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Greenhouse gas predictions may be too modest
Posted By Karin Kloosterman On June 17, 2009 @ 12:00 am In | No Comments
An Israeli scientist has discovered that previously unrecorded greenhouse gases are being emitted into the atmosphere through cracks in the earth.
Al Gore may have given us a frightening picture of climate change and our future, but now new research suggests that even his predictions could be too modest, after an Israeli scientist discovered that cracks in the earth are emitting unrecorded greenhouse gases into the atmosphere.
This is the first time this phenomenon has been observed, and since gases from these cracks have never been included in previous measurements, the new findings could change the model of how science calculates the impact of greenhouse gases on climate change.
The discovery was made by hydrologist and soil physicist, Dr. Noam Weisbrod from Ben Gurion University. While he was studying fractures in the earth in the Negev Desert, he encountered an unusual phenomenon occurring on a daily basis – an unexpectedly quick accumulation of salt within fractures between flood events. The phenomenon was even more pronounced in winter.
Following preliminary studies he and his colleagues built an “atomic bomb shelter-like” research lab under the earth, designed to explore the conditions within a fracture over the year. An array of sensors installed there enabled the scientists to explore the connection between atmospheric conditions and earth-atmosphere gas exchange rate.
As a scientist, Weisbrod knew that the naturally occurring salts found in the rocks couldn’t diffuse into the fracture surfaces at such a speed, so he started experimenting and looking for a clue as to what was happening.
“Over the years, we explored the processes occurring, due to wetting and drying cycles in fractures — after a flood event,” he tells ISRAEL21c. “During a rain event we would have a big influx of salt going out of the fracture, going downward… eventually the concentration would lessen quickly, then almost cease… it took us a few years to think about a mechanism, about a process,” he says.
Challenging today’s basic science
“It couldn’t be a continuous diffusion of salts from the rock into the fracture, because it was happening too fast for diffusion to be responsible for the observed salt concentration,” says Weisbrod. “We explored concepts and tried to think about different options, and we came up with the idea that we have thermal convection.”
This is a process, says Weisbrod, which occurs in arid and semi-arid environments like the Western US, southern Israel and about 60-70 percent of the world. “What happens after sunset is the atmospheric air becomes colder, but the air within the fracture is still warm because it’s in equilibrium with the rock.”
Since cold air is denser than warm air, it creates an unstable condition, and the cold air drives down and replaces the warm air. This unique mechanism results in conditions that make it possible for a quick transference of various gases from the subsurface of the earth to the atmosphere. The quick transfer of warm air to cold is “a never-before considered effect,” says Weisbrod that challenges the traditional model that climate change scientists have been using to quantify greenhouse gas emissions.
For example, where there are intense activities of microorganisms inside a crack, there would be a lot of gases coming into the fracture and released there. Subsequently, these gases would then be released by way of the thermal-convection mechanism Weisbrod proposes. These gases can be carbon dioxide or any other gas, he says.
“Carbon dioxide is diffused through the Earth’s crust or the Earth-atmosphere interface through diffusion,” says Weisbrod. “It’s possible that greenhouse gases can be transported through thermal convection in areas where we have fractures, cracks, caves, or warm holes… the same physics works for every hole in the ground.”
Weisbrod and his colleagues, Prof. Maria Dragila at Oregon State University and PhD student Uri Nachshon at Ben Gurion University, have now completed three years of research in this study and are guarded about jumping to conclusions.
Moving ahead cautiously
“I am trying to be very cautious, and I know that in theory it sounds good,” says Weisbrod. “It has an impact, since all models so far have ignored this phenomenon.”
Weisbrod believes that the “crack in the earth” effect is not limited to fractures, but that his newly explored mechanism might be relevant to landscapes where there is a lot of limestone, for example.
“I am trying not to jump too high before we explore the possibilities. It’s better to go slow. We are sure about the mechanism, and proved its existence. And we know in terms of potential it has the potential to be important in the transfer of gas between the earth crust-atmosphere interfaces. More research is needed from my end and my group is now looking at different angles,” he notes.
Weisbrod also works in the area of rural water development and has recently returned from Ethiopia, where he and 13 students from Ben Gurion University went to do some “practical” work with a small Texas based NGO, Water For All, which installs drinking water wells in rural areas in countries such as Ethiopia and Bolivia.
“I believe that as leading scientists in water-related issues, especially in Israel, we should contribute to people that have no access to drinking water or basic irrigation, only because of lack of technology,” says Weisbrod.
“Life is not only about complicated equations and state-of-the-art technology and science. I feel that exposing our graduate students to the type of problems and issues that exist in developing countries, and in particular in rural areas, is very important for their education and understanding water issue in a large perspective,” he adds.
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