In a report released this week, the Intergovernmental Panel on Climate Change said it will take very ambitious efforts -- a reduction in greenhouse gas emissions by up to 70 percent by 2050 -- to keep climate change at acceptable levels. The dire predictions have some asking whether it's time to think about geo-engineering: an attempt to use large-scale, high-tech methods to cool the planet. These ideas have included launching giant mirrors into space or fertilizing the oceans with iron to stimulate phytoplankton growth.
Could Geo-Engineering Cool Our Warming Planet?
Ken Caldeira, climate scientist at the Carnegie Institution for Science's Department of Global Ecology at Stanford University
Craig Miller, science editor for KQED
David Winickoff, associate professor of bioethics and society in the Department of Environmental Science, Policy & Management at UC Berkeley