The threat of climate change in marine ecosystems increases and is evidenced by the intensity of the colors of the oceans. 

Changes in phytoplankton communities will result in a 50 percent color change of the ocean by 2010. Nature Communications recently published a study by the Massachusetts Institute of Technology. MIT scientists report that water near the poles will appear greener and water near the subtropics will appear bluer. 

The temperature of the ocean is a determining factor in the population of small, vital marine organisms called phytoplankton or algae. Several studies have shown that there is a rapid rise in the temperature of the ocean. The study by MIT projected changes to the ocean through a climate model that simulated changes in the color of the world's ocean with a 3-degree Celsius increase in the temperature. 

Sunlight has different wavelengths. Only blue is not absorbed by water molecules. Thus, blue is reflected and provides the ocean with a blue hue. Phytoplanktons contain chlorophyll---a green pigment. Surfaces of the oceans with more phytoplankton appear greener while those with fewer ones appear bluer. 

The study reported that there will be different effects of phytoplankton blooming in different regions. Phytoplanktons might decrease in warmer subtropic areas and might increase in warmer polar areas. An average person might not notice the difference but the change will result in bigger problems in the ocean. 

Lead researcher Stephanie Dutkiewicz said, "It could be potentially quite serious. If climate change shifts one community of phytoplankton to another, that will also change the types of food webs they can support," in a press release by Eureka

Fish depend on phytoplankton as their source of food.  A decrease in the supply of algae could affect the population of the fish as well as an increase in carbon dioxide in the air because algae absorb atmospheric carbon dioxide.

The Washington Post reports that "Changes are happening because of climate change. It'll be a while before we can statistically show that. But the change in the color of the ocean will be one of the early warning signals that we really have changed our planet," according to Dutkiewicz.