The study is published in the journal Nature Geoscience. The scientists used a computer model developed at the Danish Centre for Earth System Science (DCESS) that analyses global changes extending 100,000 years into the future.
The DCESS model includes atmosphere, ocean, ocean-sediment, land-biosphere and lithosphere modules. According to the study, it reproduces 'observed evolutions since 1765 of key climate metrics including atmosphere and ocean warming, atmospheric gas contents and ocean and land-biosphere CO2 uptakes'.
Two emissions scenarios of the Intergovernmental Panel on Climate Change (IPCC) were evaluated: one with a moderate (3°C) temperature increase and one with a high (4.8°C) temperature rise. In both simulations, there was oxygen loss in the upper 500m of the ocean, largely in response to surface-layer warming. Importantly, overturning circulation in the deep ocean, which pulls oxygenated surface waters down to the depths of the ocean, decreased. The high-emissions scenario in particular predicted 'severe, long-term ocean oxygen depletion,' and it was clear that the suboxic regions of the ocean, which are void of fish and other larger creatures, would expand in both cases.
Observations in the oceans already show that suboxic areas are expanding as the atmosphere and ocean warm. In line with this and other supporting observations, the model projects a three- to seven-fold expansion in suboxic zones. The authors explain that as suboxic zones expand, different microbes and plankton take over. This forces a shift towards nitrogen fixers, which the researchers say would probably force large, unpredictable changes in ocean ecosystem structure and productivity, with serious consequences.
The study's conclusions are simple: 'Reduced fossil-fuel emissions would be needed to limit ongoing oxygen depletion and its long-term adverse effects.'
Extreme oceanic oxygen depletion events are thought to be behind some of the large extinction events in the Earth's history, including the largest such event 250 million years ago.
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27.06.2017 | International Institute for Applied Systems Analysis (IIASA)
Dune ecosystem modelling
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Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.
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What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.
To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...
The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....
A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...
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