Scientists were stunned by the discovery of thriving phytoplankton blooms under Arctic sea ice in July 2011. The microscopic organisms require a great deal of sunlight to thrive, making their existence in normally dark Arctic waters a signal to a significant environmental shift.
Christopher Horvat, a Harvard University oceanographer, and his colleagues used a computer simulation of sea ice conditions from 1986 to 2015 to study how Arctic ice has thinned and where the most dramatic changes have occurred.
Warming Arctic temperatures have thinned the once-dense ice that prevented light from reaching the depths and have increased the frequency of meltwater pools forming on top of the ice. These pools allow more light to pass through and create an environment suitable for phytoplankton to grow into large blooms.
These “sea ice skylights” were incredibly rare just twenty years ago, but in a May 29th report in the journal Science Advances, researchers concluded that they now spreads over roughly 30 percent of the ice-coated Arctic Ocean. However, it is still unclear whether or not the blooms really are more common under the ice and the study did not take into account whether the nutrients such as nitrogen and iron were in adequate supply to sustain the phytoplankton.
However, if blooms really are becoming more commonplace, they could reshape the Arctic environment and ecosystem as the phytoplankton could change marine food chains and absorb more harmful carbon dioxide.
Top photo courtesy of NASA Goddard Space Flight Center, CC BY 2.0
Lauren Leising is a freelance writer based in Athens, Georgia.