Howard Epstein, head of environmental studies at the University of Virginia, tracked changes in Arctic vegetation for the report card, and said that this year’s edition highlights variability, geographically and in time. Greenery has increased in some parts of the Arctic but declined in others. “From a vegetation perspective, the surprise for me is the changing dynamics,” he said. From about 1990 to 2010, the Arctic greened steadily, but since then, it has “been flat or decreasing,” he added.