Environmental Activist Bill McKibben speaks at Eckerd College's 2013 Graduation

Sunday, May 19, marked the Golden Anniversary of the annual Eckerd College graduation commencement in Saint Petersburg. More than 500 graduates, their families and well-wishers, the faculty and the board of trustees all gathered under a circus-styled big top for the ceremony. This year’s commencement address was delivered by Bill McKibben, a world-renowned environmental activist and educator.

McKibben has written several books on global warming and alternative energy, and is the founder of the grassroots climate movement 350.org. The 350 number refers to the amount of CO2 in parts per million which is the safe upper limit on a human tolerance scale.

Scientists, including McKibben, assert that an accelerated greenhouse effect will be the outcome if 350 ppm is exceeded, and that translates directly into bizarre and erratic climate change. 350.org is behind what's considered to be the largest globally coordinated protest, with 5,200 simultaneous demonstrations in 181 countries.