Carbon Lurking in Deep Ocean Threw Ancient Climate Switch, Say Researchers

[OKIsItJustMe]

https://blogs.ei.columbia.edu/2019/04/08/carbon-deep-ocean-ancient-climate-switch/

Carbon Lurking in Deep Ocean Threw Ancient Climate Switch, Say Researchers

Slowdown of Atlantic Circulation Sent Planet Into Deep Freeze

by Kevin Krajick | April 8, 2019

A million years ago, a longtime pattern of alternating glaciations and warm periods dramatically changed, when ice ages suddenly became longer and more intense. Scientists have long suspected that this was connected to the slowdown of a key Atlantic Ocean current system that today once again is slowing. A new study of sediments from the Atlantic bottom directly links this slowdown with a massive buildup of carbon dragged from the air into the abyss. With the system running at full speed, this carbon would have percolated back into the air fairly quickly, but during this period it just stagnated in the depths. This suggests that the carbon drawdown cooled the planet—the opposite of the greenhouse effect we are seeing now, as humans pump carbon into the atmosphere. But if the current keeps slowing now, we should not expect it to help us out by storing our emissions; possibly to the contrary. The study, led by researchers at Columbia University’s Lamont-Doherty Earth Observatory, appears this week in the journal Nature Geoscience.

The scientists targeted a system of currents called the Atlantic meridional overturning circulation, or AMOC. Flowing northward near the surface, it transports warm, salty water from near the equator into the latitudes near Greenland and northern Europe. Here, it hits colder water from the Arctic, becomes denser and sinks into the abyss, taking with it large amounts of carbon absorbed from the atmosphere. The deep water then circles back south, where much of it re-merges in the Southern Ocean, to release carbon back to the air. The journey takes place over decades to centuries.

A 2014 study by Lamont-Doherty scientists Steven Goldstein and Leopoldo Pena–both of whom also are coauthors of the new study–showed that this current system abruptly slowed around 950,000 years ago. The new study shows that this slowdown correlated directly with a huge buildup of carbon in the deep Atlantic, and corresponding decline of carbon in the air. This event was the apparent trigger for a series of ice ages that came every 100,000 years, versus previous ones that occurred about every 40,000 years, and which built up less ice than those that came later. Scientists call this turning point the Mid-Pleistocene Transition, and the new pattern has persisted right through the last ice age, which ended about 15,000 years ago. Exactly why the pattern has continued no one knows, but the study clearly demonstrates that the carbon missing from the air ended up in the ocean, and had a powerful effect on climate.

The Atlantic meridional overturning circulation, seen here in simplified form, brings warm water northward (red arrows) until it reaches the region around Greenland and northern Europe. Here, it sinks and travels southward (yellow arrows). Much of the water re-emerges in the Southern Ocean. (Courtesy Francesco Muschitiello/Lamont-Doherty Earth Observatory)

“It’s a one-to-one relationship. It was like flipping a switch,” said lead author Jesse Farmer, who did the work while a PhD. student at Lamont-Doherty. “It shows us that there’s an intimate relationship between the amount of carbon stored in the ocean, and what the climate is doing.”

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https://dx.doi.org/10.1038/s41561-019-0334-6

[True Dough]

1. It's stuff like this

that makes me think household efforts to curb carbon emissions are too late now. Either we come up with some game-changing technology that saves our bacon or we succumb to the forces of nature.

[OKIsItJustMe]

2. "Household efforts" may be too late now, on their own.

However, “household efforts” will be an essential part of any successful larger effort.

[True Dough]

3. "household efforts" will be an essential part of any successful larger effort

I'm not educated enough to know, but how does household carbon compare to industrial carbon? Let's say all the households in America reduce carbon by 50 per cent, or even 75 per cent. Would that offset Trump's moves to reinvigorate the coal industry, for instance? Would it "compensate" for all the oil drilling and fracking?

And how would households reduce carbon output by that much? Purchase and install solar panels. Can you afford to do that? I can't, not right now. How about buying an electric vehicle? Can you afford that? I definitely cannot. Yes, those technologies are improving and getting cheaper, but they're still expensive, at least up front.

I don't have answers, other than to get Trump out of office. That's a big first step. Where things go from there requires greater minds than my own. In the meantime, I feel rather helpless, to be honest.

[OKIsItJustMe]

4. Sources of Greenhouse Gas Emissions - EPA

https://www.epa.gov/ghgemissions/sources-greenhouse-gas-emissions

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The primary sources of greenhouse gas emissions in the United States are:

• Transportation (nearly 28.5 percent of 2016 greenhouse gas emissions) – The transportation sector generates the largest share of greenhouse gas emissions. Greenhouse gas emissions from transportation primarily come from burning fossil fuel for our cars, trucks, ships, trains, and planes. Over 90 percent of the fuel used for transportation is petroleum based, which includes gasoline and diesel.²
• Electricity production (28.4 percent of 2016 greenhouse gas emissions) – Electricity production generates the second largest share of greenhouse gas emissions. Approximately 68 percent of our electricity comes from burning fossil fuels, mostly coal and natural gas.³
• Industry (22 percent of 2016 greenhouse gas emissions) – Greenhouse gas emissions from industry primarily come from burning fossil fuels for energy, as well as greenhouse gas emissions from certain chemical reactions necessary to produce goods from raw materials.
• Commercial and Residential (11 percent of 2016 greenhouse gas emissions) – Greenhouse gas emissions from businesses and homes arise primarily from fossil fuels burned for heat, the use of certain products that contain greenhouse gases, and the handling of waste.
• Agriculture (9 percent of 2016 greenhouse gas emissions) – Greenhouse gas emissions from agriculture come from livestock such as cows, agricultural soils, and rice production.
• Land Use and Forestry (offset of 11 percent of 2016 greenhouse gas emissions) – Land areas can act as a sink (absorbing CO2 from the atmosphere) or a source of greenhouse gas emissions. In the United States, since 1990, managed forests and other lands have absorbed more CO2 from the atmosphere than they emit.

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