Global warming is changing the color of the oceans

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The study predicts that the blues will intensify, most likely in subtropical regions where phytoplankton will decrease.

Stephanie Dutkiewicz, the study's lead author, stated that the subtle shifts in the changing colour of the ocean are an early warning sign.

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. Warmer waters will bring more phytoplankton blooms, causing the waters to appear a deeper green than ever before.

"In the same way that plants on land are green, phytoplankton are green as well, so the amount and different types of phytoplankton affect the colour of the ocean surface", said Dr Anna Hickman, co-author of the research from the school of ocean and earth science at the University of Southampton. "But it'll be enough different that it will affect the rest of the food web that phytoplankton supports".

Oceans will change color by the end of the century, as climate change significantly alters phytoplankton in the world's seas, according to a new study. Likewise, the more abundant they are, the less blue the water will be.

For their study, the researchers developed a model simulating the growth and interactions of different phytoplankton species, and ran simulations based on the planet warming by 3C. "The impact will be felt all the way up the food chain", she said stating the importance of phytoplankton as it is the base of the marine food web. If there are any organisms in the ocean, they can absorb and reflect different wavelengths of light, depending on their individual properties.

As ocean waters continue to warm - killing off vital coral reefs and disrupting ecosystems in the process - the tiny plants that make up phytoplankton will begin to thrive in new areas and die off in others.

What the new hues will essentially reflect is life in those regions.

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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.

Since the late 1990s, satellites have been taking continuous measurements of the ocean's colour to determine the amount of chlorophyll-and, in turn, phytoplankton-in an oceanic region.

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

The change in oceans' colour takes place because of the difference in quantities of phytoplankton, the microscopic algae that gives water bodies their distinct green colour.

When the temperature value is tweaked, the model's output shows the change in the colour of Earth's oceans: The blue and green parts of the spectrum being the most responsive, showing drastic change with increased temperatures.

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

As the researchers cranked up global temperatures in the model, by up to 3 degrees Celsius by 2100 - what most scientists predict will occur under a business-as-usual scenario of relatively no action to reduce greenhouse gases - they found that wavelengths of light in the blue/green waveband responded the fastest.

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. "By the end of the century, our blue planet may look visibly altered", wrote Jennifer Chu in the press release.

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