 Global temperatures are rising rapidly due to human activities, and this rise is putting us outside of the normal range of temperatures experienced by our planet over the last few thousand years. This means that sea levels will continue to rise, threatening coastal communities around the world. To prevent further damage from climate change, we must reduce our emissions of greenhouse gases and find ways to remove excess carbon dioxide from the atmosphere. This article was authored by J. Hansen, M. Sato, P. Kurecha, and others.