For years science fiction writers and astronomers have speculated about the feasibility of terraforming other planets.
One dream is to make Mars habitatable for humans by warming the planet and therefore building up a wetter and thicker atmosphere.
The irony today is that scientists are now talking about "retro-terraforming" Earth of all places! The goal is to try and offset the effects of mankind's contribution to global warming. For example the production of electricity by burning oil and coal accounts for 40 percent of emissions that dump the greenhouse gas carbon dioxide into the atmosphere.
In a bold move toward cleaner energy, last week President Obama announced $8.3 billion in loan guarantees to build the first U.S. nuclear power plant in nearly three decades. (In hindsight I find it very ironic that our timidity about nuclear power since the 1970s has helped contribute to climate change.) With the shift toward minimally-polluting energy sources we could "de-carbonize" electricity production within 25 years, say some experts.
But even if we instantly stopped industrial carbon emissions world temperature will remain high for the next 1,000 years predicts David Keith of the University of Calgary. He calculates that only after 10,000 years global carbon dioxide levels would drop to about half of what they are today. (By contrast after 10,000 years nuclear fission waste is 1/3000th as radioactive as the day it left the power plant.)
This has inspired a spirited discussion among scientists about a planet fix-it strategy called geoengineering. Major technological steps would be taken to alter the atmosphere to cool off Earth faster.
One approach is to inject a sulfur aerosol into the atmosphere to make it reflect away more sunlight. Alternatively, spraying seawater into the atmosphere would create more white clouds that would reflect sunlight.
Another approach would be finding ways to absorb excess carbon dioxide in the atmosphere. One idea is to spread iron filings on the surface of the Pacific Ocean to boost phytoplankton growth, which in turn would absorb more carbon dioxide.
"Our current understanding of climate systems suggests that intelligently executed climate engineering would reduce risks to the environment," says Keith.
But critics of geoengineering say that it isn't nice to screw around with Mother Nature any more than has already been done. And, if the global cooling experiments fail we have no "Plan B." There is no other planet to evacuate to! Also, if the nations just stopped funding a large-scale geoengineering program it could accelerate global warming say some experts.
"Geoengineering is in fact untested and dangerous," says James Fleming of Colby College in Maine. We don't understand it, we can't test it on smaller than planetary scales, and we don't have the political capital, wisdom, or will to govern it."