Large-scale changes in Earth’s climate may originate in the Pacific 

Posted: October 9, 2020 by oldbrew in climate, data, Ocean dynamics, paleo, research
Tags:


Some interesting theorising arises from this research, but as one expert commented: “These new data may raise more questions than they answer.” At least one existing belief about long-term climate change finds itself challenged.
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The retreat of North America’s ice sheets in the latter years of the last ice age may have begun with “catastrophic” losses of ice into the North Pacific Ocean along the coast of modern-day British Columbia and Alaska, scientists say.
[Science News reporting].

In a new study published October 1 in Science, researchers find that these pulses of rapid ice loss from what’s known as the western Cordilleran ice sheet contributed to, and perhaps triggered, the massive calving of the Laurentide ice sheet into the North Atlantic Ocean thousands of years ago.

That collapse of the Laurentide ice sheet, which at one point covered large swaths of Canada and parts of the United States, ultimately led to major disturbances in the global climate (SN: 11/5/12).

The new findings cast doubt on the long-held assumption that hemispheric-scale changes in Earth’s climate originate in the North Atlantic (SN: 1/31/19).

The study suggests that the melting of Alaska’s remaining glaciers into the North Pacific, though less extreme than purges of the past, could have far-ranging effects on global ocean circulation and the climate in coming centuries.

“People typically think that the Atlantic is where all the action is, and everything else follows,” says Alan Mix, a paleo-climatologist at Oregon State University in Corvallis. “We’re saying it’s the other way around.”

The Cordilleran ice sheet fails earlier in the chain of reaction, “and then that signal is transmitted [from the Pacific] around the world like falling dominoes.”

In 2013, Mix and colleagues pulled sediment cores from the seafloor of the Gulf of Alaska in the hope of figuring out how exactly the Cordilleran ice sheet had changed prior to the end of the last ice age.

These cores contained distinct layers of sand and silt deposited by the ice sheet’s calved icebergs during four separate occasions over the last 42,000 years.

The team then used radiocarbon dating to determine the chronology of events, finding that the Cordilleran’s ice purges “surprisingly” preceded the Laurentide’s periods of abrupt ice loss, known as “Heinrich events,” by 1,000 to 1,500 years every single time.

“We’ve long known that these Heinrich events are a big deal,” says coauthor Maureen Walczak, a paleoceanographer also at Oregon State University. “They have global climate consequences associated with increases in atmospheric CO2, warming in Antarctica … and the weakening of the Asian monsoon in the Pacific. But we’ve not known why they happened.”

Though scientists can now point the finger at the North Pacific, the exact mechanism remains unclear. Mix proposes several theories for how Cordilleran ice loss ultimately translated to mass calving of ice along North America’s east coast.

Full article here.

Comments
  1. Jamie Spry says:

    Reblogged this on Climatism and commented:
    “Settled science”, update…

  2. saighdear says:

    Eh? ‘may originate in the Pacific ‘ …. … am I dreaming or wha ? “The Fingerprint of the Sun is all over Earths Climate”…. what language are we speaking here?

  3. JB says:

    When mega flora (subtropical) and fauna are found at the Clovis layer, just below the black mat across Canada and northern US I find it hard to accept there was any ice cap anywhere by 13,000BCE.

  4. Paul Vaughan says:

    So they’ve chalk-marked their local place on a differintegral wheel:

  5. Paul Vaughan says:

    Conclusion

    Western math education is grossly deficient.

  6. Paul Vaughan says:

    Supreme Freedom

    Monster wealth barely spins elections we quickly forget.
    Imagine better philanthropist bets:

    “Mathematics is the queen of the sciences—and number theory is the queen of mathematics.” — Gauss

  7. oldbrew says:

    ‘They have global climate consequences associated with increases in atmospheric CO2’

    But the action precedes the CO2 changes, making them an effect, not a cause.

  8. Curious George says:

    Correlation is not causation?

    What a nonsense. It is causation, and we can even tell what causes what. Long live modern science! /sarc

  9. I suspect that seeking a terrestrial cause of terrestrial climate change is most likely a tad short sighted.

  10. Graeme No.3 says:

    Interesting article(s) about icebergs in the Southern Ocean in the last half of the 19TH Century.
    http://www.warwickhughes.com/climate/Iceberg.htm 2000AD

    Talks of Earth’s angular momentum being influenced.
    “One last point is worth making.  Whether the ice enters the sea from Greenland or Antarctica should make no difference.  The inertial impact will be manifest as climate change in the northern North Atlantic Basin.  The current surging of ice streams in both West Antarctica and Greenland needs to be watched – in relation to their potential impact on northern climate”.

  11. oldbrew says:

    From Graeme’s link:

    Continental ice launched at high latitudes becomes water in equatorial seas, and the Globe’s radius of gyration increases as a result.

    Angular momentum must be preserved; hence the Globe slows down, and length-of-day increases.

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