The researchers analyzed satellite data on the open ocean collected from 2003 to 2022 by a NASA instrument that combs through the planet every two days to measure light wavelength, according to the paper.
The presence of chlorophyll in open ocean is a proxy for concentrations of phytoplankton biomass. The colors indicate how chlorophyll concentration is changing at specific latitudes, in which the subtropics are generally losing chlorophyll, and the polar regions -- the high-latitude regions -- are greening, the researchers said.
Green areas became greener, especially in the northern hemisphere, and blue regions "got even bluer," according to a press release by Duke University.
