The air contains greenhouse gases such as CO2, which are now known to be responsible for global warming because their concentration has risen continu-ously for a number of years. In contrast to the atmosphere, the concentration of CO2 in the oceans is sixty times higher.
In the global carbon cycle the sea ab-sorbs a proportion of the atmospheric CO2 but also releases CO2 into the at-mosphere again. About half of the anthropogenic emission of CO2 is absorbed naturally by the oceans. Thus it is all the more important to understand how the exchange of CO2 between the ocean and the atmosphere functions with regard to a world that is warming up. The newly available study shows that the ocean was able to store more CO2 during the ice age than it can today.
Practically static bodies of water
Together with North American colleagues, an ETH Zurich research team made measurements on sea bed sediments. These sediments originate from moun-tains lying at a depth of about three kilometres below the water surface of the sub-Arctic Pacific Ocean. At that point the water temperatures are close to freezing and the conditions are very stable, because there is practically no mix-ing between the deep bodies of water and the surface water. The circulation of the water is measured using the radio-carbon method, which is based on the radioactive decay of the carbon isotope 14C. Measurements showed that the deep Pacific water has not been at the surface for more than 2,000 years.
Tiny single-celled organisms betray the CO2 level
To find out how the situation has changed compared to the last ice age, the re-searchers studied mud from the sub-Arctic Pacific Ocean lying approximately one metre below the present sea bed and about 20,000 years old. Tiny single-celled organisms with limestone shells known as foraminifera were selected from this mud under a microscope and afterwards measured with mass spec-trometers. These foraminifers locked in the carbon isotope signature of the seawater of their day - like in a time capsule. The research team has now been able to measure the 14C content precisely. This enabled them to show that the water in the ocean depths exchanged less CO2 with the atmosphere than at present.
A sobering result
The team also looked for key indicators that provide some information about the chemical composition of the ice age water. They found unusually clear evidence that this water captured more CO2 from the atmosphere than the water at the present day. The latest research results show that the oceans are generally able to fix more CO2 when they are cold.
Oceans that warm up as a result of climate change release more CO2 into the atmosphere. This discovery has far-reaching consequences for the climate. The ocean warming caused by humans contributes to the formation of additional greenhouse gases, mainly CO2. Consequently the positive feedback with the atmosphere associated with the latter leads to an even greater acceleration in global warming.
Samuel Jaccard, Research Assistant at ETH Zurich and one of the two principal authors of the study thinks that: "With a system as complex as the climate, even if we cannot draw conclusions directly from the natural cold past that are appli-cable to the warm future modified by humans, our results show that anthropo-genic warming causes additional critical feedback on the CO2 balance."
Original paper: Galbraith, E.D., Jaccard, S.L., Pedersen, T.F., Sigman, D.M., Haug, G.H., Cook, M., Southon, J.R., Francois, R. Carbon dioxide release from the North Pacific abyss during the last deglaciation, Nature, 449, 890-894.
Renata Cosby | idw
Monitoring lava lake levels in Congo volcano
16.05.2018 | Seismological Society of America
Ice stream draining Greenland Ice Sheet sensitive to changes over past 45,000 years
14.05.2018 | Oregon State University
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...
A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.
The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...
Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.
Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...
A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.
Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...
02.05.2018 | Event News
13.04.2018 | Event News
12.04.2018 | Event News
18.05.2018 | Power and Electrical Engineering
18.05.2018 | Information Technology
18.05.2018 | Information Technology