| NEW YORK
NEW YORK Scientists who flew a modified corporate jet from pole to pole to study how greenhouse gases move found carbon dioxide piling up over the Arctic, but also higher than expected levels of oxygen over the Antarctic.
The three-week, $4.5 million mission this month in a specially equipped Gulfstream V jet was the first of five flights planned over the next three years by a Harvard University-led project based in Colorado.
The research will help scientists understand how carbon is stored in the planet and how much carbon dioxide, the main greenhouse gas, is released by cars and factories burning fossil fuels, or by the burning of forests.
The jet, which flew from Colorado to the Arctic and back south to the Hawaiian Islands toward Antarctica, is equipped to suck in air samples and test them in a laboratory aboard.
Initial observations point to a carbon dioxide build up over the Arctic, which may be due to industrial pollution and burning of trees over the last few centuries, scientists told reporters on Thursday in a teleconference about the mission.
The slightly increased levels of oxygen over Antarctica may result from increased growth of plants in the tropics due to higher levels of carbon dioxide or higher temperatures, said Britton Stephens of the Boulder, Colorado-based National Center for Atmospheric Research.
Much of this may have to do with yearly biological changes in plants, Stephens said. Forests in the North absorb carbon dioxide in the summer and release it in the winter when leaves fall off and rot.
"There's a strong need to understand what the forests and oceans are doing now so we can predict whether or not they'll continue to protect (us) in the future," Stephens said.
As more than 180 countries try to agree on a successor agreement to the Kyoto Protocol on global warming, which runs out in 2012, atmospheric-based measurements are expected to play a larger role in trying to show how carbon dioxide and other greenhouse gases move across the atmosphere.
On Thursday, the U.S. space agency NASA said it will launch a satellite next month to measure carbon dioxide in the atmosphere, and Japan is also working on satellite research.
The combined measurements could eventually inform the world more accurately about the best way to slow global warming, which scientists warn could lead to more deadly heat waves, droughts, floods and storms.
One of the major challenges scientists face is tracking the estimated 30 billion tons of carbon emitted each year by motor vehicles, factories, deforestation and other sources. About 40 percent of the gas accumulates in the atmosphere, with the rest apparently being absorbed by oceans and forests.
Stephens said data from flights on the research jet will complement some 20 models that predict how greenhouse gases move through the atmosphere. Until now, these models run by universities and governments, have been based on observations from the surface of the planet.
Steven Wofsy, a Harvard professor of atmosphere and environmental science, said the flights should also provide a baseline for atmospheric observations that occur some 10 or 15 years into the future.
The next missions will be take place at different times of the year to help scientists learn more about the role seasons play in variations of carbon levels and to help make predictions about how much fossil fuel can be burned safely.
(Reporting by Timothy Gardner, editing by Anthony Boadle)