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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.

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