Yep, it's the biggest problem we've ever faced. But you can get the basics in 600 words.
1. Global warming isn't happening slowly, and it's not a problem (just) for the future. We've already burned enough coal and gas and oil to increase the temperature more than a degree, and this has already caused enormous changes across the planet: Arctic sea ice is melting very fast, along with almost every other frozen thing on the planet. Because warm air holds more water vapor than cold, we're seeing far more deluge and flood. People are dying already, and species are going extinct. That one degree will become four or five degrees before the century is out -- unless we quickly take the steps to stop burning that coal and gas and oil.
2. Scientists are not unsure or confused. Scientists are scared. Their professional societies and national academies have called on governments to take action. Here's Lonnie Thompson, perhaps the earth's greatest glaciologist, speaking of his fellow researchers: "Virtually all of us are now convinced that global warming poses a clear and present danger to civilization."
3. Just like the scientists, engineers have done their job too. We have myriad new technologies that can provide us with clean kinds of energy. Wind power, for instance, is the fastest-growing source of electric generation around the planet -- but it starts from such a small base that it isn't increasing fast enough to head off global warming. If we made fossil fuels foot the bill for the damage they're doing to the atmosphere, we could move much more quickly.
4. The fossil fuel industry is the main impediment to real change. Other big businesses have increasingly come out in support of new energy policies, but the coal, oil, and gas companies fight change every step of the way. Why? Because they're making money. Exxon made more money in 2009 than any company in the history of money. One reason is because of their attractive business model: They get to use the atmosphere as an open sewer into which to dump their main waste product, carbon dioxide. For free.
5. Our political leaders haven't taken action because the power of the fossil fuel industry has been sufficient to scare them off or buy them off. The Senate wouldn’t even vote last year on a modest and tame proposal to begin tackling global warming; the U.S. Chamber of Commerce, which fronts for a handful of dinosaur companies, is even now trying to gut the Clean Air Act to make sure the EPA doesn't force any change.
6. It would be sweet to simply bypass politics and just solve this problem one community, one light bulb, one bus or bike or hybrid car at a time. And we need to do those things, badly. We all should be working for strong, clean communities. But unfortunately the math won't work out if that’s all we do. Physics and chemistry simply aren’t going to give us the time we need to work solely from the bottom up. We also need our national leaders to make big changes, and then see those changes ratified globally. It's hard work, and right now we’re losing.
Given all that, there's only one thing we don’t know. Can we build a movement quickly enough to carry the day? The beta test is suggestive. At 350.org, we’ve managed to organize 15,000 protests in 188 countries over the last two years. But we’ve got to get bigger faster. The only open question about climate change: What will you do?
Bill McKibben is founder of 350.org.