New evidence of a long-term planetary thermostat to remove excess CO2

July 26, 2016 by Jim Shelton, Yale University
Researchers Richard Norris, left, Donald Penman, and Pincelli Hull study core samples of sediment from the North Atlantic. Credit: Yale University

Scientists working in the North Atlantic have found the clearest geologic evidence yet of a planetary thermostat that counteracts the warming cause by massive amounts of greenhouse gas by absorbing CO2 into the rocky sediments of the Earth itself.

The researchers said they analyzed ocean floor sediment off the coast of Newfoundland to confirm a sudden release and subsequent removal of CO2 that occurred 56 million years ago during the Paleocene-Eocene Thermal Maximum (PETM). That event, in which thousands of petagrams of were released into the atmosphere and ocean in just a few thousand years, is considered by many researchers to be the closest ancient analogue to today's rise in atmospheric carbon levels.

"It's long been thought that when the planet warms, as it did during the PETM, the rate of rock weathering on land, which absorbs CO2 from the atmosphere, increases. This draws down CO2 and cools the planet back down again," said Yale University geologist Donald E. Penman, a postdoctoral fellow in the lab of Pincelli Hull and first author of a paper reporting the findings in the journal Nature Geoscience.

The products of that weathering process, Penman explained, are dissolved ions that end up in the ocean, where organisms such as plankton and corals turn them into . The carbon is not fully removed from the system until that calcium carbonate is buried in sediments.

"What our paper details is a pulse of carbonate burial in the aftermath of the PETM," Penman said. "We analyzed a sediment core in which, before the PETM, there is no carbonate at all, and then in the recovery phase of the event, it has lots of carbonate."

The work builds upon a large body of research about carbon cycling begun a generation ago by the late Yale geochemist Robert Berner. It was Berner who pioneered the notion of a planetary thermostat mechanism via rock weathering and carbonate burial in sediments.

Penman and his co-authors collected core samples from sea floor sediments located in an area known as the Newfoundland sediment drifts. The effort was part of a research voyage undertaken by the Integrated Ocean Drilling Program, aboard the scientific drilling ship JOIDES Resolution. The chief scientists on the voyage were Richard Norris of the Scripps Institute of Oceanography and Paul Wilson of the University of Southampton, in the United Kingdom. Norris is a co-author of the new paper.

The data will help scientists as they try to understand the causes and effects of the PETM, say the researchers, and also may provide insight into how Earth will handle rising carbon levels in the future.

"We believe this process is going to operate in response to carbon emissions related to human activity," Penman said. "But if the PETM is any guide, it will take tens of thousands of years."

Explore further: Human carbon release rate is unprecedented in the past 66 million years of Earth's history

More information: An abyssal carbonate compensation depth overshoot in the aftermath of the Paleocene-Eocene Thermal Maximum, Nature Geoscience, DOI: 10.1038/ngeo2757

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ChiefFartingDog
Jul 26, 2016
This comment has been removed by a moderator.
Benni
2.1 / 5 (11) Jul 26, 2016
CFD......your CFD handle already tells us everything we need to know about the level of science in which you have the intellectual capacity to function. So knowing what your smelling & where your doggie nose is spending so much of it's time, what's to care what you & Phys 1 think about anything?
PPihkala
4.6 / 5 (10) Jul 27, 2016
So if I understand this right, the carbon we have polluted to atmosphere in two centuries, will take nature hundreds of centuries to scrub out. So during that time we have to endure the heat or clean this mess by ourselves.
Maggnus
4.2 / 5 (10) Jul 27, 2016
So if I understand this right, the carbon we have polluted to atmosphere in two centuries, will take nature hundreds of centuries to scrub out. So during that time we have to endure the heat or clean this mess by ourselves.

Yes, essentially that is correct. The carbon cycle is slow
ForFreeMinds
2.5 / 5 (10) Jul 30, 2016
The way I read this, rock weathering on earth consumes carbon (and more weathering with higher temperatures), which then eventually gets to the ocean and plankton that die, sink, and bet buried in the sediment. It also suggests that some of this carbon might escape back to the atmosphere before it gets buried in sediment. And it's likely a non-linear relationship that isn't well known given all the different types of rock and their different weathering characteristics from a carbon sink point of view.

The more we learn, the more we know that our climate models only model part of the system. Which helps partly explain why their predictions have been so wrong.
Maggnus
4 / 5 (8) Jul 30, 2016
The way I read this, rock weathering on earth consumes carbon (and more weathering with higher temperatures), which then eventually gets to the ocean and plankton that die, sink, and bet buried in the sediment. It also suggests that some of this carbon might escape back to the atmosphere before it gets buried in sediment. And it's likely a non-linear relationship that isn't well known given all the different types of rock and their different weathering characteristics from a carbon sink point of view.
This is very true, and deserves a 5. It is a complex system, a system we are learning more and more about.
The more we learn, the more we know that our climate models only model part of the system. Which helps partly explain why their predictions have been so wrong.
No. That we don't know everything does not mean we know nothing. Our climate predictions have proven to be remarkably accurate.
BackBurner
1.4 / 5 (9) Jul 30, 2016
"Our climate predictions have proven to be remarkably accurate. "

You mean they predicted tomorrow would be warmer than today and they were right almost 50% of the time? That accurate?

I have a model that's almost guaranteed to double your investments in the stock market. We're talking proven, top notch stuff. You send me $35 and I'll send you the software. It's the trading platform of the 21st century. Don't leave home without it!
Da Schneib
4.3 / 5 (6) Jul 30, 2016
The more we learn, the more we know that our climate models only model part of the system.
You do realize that this only means that after it gets really hot, in a hundred thousand years or so it will get better, right?

Right?
Maggnus
4.4 / 5 (8) Jul 30, 2016
You mean they predicted tomorrow would be warmer than today and they were right almost 50% of the time? That accurate?[
Another poser who doesn't understand the difference between 'climate" and "weather".

I have a model that's almost guaranteed to double your investments in the stock market. We're talking proven, top notch stuff. You send me $35 and I'll send you the software. It's the trading platform of the 21st century. Don't leave home without it!
What does one say to such stupidity? Sure dumdum, send me your address.
Da Schneib
5 / 5 (4) Jul 30, 2016
If anybody doubts it, here is the abstract of the paper: http://www.annual...0-133431

The period of carbon release is thought to have lasted <20 ka, the duration of the whole event was ∼200 ka, and the global temperature increase was 5–8°C.
200,000 years.
Jayded
5 / 5 (2) Aug 01, 2016
All this means is that runaway climate change is prevented over the course of a tens of thousands of years. What is does not state which it should is the living conditions of a planet with those levels of CO2 in the atmosphere. PETM is synonymous with mass extinctions and complete upheaval in the fossil record. In a nutshell, the earth's system can self regulate but the world we live into today would never survive the time it took to do so.

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