The color change is a result of how climate change will impact populations of phytoplankton – the microscopic algae that give the ocean its greenish tint. As the ocean warms, the tropics could become hot enough to cause the population of phytoplankton to fall. In turn, waters around the equator will become increasingly blue in color. Near the poles, where frigid temperatures have traditionally kept phytoplankton populations at bay, warming waters could encourage blooms of algae that turn the water more green.
The reason all of this matters is that in addition to giving the ocean its color, phytoplankton serve as the base of the marine food chain. Any change in the abundance and distribution of these algae around the planet could have dramatic impacts on the fish that humans rely on for food. While estimates of how fish populations will change in response to changes in phytoplankton populations vary widely, the World Economic Forum estimates that the total amount of fish caught for food could decline by as much as 20% by the year 2300.
It’s worth noting that any changes in the color of the oceans won’t be dramatic enough to see with the naked eye. But, any changes in ocean color are immediately evident to satellites – which means researchers can track how climate change is affecting phytoplankton populations over the years ahead.