Sifting through geological records, scientific data, and computer models, Mark Lynas distills and projects the effect of global warming on humanity and the planet over the next hundred years. After that, he predicts, life as we know it may not exist.

Author of High Tide: The Truth About Our Climate Crisis, Lynas believes survival depends upon taking action today. "I think there is a 50-50 chance we can avoid a devastating rise in global temperature. If you were diagnosed with a potentially deadly disease and given those odds, you wouldn't hesitate to go through treatment. So why wouldn't we respond the same way when the whole of the planet is at stake?"

Implementing new technologies won't be enough, he cautions. "The problem is more profound and complex than that. The world's whole system of economic growth is linked to fossil fuel consumption. Even the most optimistic projections show technology can't match the rapid pace of worldwide development. It's like chasing a runaway train. It will take fundamental changes to our economic and political structures."

Inaction, as Lynas presents it, is terrifying. "This is not information I'm digging out of eco-alarmist pamphlets," he notes. "It's from scientific journals." In 2001, the Intergovernmental Panel on Climate Change (IPCC) released a landmark report projecting average global surface temperatures to rise between one and six degrees Celsius (two to ten degrees Fahrenheit) by the end of this century.

An upcoming book by Lynas, Six Degrees, will outline what to expect from a warming world, degree by degree. At one degree Celsius (two degrees Fahrenheit), most coral reefs and many mountain glaciers will be lost. A three-degree-Celsius (five-degree-Fahrenheit) rise would spell the collapse of the Amazon rain forest, the disappearance of Greenland's ice sheet, and the creation of deserts across the midwestern U.S. and southern Africa. A six-degree-Celsius (ten-degree-Fahrenheit) increase would eliminate most life on Earth, including much of humanity.

As sea levels rise, storms intensify, and drought zones expand, Lynas cites probable human consequences: "Food shortages will send grain prices soaring; refugees will flee into enemy territories; shrinking water supplies will trigger water wars; oceans will swallow up islands, leaving entire cultures homeless; and civilization will break down."

Many of Lynas's projections are based on the Earth's geological past. "The only other time our planet warmed by six degrees Celsius [ten degrees Fahrenheit], 95 percent of the world's species were wiped out. That was 251 million years ago, and it took another 50 million years for biodiversity to return to its previous level. In fact, since life on Earth began, every episode of mass extinction has been associated with a change in climate. This time, the greenhouse gases created by humans are causing warming to occur exponentially faster. And since half the world's forests have been cut down, and most of the natural land surface destroyed, the regulatory systems, which keep climate habitable, can't function. It's as though we've turned up the thermostat after disabling the safety mechanisms. In this precarious position, a mass extinction now would be worse than any in the past."

Lynas was born in Fiji and grew up in Peru, Spain, and the United Kingdom. After earning a degree in history and politics from the University of Edinburgh, he helped turn OneWorld.net into the world's most accessed Internet portal for human rights and sustainable development issues. In 2000, he left to work full-time on climate change as a broadcast and newspaper journalist, author, and world-wide lecturer.

As the human footprint spreads over more of the planet's surface, Lynas believes time is running out, but not gone. "Society can actually change more rapidly than we might think—even when patterns of behavior are entrenched. Just consider people's attitudes about the automobile. At the turn of the 1900s, no one thought having a car was a human right—that's all come about in just a few short decades. I also believe there's an instinct in all of us to support the little guy. Today, nature is the little guy, and without us it has no voice."