An expansion of Europe's forests towards dark green conifers has stoked global warming, according to a study on Thursday at odds with a widespread view that planting more trees helps human efforts to slow rising temperatures. Forest changes have nudged Europe's summer temperatures up by 0.12 degree Celsius (0.2 Fahrenheit) since 1750, largely because many nations have planted conifers such as pines and spruce whose dark color traps the sun's heat, the scientists said. Lighter-colored broad-leafed trees, such as oak or birch, reflect more sunlight back into space, but have lost ground to fast-growing conifers, used for everything from building...