Forest and the Trees

boreal forest map                                                                                          National Geographic

Three trillion. Really. Three trillion! (Actually, a little more.) That's how many trees are on planet Earth right now, and that's eight times more than we previously thought. That, says Yale University's Dr. Thomas Crowther, who conducted the survey with colleagues, is about 420 trees per person. But, he's careful to explain, "It's not like we've discovered a load of new trees; it's not like we've discovered a load of new carbon." In other words, it's not good, it's not horrible; it doesn't change reality. How did they come up with this new, more accurate count? Using old- and new-school techniques, they combined satellite photographs, which show the area covered by a forest but not so much how many individual trees make up that area, with data from workers who had actually counted the individual trees in different kinds of forests. The other numbers they've come up with is that we're removing about 15 billion trees a year but replacing them with only 5 billion: http://www.bbc.com/news/technology-34129490