The science of climate change is unforgiving. 2015 was the hottest year on record by a mile, and 14 of the 15 warmest years on record have occurred in this century. Already, communities across America are seeing the impacts of climate change, from longer, hotter wildfire seasons in the West to rising sea levels flooding streets in Miami and Annapolis at high tide. Scientists are concerned that climate change is making it easier for vector-borne diseases like Zika to spread -- and we know this won't be the last public health challenge we’ll face. The Obama Administration recently awarded a grant to the state of Louisiana to resettle the entire population of the Isle de Jean Charles, which has lost 98 percent of its land mass to coastal erosion and rising seas -- and we know they won't be the last community facing that hard choice here in America or elsewhere in the world. Climate change is a real and urgent threat, and we must use every tool we have to tackle it.