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Global Warming: A Cloudy Issue
Calvin alum looks for answers in this heated debate
By Lynn Bolt Rosendale '85


I've looked at clouds from both sides now,
Both win and lose and still some how,
It's clouds' illusions I recall.
I really don't know clouds at all.
--Judy Collins 1967

If there is one, the person who ought to know about clouds is Tom Ackerman '70. He has been studying clouds for more than 20 years. But even Ackerman admits he's only scratched the surface.

"Clouds are a great mystery," said Ackerman, chief scientist for the Atmospheric Radiation Measurement (ARM) Program of the U.S. Department of Energy. "It seems like the more we know, the more we find out that we don't know."

Ackerman has written about such topics as the distribution of clouds in the atmosphere, aircraft measurements in and around clouds, heating rates in clouds, distribution of cloud properties (like the size of cloud drops and ice crystals) and fractal statistics of cloud properties.

It was about ten years ago, though, that Ackerman gained company in his cloud studies. The scientific community started to take a real interest in finding out more about clouds. For it was in the early 1990s that "global warming" became a hot topic and Ackerman found himself in the middle of a very heated debate.

"I hesitate to use the words 'global warming,'" said Ackerman. "People get so worked up about those two words. There isn't any doubt that we're warming the place up. If you add carbon dioxide to the atmosphere, it warms, which in turn increases the amount of water vapor in the atmosphere. This warms the atmosphere even more. No one questions that. The real questions are: how much have we warmed it? how much will we continue to warm it? and how fast?"

That's where clouds come in.

"Once the magnitude of the problem was recognized around 1990, the lack in understanding of the cloud process became apparent," said Ackerman. "People realized we didn't know enough about clouds and that pointed the field in this direction."

That direction was right at Ackerman, who was a professor of meteorology at Pennsylvania State University and had also worked ten years for NASA researching planetary atmospheres. He was named the chief scientist for the ARM Program in 1998. While still a professor at Pennsylvania State in the early 1990s, he was a part of the original science team for ARM and became the site scientist for the Tropical Western Pacific site leading to his appointment as chief scientist.

The problem, in the early 90s, was a tremendous lack of data with which to begin the research.

"We needed a way to measure everything we could in the atmosphere that is over our heads," said Ackerman, "and certainly that includes clouds, along with radiant energy going up and down and surface temperatures and many other things. Once we've collected a significant amount of data we can build models that duplicate what we observe. The understanding of a phenomenon is not complete until you can build a model of what is going on, but models have to have data."

So Ackerman, who was among a team of 60 researchers, built the first site in Oklahoma in 1994.

The half-mile by half-mile central facility is equipped with numerous instruments including radar, lasers, weather vanes and a 200-foot tower. "This is a very well-instrumented facility," he said. "It's the best in the world to do what we do."

Around the central facility, in a 75-mile radius, are 20 smaller facilities collecting additional data.

While the Oklahoma site got the project off to a good start, additional data was needed from other climate zones to build a complete model. So in 1996, a tropical site in New Guinea was added and in 1997, a site on the northern slope of Alaska at Point Barrow. Finally, in 1998, a site on the island of Nauru, which measures three by five kilometers and is located on the Equator in the Pacific Ocean, was added to closely simulate the atmosphere directly over the ocean. Ackerman was directly responsible for the development and implementation of the two tropical sites.

Each of these sites collects data 24 hours a day, 365 days a year to help produce climate models that will aid in forecasting for the future.

"What we have begun to do with the data is build models that we think will work," said Ackerman. "That's the thing about science," he said. "People have a vision of science that is colored by the Noble Prize hype. They think science is about discovering an incredible thing one day, but most science is like what I do. You have a bunch of people together trying to build a castle with no blueprint. You start by laying bricks one at a time. Some days the bricks are right, but some days you have to come in and knock down the bricks from yesterday. You can only build on what you knew the day before. There are many, many details and then one day you get a brilliant idea about how it all fits together."

While all of the pieces of clouds and their effect on global warming haven't fit together yet, advances have been made in the last ten years thanks to the efforts of the ARM research team.

In the pre-industrial age there was 280 parts of carbon dioxide per million in the atmospthere. Now, there are 370 parts per million. That increase in carbon dioxide has increased the water in the atmosphere which affects the distribution of clouds. We get more clouds and maybe thicker clouds than we had before, explained Ackerman.

The debate about global warming ultimately begins in the clouds.

"If we get thick, low clouds which deflect the sunlight, the surface temperature cools down," said Ackerman. "If we get thin, high clouds which absorb infrared rays trying to get out, we get higher temperatures and we increase the initial warming that we already had."

Where the difficulty in research comes is whether the production of the clouds is going to amplify the warming effect, negate it a little or completely negate it.

"The best answer we have to that right now it that clouds amplify the warming," said Ackerman. "That is the truth with a small t. It's the truth as we know it today. That might change tomorrow because of something additional that we learn."

That is why there has not much consensus about the problem, he said.

"The discovery of an ozone problem in 1974 was extremely controversial," said Ackerman. "Two atmospheric chemists wrote a paper describing their theory and the larger scientific community spent 12 years running models and carrying out a whole sequence of experiments in order to prove that the original study was largely correct."

Finally, the scientific consensus was strong enough to negotiate a protocol and the use of Freon was phased out and the ozone layer should recover in 30-40 years."

The global warming problem is similar, he said. There isn't enough scientific consensus to get quick action.

"In my professional judgement, I don't think the next 10 to 20 to 30 years are going to fundamentally alter what we now know," he said. "But the problem is not going to go away."

But many argue, what exactly is the problem?

"The problem we're looking at is if we continue to use fossil fuels, what will a climate like this produce?" Ackerman said. "What I see are strong indicators that we are experiencing and will continue to experience global warming and we've warmed more lately than we did earlier and we ought to be taking steps to reduce that danger."

And what is that danger?

"In the western United States, the biggest reservoir of water is in the snow pack," said Ackerman. "California, Colorado and Oregon, for example, all depend on the snow pack to supply water all summer. If we continue to lose snow pack, as we know we are, that has societal implications. If we conclude that there will be less snow pack, then we need to account for this in our water strategy decisions and try to adapt to it-in other words, plan for changes in the climate as we now know it."

Such plans might not be necessary however if steps were taken to reduce the use of fossil fuel now, he said.

"It's basically risk assessment," said Ackerman, "and we do this throughout our lives. When we have young children over at our house we take grandma's antique bowl and put it up a few shelves. We don't redo all of the furniture in the house, but we make choices about what would be feasible. For us now, we need to look at what we can economically do and take steps towards that. The U.S. is the biggest generator of carbon dioxide in the world, we should take the lead role. The really scary thing is though that for countries like China, which are set on industrializing, their available fuel is coal and that produces significantly more CO2 than fossil fuel."

Ackerman claims the U.S. knows what steps to take. "We did it before during the oil shortage in the early 1970s. People turned their thermostats down, bought smaller cars and thereby reduced our dependence on fossil fuel. That's what we need to do in addition to seeking alternative types of fuel."

Ackerman's concerns were affirmed at the Kyoto (Japan) Protocol two years ago when representatives from all over the world confirmed that we are indeed experiencing global warming and we should seek to reduce CO2 emission to the atmosphere.

While the discussion goes on, Ackerman continues to study clouds and the atmosphere at his four research stations around the world.

"People want answers, but this is a long study project," he said. "The challenge is that people don't have a ten-year attention span in this country-that's a problem. When people lose interest, the problem is forgotten. The trouble is it's not going to go away."


Lynn Rosendale is Calvin's publications coordinator.




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