Join Dr. Michael Oppenheimer for a live online Q&A, right here, on Sunday, July 16, at 11 p.m. ET. Oppenheimer, the Albert G. Milbank Professor of Geosciences and International Affairs at Princeton University, is one of the world's leading scientists studying the potential effects of global warming and co-founder of the Climate Action Network. He will seek to bring clarity to this hot topic and answer your questions. Don't forget to tune in to Global Warming: What You Need to Know with Tom Brokaw on Sunday, July 16, at 9 p.m. ET/PT.

So, scientists say that there has been a worldwide rise in temperature--1 degree F over the course of the 20th century and increasing sharply. So what do you say? What is going on and what can we do?