Researchers uncover a natural cause for early 20th century Arctic warming

Posted: May 30, 2017 by oldbrew in Natural Variation, Ocean dynamics, research, sea ice
Tags: ,

Arctic Ocean


Scientists have surprised themselves by noticing multi-decadal natural variability in the Arctic, and discovering some of its effects, as Phys.org reports. More than a hint of cyclical warming and cooling is implied, although they try to downplay it.

Is a warmer Arctic a canary of global warming? Since the 1970s the northern polar region has warmed faster than global averages by a factor or two or more, in a process of ‘Arctic amplification’ which is linked to a drastic reduction in sea ice.

But then how to explain a similar rapid warming that occurred during the early 20th century, when the effects of greenhouse gases were considerably weaker than today? And what can we prove about the period, given the scarcity of usable data and observations prior to the 1950s?

Now scientists from Kyoto University and UC San Diego have discovered that this phenomenon occurred when the warming phase—’interdecadal variability mode’—of both the Pacific and Atlantic Oceans coincided.


The team’s findings appeared recently in the journal PNAS. “We found that early 20th century sea surface temperatures in the tropical Pacific and North Atlantic had warmed much more than previously thought,” explains lead author Hiroki Tokinaga of Kyoto.

“Using observations and model simulations, we’ve demonstrated that rising Pacific-Atlantic temperatures were the major driver of rapid Arctic warming in the early 20th century.”

Previous explanations for early Arctic warming have including decreased volcanic aerosols and increased solar radiation, but none of these have been able to simulate observed conditions from the period.Tokinaga’s team found that when the interdecadal rise in sea surface temperatures was included in simulation calculations, the results properly reflected early Arctic conditions.

“Coupled ocean-atmosphere simulations also support the intensification of Arctic warming,” continues Shang-Ping Xie of UCSD, “which was caused by a concurrent, cold-to-warm phase shift of Pacific and Atlantic interdecadal modes.” The researchers explain that these new findings can help constrain model climate projections over the Arctic region.

“It is likely that temperatures in the Arctic will continue to rise due to anthropogenic global warming,” concludes Tokinaga. “Our study does not deny this. We are rather suggesting that Arctic warming could accelerate or decelerate due to internal variability of the Pacific and the Atlantic.”

“It is a challenge to accurately predict when the next big swing of multidecadal variability will occur. Careful monitoring is essential, given the enormous impact on the Arctic climate.”

Source: Researchers uncover a cause for early 20th century Arctic warming

Comments
  1. Timo Soren says:

    Wow publish a paper that shows natural variability is much higher than thought and the MUST include a ‘we are not deniers’ statement! Shows how they themselves recognize the intolerant GW’s in academia.

  2. tallbloke says:

    “Now scientists from Kyoto University and UC San Diego have discovered that this phenomenon occurred when the warming phase—’interdecadal variability mode’—of both the Pacific and Atlantic Oceans coincided.”

    And they’ve only just noticed this? How much have we been paying them these last several decades again?

    Time to ask for our money back…

  3. Richard111 says:

    “‘Arctic amplification’ which is linked to a drastic reduction in sea ice.”

    Current Arctic ice is within 1 standard deviation of readings from 1981 to 2000.

    Just how “drastic” is this reduction?

  4. tom0mason says:

    I still do not understand the intense scrutiny ‘climate science’ puts on the Arctic as if it means something special about what is happening to the planet.
    I have always said that the ice at the North pole is just an indicator of the local climate (not anything very global) and is governed largely by the ocean temperatures and prevailing winds (and sometimes by solar events).
    Wow they confirmed the bleeding obvious. Next up they’ll say as a global indicator of climate trends its damned poor (which is also bleedin’ obvious).
    Also is it not possible that for at least part of the last ice-age there was no ice at the North pole as the ocean was just warm enough while the sun had a long lived coronal hole, blasting lots of solar particle this way, ensuring the pole stayed warmer than the immediate surrounding land? (Do changes in oxygen isotope levels reflect this effect?) Fanciful yes, improbable even, but to me not impossible.

    If they want to study global effect and climate change in icy conditions then the other pole — the Antarctic — is by far the better candidate.

  5. erl happ says:

    Wow, they’ve re-discovered the Arctic Oscillation!

  6. stpaulchuck says:

    Annnnnnnnnd here come’s the throw-away line…. “It is likely that temperatures in the Arctic will continue to rise due to anthropogenic global warming,” concludes Tokinaga. “Our study does not deny this. ”

    Otherwise they probably could not have gotten this paper published.

  7. oldbrew says:

    “It is a challenge to accurately predict when the next big swing of multidecadal variability will occur. Careful monitoring is essential, given the enormous impact on the Arctic climate.”

    ‘Enormous impact’. Where does that leave puny trace gases like CO2? Be realistic.

  8. Caleb says:

    They have just discovered this? Skeptics have been attempting to point out the variations in sea-ice for years, but never get listened to.

    I suppose this is what happens to Alarmists when they are so gung-ho to make their point that they succumb to ploys such as “erasing the Medieval Warm Period.” Science has a habit of rediscovering Truth.

    There are old DMI ice-extent maps, using information from fishermen, carefully gathered by hard working scientists back before airplanes crossed over the ice (let alone satellites), but you would think the old maps didn’t exist. All you need to do is look at those old maps (probably more accurate close to Denmark than over towards Alaska) and you can see the ice has retreated and advanced in the arctic before, and likely will do so again.

    Back in 2012 a short-lived website called “Hide The Decline” produced a rather elegant post using those old maps. It still is worth looking at:

    http://hidethedecline.eu/pages/posts/arctic-sea-ice-data-collected-by-dmi-1893-1961-259.php

    I could point out other examples of Skeptics digging into the history and coming up with evidence the Arctic Sea has gone through some amazing variations in the amounts of sea-ice it holds, but after a decade of involvement in the “Climate Wars” I’m very aware the Alarmist response tends to be “La-la-la! I’m not listening.”

    That is why scientists walk on eggs, genuflecting to the god of Global Warming, when they “discover” what was already known, and likely was known back in the days of whaling ships.

  9. I wonder if the Kyoto folks read the Japanese Naval Reports from the years before WWII? The Navies in the North Pacific noticed ice retreat and reported to their Governments.
    Observations often lead to discoveries. Well, unadjusted ones do.

  10. oldbrew says:

    From Caleb’s link:
    Fig 11.
    1938: Unprecedented areas of open waters.
    (And again, this is not the ice minimum but just the August ice area)

    Fig 12. 1931-1946
    Already the year after, 1939, the ice extend resembles the pre 1923 extend.
    We see that a decline in Arctic ice area from around 1921 ends possibly in 1938.
    – – –
    Tony Heller regularly shows old news reports along these lines on his blog.
    https://realclimatescience.com/government-arctic-sea-ice-fraud/

    Here’s one of TH’s graphs (from the US Dept. of Energy):

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s