Warmists Wheel Out “Record Cold Due To Global Warming” Argument Again
Alarmists Wheel Out “Record Cold Due To Global Warming” Argument Again
By Paul Homewood
Whenever we get a warm summer, it’s a sign of climate change. And when we get a cold winter, it’s climate change as well!
According to Breitbart:
Jonathan Overpeck, a climate scientist at the University of Michigan, claimed that the recent record-cold weather is not only happening despite global warming, but, indeed, “at least in part” because of it.
Overpeck’s theory is that a loss of Arctic ice has allowed more heat to transfer from the ocean to the atmosphere, causing a weakening of the polar vortex winds over the Arctic. As a result, more freezing Arctic air is swooping further south, he proposes.
“That is due to the warming of the Arctic, which in turn is due to human emissions of greenhouse gases and primarily burning of fossil fuels,” Overpeck declared.
The NYT takes things further:
As bitter cold continues to grip much of North America and helps spawn the fierce storm along the East Coast, the question arises: What’s the influence of climate change?
Some scientists studying the connection between climate change and cold spells, which occur when cold Arctic air dips south, say that they may be related. But the importance of the relationship is not fully clear yet.
The Arctic is not as cold as it used to be — the region is warming faster than any other — and studies suggest that this warming is weakening the jet stream, which ordinarily acts like a giant lasso, corralling cold air around the pole.
“There’s a lot of agreement that the Arctic plays a role, it’s just not known exactly how much,” said Marlene Kretschmer, a researcher at the Potsdam Institute for Climate Impact Research in Germany. “It’s a very complex system.”
Much of the Northern Hemisphere is cold this time of year (it’s winter, after all). Cold snaps have occurred throughout history — certainly long before industrialization resulted in large emissions of greenhouse gases. And as with any single weather event, it’s difficult to directly attribute the influence of climate change to a particular cold spell.
But scientists have been puzzled by data that at first seems counterintuitive: Despite an undeniable overall year-round warming trend, winters in North America and Europe have trended cooler over the past quarter-century.
“We’re trying to understand these dynamic processes that lead to cold winters,” Ms. Kretschmer said.
She is the lead author of a study published last fall that looked at four decades of climate data and concluded that the jet stream — usually referred to as the polar vortex this time of year — is weakening more frequently and staying weaker for longer periods of time. That allows cold air to escape the Arctic and move to lower latitudes. But the study focused on Europe and Russia.
“The changes in very persistent weak states actually contributed to cold outbreaks in Eurasia,” Ms. Kretschmer said. “The bigger question is how this is related to climate change.
Timo Vihma, head of the polar meteorology and climatology group at the Finnish Meteorological Institute, explained that warmer air in the Arctic reduces the temperature difference between it and lower latitudes and weakens the polar vortex.
“When we have a weak temperature gradient between the Arctic and mid-latitudes, the result is weaker winds,” he said.
Ordinarily the jet stream is straight, blowing from west to east. When it becomes weaker, Dr. Vihma said, it can become wavy, “more like a big snake around the Northern Hemisphere.”
The weaker winds are more susceptible to disturbances, such as a zone of high pressure that can force colder air southward. These “blocking” high-pressure zones are often what creates a severe cold spell that lingers for several days or longer.
This is all a rehash of the junk science originally promoted by Jennifer Francis in 2014:
The rapid retreat of Arctic sea ice caused by climate change may be to blame for more frequent prolonged spells of extreme weather in Europe, Asia and North America, such as heat waves, freezing temperatures or storms.
They are related to “stuck” weather patterns, Jennifer Francis of Rutgers University in New Brunswick, New Jersey, told a conference on Arctic sea ice reduction in London on 23 September. “Is it global warming? I think it’s safe to answer yes,” she told the meeting.
Francis said a growing number of studies, including her own, suggest that the melting Arctic is having knock-on effects on the jet stream, the river of air that snakes around the northern hemisphere at an altitude of around 5 to 6 kilometres, and which has a profound impact on the world’s weather….
Francis thinks that, as the cool air of the Arctic becomes warmer, the jet stream is slowing down, almost to the point of stopping trapping weather systems in one place for prolonged periods. Instead of swirling round the world, winds reverberate back and forth in the same place, creating what she calls “extreme waves”.
There is one slight problem with all of this junk science – we had just the same weather patterns in the 1960s and 70s, which proper scientists attributed to the Arctic getting colder.
For instance, HH Lamb wrote this in 1982:
Such world-wide surveys as have been attempted seem to confirm the increase of variability of temperature and rainfall [since the middle of the 20thC].
In Europe, as has been noted by Prof Flohn and by Dr Schuurmans of the Netherlands meteorological service, there is a curious change in the pattern of variability: from some time between 1940 & 1960 onwards, the occurrence of extreme seasons – both as regards temperature and rainfall- has notably increased.
A worldwide list of the extreme seasons reported since 1960 makes impressive reading. Among the items are:
These variations, perhaps more than any underlying trend to a warmer or colder climate, create difficulties for the planning age in which we live. They may be associated with the increased meridionality of the general wind circulation, the greater frequency of blocking, of stationary high and low pressure systems, giving prolonged northerly winds in one longitude and southerly winds in another longitude sector in middle latitudes.
Over both hemispheres there has been more blocking in these years… The most remarkable feature seems to be the an intensification of the cyclonic activity in high latitudes near 70-90N, all around the northern polar region. And this presumably has to do with the almost equally remarkable cooling of the Arctic since the 1950’s, which has meant an increase in the thermal gradient between high and middle latitudes.
Climate, History and the Modern World – pp267-269
And it was not only Lamb. CC Wallen, Head of the Special Environmental Applications Division of the World Meteorological Organization, had this to say about the consequences of the cooling trend since 1940:
The principal weather change likely to accompany the cooling trend is increased variability-alternating extremes of temperature and precipitation in any given area-which would almost certainly lower average crop yields.
During cooler climatic periods the high-altitude winds are broken up into irregular cells by weaker and more plentiful pressure centers, causing formation of a “meridional circulation” pattern. These small, weak cells may stagnate over vast areas for many months, bringing unseasonably cold weather on one side and unseasonably warm weather on the other. Droughts and floods become more frequent and may alternate season to season, as they did last year in India. Thus, while the hemisphere as a whole is cooler, individual areas may alternately break temperature and precipitation records at both extremes.
And he even gave us these diagrams.
Now scientists in the 1970s may have been wrong about the causes of this meridional circulation. But what cannot be denied is that such changes occurred.