Arctic climate change may not be making winter jet stream ‘weird’ after all

Posted: August 1, 2021 by oldbrew in modelling, research, Temperature, weather, wind
Tags: ,


Arctic sea ice [image credit: Geoscience Daily]

‘New research is pouring cold water on once-hot theory’ – WashPo. Researchers refer to ‘overestimation’. (Weird in this context at least tends to mean something like ‘not well understood’).
– – –
An influential, highly publicized theory — that a warming Arctic is causing more intense winter outbreaks of cold and snow in midlatitudes — is hitting resistance from an ongoing sequence of studies, including the most comprehensive polar modeling to date, says the Washington Post.

The idea, first put forth in a 2012 paper by Jennifer Francis, now at the Woodwell Climate Research Center, and Stephen Vavrus, at the University of Wisconsin at Madison, is that two well-established trends — Arctic amplification (intensified global warming at higher latitudes) and depleted sea ice — can force the polar jet stream to dip farther south, thus causing more intense bouts of winter weather than might have otherwise occurred.

Over the past decade, this hypothesis sparked widespread public interest and scientific debate, as various high-profile cold waves and snow onslaughts hit North America and Eurasia, including a deadly, prolonged cold wave in Texas last February.

Winter temperatures over the past three decades have shown cooling in some areas of the northern midlatitudes, especially eastern Asia.

But the cooling has been far from ubiquitous and the Arctic-midlatitude link has been difficult to detect in simulations by global computer models.

Instead, the models point more strongly toward the gradual, longer-term trend of milder midlatitude winters that one would expect in a human-warmed climate. [Talkshop comment – or any warmed climate].

(A separate line of research is addressing extremes during the summer, such as the unprecedented heat wave that struck the Pacific Northwest in June; see below.)

Some emerging work, not yet peer-reviewed, does reveal faint fingerprints of the Francis-Vavrus hypothesis in new simulations of Arctic and midlatitude winter climates, part of the Polar Amplification Model Intercomparison Project (PAMIP).

“It does look like there’s something there, but it looks fairly weak,” James Screen, a climate scientist at the University of Exeter, said in an interview. “That doesn’t mean it’s not one part of the overall jigsaw.”

“There’s genuine reason to be concerned about climate change and its effects,” Screen added, “but an increase in the frequency in cold events would not be at the top of my list.”

Screen has published several related studies with Russell Blackport, now at Environment and Climate Change Canada, over the past two years. The title of one of their latest, published in April in the Journal of Climate, is itself an assertion: “Observed Statistical Connections Overestimate the Causal Effects of Arctic Sea Ice Changes on Midlatitude Winter Climate.”

In this study and others, Screen and Blackport suggest that the connection between Arctic sea ice loss and extreme midlatitude events is real, but not necessarily causal. Instead, they argue, a third factor — most likely large-scale changes in atmospheric circulation that may not be permanent — is probably driving both the sea ice loss and the extreme winter events.

Full article here.

  1. JB says:

    “…an increase in the frequency in cold events would not be at the top of my list.” said James Screen just before his winter heating bills skyrocketed beyond sight.

    “…most likely large-scale changes in atmospheric circulation that may not be permanent — is probably driving both the sea ice loss and the extreme winter events.”

    Yeah, the increase of cosmic radiation, the lack of sunspots modulating the spiraling Birkeland currents at the poles.

  2. craigm350 says:

    Reblogged this on WeatherAction News and commented:
    The theory was always bunk. A cursory look at historical patterns would show that these patterns have occurred before, long before polar amplification could have possibly

    For example, Matt Brewer and I looked at global climate models driven by rapidly increasing greenhouse gases and found that high-pressure areas like that seen last week will WEAKEN under global warming. Just the opposite of what Professor Mann was suggesting.

  3. oldbrew says:

    One idea was that the atmosphere shrinks due to cooling around solar minimum, which compresses the jet stream in unpredictable ways, or at least can do so.

  4. Gamecock says:

    ‘including the most comprehensive polar modeling to date, says the Washington Post’

    What exactly is ‘most comprehensive polar modeling?’

    I assume we are expected to believe it’s “better.” Are they throwing out all previous modeling that wasn’t as ‘comprehensive?’

    These kinds of assertions, which are made several times a year, are tacit admissions that all previous models were junk, and, by extension, current models will be junked by the next generation of super mo’ betta models coming to a media outlet near you in the near future.

    There is no continuity in climate science.

  5. Stephen Wilde says:

    Still looking good for my hypothesis which is that solar particle and wavelength variations have different effects on the ozone creation/ destruction balance in the stratosphere above equator and poles so that solar changes alter the gradient of tropopause height between equator and poles.
    It is the changes in that gradient which result in variable zonality/ meridionality in jet stream tracks.
    Zonal gives less clouds and warming.
    Meridional gives more clouds and cooling.
    More clouds with meridionality simply because there are longer lines of air mass mixing and such mixing leads to cloud formation when the cooler air mass reduces to warmer air mass to beneath its dew point.
    If the sun remains quiet the next stage will be an increase in La Ninas relative to El Ninos whereupon true cooling should set in and then the atmospheric CO2 levels can be expected to stop growing or even begin to decline.
    It is likely that the ice cores do not capture the short term CO2 variations induced by solar and oceanic variability so we have a false sense of how stable or unstable it actually is in the atmosphere.

  6. Alan Lowey says:

    “Arctic amplification (intensified global warming at higher latitudes)”

    Why has the question of why the Northern hemisphere has 3x warming of the Southern hemisphere never queried anymore? Perhaps because it doesn’t fit with the manmade CO2 emissions causing global warming theory?

    (The alternative is a new physics solution. Extra energy is coming into the system due to the Sun’s exotic core tilting towards the plane of the planets. Gravitational forcing is pushing warm equatorial waters to higher latitudes. Even the world map of ocean temperature change given in AR5 for policy makers allows for this hypothesis. The data is pixelated white around the equator compared to the familiar reds & oranges of the mid-latitudes.)

  7. michael hart says:

    “There’s genuine reason to be concerned about climate change and its effects,” Screen added, “but an increase in the frequency in cold events would not be at the top of my list.”

    Easy to say when you live in Exeter, not Aberdeen.

  8. michael hart says:

    ..To which I’ll add a story I never tire of telling.

    As a grad student, I met a Russian post-doc at the University of Washington in Seattle. He had done his PhD in Aberdeen, and sported a fine half-Scottish accent. I asked him what he thought of the place. He shuddered and made an exclamation about the terrible winter weather. He came from Moscow.

    And another one. During my years living in Lancaster, I knew an American student from Billings, Montana. She also thought the winters in Lancaster were utterly horrible.

  9. pochas94 says:

    So the models don’t pick up greater loopiness and stationarity of the jets? Wonder why.

  10. Phil Salmon says:

    More egregious paleo climate fraud: computer models coded to show CO2 warming, find past Oligocene cooling to have been caused by (rather than being the cause of) CO2 decline.

    Since cooling causes CO2 decrease and vice versa warming, for reasons too obvious to mention, this cause-effect inversion fraud is all too easy and rubber stamped into a climate science literature that is emptying itself of value through political obeisance.

    [reply] indeed

  11. dennisambler says:

    Polar Amplification was always a theory:
    “A Century of Climate Change in Nuuk Fjord, Greenland” Taurisano, A. et al 2004
    “…the temperature data “show that a warming trend occurred in the Nuuk fjord during the first 50 years of the 1900s, followed by a cooling over the second part of the century, when the average annual temperatures decreased by approximately 1.5°C.”

    “Climate variation in the European Arctic during the last 100 years” Hanssen-Bauer, Forland: Norwegian Meteorological Institute: CliC International Project Office June 2004
    “Analyses of climate series from the European Arctic show major inter-annual and inter-decadal variability, but no statistically significant long-term trend in annual mean temperature during the 20th century in this region. The temperature was generally increasing up to the 1930s, decreasing from the 1930s to the 1960s, and increasing from the 1960s to 2000. The temperature level in the 1990s was still lower than it was during the 1930s.”

    “Observationally based assessment of polar amplification of global warming”
    Igor V. Polyakov et al 2004

    “Modulated by multi-decadal variability, SAT trends are often amplified relative to northern-hemispheric trends, but over the 125-year record we identify periods when arctic SAT trends were smaller or of opposite sign than northern-hemispheric trends. Arctic and northern-hemispheric air-temperature trends during the 20th century (when multi-decadal variablity had little net effect on computed trends) are similar, and do not support the predicted polar amplification of global warming.”

    International Journal of Climatology Volume 22, Issue 9, Published Online: 5 Jul 2002
    2002 Royal Meteorological Society

    “A detailed analysis of intraseasonal (within season) and interannual (between years) temperature variability for the whole Arctic for the period 1951-90 is provided. The absence of significant changes in intraseasonal and interannual variability of TMEAN, TMAX, TMIN and DTR is additional evidence (besides the average temperature) that in the Arctic in the period 1951-90 no tangible manifestations of the greenhouse effect can be identified.”

  12. oldbrew says:

    dennisambler says: August 8, 2021 at 6:49 pm
    – – –
    Probably career-ending stuff now, but maybe not ~20 years ago?

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