Here's what we know: an overwhelming majority of scientists tell us that the Earth's climate is heating largely due to rising greenhouse gas emissions, which, in turn, is driving more extreme weather and climate events. The underlying changes -- warmer oceans, more intense precipitation events, and rising sea levels -- are significant contributors to storms like Sandy. Around the world, we're seeing heavier rainfall and record-breaking high temperatures, and many areas are experiencing more severe droughts and more wildfires. These patterns are precisely what climate scientists have said we should expect in a warming world. Further, these extreme weather and climate events are taking a serious toll as they disrupt people's lives and our economy.