President Donald Trump's main stance on climate change is usually denial, but if he does take action it could be with the controversial approach of geoengineering. Large-scale climate engineering didn't receive much support under President Barack Obama, but now environmental organizations are saying in the new administration interest may be building for solar geoengineering, or spraying sulphate particles in the air with the hope of reflecting the sun's radiation back into outer space to lower Earth's temperature. Harvard University scientists David Keith and Frank Keutsch, who started the largest solar geoengineering research program in the world, may find support in the new administration.