But that effect was offset by warming-associated drought that limited growth in the Southern Hemisphere, resulting in a net global loss of land productivity.

Scambos explains that, although the Northern Hemisphere experienced significant snowfall in early 2010, spring melt was rapid, exposing land surfaces to sunlight sooner than usual.

Seventy-four percent of those islands are found in the northern hemisphere, though that is not necessarily a surprise because roughly two-thirds of the world's land mass lies north of the equator.