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Oceans will change colour in 100 yrs

07 February 2019

"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". They are home to a stunning range of lifeforms of all shapes and sizes, all of which have unique properties and reflect different wavelengths of light.

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.

In other words, oceans that are rich in phytoplankton tend to look greener, whereas tropical waters with less phytoplankton take on an Instagram-worthy blue or turquoise hue. By contrast, barren regions of open ocean appear as deep blue from space.

Previous research has shown that with warming, the oceans will see a reduction in phytoplankton in many places.

Mayotte, an archipelago in the Indian Ocean. Phytoplankton, for instance, contain chlorophyll, which absorbs mostly blue parts of the light.

The best example is phytoplankton - an aquatic micro-organism.

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.

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. They pull carbon into the ocean while giving off oxygen. "Everything in the ocean requires phytoplankton to exist". 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. When there are more of these creatures in the water absorbing sunlight, they make the water look greener.

Dutkiewicz said various scientific models suggest that there is likely to be a decrease in the overall amount of phytoplankton in the oceans over time.

While these changes may seem small, scientists say that they are deep and long-lasting. "So that's where we should be looking in satellite measurements, for a real signal of change".

The ocean is awash in blue thanks to water. And in a world that warms by 3 degrees Celsius, it found that multiple changes to the colour of the oceans would occur.

Numbers of phytoplankton in areas such as the subtropics are predicted to fall, causing oceans to take on a much bluer colour.

The ocean's colors could change as the climate warms, though it won't be very noticeable to the naked eye.

The changes should be visible to satellites in low-Earth orbit. Satellites should detect these changes in hue, providing early warning of wide-scale changes to marine ecosystems. "But they're important because they tell us a lot about what's changing in the ocean".

Rarotonga, in the Pacific Ocean. "But it will be enough different that it will affect the rest of the food web that phytoplankton supports", Dutkiewicz said.

"This finding reinforces the importance of long-term monitoring of phytoplankton community composition", she added.

But in the scientific world, they could mean significant shifts.

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

Oceans will change colour in 100 yrs