William Ernest "Bill" McKibben (born 1960) is an American environmentalist, author, and journalist who has written extensively on the impact of global warming. He is the Schumann Distinguished Scholar at Middlebury College. In 2010, the Boston Globe called him "probably the nation's leading environmentalist"  and Time magazine described him as "the world's best green journalist."
He founded 350.org, whose mission we, in San Antonio, are joining,
350.org is building a global grassroots movement to solve the climate crisis.Our online campaigns, grassroots organizing, and mass public actions are led from the bottom up by thousands of volunteer organizers in over 188 countries.
350 means climate safety. To preserve our planet, scientists tell us we must reduce the amount of CO2 in the atmosphere from its current levels of nearly 400 parts per million to below 350 ppm. But 350 is more than a number—it's a symbol of where we need to head as a planet.
350.org works hard to organize in a new way—everywhere at once, using online tools to facilitate strategic offline action. We want to be a laboratory for the best ways to strengthen the climate movement and catalyze transformation around the world. We believe that if a global grassroots movement holds our leaders accountable to realities of science and principles of justice, we can realize the solutions that will ensure a better future for all.