Climate change to make Earth more blue

Birdseye shot of green ocean creating waves on a sandy beach

Rising temperatures to make oceans bluer and greener

"If they were to magically change - or if we were to kill them off completely - there would be a lot of carbon coming out of the ocean and back into the atmosphere, and creating more problems that we have now". These organisms are responsible for much of the colour we see. When sunlight hits the ocean, water molecules absorb most of the light, except for the blue part of the spectrum, which is reflected back. "That basic pattern will still be there".

An MIT study is reporting that by the end of the 21st century, 50 percent of the world's ocean, will be a different color.

The research effort for the new finding was two-fold: Scientists built a detailed model of phytoplankton communities across the globe to accurately simulate the impacts of climate change on the ratios of different algae species. "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".

Using a model that tracks the movements of these organisms, the researchers made predictions about the ocean's color as environmental conditions change in the future.

Satellites have been taking continuous measurements of the ocean's color since the late 1990s, the researchers noted. According to Nasa, warming changes key properties of the ocean and can affect phytoplankton growth, since they need not only sunlight and carbon dioxide to thrive, but also nutrients.

Researchers used the past satellite images to develop a model that would predict phytoplankton changes with rising temperatures and ocean acidification. The subtropics-which include California, Texas and Florida-will become more blue, while areas near the poles, where warmer temperatures will lead to more diverse phytoplankton, will become greener.

The more phytoplankton there are in the water, the greener the colour, the fewer there are the bluer the colour.

In places with large phytoplankton booms, the ocean appears greenish blue. But Dutkiewicz says chlorophyll doesn't necessarily have reflect the sensitive signal of climate change.

"Sunlight will come into the ocean, and anything that's in the ocean will absorb it, like chlorophyll", Dutkiewicz says.

A United Nations-backed panel of scientists said past year that it will require "unprecedented" action over the coming decade for the world to limit warming and stave off the most catastrophic consequences of climate change. "So that's where we should be looking in satellite measurements, for a real signal of change".

"Other things will absorb or scatter it, like something with a hard shell".

Another difference from previous studies is that this time, the researchers are looking exclusively at satellite measurements of reflected light from the phytoplankton. The consequences of doing nothing are many, and a new study by MIT suggests that the ocean will actually change color as a result, and perhaps even within the century. And in a world that warms by 3 degrees Celsius, it found that multiple changes to the colour of the oceans would occur.

Climate change is already having profound effects on our planet, and here's one more: It's changing the color of the oceans, with the blues getting bluer and the greens getting greener. "Different types of phytoplankton absorb light differently, and if climate change shifts one community of phytoplankton to another, that will also change the types of food webs they can support", Dutkiewicz added.

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