NASA Satellites Underestimating Southern Ocean Phytoplankton by Half, Algorithm Finds

NASA satellites may have underestimated the number of phytoplankton located in the Southern Ocean by more than 50 percent, a new study suggests. Such a major miscalculation, if true, would mean current estimates regarding the region's carbon capture potential are inaccurate.

Conducted by researchers from University of Tasmania's Institute for Marine and Antarctic Studies (IMAS), the study included more than 1,000 phytoplankton samples collected from the Southern Ocean over a 10 year period. These samples were then compared to satellite measurements.

The scientists then developed a new algorithm that, when used to process satellite data, yielded an estimate far closer to the reality.

"This new algorithm allows us to detect changes in plankton numbers that have previously gone unnoticed," Rob Johnson, a PhD student at the university and lead author of the study, said in a press release. "This better understanding of the phytoplankton population will, in turn, allow us to gain a much more accurate idea of how much carbon this ocean can take up."

Despite their small size, phytoplankton play a major role both in the ocean's ecosystem where they form the base of the food chain. What's more, they are estimated to produce half of the oxygen on Earth as well as contribute to the ocean's current absorption of roughly a third of total human-induced carbon dioxide emissions.

A clear idea of exactly how many call the ocean home, therefore, is crucial to accurately assessing overall climate change trends.

"Our improved satellite chlorophyll algorithms will be used to produce higher-accuracy observations on the vitally important phytoplankton of the Southern Ocean and Antarctica," Peter Strutton, associate professor and co-author, said. "This will go a long way towards improving our understanding of how the Southern Ocean works and how the movement of carbon is changing in these remote waters."