Oceans will turn more blue as result of climate change; study

Pablo Tucker
February 5, 2019

But it isn't just global warming that causes a change in algal blooms and chlorophyll; naturally occurring weather events like El Nino could also temporarily cause a spike in phytoplankton bloom, causing an increase in chlorophyll.

The study further suggests that the blue regions would become bluer indicating less phytoplankton and life in those parts of the ocean whereas areas where the colour of the ocean is green, may get even deeper green as rising temperatures would facilitate more growth of different species of phytoplankton.

The findings showed that climate change has been significantly affecting phytoplankton - the tiny sea creatures - in the world's oceans, which will lead to the change in colour - intensifying its blue and green regions. When there is too little, the quantity of life in the waters goes down and water's natural blue comes through.

"What this study is trying to explain is that in parallel to measuring the amount of phytoplankton in the water, we should also be measuring the light coming from the water", Maycira Costa, professor and coastal oceanography researcher at the University of Victoria, told CTV News.

Owing to climate change surface of the oceans will change colour by end of 21st century leading our blue planet to look visibly altered, finds a new study from the Massachusetts Institute of Technology (MIT).

The predictions are, high intensity of heat will change the composition of phytoplankton and thus marine species will absorb and reflect light at a faster pace. They also "fix" nitrogen (convert Nitrogen from the air into compounds), making them an important part in the enrichment of oceanic waters.

The researchers then used the model to look into the future, raising the global temperature by 3 degrees Celsius by 2100, and saw a very clear shift in ocean color. Water molecules alone absorb nearly all sunlight except for the blue part of the spectrum, which is reflected back out.

Ocean colour varies from green to blue, depending on the type and concentration of phytoplankton, or algae, in any given area. "We are interested in phytoplankton because they are tiny marine plants, they contribute about half of global photosynthesis, they are the base of the marine food web".

"Chlorophyll is changing, but you can't really see it because of its incredible natural variability", Dutkiewicz says.

"The model suggests the changes won't appear huge to the naked eye, and the ocean will still look like it has blue regions in the subtropics and greener regions near the equator and poles", said Dutkiewicz. "But you can see a significant, climate-related shift in some of these wavebands, in the signal being sent out to the satellites".

Since the 1990s, satellites have taken regular measurements of how much chlorophyll is in the ocean.

The color change won't be obvious to human onlookers, but spectral analysis by satellite cameras could help scientists use color shifts as a proxy for the development of climate change.

"More of the ocean is going to show a change in colour over the next few decades than we would see in chlorophyll, the changing colour is going to be more of a warning signal". "It could be potentially quite serious". Different hues of chlorophyll absorb different wavelenghts of light, and such climate-induced changes could have a dramatic impact on the ocean's food webs, the team concludes.

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