Unfortunately, if it takes until the 2020s for Americans to become convinced enough to act, then action will have become enormously more expensive and less effective. And if other nations can continue pointing to American intransigence to excuse their own, then we're in trouble.
DrM: Increased frequency and severity of heatwaves are one of the things that climate change is about.
Left Wing Extremist: Actually, global winter temps have been rising faster than summer temps (and night temps faster than day temps). Both these patterns were accurately predicted by the models many years ago.
Trevor as always has an excellent answer. Thanks Trevor! I often feel like there is little more to do than recommend your answer once you've said it. And no, I am not a sock-puppet for Trevor, he just talks a lot of sense and does the hard yards of providing plenty of links. That ought to be respected.
Jim Z: Droughts and floods are both entirely consistent with climate change. They are both modifications of the hydrological cycle (water cycle) that result from more energy in the atmosphere, which not only increases the amount of moisture it can hold (so we get heavier precipitation events (snowstorms and floods)), but also changes the pattern of their distribution, both geographically and seasonally. So there is no contradiction involved. Just because climate change isn't simple is no reason to write it off. It's the *climate*; of course it isn't simple.