What is Global Warming?
For many, the greatest environmental threat that humans have ever faced is a political issue. But it’s not. Global warming is a matter of scientific fact: 2006 was the sixth warmest year on record since 1850; the top five spots are held by 1998, 2005, 2003, 2002, and 2004. Whether you’re a Kiribati fisherman losing your island home to the rising sea or a snowboarder who couldn’t find any snow last January, climate change is making its presence known.
If we fail to recognize the immediate nature of this threat, the consequenses could be catastrophic. Rising seas, soaring temperatures, killer storms, drought, plague, pestilence. Finding solutions begins with identifying the problem. Briefly, here’s how global warming works. Energy from the Sun, in the form of light and heat warms the Earth. Heat rises, and some of it heads back into space. Most of it, though, is trapped by molecules in the atmosphere-molecules of “greenhouse gases”, named because their effect is just like that of a greenhouse. Water vapor is a primary greenhouse gas, in addition to carbon dioxide (CO2), methane, and nitrous oxide. All are natural – indeed, without the greenhouse effect, the Earth would be cold and uninhabitable.
The problem is, we have greatly increased the amount of CO2, methane and nitrous oxide in the atmosphere – mostly by burning things, like forests and fossil fuels. Before the Industrial Revolution, there were 280 parts per million (ppm) of CO2 in the atmosphere. Today, CO2 is about 380ppm. Factor in all the other man-made emissions, and the result is equivalent to 430 ppm of CO2.
The more greenhouse gas molecules, the more heat the Earth keeps. The atmosphere is so huge, change seems to occur slowly, if it all, but these increases are adding up. Over the last 30 years, the Earth’s average temperature has warmed by a full 1°F. One degree may not sound like much – but the Little Ice Age in the middle of the last millennium was signaled by a shift of only 2°F to 4°F. Inertia in the system will warm us at least another 1°F by 2020.
But humans are not sitting still; greenhouse emissions are accelerating, and at the current growth rates we will double the preindustrial levels of gases by 2050. If countries such as China and India adopt some carbon crutch the U.S. relies upon, the doubling could arrive as early as 2035.
What happens then? With a doubling of greenhouse gases, a 4°F rise in global average temperature becomes likely within this century. And all kinds of nastiness kick in at that point. By 2080, up to three billion people could suffer water shortages, and 200 to 600 million could face famine. Twenty to 30% of all species may face extinction. The melting of the Greenland Ice Sheet would accelerate, rising sea levels by as much as 23 feet.
We are speeding into a troubling void. Nobody knows exactly how it’s going to unfold. But the broad outlines are quite clear, absolutely devastating, and backed by evidence that almost every reputable scientist now calls overwhelming and unequivocal. These are not common words in the scientific vocabulary. But after decades of studies and debates, the leading scientific organizations around the world now call climate change a real pressing threat.
Science has given us unprecedented foresight. Now we must find the conviction to act. James Hansen, a NASA climate researcher, believes that “we have a very brief window of opportunity to deal with climate change… no longer than a decade, at most.” How we face the next few years could profoundly affect the rest of history. If we don’t begin to change today, it may be too late.
The task ahead is monumental. It’s far bigger even than what one country can do. Just to keep greenhouse gases at their present level will require slashing our emissions by 60%. To lower the level of gases and to reserve the warming already underway, the entire fossil fuel economy that brought us to unprecedented prosperity and technological prowess will need rethinking. In the short term, we need to tweak it. In the long term we may need to remodel, reinvent, and renew some major building blocks of society.
Your help is needed. You’ve got to take your share of small steps – around the house, around the office, in your neighborhood – because little things multiplied by the million add up. We also need to educate your friends about policy initiatives, to support and vote for leaders who have the vision to make a difference, to help remodel our cities, and to invent the technologies of the future. The journey begins with some small talk about the weather.