TECHNOLOGY

Crank up plankton growth. Blanket deserts in reflective plastic. Pump greenhouse gases into rock formations. Make clouds shinier. Build volcanoes.

These ideas -- called geoengineering -- are not just the stuff of fantasists.

No less an agency than NASA has issued a report on "managing solar radiation." U.S. Energy Secretary Steven Chu recently suggested that global warming could be slowed with white roofs. A Nobel laureate has written of putting sun-shading particles into the upper atmosphere.

Mainstream scientists -- many of the same people who are convinced that mankind accidentally and dangerously cranked up Earth's temperatures -- think man should at least contemplate his power to deliberately control the climate.

"We've been inadvertently engineering the climate for 200 years," said Mike Tidwell, the director of the Chesapeake Climate Action Network. "So why don't we do it deliberately for a while?"

Yet the prospect that such a fix is possible conjures twin anxieties. Action bold enough to work could create new problems on a global scale. And a world that believes it can compensate for climate change might quickly lose its motivation to treat the causes.

"You're not really solving the problem. You're just starting a second experiment," said Johannes Feddema, a geographer at the University of Kansas. "Most scientists are very leery."

Feddema's own work is a type of geoengineering on a local scale. Through computer models, he studies how human land cover -- from homes to roads to farms -- makes the planet warmer or cooler.

Feddema is looking at solutions as simple as painting our roofs and buildings white. He studies Mediterranean villages of blinding white buildings that reflect the sun and narrow streets that stay shaded most of the day. He has pondered using water columns to absorb heat in the day and radiate warmth at night. Hanging dark curtains should keep a home warmer in a cool climate, and reflective curtains can fight off the heat in the tropics.

But even those low-tech fixes don't offer simple solutions for a warming planet. Putting white roofs on buildings in Minnesota might help cool the planet ever so slightly, but it might also require the burning of more fossil fuels -- and create more planet-toasting greenhouse gases in the process -- to keep Minnesotans cosy in the winter.

"The measurements are pretty tricky," Feddema said. "You start calculating in the winds. And then a car drives by. What difference does that make?"

Feddema is among the broad majority of scientists convinced that the Industrial Age is responsible for the buildup in the atmosphere of carbon dioxide and other greenhouse gases, and that those gases are warming the planet far more quickly than seen in the history of natural climate cycles.

These scientists imagine a time, perhaps within a few decades, when melting glaciers and polar ice raise oceans high enough to threaten coastal cities and alter temperatures enough to turn rich agricultural areas into arid deserts.

That prompts various geoengineering strategies. Foremost among them is misting the stratosphere with aerosol sulfates. The technology is already here. Send tanker planes aloft to unload cheap and plentiful sulfur dioxide gas. Some of the sun's rays are deflected. Temperatures should drop.

That "would cool the planet, stop the melting of sea ice and land-based glaciers, slow sea level rise" and reverse carbon dioxide levels, Rutgers University meteorologist Alan Robock wrote in a recent scientific paper.

Nature has already tested the idea. Volcanic eruptions belch sediment into the skies that has proven to lower temperatures across the globe. (Predictions that atomic warfare would create a nuclear winter come from the same model, and some geoengineers have floated the idea of putting giant exhaust pipes on mountaintops to mimic a volcano's cooling powers.)

But Robock said seeding the stratosphere is a bad idea. It easily could trigger droughts, deplete the atmosphere's ozone layer, make less energy available for solar power systems, obscure the stars to astronomers and possibly destroy great swaths of ocean life. The sky would even be less blue, Robock said.

"This might be our last-gasp effort if we're balancing one bad thing against another bad thing, but it would be risky," he said. "We wouldn't really know what the side-effects would be until we gave it a try."

Consider what happened when Mount Pinatubo erupted in 1991 in the Philippines. It kicked up tens of millions of tons of sulfur dioxide that spread around Earth and lowered global temperatures about 1 degree. It was followed by the third-coldest and third-wettest U.S. summer in 77 years. When the Laki volcano blew in 1783 in Iceland, droughts the following summer triggered famine in India, Japan and Egypt.

Despite worries that a mechanical fix could have similar dire effects, some scientists think the buildup of greenhouse gases is too great to reverse by switching to electric cars and windmills.

"Like anything, we have to weigh the costs and benefits and then let 'er rip," said Anthony Lupo, a professor of atmospheric science at the University of Missouri.

Lupo said he's not convinced that the planet's rising temperatures are the result of human activity, but he thinks they are real. While he's wary of the unintended consequences of geoengineering, Lupo said he thinks it's ammunition we might want to stockpile.

The ideas are varied. Some people think that a mountaintop mini-volcano might be simplest, or that misting the stratosphere would be most effective. Others suggest launching a mirror in space between Earth and the sun. There also is a theory that injecting salt in clouds would make them more reflective, which would cool the planet.

Geoengineering theories aren't new. Russian scientists once proposed damming the Bering Strait and the Strait of Gibraltar to warm the Arctic and make Siberia more hospitable to humans. For decades, papers have been published in scientific journals raising the prospect of cooling the planet with giant engineering projects. In 1999, scientists dropped iron filings off the coast of Antarctica to see if a resulting plankton bloom would consume carbon and carry it to the ocean floor. Scientists still are skeptical it will work.

But the field got a boost in 2006, when Paul Crutzen, who won the Nobel Prize in chemistry, raised anew the idea of seeding the stratosphere with a sun blocker.

That, in turn, has prompted worries that building up expectations of ways to cool the planet would relieve pressure to stop heating it.

In the meantime, scientists work on other large-scale solutions aimed at the causes of climate change. For instance, Kansas State University geophysicist Abdelmoneam Raef has studied how to capture the carbon dioxide that comes from natural gas drilling and injecting it in porous ground under the sea. Pilot studies have shown the greenhouse gas can be captured there indefinitely.

"It is promising because the storage capacity is huge," Raef said.

So far, his work has been in the North Sea, " but there are areas in Kansas where we could do the same thing."

If those efforts aren't enough to stop global warming, or if it is simply too late to reverse what already has built up in the atmosphere, scientists say it makes sense to have a backup plan that shades Earth.

"Just trying to get greenhouse gases reduced might not be enough," said Simone Tilmes, a scientist at the National Center for Atmospheric Research. "It's definitely worth looking at alternatives."

-- The Kansas City Star.

Republished from the Winnipeg Free Press print edition August 30, 2009 B3