Oceans will turn bluer due to effects of global warming, study says

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Many of the world’s oceans will turn a brighter shade of blue and green due to global warming, a scientific study has found.

Researchers say the changing ocean temperatures will alter the populations of small, microscopic algae known as phytoplankton, which convert sunlight into energy through photosynthesis.

Cold, nutrient-dense waters with higher populations of phytoplankton are typically greener in colour. Tropical waters with less phytoplankton have a bluer or turquoise hue.

But populations of phytoplankton are expected to decrease, which will change the waters to lighter shades of blue.

Meanwhile colder algae-rich green waters near the north and south poles will become a deeper green as warmer temperatures spur the growth of more algae.

“There will be a noticeable difference in the colour of 50% of the ocean by the end of the 21st century,” said lead author Stephanie Dutkiewicz.

“It could be potentially quite serious. 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.”

The colour of the seas have been measured by scientists since the 1990s and have been used to determine chlorophyll levels.

Published in the journal Nature Communications, the study used a computer model that predicts how the changes in temperature, ocean acidity and ocean currents could affect the growth and types of phytoplankton in the water.

It could also predict the levels of other coloured organic matter and detritus.

Unlike previous studies, scientists explored how such changes would affect the absorption and reflection of light at the ocean surface.

The results revealed that when global temperatures increase by 3C (37.4F), predicted to occur by 2100, the colour of more than half of the oceans, including the North Atlantic, will change.

Climate-driven changes to chlorophyll could begin as soon as 2055.

“Sunlight will come into the ocean, and anything that’s in the ocean will absorb it, like chlorophyll,” Ms Dutkiewicz said.

“Other things will absorb or scatter it, like something with a hard shell. So it’s a complicated process, how light is reflected back out of the ocean to give it its colour.”

While the colour changes will not be visible to the naked eye, the team of experts think satellite images could be used to monitor the process.

(c) Sky News 2019: Oceans will turn bluer due to effects of global warming, study says

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