How Greenland Melt Can Kick off A Warm “Ill Wind” Near Antarctica

Sixteen thousand years ago, Greenland melt set off a cascade of impacts to the world ocean and atmosphere that led to the dredging of carbon rich waters from deep below the Pacific surface. These waters then disgorged enough carbon into the atmosphere to ultimately raise CO2 levels by 40 parts per million.

(Related: Bad Climate Wind Rises.)

A recent report in Nature Communications found that:

“During this earlier period, known as Heinrich stadial 1, atmospheric CO2 increased by a total of ~40ppm, Antarctic surface atmospheric temperatures increased by around 5°C and Southern Ocean temperatures increased by 3°C.”

How did it all happen? According to the science, Greenland melt slowed down North Atlantic Deep Water formation. This, in turn, caused the North Atlantic to cool and the South Atlantic to warm. The resulting change in temperature then shoved the band of stormy weather called the Inter-Tropical-Convergence-Zone southward. Subsequently, the westerlies in the Southern Hemisphere were shifted poleward and strengthened. Stronger, more southward running winds around the southern pole dredged up carbon rich deep water near the pole and on into the Pacific. This carbon then transferred to the atmosphere.

It’s an interesting bit of science. But it has a good degree of relevance to the present day. That’s because Greenland is again melting greater volumes of water into the North Atlantic. The North Atlantic is again cooling. And the Southern Ocean winds are again being driven south as they strengthen.

(How Greenland melt pulled carbon from the Southern Ocean. A process that is being driven to repeat by present human-forced climate change. Image source: Nature Communications.)

According to lead author Dr. Laurie Menviel:

“With this in mind, the contraction and strengthening of westerly winds today could have significant implications for atmospheric CO2 concentrations and our future climate.”

This is a kind of feedback that results from the warming humans have caused that can result in more carbon being wrung from the ocean. And it’s a concern because it shortens the available time-frame in which to respond to the crisis that is climate change.

(Greenland melt, the North Atlantic cool pool, and strengthening, southward moving Southern Ocean winds. These dynamics set off a carbon feedback about 16,000 years ago. Similar dynamics are coming into play today due to human caused climate change. Image source: Earth Nullschool.)

To be clear, present rates of fossil fuel burning are dumping an amount of carbon into the atmosphere at a much higher rate than this identified Earth System response could ever match. But, as the study authors note, the Southern Ocean has already sequestered 10 percent of carbon emitted by humans. If that sequestration halts and then reverses, then the rate of atmospheric CO2 accumulation, even if emissions stay stable, will rise by about 0.2 to 0.4 ppm per year.

This report lends further urgency to global efforts by responsible institutions and individuals to reduce global carbon emissions and transition to clean energy. Bringing the more difficult outcomes of rising heat trapping gasses closer and closer to the present day.

Please read more here.

Hat tip to mlp in NC.


How Arctic Sea Ice Loss Could Make the Hot Pacific Blob Permanent 

From the North Pacific to the tropics, loss of sea ice will result in a vastly heated Pacific Ocean in which events like the recent Hot Blob become far more common. Those were the conclusions of a new model study conducted by Wang, Deser, Sun and Tomas and recently published in Geophysical Research Letters.

(Understanding how sea ice loss in the Arctic can result in large-scale Pacific warming.)

An ocean heating event called the Blob resulted in mass loss of sea life during the period of 2013-2014. It was associated with a towering high pressure ridge in which the upper level winds ran far to the north and into the Arctic. Beneath the ridge, temperatures both at the land and ocean surface grew to be much warmer than normal.

Though viewed as a fluke by some, many began to draw connections between the powerful ridge feature, the related Pacific warming, and sea ice loss in the Arctic. Now, a new scientific study using climate models has produced some rather telling findings. First, the study found that Arctic sea ice loss results in large scale Pacific Ocean warming within just 10-20 years of widespread Arctic Ocean ice reductions. Second, the study models indicated that warming occurred first and strongest in the North Pacific, but then rapidly translated toward the Equator.

(Sea surface temperatures across the North Pacific were much warmer than normal during the hot Blob event of 2013-2014. A new model study finds that sea ice loss will make such extreme events common.)

The reason for this change in planetary and Pacific Ocean energy balance is scientifically described as a teleconnection. In very basic terms, loss of sea ice at the Arctic Ocean surface produces changes in local wind patterns that ripple through the global atmosphere. After a rather short period of time, wind patterns in the upper levels of the atmosphere and at the surface in the Pacific Ocean become involved.

Winds are often the vehicle by which energy is transferred throughout the atmosphere and at the surface. So a change in winds, from the top of the atmosphere to the bottom, can swiftly translate to a change in surface temperatures.

(A new model study shows radical changes in Pacific sea surface temperatures in response to Arctic Ocean sea ice loss.)

Looking at the study, it appears more likely now that the Northern Pacific Hot Blob of 2013-2014 was not a fluke, but instead an early knock-on effect of Arctic sea ice loss. A kind of event that will tend to become commonplace as the Arctic Ocean ice continues to melt. And that eventually, sooner rather than later, the heat build-up in the North Pacific will translate south to the Equator. First warming the Eastern Pacific in a more persistent El Nino type pattern and then spreading west (see image above).

As with the Blob, everything from the health of sea life to the intensity of extreme weather would be substantially impacted by such large scale changes. In other words, it looks like large scale losses of Arctic sea ice are enough to affect a broad and disruptive change in the global climate regime.

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