SOMETHING NEW TO WORRY ABOUT--QUASI-RESONANT AMPLIFICATION

Picture a river flowing down from the mountains to the plains. In the high country, where the river's descent is steep and hedged in by canyon walls, it's likely to follow a relatively straight path, basically tracing the shortest route down. Once it gets to the plains, however, there's no big difference between one path and another, and the river will begin to meander.

 Meandering river

Credit: Alana Whitman

Something similar is true for the jet streams, vast rivers of air that circle the globe from west to east, sometimes reaching speeds of 250 miles per hour. Like rivers, jet streams typically meander north and south. The size of those meanders and the speed with which they gradually drift eastward have major impacts on the weather. The UK, for example, was deluged by record floods in 2007 and again in 2012 when the jet stream looped far to the south and then stalled, unleashing extended periods of heavy rains.

Meandering polar jet stream

Credit: NASA/Goddard Space Flight Center 

That, in turn, gets us to climate change and quasi-resonant amplification (QRA). 

One of the most dramatic impacts of global warming and climate change is that the far north and south are warming much faster than the mid-latitudes and the tropics, a phenomenon known as polar amplification. What this means is that the temperature difference between the poles and the tropics-- which is what creates and drives the jet streams--is reduced. And like a river crossing a plain, this reduced gradient lets the jet stream meander farther north and south, and also tends to make the individual loops, known as Rossby waves, drift more slowly from west to east.

At the extreme, the meanders in the jet stream can form a stable sequence of exaggerated loops around the planet that can stay in place for weeks or months. This is known as quasi-resonant amplification  (QRA) and its results can be devastating. Warm, sunny days can extend into deadly heat waves, droughts and wildfires; while cool, rainy weather can linger, drenching an unlucky region with unprecedented rains and floods.

Michael Mann, a distinguished professor of atmospheric science and Pennsylvania State University, says that as of 2018 this phenomenon has now passed from the theoretical to the all-too-real and threatening. "It played out in real time on our television screens and newspaper headlines in the form of an unprecedented hemisphere-wide pattern of extreme floods, droughts, heatwaves and wildfires," he says.

Unfortunately, Mann adds, climate models indicate that such QRA-caused weather extremes will grow more frequent and more severe unless we get a handle on global warming. Recent research reinforces the link between reduced Arctic sea ice and the meandering jet stream, along with equally dire predictions. We can hope that humanity (and the politicians and corporations who hold the reins) will get their act together. In the meantime, however, we can all expect more QRAs and the devastating weather extremes they bring coming to a region near us.

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You can read an earlier post on this subject here.

For more detail on arctic warming and its impacts on our weather click here.

And for a new study that shows that these destructive "blocking events" will cover greater areas as the world heats up, navigate to this URL.

(As-yet unpublished research shows that these stalled atmospheric waves have the potential to cut crop production across much of the northern hemisphere.)

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ARCTIC WARMING --> MEANDERING JET STREAM --> MISERABLE WINTERS IN US AND UK

If you live in the eastern US or in the UK, you've suffered through some of the coldest winters in recent history during the last decade.

North American cold wave November 4-23, 2014

Credit: Wikipedia

An international team of climate researchers from a variety of disciplines has now concluded that those extremely cold winters were the product of natural variability made worse by Arctic warming and ice melt.

Writing in the prestigious journal Nature Climate Change, the authors conclude that a reduced temperature gradient caused by more rapid warming at high latitudes has contributed to a slowed jet stream that meanders farther north and south, and takes longer to shift from one location to another. 

Global air temperature anomalies, January 2016
from Overland, et al., "Nonlinear response of mid-latitude weather to the changing Arctic"

When an extreme dip to the south stalls over a particular region--most recently the UK and the eastern US--arctic air can pour down and stay.

"We've always had years with wavy and not so wavy jet stream winds," says Edward Hanna, a professor of climate change at the University of Sheffield, in the UK, "but in the last one to two decades the warming Arctic could well have  been amplifying the effects of the wavy patterns."

That extra-wobbly jet stream is likely to continue or even grow worse as still-increasing levels of atmospheric CO2 warm the far north and melt more ice. However, the unlucky regions that serve as parking garages for prolonged blasts of Arctic air can vary from year to year. Hanna and his colleagues hope to use what they've learned to sharpen up forecasts of future extra-bitter winters.

“This would be hugely beneficial for communities, businesses, and entire economies in the northern hemisphere," says Hanna. "The public could better prepare for severe winter weather and have access to extra crucial information that could help make live-saving and cost-saving decisions.”

ARCTIC SEA ICE MELTDOWN--STRIKING 3D VISUALIZATION

The volume of arctic sea ice varies season by season and year by year. Unfortunately, the trend is clearly down, with current ice volume about one-quarter of what it was in 1980. That's not good news, since it's part of a vicious cycle of warming, melting and carbon dioxide release and that impacts the entire northern hemisphere.

NASA finds oldest and thickest Arctic sea ice is melting fastest

Credit: NASA Goddard

You can find more details plus a brilliant 3D visualization of the data -- thanks to physicist and climate expert Joe Romm andmulti-talented IT consultant Andy Lee Robinson -- at this URL.

The loss of Arctic sea ice cover does not only impact polar bears and Inuit communities. Scientists are becoming increasingly sure that a smaller temperature difference between the Arctic and the rest of the northern hemisphere makes for a much wobblier jet stream, which, ironically, can cause much colder winters, for example in the eastern U.S. and the U.K.

For another brilliant--and scary-visualization, check out Ed Hawkins' spiral map of global temperature change from 1850 to 2016. It's the most powerful anti-denial intervention I've ever come across.

Credit: Ed Hawkins

Fire threatens the Arctic tundra for the first time in 11,000 years


As reported in the 24 July, 2011 issue of Nature, a research team studied the aftermath of a large, unprecedented wildfire that scorched Alaskan tundra in 2007. Tundra fires, in which the carbon-rich soil actually burns, have been small and infrequent for the last 11,000 years. This fire, however, released a huge amount of carbon into the atmosphere, as much as the entire tundra biome, which stretches across the far north of Alaska, Canada and Eurasia, stores in a year.

You can read more about this fire and its implications for climate change in the Arctic and globally at Suite101.
You can access the abstract of the original Nature article here.

Pinko Polar Bears

On May 22, columnist George Will recast the U.S. government's reluctant decision to protect polar bears as part of a supposed war against all things good, true and American by the "green left," which he then equates with the "red left." He makes a big deal over some worries about global cooling that appeared three decades ago. You can read his rather slimy diatribe here. The institute's response follows:

Dear George,

I think you confuse the assiduous work of the scientific community
with a leftist agenda to establish complete government control.

If you would read the data and reports of the scientists instead of
relying upon your ideological perspective you might find that the
international community has come up with a broad consensus and a few
articles from 33 years ago do not prove them wrong.

When large insurance (and reinsurance) companies, most of the Fortune 500, every
other industrial nation, financial institutions, and stockholders such as
the Rockefeller family agree that climate change/global warming is a
threat that needs to be attacked immediately, one has to wonder why
all of these entities with their own scientific teams have decided
one way, and you with a seemingly impermeable ideological bent have
decided the other.

Perhaps, George, the experts--including the 1700 leading scientists who just published yet another urgent warning on climate change--are right and you are wrong.

Lou Miller, PhD