Wednesday 29 January 2014

The Canadian Arctic

The Hockey Stick Lives: Canadian Arctic Warming Unprecedented In 120,000 Years
Joe Romm

27 January, 2014

Recent warming has been unprecedented in speed, scale, and cause. Last year, we reported on a study that found the rate of warming since 1900 is 50 times greater than the rate of cooling in the previous 5000 years, which threatens to destroy the stable climate that enabled civilization.

The warming is so fast that it’s easy to forget how cold it used to be just a few decades ago, which is the point of a recent Climate Central analysis and the awesome xkcd cartoon based on it (above).

We’ve known for a while that the Arctic — which is warming at twice the rate of Earth as a whole — is now warmer than it has been in at least 2000 years. As a National Center for Atmospheric Research study found in 2009:

Arctic temperatures in the 1990s reached their warmest level of any decade in at least 2,000 years, new research indicates. The study, which incorporates geologic records and computer simulations, provides new evidence that the Arctic would be cooling if not for greenhouse gas emissions that are overpowering natural climate patterns.

That is one long hockey stick. But now a new study led by UC Boulder Institute of Arctic and Alpine Research Associate Director Gifford Miller takes things way, way back:

Average summer temperatures in the Eastern Canadian Arctic during the last 100 years are higher now than during any century in the past 44,000 years….

Since radiocarbon dating is only accurate to about 50,000 years and because Earth’s geological record shows it was in a glaciation stage prior to that time, the indications are that Canadian Arctic temperatures today have not been matched or exceeded for roughly 120,000 years, Miller said.

The key piece here is just how unprecedented the warming of Arctic Canada is,” said Miller…. “This study really says the warming we are seeing is outside any kind of known natural variability, and it has to be due to increased greenhouse gases in the atmosphere.”

A video explaining the study can be found here. This research answers the key question of whether recent warming exceeded that of the highest temperatures following the end of the last Ice Age:

The study is the first direct evidence the present warmth in the Eastern Canadian Arctic exceeds the peak warmth there in the Early Holocene, when the amount of the sun’s energy reaching the Northern Hemisphere in summer was roughly 9 percent greater than today, said study leader Gifford Miller. The Holocene is a geological epoch that began after Earth’s last glacial period ended roughly 11,700 years ago and which continues today.

And so we have the hockey stick, which countless studies have now vindicated.
Since the climatologist Michael Mann is most closely associated with the hockey stick and the unprecedented nature of recent warming, I asked him for a comment on the new study. He replied:

This study is just one more brick in the wall of evidence telling us that the planetary warming we are now seeing is without precedent in the period of human civilization. But we have only seen the tip of the proverbial iceberg. If we continue with business as usual burning of fossil fuels, we will see far greater, far more devastating, and potentially irreversible changes in climate in the decades ahead. This study reminds us of the urgency of placing limits now on our emission of greenhouse gases into the atmosphere.

In case you were wondering what business as usual would mean, here’s the classic figure:

Temperature change over past 11,300 years (in blue, via Science, 2013) plus projected warming this century
on humanity’s current emissions path (in red, via recent literature).

Are we really so myopic a species that we’re going to do this to ourselves?

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