John Vechey of PopCap Games recently joined The Motley Fool for a climate change summit. His first panel guests were Dr. Rachel Cleetus and Dr. Joe Casola. Rachel is a climate economist with the Union of Concerned Scientists, where she advocates for effective global warming policies at the state, regional, federal, and international levels. Joe is the program director for science and impacts at the Center for Climate and Energy Solutions, which works to assess the current state of knowledge regarding climate change and its impacts, and to promote actions that strengthen climate resilience.

Joe offers a helpful analogy to show why, although scientists will never attribute a specific weather event to climate change, we can still clearly see its "fingerprints" on everything from drought to flooding to major storms.

Joe also discusses particular risks to offshore oil rigs in the Gulf of Mexico. BP (NYSE:BP) will have six rigs under firm contract there by December 2014, more than any other operator. Shell (NYSE:RDS-A) will come in second with five rigs. Anadarko Petroleum (NYSE:APC) is expected to have four operating rigs by then, followed by Chevron (NYSE:CVX) with three under firm contract and ExxonMobil (NYSE:XOM)(NYSE:XOM) with two. Watch the following video to learn how climate change could affect these companies.

Sara Murphy has no position in any stocks mentioned. Follow her on Twitter: @SMurphSmiles. The Motley Fool recommends Chevron. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.