Mercury Rising on OneWorldJourneys.com

Standing in the empty rookeries of displaced Adelie penguins, I've caught the chill off broken, huge chunks of a receding ice shelf on the Antarctic Peninsula. In Alaska, I saw young black spruces growing higher than ever before on boreal hillsides. Near my home in the Pacific Northwest, I can see the ablation of glaciers. Comparing my photographs of great Andean glaciers to images 65 years old, I've witnessed the story of their wasting away. In the woods of Eastern North America, I walked through spring wildflowers and spotted incoming migrant songbirds, knowing many of them were increasingly early. Along the coasts, I have seen rising tides and heavy storms erode beaches.

I made these and other observations during 1999 and 2000 as part of a personal photographic project, "World View of Global Warming." I wanted to get beyond the raw statistics, the charts, and the predictions. I wanted to create an alternative to the numbers, to the arguments over "who is to blame," and to whatever palliative measures governments and corporations might be willing to take. So I looked at Earth itself, with the eyes of a natural history photographer.

What I saw through the lens was that global warming and the related climate changes are actually in motion. Physical systems, ecosystems, and species are already changing. In remote locations and in our familiar gardens and parks, scientists are devoting their careers to documenting the effects, taking measurements, and interpreting the results in peer-reviewed scientific studies. Although these results are not part of the public's general conversation, the scientific writers of the UN's Third International Panel on Climate Change wrote a report that considers these scientific findings significant enough for a special section about climate change effects on ecosystems.

Photographing these effects poses a great problem, however. Changes have been unfolding for 50 years or more. They are subtle and minute, if not literally invisible, and accumulative. But a year and a half of photography and of research -- visiting scientists at their sites and hearing their passionate concerns, working with past photos and records, and documenting the meticulous record keeping of scientific field work -- produced persuasive results. The images are compelling to those who have been skeptical.

Do any photos "prove" that global warming is a fact? The pictures, like the natural science they depict, do not render courtroom proof, but rather evidence of tight correlations among physical events carefully observed over the long term. Such evidence begins to add up.

Photography's message is strengthened because global warming's effects appear in Earth's most beautiful and sensitive landscapes. Treasured and threatened ecosystems and creatures are in transition. Like some early signs of heart disease or cancer in our bodies, the first effects are strongest in the extremities of our planet: the poles, the mountains, the animals and plants on the edge of their ranges.

I have come to feel that I am documenting one of the crucial, overarching events of the 21st century. As it exacerbates overpopulation and food crises, climate change may affect more people than did war in the last century. Whether or not humans are to blame, there happen to be 6 billion of us on the planet now and we are deeply interconnected and affected by all these changes. We are going to have to adapt to them, to live through them, and to reduce activities that worsen them.

This is a magnificent and urgent story that is just beginning to be told -- all of us will see it and live it.