While the thawing land spins up one vicious cycle, scientists are watching another taking place out on the ice.
Greenland is darkening.
While the island seems remote, global atmospheric circulation patterns blow in bits of desert dust, volcanic ash, forest-fire soot and industrial pollution from as far away as China. These particles sully the pure white of Greenland’s ice ever so slightly.
While pure, white snow and ice reflect sunlight, anything that darkens the ice sheet increases the amount of energy it absorbs. More absorbed energy means more melting.
As the ice melts, these particles are concentrated on the surface.
“As (they) accumulate on the surface, it only accelerates the speed of more melting and the exposure of more sediment that was deeper in the core,” Virginia said.
What’s more, algae living on the ice darken the surface still further. Researchers are only now beginning to study how much the algae and the particles contribute to the graying of Greenland, and how they may work together to accelerate the process.
“That’s how a little melt leads to more melt, leads to more melt,” Virginia said. “Change makes more change.”
Greenland is melting faster than expected. These vicious cycles may help explain why.
“We’ve been underestimating rates of change,” Virginia added. “We’re now understanding these feedbacks that we really need to dig into, and understand how physical change affects biology and how biology affects physical change.”