The prospect of geoengineering, the intentional large-scale manipulation of the climate to offset the effects of global warming, continues to draw the attention of top scientists and policymakers. The prestigious journal Science is publishing two papers on the subject in its next issue, and next week the Science Committee of the House of Representatives will hold its second hearing on the subject.

According to some climate models, climates could change very quickly as greenhouse gas emissions rise, such as when thawing permafrost releases methane (a powerful heat-trapping gas), or loss of ice causes the earth to absorb more heat. Such outcomes might not be very likely, but even the chance that they could happen has scientists worried, as they could lead to widespread severe drought and famine and rapid sea level rise, among other things. Even the most ambitious efforts to curb greenhouse emissions might not be enough to prevent disastrous climate change, some say. And ambitious efforts to cut emissions seem ever more unlikely, after the limited success of the recent summit in Copenhagen, and opposition to a climate change bill in the Senate.

In one of the Science articles, researchers say testing of geoengineering strategies may prove necessary, but before testing can occur, they say an international agreement should be reached. Such testing could cause changes in weather patterns that could hurt some countries, for example, and an agreement needs to be in place to establish standard testing procedures and methods for dealing with international disputes arising from such testing.

Such an agreement might be even more important if the argument of another Science paper proves to be correct. In that paper the researchers argue that the only way to effectively test geoengineering is through full scale implementation of a particular geoengineering scheme--and such a large deployment could have big, unforeseen consequences.

There may be a technological solution to one of the trickiest issues at the Copenhagen climate change talks--verifying that nations are adhering to the limits on emissions that they agree to when those nations don't want international inspectors snooping around their factories and power plants and ports.

Earlier this week Chinese negotiators balked at any kind of international monitoring of its emissions levels, according to multiple news sources, although they've since backed off this absolutist stance. In his address at the talks today, President Obama expressed what seemed like frustration at the resistance of some countries to verification. "I don't know how you have an international agreement where we all are not sharing information and ensuring that we are meeting our commitments. That doesn't make sense."

But there may be a way around the concerns of the Chinese and others about verifying emissions. An ideal monitoring scenario would include equipment at power plants and factories, and close tracking of fossil fuel distribution. But if a country objects to monitoring within its borders, it would still be possible to monitor its emissions from outside. A network of ground-based greenhouse gas monitoring stations, weather balloons and satellites could make it possible to accurately monitor the emissions of a country as small France or Germany--without the need for invasive inspections, says Ronald Prinn, a professor of atmospheric science at MIT. It would cost billions, but without it, it could be hard to know if a treaty is actually bringing down emissions as planned.

Such a network would build on an existing set of ground monitoring stations around the world that sample greenhouse gas concentrations at a relatively high frequency. While some monitoring stations only collect information on a weekly basis, they can measure concentrations 20 to 30 times a day--enough to keep up with shifting winds that change where the gases are coming from. Paired with detailed monitoring of air circulation from weather monitoring stations and sophisticated computer models of air circulation, it would be possible to get a good idea of where emissions are coming from.

Right now, however, there aren't nearly enough greenhouse gas monitoring stations. At best, the estimates these stations produce only work for large areas and come with a large error range of plus or minus 20 to 30 percent. There are only 11 high frequency stations. "We need 10 to 100 times more," says Prinn.

It will also be important to have more weather monitoring stations, especially in places such as Africa, which have very few currently. And measurements should be paired with observations from satellites. Satellites can measure carbon dioxide concentrations closer to the sources, and they monitor the entire column of air beneath them, unlike ground-based monitors, which only sample from the lower part of the atmosphere called the boundary layer. A satellite designed to monitor carbon dioxide levels crashed into the sea earlier this year during a failed launch. Prinn says another should be launched.

The combination of satellite measurements and a network of weather and greenhouse gas stations could make it possible to monitor countries as small as France or Germany, he says, with an accuracy of plus or minus 5 percent. It would work, even if a country such as China wouldn't allow any greenhouse monitoring stations within the country--as long as the neighboring countries do.

"This is what is going to be needed," Prinn says. "But we're nowhere near it now."

On the first day of the Copenhagen climate change conference the U.S. Environmental Protection Agency has found that greenhouse gases constitute a threat to human health--a prerequisite for the agency to start regulating the gases.

The timing of the announcement is intended to boost efforts to reach a climate change agreement at the conference. Many countries have criticized the lack of action on climate change from the U.S., but now U.S. negotiators have an argument that their country is taking greenhouse gases seriously. If Congress fails to legislate for greenhouse gas emissions reductions, the EPA will step in.

"Today's action is a step towards enduring, pragmatic solutions to the enormous challenge of climate change," EPA administrator Lisa Jackson said (according to a copy of her speech). "It also means that we arrive at the climate talks in Copenhagen with a clear demonstration of our commitment to facing this global challenge. We hope that today's announcement serves as another incentive for far-reaching accords in our meetings this week."