves across the northern hemisphere.

“We can’t finger point directly at the Arctic to say that this summer’s crazy weather is directly related to the rapid warming up there, but it certainly fits the story that we’ve been putting together over the last several years,” Francis told CBC News in July.

Cato Institute climate scientist Ryan Maue criticized Mann’s blaming of a wobbly jet stream for summer weather, tweeting “that’s typical of ‘summer’ in Northern Hemisphere regardless of climate change.”

However, this thinking is consistent w/null hypothesis that climate change impacts [affects, causes, intensifies] all extreme weather events [always].

These jet stream “slow downs” or blocking events are actually poorly understood features of the climate system.

— Ryan Maue | weathermodels.com (@RyanMaue) August 7, 2018

Indeed, the latest National Climate Assessment special report found that “confidence is low regarding whether or by what mechanisms observed arctic warming may have influenced midlatitude circulation and weather patterns over the continental United States.”

Jet stream hysteria peaked in 2014 when former White House science czar John Holdren put out a video where he claimed record cold weather was actually a sign of global warming.

Holdren later admitted that his video was based on his “personal opinion” of the science, but environmental activists still fall back on it every time frigid weather shakes Americans’ faith in global warming.

As cold and snow pummeled the northeast in early 2018, former Vice President Al Gore claimed it was the product of man-made warming. Mann wrote a blog post for Gore’s environmental group on the subject.

At the time, Mann wrote it is “precisely the sort of extreme winter weather we expect because of climate change.” However, climate scientists challenged Mann’s assertion that warming was making it colder in the eastern U.S.

“Such claims make no sense and are inconsistent with observations and the best science,” University of Washington climatologist Cliff Mass said in January.

“The frequency of cold waves have decreased during the past fifty years, not increased. That alone shows that such claims are baseless,” Mass said.

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