The reports consider the two main ways humans could attempt to steer the Earth's system: We could try to take carbon dioxide out of the atmosphere. Or we could try to reflect more sunlight back into space. The committee examined the socioeconomic and environmental impacts as well as the costs and technological readiness of approaches in each category.
The researchers said that certain CO2-removal tactics could have a place in a broader climate change response plan. But the sunlight reflecting technologies, on the other hand, are too risky at this point. They underscored how important it is for humans to limit the levels of CO2 they put into the atmosphere in the first place, and they called for more research into all climate intervention approaches.
"I, for one, am concerned with the continuing rise in CO2 concentrations without clear efforts to reduce emissions," Penner said. "The widespread impacts from these increases are readily apparent, and the cost of climate change impacts is likely to be high.
...While the committee said that some of the CO2 removal strategies including "carbon capture and sequestration" have potential to be part of a viable plan to curb climate change, it noted that only prototype sequestration systems exist today. Much development would have to occur before it could be ready for broad use....