Colour of oceans to change by end of 21st century

Rising temperatures to make oceans bluer and greener

Climate change will even change the color of the oceans, study says

Since much of the ocean's color comes from phytoplankton, Dutkiewicz and her team suspected that if these communities change, then the color of the ocean is likely to vary along with them.

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. The changes won't be dramatic, in fact, they likely won't be visible to the naked eye, but it suggests that the hue of the ocean could be an important marker for scientists watching to see how climate change will affect our seas.

By simulating the world's oceans up until the year 2100, the model showed that more than 50pc of the oceans will become brighter, with the subtropics becoming more blue, indicating a lack of phytoplankton - and life itself - within the water.

According to the researchers, the ocean will see its blue and green regions intensify so much so that satellite imaging will detect these the new hues. 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 colour of the oceans could be about to change.

According to Nasa, when sunlight hits the ocean, some of the light is reflected back directly, but most of it penetrates the ocean surface and interacts with the water molecules it encounters.

That, the authors say, reflects shifts in phytoplankton populations, and knock-on effects, that stem from factors including a retreat of sea ice near the poles, rising temperatures and less mixing of waters.

Phytoplankton contain chlorophyll, a pigment that mostly absorbs in the blue portions of sunlight to produce carbon for photosynthesis, and less so in the green portions.

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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. "That basic pattern will still be there".

Phytoplankton are microscopic algae that float at the bottom of the ocean food web, forming a key part of most ocean ecosystems. By looking at these measurements, the level of chlorophyll can be determined, which could be due to global warming or weather-related phenomena, such as an El Niño or La Niña, Dutkiewicz said.

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

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.

The model that predicted the major colour change was based on the business-as-usual scenario whereby global average temperatures would be three degrees Celsius warmer in 2100 than they are today if no serious climate action is taken.

Climate change will bring a color change to half of the world's oceans by the end of the21st century, the study says.

Importantly, she said, the shift in reflectance of blue/green light appeared to give an earlier indication of changes to phytoplankton than estimates of the amount of chlorophyll present, a measure now used to monitor phytoplankton levels.

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