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Controversy again surrounds Aslam Khalil's research on methane.

FOR NEARLY 30 YEARS, atmospheric physicist Aslam Khalil has been ruffling the feathers of scientific colleagues across the globe—and time after time, seeing the establishment come around to his way of thinking.

His work, which has often led to controversy, is incorporated into the Kyoto protocol on global warming and the Montreal protocol on ozone depletion.

Now, Khalil, professor of physics and director of PSU’s Environmental Science and Resources Program, is at it again.

In a paper published in a recent issue of Environmental Science and Technology, Khalil reported that his research team has found that global annual emissions of methane—one of the most potent greenhouse gases in the Earth’s atmosphere—have not increased for the past 25 years after more than doubling in the past century.

Methane is the second most harmful greenhouse gas after carbon dioxide.

The sticking point is that Khalil believes the stability will last. Other scientists are incredulous, sure that regulation is required to guarantee any lasting change.

WHAT’S AT STAKE? If Khalil is right, climate models predicting global warming will need to be revised.

Khalil and his team analyzed methane levels measured in recent years at strategic locations around the globe, then combined that data with their own measurements going back nearly 25 years to create the longest timeline of methane measurements yet. They found that atmospheric concentrations of this greenhouse gas had leveled off during this time period despite a growing human population. Basically, the amount of methane emitted into the atmosphere is being destroyed in the atmosphere at about the same rate.

In the scientific community, though, members are skeptical. One group of researchers reported in the September issue of Nature that they believe the slowdown is temporary, caused by a worldwide drought that has temporarily shrunk wetlands, which contribute a large share of the world’s atmospheric methane. Furthermore, the article says, methane emissions from industrial sources are actually increasing.

That may be so, says Khalil, but he maintains that other sources of methane, such as China’s rice paddies, are decreasing, which is why levels will continue to hold steady.

BEFORE HIS RESEARCH on methane more than 20 years ago, even less was understood about the naturally occurring gas and its sources. Reference books listed methane as a stable component of the Earth’s atmosphere.

Khalil found otherwise.

He worked with his mentor, Reinhold Rasmussen of the Oregon Graduate Institute (now part of Oregon Health & Science University). Analyzing Rasmussen’s measurements of atmospheric gases taken at Oregon’s Cape Meares in the early 1980s, Khalil found an increase in the levels of atmospheric methane and published his findings.

The scientific community immediately scoffed.

“It was the first instance of a gas other than carbon dioxide increasing,” he says. “It started a new wave of people trying to validate the findings.”

And they did. Out of that flood of research came a greater understanding of methane and its sources.

Now, after raising the first alarm, Khalil has the ironic job of saying things aren’t looking quite so grim.

Having proved to his own satisfaction that methane is stable, Khalil is ready to move on to a study of the interaction of methane and nitrous oxide, an even more harmful greenhouse gas.

As for the rest of the scientific community? Time will tell—and that’s just fine with Khalil.

More about Khalil's research.

Melissa Steineger, a Portland freelance writer, wrote the article “True Crime” in the winter 2007 Portland State Magazine.

Grounded in Science

FOR MANY YEARS, Aslam Khalil has worked where the rice is—China. Recently, he has focused on growing the grain closer to home in a controlled environment.

In a greenhouse outside Science Building 2, Khalil and his assistants are studying the interaction between methane and nitrous oxide created when nitrogen and organic fertilizers are applied to the rice crops.

That on-campus research will get a boost when a new research-grade greenhouse is built later this year, and when the proposed Science and Research Teaching Complex project is completed. PSU has identified a $41 million funding need to fully upgrade Science Building 2 infrastructure while improving its laboratories and creating more teaching and research space.

The goal is to complete these and other improvements by 2010.

Khalil looks forward to an environment better suited for research, and for that other basic of scientific endeavors—finding grants. Modern laboratories and other facilities will give funders the confidence that grant money will be well spent, he says.