In tomorrow's New York Times, I take a look into nature's crystal ball. Scientists have long been warning that we may be headed into Earth's sixth mass extinction. But most projections just carry forward the causes of recent extinctions and population plunges (overfishing, hunting, and the like). Global warming is already starting to have an effect on many species--but it's a minor one compared with the full brunt that we may experience in the next century. I've written in the past about studies scientists have carried out to project what that impact will be like. I decided to revisit the subject after reading a spate of provocativepapers and books recently. While the scientists I talked to all agree that global warming could wreak serious havoc on biodiversity in coming decades, they're debating the best way to measure that potential harm, and the best way to work against it. We all crave precision in our forecasts, but biology is so complex that in this case we may well have to live without it. Check it out. [Image: Photo by DJ-Dwayne/Flickr]