We need to stop runaway climate change, by reducing greenhouse gas emissions by at least 95% by 2030, over 1990 levels.

Climate change is the gravest environmental, social and economic peril that humanity has ever met. Across the world, it is causing vanishing polar ice, melting glaciers, growing deserts, stronger storms, rising oceans, less biodiversity, deepening droughts, as well as more disease, hunger, strife and human misery. It is a tragedy unfolding in slow motion.

Greenhouse gases warm the Earth by trapping heat in the atmosphere. Much of that heat is initially absorbed by the ocean, creating roughly a 30-year delay in the impact of that heat at the surface of the planet. Practically speaking, that means that the melting glaciers and expanding deserts of 2009 were the result of greenhouse gases dumped into the atmosphere in the late 1970s, when the level of carbon dioxide in the atmosphere was below 350 parts per million (ppm). To return to a safe level of greenhouse gases in Earth's atmosphere, we must reduce atmospheric greenhouse gases as quickly as possible to levels that existed before 1980, to 350ppm carbon dioxide.