Last week, the U.S. Global Climate Research Program released a report concluding that climate change is happening now and is already having a significant impact on the United States. Bill McKibben was one of the first voices to warn of climate change - two decades ago, in his 1989 book, The End of Nature. He is still speaking out.

Bill McKibben is an environmentalist, writer, activist and scholar-in-residence at Middlebury College in Vermont

McKibben was born in 1960 in Lexington, Massachusetts, the birthplace of the American Revolution. During his summers in high school, McKibben led tours on the Lexington battlefield telling the story of American democracy and freedom. He says the experience taught him a valuable history lesson.

"I've never confused dissent with the lack of patriotism; if anything, just the opposite. You know the people I was talking about showed their patriotism by dissenting from big power."

Writing about nature in peril

After graduating from Harvard with a degree in journalism, McKibben spent several years as a magazine columnist before moving to a remote part of New York state. He says that's where he fell in love with the wild woods.

McKibben's first book, The End of Nature, about the perils of climate change, has been translated into more than 20 languages

"And it was striking me very hard, the sudden intuitive understanding that it wasn't so wild anymore, that people were changing the temperature of that place, and hence the seasons and the flora and the fauna."

That insight was the basis for The End of Nature, the first book on global warming written for a general audience. McKibben says he thought that if he simply pointed out ecological problems, people would do something about them.

"I was a 27-year-old and more than a little naive. I completely failed to understand the depth of the kind of cultural transformation that we were going to have to make if we were ever going to deal with climate change."

Explaining climate change to readers

Nevertheless, The End of Nature established McKibben as an environmental writer, and he has written 11 more books addressing climate change from many different angles.

"So I wrote about population. I wrote about popular culture and television and nature. I went around the world looking for hopeful places to bring back to America to say that our way is not the only way of organizing things in the world, on and on and on."

His latest book, Deep Economy, addresses what McKibben sees as shortcomings of the growth economy and envisions a transition to smaller, more local-scale enterprises.

"But in recent years, I think the dominant idea of American environmental writing has shifted away from wildness and towards community, human community, natural community. How are we going to live on this earth in such a way that the earth will somehow prosper?"

Stepping up fight against global warming

McKibben says environmentalism alone can no longer counter the excesses of the American consumer culture. He says the movement is not powerful enough to deal with global climate change and the overload of carbon in the atmosphere largely from the burning of coal, gas and oil. To do that, he says, a price must be put on energy.

"…to make fossil fuel reflect in its cost the damage it does to the earth."

In the summer of 2006, McKibben led a walk of hundreds of people to Vermont's capitol to demand strong action on climate change

These are fighting words for Bill McKibben. In 2006, he led 1,000 people across his home state of Vermont to demand new laws on global warming. A year later, he got six Vermont college students to work with him on a national campaign called Step It Up.

"We managed to organize about 14-hundred demonstrations around the country. And we took our goal, that Congress should cut carbon emissions 80 percent by 2050, we took it as a kind of fringe position endorsed by scientists and helped bring it into the center of the political debate. Within a week after the end of those demonstrations, both [then-presidential candidates] Barack Obama and Hillary Clinton had endorsed that demand as the centerpiece of their environment and ecology platform[s]."

Grassroots campaign for clean energy

And now, the U.S. Congress is debating legislation to meet that goal. The American Clean Energy and Security Act of 2009 would require the nation's industries to reduce their greenhouse gas emissions by 83 percent over the next four decades.

In every corner of the earth, people of all ages are taking part in an international grassroots campaign to spread the idea that 350 represents safety from the climate crisis

McKibben is supporting those efforts as head of a global grassroots, Internet-based campaign called 350.org. The goal is to spread the message that 350 parts per million of carbon dioxide in the atmosphere is too much.

"It is a very tough number, because we are already past it. We are [at] 385 [parts per million of CO2]. And we want to have actions and rallies and events and art and music in every nation on earth to just try and take this number and at the very least make sure that humanity knows what its bottom line is."

McKibben says the challenge, simply put, is that saving the earth will require political will. He hopes communal voices like 350.org that promote activism across the globe can help turn the tide of climate change before it is too late.