Do you really want to start messing with the atmosphere? If not, then stop emitting so much CO₂. Or so argues the U.K.-based Royal Society, the same people who brought you Isaac Newton, Charles Darwin and Stephen Hawking. A new report by the Society analyzes so-called geoengineering—"the deliberate large-scale manipulation of the planetary environment," or consciously tweaking Earth's climate in an attempt to stave off global warming—and finds that it is feasible and worth studying carefully, but probably not something we want to get involved in.

Artificial volcanoes, mirrors in space or other climate-altering schemes might be the last, best hope for mankind if we don't get started reducing greenhouse gas emissions pronto—specifically a 50 percent reduction (at minimum) in global emissions from 1990 levels by mid-century, according to a 12-member panel convened by the Society. "Geoengineering and its consequences are the price we may have to pay for failure to act on climate change," said report chair and climate modeler John Shepherd of the University of Southampton in a prepared statement. "Used irresponsibly or without regard for possible side effects, geoengineering could have catastrophic consequences similar to those of climate change itself."

A now-defunct California company back in 2007 attempted to fertilize the ocean off the coast of Ecuador with iron to prod plankton to grow. Such a bloom, it proclaimed, would suck up carbon dioxide (CO₂) and then send it to the ocean floor as the one-celled plants died and sank. The company, Planktos, sank last year before that could ever happen. But new research suggests that its CEO Russ George and his ilk may have been on to something: plankton blooms do eliminate more CO₂ than regular growth.

Raymond Pollard of the U.K.'s National Oceanography Center in Southampton and his colleagues observed the natural plankton blooms near the Crozet Islands some 1,400 miles (2,200 kilometers) southeast of South Africa, near Antarctica. The waters to the north of the islands are enriched with iron from their volcanic rocks and, each spring, a more than 46,000 square mile (120,000 square kilometer) bloom blossoms.

If mimicking a massive volcanic eruption by spraying sulfur dioxide into the air or flying thousands of mirrors into space to shade Earth to halt climate change doesn't cut it for you, how about this? A fleet of 1,500 automated ships, dubbed "albedo yachts," spewing saltwater into the sky to make denser clouds that reflect more sunlight—and cool the world.

Atmospheric physicist John Latham of the National Center for Atmospheric Research in Boulder, Colo., and a host of British colleagues propose that a such a battalion—total tab at least $2.6 billion—would ply the world's oceans thickening clouds as they went. The idea—minus the ships to accomplish it—was first proposed by Latham in 1990 and has popped up with new details every couple of years since.