|
Ancient climate switch could signify sharp increase in today's global temperature
November 24, 2004A paper published in today's Nature suggests that global warming could rapidly accelerate due to a positive feedback mechanism caused by water vapour or rainfall. The paper, which examines a period of rapid climate change 55 million years ago, during the Paleocene and Eocene, offers a clear indication of how gradual global warming can rapidly speed up, causing catastrophic effects.
Until recently, the prevailing view was that the temperature rise during the Paleocene/Eocene, of between five and ten degrees Celsius, was caused by a massive release of methane from the sea floor. Methane is a greenhouse gas, capable of causing a rise in temperature. However, work by scientists from the Universities of Sheffield and California, began to cast doubt on this theory, and further investigation found a new reason for this rapid change in climate.
Professor David Beerling, from the University of Sheffield and co-author the study explains, "Methane is an easy gas to look for as it leaves a negative isotope trail behind, meaning that we can detect a methane release event in sediments from any given era.
"When we examined sediments from across the Paleocene-Eocene boundary we found that methane had left a far bigger signature behind in sediments on land than in the sea. This effect was replicated across several continents. Our challenge was to explain why this amplification on land had occurred.
"Methane's geochemical signature would only be higher in terrestrial sediments if plants had had more water available to them, either from the air in water vapour, or due to increased rainfall. When this occurs plants are able to photosynthesise better, which changes the isotopes they deposit on the ground in the form of dead matter. This, in turn affects the magnitude of the methane signature then found in the fossilized sediments.
These results suggest that a gradual increase in temperature causes a switch to a more humid/wetter climate state, which in turn amplifies global warming, causing it to warm more quickly. This can lead to sudden and dramatic increases in global temperature.
"The relevance of this research for today is that we are currently going through a similar process of gradual global warming to that that occurred during the Paleocene/Eocene. It suggests that the planet could again experience a rapid rise in temperature, if water vapour increases and amplifies the effects of current global warming.
"Scientists predicting the future effects of climate change rely upon computer models, since we have never lived through this kind of change before. However, by looking back to what has happened in the past we can better predict and test our models of future climatic change."
Sheffield, University of
"When we examined sediments from across the Paleocene-Eocene boundary we found that methane had left a far bigger signature behind in sediments on land than in the sea. This effect was replicated across several continents. Our challenge was to explain why this amplification on land had occurred.
"Methane's geochemical signature would only be higher in terrestrial sediments if plants had had more water available to them, either from the air in water vapour, or due to increased rainfall. When this occurs plants are able to photosynthesise better, which changes the isotopes they deposit on the ground in the form of dead matter. This, in turn affects the magnitude of the methane signature then found in the fossilized sediments.
These results suggest that a gradual increase in temperature causes a switch to a more humid/wetter climate state, which in turn amplifies global warming, causing it to warm more quickly. This can lead to sudden and dramatic increases in global temperature.
"The relevance of this research for today is that we are currently going through a similar process of gradual global warming to that that occurred during the Paleocene/Eocene. It suggests that the planet could again experience a rapid rise in temperature, if water vapour increases and amplifies the effects of current global warming.
"Scientists predicting the future effects of climate change rely upon computer models, since we have never lived through this kind of change before. However, by looking back to what has happened in the past we can better predict and test our models of future climatic change."
Sheffield, University of
Methane News and Current Methane Events RSSDo the hyper-coordinate planar transition metal atoms exist?
A study reported in Vol 51, Issue 7 (July, 2008) of Science in China Series B: Chemistry has shown that wheel-shaped structures with octa- and enneacoordinate planar cobalt, iron and nickel centered in perfect octagonal and enneagonal boron rings, are stable on corresponding potential hyper-surfaces. This suggests that the central element bonding capacities have not been exhausted.
Ancient Oak Trees Help Reduce Global Warming, MU Study Finds
The battle to reduce carbon emissions is at the heart of many eco-friendly efforts, and researchers from the University of Missouri have discovered that nature has been lending a hand. Researchers at the Missouri Tree Ring Laboratory in the Department of Forestry discovered that trees submerged in freshwater aquatic systems store carbon for thousands of years, a significantly longer period of time than trees that fall in a forest, thus keeping carbon out of the atmosphere.
Permafrost Threatened by Rapid Retreat of Arctic Sea Ice, NCAR Study Finds
The rate of climate warming over northern Alaska, Canada, and Russia could more than triple during periods of rapid sea ice loss, according to a new study led by the National Center for Atmospheric Research (NCAR).
NASA Scientists Pioneer Method for Making Giant Lunar Telescopes
Scientists working at NASA's Goddard Space Flight Center in Greenbelt, Md., have concocted an innovative recipe for giant telescope mirrors on the Moon. To make a mirror that dwarfs anything on Earth, just take a little bit of carbon, throw in some epoxy, and add lots of lunar dust.
Biodesign's Rittmann offers promising perspectives on society's energy challenge
Perhaps there is no greater societal need for scientific know-how than in finding new ways to meet future energy demands. Skyrocketing gas prices, an uncertain oil supply, increasing demand from around the world, and the looming threat of climate change have made identifying and developing realistic energy alternatives a national priority.
Astronomers Weigh the Coldest Brown Dwarfs with Astronomy's Sharpest Eyes
Astronomers have used ultrasharp images obtained with the Keck Telescope and Hubble Space Telescope to determine for the first time the masses of the coldest class of "failed stars," a.k.a. brown dwarfs.
Methane Release Could Cause Abrupt, Far-Reaching Climate Change
An abrupt release of methane, a powerful greenhouse gas, from ice sheets that extended to Earth's low latitudes some 635 million years ago caused a dramatic shift in climate, scientists funded by the National Science Foundation (NSF) report in this week's issue of the journal Nature.
Hubble, Keck images show continued turbulence in Jupiter's atmosphere
Increased turbulence and storms first observed on Jupiter more than two years ago are still raging, according to astronomers from the University of California, Berkeley, and the W. M. Keck Observatory in Hawaii, who snapped high-resolution pictures of the planet earlier this month.
Halting methane squanderlust
The pipes that rise from oil fields, topped with burning flames of natural gas, waste fossil fuels and dump carbon dioxide into the air. In new work, researchers have identified the structure of a catalytic material that can turn methane into a safe and easy-to-transport liquid. The insight lays the foundation for converting excess methane into a variety of useful fuels and chemicals.
Deep sea methane scavengers captured
Scientists of the Helmholtz Centre for Environmental Research (UFZ) in Leipzig and the California Institute of Technology (Caltech) in Pasadena succeeded in capturing syntrophic (means "feeding together") microorganisms that are known to dramatically reduce the oceanic emission of methane into the atmosphere.
More Methane News Articles
| © 2008 BrightSurf.com |