But if humans can survive disasters like the Black Plague and the Great Depression, surely we can adapt to a little global warming.

Maybe, but if current trends continue, the world might face an environmental catastrophe so extreme it will test our ability to survive. Rising sea levels would flood coastal areas, where most humans live -- stronger and more frequent hurricanes would spread the destruction even farther inland.

Warmer weather would spread incurable diseases like malaria that are now largely confined to the tropics. Wildfires, drought and heat waves would devastate vast areas. The widespread collapse of agriculture would bring worldwide famine. All these catastrophes combined would overwhelm even the resources of stable, industrialized nations. Increased competition for fewer resources could spark unprecedented outbreaks of crime, civil unrest and global warfare. Mass extinctions would be inevitable, though human civilization would probably survive in some form. Perhaps worst of all, it's believed that the impacts of climate change will persist for many centuries.

Bummer. Why aren't people doing more to stop global climate change?

The momentum to halt climate change is growing, but although warning bells have been sounded for years in many places -- academic research centers, insurance companies, government institutions -- other sectors of the economy have demonstrated a mulish resistance to any talk of climate change.

The U.S. Chamber of Commerce is an interesting case study: The pro-business lobby has for years denounced any efforts to address climate change, claiming such activity would hurt the economy. But some blue-chip companies like Nike and Apple have defected from the Chamber's position. Even energy companies like Exelon (the nation's largest electric utility) left the organization due to its head-in-the-sand posture on climate change.

What are governments doing about climate change?

So far, not much. The Kyoto Protocol required developed countries to reduce greenhouse gas emissions below 1990 levels by 2012 -- though it was ratified by over 180 countries (not including the U.S.), even those countries that approved the Kyoto Protocol show few signs of nearing that goal. Some states and cities are taking action, but the severity and scale of climate change require an international response. Developing giants like China and India present a particularly thorny patch in any negotiations, since their fast-growing economies might suffer under strict emission standards. Much hope was therefore pinned on developments in Copenhagen, where another summit took place in December, 2009. The results? Again, not much.

This is really discouraging. Isn't there anything ordinary people like me can do about climate change?

Yes, plenty. Besides putting pressure on all your elected officials to take action against climate change, living a more sustainable life with a smaller carbon footprint is a positive step forward. Leading by example means using less energy to heat and cool your home and office, using less gas by driving smarter, and "living la vida local" -- buying food and other products that are made locally. All these efforts will help to make a difference, even though some folks say managing climate change by living green is like bailing out the Titanic with a teaspoon. Decisive, immediate action on an international level is probably the only thing that will effectively stave off global climate change.