Ocean sink for human-made carbon dioxide measured — ScienceDaily

Not all CO 2 produced during the burning of fossil fuels will remain in the atmosphere and cause global warming. Marine and terrestrial ecosystems emit large amounts of these anthropogenic emissions from the atmosphere.

The ocean takes CO in two steps 2 : First, CO 2 dissolves in surface water. Later, the ocean's inversion cycle distributes it: ocean currents and mixing processes transport dissolved CO from the surface deep into the interior of the ocean, accumulating over time.

Carbon sink in the ocean

This flipping cycle is the driving force behind the ocean settlement of CO 2 . The size of this sink is very important for the atmosphere: without this sink, the concentration of CO in our atmosphere and the extent of human climate change will be much higher than this level. .

It has long been a priority for climate researchers to determine the share of artificial CO absorbed by the oceans. The team of international scientists led by Nicholas Gruber, a professor of environmental physics at the Federal Institute of Technology in Zurich, has now determined that the ocean has a settling period of 13 years. As reported in the latest issue of Science the researchers found that the oceans absorbed 3.4 billion tons of man-made carbon (billions of metric tons) from the atmosphere between 1994 and 2007. This figure is equivalent to 31% of the total emissions of CO 2 during this period.

The sea is sunk intact

This percentage of ocean absorption (19,459,002) remained relatively stable compared to the previous 200 years, but the absolute number increased significantly. This is because marine sediments increase more or less proportionally as long as the atmospheric CO rises: the more CO in the atmosphere the more it is absorbed. Ocean – until it eventually becomes saturated.

So far, this has not been achieved. “During the review, the global ocean continued to absorb artificial CO at a rate consistent with the increase in atmospheric CO Gurberexplained

These data-based studies also confirm the early model-based early estimates of oceanic sinks by artificial CO . “This is an important insight that makes us believe that our approach is correct,” adds Gruber. The results further led the researchers to draw conclusions about the settlement of terrestrial ecosystems, which are more difficult to determine.

Regional Differences in Absorption Rate

Although the overall results indicate complete ocean subsidence of man-made CO, the researchers also found considerable deviations from the expected rise in atmospheric CO in different ocean basins . For example, the North Atlantic's absorption is 20% less than expected between 1994 and 2007. “This may be due to the slowing of the North Atlantic meridional overturning circulation in the late 1990s. It is likely to be the result of climate change,” Gruber explained. However, this lower sink in the North Atlantic was offset by the massive absorption of the South Atlantic, so the absorption of the entire Atlantic developed as expected.

The researchers recorded similar fluctuations in the Southern Ocean, the Pacific Ocean, and the Indian Ocean. Gruber stressed: "We understand that ocean subsidence does not only respond to the increase in atmospheric CO. It is substantially sensitive to climate change, suggesting that feedback is significant as the climate changes."

Results of two investigations

The results are based on a global survey of CO 2 and other chemical and physical properties in various oceans, measured from the surface to a depth of up to 6 km. Scientists from seven countries participated in the international coordination plan that began in 2003. On a global scale, they conducted more than 50 studies before 2013 and then synthesized them into global data products.

For their analysis, the researchers used new statistical methods developed by Gruber and his former Ph.D. Student, Dominique Clement. This approach allows them to distinguish between changes in artificial and natural constituents that constitute a change in the total concentration of dissolved CO in the water. 2 . Natural CO 2 refers to the number of CO 2 that existed in the ocean before industrialization.

Gruber has been involved in a similar study around the millennium. Based on observations from the first global survey conducted in the late 1980s to the mid-1990s, the study estimated that the oceans absorbed approximately 11.8 billion tons of carbon from the beginning of industrialization around 1800. His current research team extended this analysis to 2007, not only allowing them to budget for artificial CO 2 from 1994 to 2007, but also to assess the integrity of the ocean. Carbon sink.

Increasing the amount of CO 2 will make the marine habitat acidified

By regulating the rate of global warming, man-made ocean subsidence provides an important service for humans, but it has its cost: CO 2 dissolves in the ocean to acidify water. “Our data shows that this acidification goes deep into the ocean and partially extends to depths of more than 3,000 meters,” Gruber said.

This can have serious consequences for many marine life. Calcium carbonate spontaneously dissolves in an acidified environment, posing a hazard to shells and bones made of calcium carbonate and mussels. Changes in marine chemical composition can also affect physiological processes such as fish breathing. Gruber firmly believes: “Recording human activities is critical to the chemical changes that occur in the oceans, especially in understanding the effects of these changes on marine life.”

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Materials provided by ETH Zurich [19459008 . The original was written by Michael Keller. Note: Content can be edited for style and length.

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