Warming temperatures may help to “darken” the ice sheets of Greenland as algae on the surface blooms, a process that could lead to the acceleration of melting and cause sea levels to rise further than predicted.
This is not the first time that the presence of algae on the ice sheets of Greenland have been noticed, but until now few considered what impact it might have. According to the BBC, scientists are concerned that as temperatures increase, it will encourage the plants to grow and make the surface of the ice sheets darker. This in turn will absorb more heat and increase the ice melt.
By making the surface darker, the algae alters the ice sheets albedo effect. This is the term used to describe how much solar radiation is reflected. White snow reflects much of the sunlight that hits it, which in turn has a cooling effect on the snow and ice. As the algae grows, it reduces this albedo effect and rather than cooling, it warms the ice. This increases the rate at which it then melts.
Researchers have started a five-year project, called Black and Bloom, to track how the different species of algae on the ice sheets move and colonize new patches. From this, they hope to make better projections about what might come in the future as temperatures continue to rise, particularly in relation to the sea level.
“People are very worried about the possibility that the ice sheet might be melting faster and faster in the future,” Professor Martyn Tranter, who is leading the current project, told the BBC’s David Shukman. “We suspect that in a warming climate these dark algae will grow over larger and larger parts of the Greenland ice sheet and it might well be that they will cause more melting and an acceleration of sea level rise.”
Algae is not thought to be the only way in which the albedo effect is reduced, however. Researchers have also been investigating how pollution from cities, soot from wildfires, and ash from biomass burning settles on the ice sheets and again causes a darkening in Greenland.
It is currently thought that the melting of Greenland’s ice sheets add about 1 millimeter to the average global sea level every year. If it were all to melt in one go, it would be catastrophic for many low-lying countries and cities around the planet. Understanding how Greenland's ice sheets are changing, therefore, is of worldwide significance.
