As a last resort, the White House would look at shooting particles into the atmosphere to cool the climate, Obama's new science adviser John Holdren told the Associated Press. Some media are playing up the "radical" aspect of the idea.

Well, it's certainly out there, and there's no agreement among scientists as to whether it'd be smart. Here's how it would work:

Certain types of aerosols, or tiny particles suspended in the air, are thought to have an overall cooling effect on the atmosphere. These particles intercept some solar radiation and scatter it back into space. The cooling effect on the Earth's climate can be seen after a volcanic eruption, which can spew millions of tons of sulfur into the atmosphere. Some scientists have suggested that we mimic nature and inject a bunch of sulfur into the atmosphere to counteract global warming. One problem with this plan is the increased amount of acid rain this would generate. Another is that sulfur would have to be regularly injected into the atmosphere to keep up the cooling, or global warming would pick up right where it left off.

Read more about this and 9 other wild and crazy environmental ideas we looked at recently as ways to improve the health of the planet, including such complex tasks as burying carbon underground and simple ideas like changing your diet.

Holdren (and presumably his boss) are worried we'll reach a tipping point on global warming before emissions can be reigned in. Like many scientists, the White House aims to reduce emissions. But how? That's fast becoming the multi-billion dollar question, as high-profile fuels like ethanol have not panned out as expected, and energy companies are not as excited about funding alternative projects as many had hoped.

Here are our recent analyses of 15 of the most viable alternatives:

Biodiesel, Clean Coal, Electric Cars, Ethanol, Geothermal Energy, Hybrid Vehicles, Hydrogen Vehicles, Nuclear Power, Ocean Thermal Energy Conversion, Power from Flowing Water & Waves, Solar Energy at Home, Solar Farms, Wind Power at Home, Wind Farms.

... And go here to vote on the one you think we should pour money into.

[Read the Full Story from AP]

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