So is there anything we can do to stop it?
Here's an idea: pump tons and tons of sulfate particles into the atmosphere to block some sunlight from reaching earth--kind of like what happens in the aftermath of a gigantic volcanic explosion. That's the notion put forth by scientists at the National Center for Atmospheric Research. Using computer models, they showed that adding something like one million metric tons of small aerosol particles to the atmosphere could cut the rise in global temperature in half, from four degrees to two degrees Fahrenheit. So the earth would still warm, but not as much. And this would presumably mean that the disruptive effects of global warming, like drought in some places and too much rainfall in others, wouldn't be as bad.
To be clear, the researchers' predictions are based on computer simulations, which don't always prove to be accurate. And there are a few caveats. First, the simulations also showed that adding too much sulfate to the atmosphere could cool things down too much, which could be just as bad as excessive warming. Also, it's not clear how the sulfate would behave. Instead of spreading evenly throughout the atmosphere it could concentrate in certain areas and cause uneven cooling.
So the sulfate solution probably won't actually happen any time soon. But it's a start in coming up with creative ways to stop global warming, or at least slow it down.