Forest chump? Scientists take a closer look at tree planting projects

If your work and lifestyle leave a heavy carbon footprint, you can have trees planted to compensate. Companies do the same, because trees store carbon dioxide (CO2), which helps the climate, right? Mostly yes, though it can be more complicated. Even if planted trees benefit the climate, the degree to which they do so is often impossible to quantify, say scientists. In the worst case, planting trees can even have the opposite effect, though in principle, the idea is not a bad one, says Christopher Reyer of Germany's Potsdam Institute for Climate Impact Research (PIK). "We need more forests," is...