The Arctic Is Turning Green at an Alarming Rate, and Scientists Finally Know Why

Melt ponds on the surface of Arctic ice. Credit: NASA

Arctic sea ice is turning progressively greener, and for years now, scientists couldn't for the life of them figure out what was going on. 

They knew the green had to come from blooms of microscopic marine plants called phytoplankton growing under the sea ice, but that didn't make sense - phytoplankton need light to photosynthesise, and it should have been far too dark for them to survive down there, let alone thrive.

Now, an international team of researchers has cracked the mystery, and the truth is pretty unsettling.

The record low levels of sea ice we now see in the Arctic have worn down the barrier for sunlight, so instead of being reflected, it's being absorbed by dark melt pools that are proliferating on the surface.

The ice that remains is now darker and thinner than ever before, and below, phytoplankton colonies are booming as light penetrates the ocean below.

"We went from a state where there wasn't any potential for plankton blooms to massive regions of the Arctic being susceptible to these types of growth," says one of the team, Chris Horvat from Harvard University.

The research has been published in Science Advances.