For the first time, they have reconstituted tthe evolution, over 800,000 years, of levels of carbon dioxide and methane, the two main greenhouse gases after water vapor. With these new numbers, the researchers now have access to data which will help them better predict future climate changes on earth. The results are published in two articles in the 15 May 2008 issue of /Nature/.*
In the absence of greenhouse gases (water vapor, carbon dioxide, methane...), the average temperature on earth would be -18°C, resulting in conditions unable to sustain life. The concentration of these gases in the atmosphere has substantially increased over time, due to human activity (fossil fuel combustion, development of agriculture). Studying the evolution of these concentrations allows us to better understand their interaction with the earth's climate, and this type of study is carried thanks to ice cores, which contain the only available records of greenhouse gas levels.
An ice core drilled in Antartica near the Franco-Italian base Dome Concordia, as part of the EPICA project, reached 3270 meters in December 2004, stopping a few meters above solid rock. At these depths, the ice dates back 800,000 years, or 8 glaciary-interglaciary climatic cyles. This is the oldest ice ever cored until now, and the analysis of gas bubbles trapped in the ice has allowed recordings of levels of carbon dioxide (CO2) and methane (CH4) in the atmosphere 800,000 years ago (previous recordings only went back as far as 650,000 years ago). In light of these new measurements, researchers have access, for the first time, to reference curves for levels of CO2 and CH4, showing the evolution of the gases in ancient times. This is precious information for scientists attempting to understand the correlation between climate change on earth and the carbon cycle. These results give hope for better predictions of future levels of greenhouse gases, and in theory, of the earth's climate.
This work has already enabled researchers to make major progress in certain areas. It confirms the close correlation between temperatures recorded in Antartica in the past and atmospheric levels of CO2 and CH4. Another significant observation is that never, in 800,000 years, have greenhouse gas levels been as high as they are today (current levels surpass 380 ppmv (5) for CO2 and 1800 ppbv (6) for CH4). The CO2 curve also shows that the lowest levels ever recorded were 172 ppmv, 667,000 years ago. Moreover, researchers have shown the existence of a modulation in atmospheric CO2 levels on a relatively long time scale, namely several hundreds of thousands of years. This unique phenomenon could stem from the more of less significant intensity of continental erosion which affects the carbon cycle over large time scales.Thanks to the remarkably detailed records of atmospheric methane, researchers have noted an increase over time in the periodicity of a component called precession . This signal, which is correlated to monsoon intensities in South East Asia over millenia, probably reflects an intensification of the monsoon in tropical regions over the last
which helps to redistribute temperature around the globe). The issue of why this phenomemon appears at the beginning of the ice ages remains to be explained.
(6) This means that for every billion air molecules, 1800 are CH4 molecules. ppbv = part per billion in volume.*BIBLIOGRAPHY*
Orbital and millennial-scale features of atmospheric CH4 over the last 800,000 years. Loulergue, L., A. Schilt, R. Spahni, V. Masson-Delmotte,T. Blunier, B. Lemieux, J.-M. Barnola, D. Raynaud, T.F. Stocker, and J. Chappellaz. /Nature/. 15 May 2008.
Julien Guillaume | alfa
Joint research project on wastewater for reuse examines pond system in Namibia
19.12.2016 | Technische Universität Darmstadt
Scientists produce a new roadmap for guiding development & conservation in the Amazon
09.12.2016 | Wildlife Conservation Society
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.
The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...
UMD, NOAA collaboration demonstrates suitability of in-orbit datasets for weather satellite calibration
"Traffic and weather, together on the hour!" blasts your local radio station, while your smartphone knows the weather halfway across the world. A network of...
Fiber-reinforced plastics (FRP) are frequently used in the aeronautic and automobile industry. However, the repair of workpieces made of these composite materials is often less profitable than exchanging the part. In order to increase the lifetime of FRP parts and to make them more eco-efficient, the Laser Zentrum Hannover e.V. (LZH) and the Apodius GmbH want to combine a new measuring device for fiber layer orientation with an innovative laser-based repair process.
Defects in FRP pieces may be production or operation-related. Whether or not repair is cost-effective depends on the geometry of the defective area, the tools...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
16.01.2017 | Power and Electrical Engineering
16.01.2017 | Information Technology
16.01.2017 | Power and Electrical Engineering