Climate change is actually changing the color of the ocean

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". In areas where the tiny plants begin to die out in even greater numbers than we've seen already, those organisms will have a much tougher time sustaining themselves, and the effects are felt all the way up to the top, including humans. Phytoplankton produce chlorophyll, which absorbs much of the spectrum but reflects green light.

"Phytoplankton are the base of the food web-less phytoplankton [means] less food for the rest of the marine ecosystem", study co-author Stephanie Dutkiewicz, a principal research scientist in MIT's Department of Earth, Atmospheric, and Planetary Sciences, told in an email. "Phytoplankton are at the base, and if the base changes, it endangers everything else along the food web, going far enough to the polar bears or tuna or just about anything that you want to eat or love to see in pictures".

In order to account for these natural events, the researchers tweaked a previous global model used previously to predict phytoplankton changes in response to rising temperatures and ocean acidification to instead predict how climate change is affecting phytoplankton. Scientists have been constantly recording the ocean's colors via satellite images since the 1990s as a way to measure the amount of chlorophyll, and by extension, phytoplankton in the water. The researchers also simulated the way phytoplankton absorb and reflect light, and how the ocean's color changes as global warming affects the makeup of phytoplankton communities.

The ocean looks blue or green to us because of a combination of how sunlight interacts with water molecules and with whatever else lives in that water.

Some regions that are greener now, such as near the poles, may turn a deeper hue, as warmer temperatures brew up more diverse phytoplankton.

A United Nations-backed panel of scientists said a year ago 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.

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

Phytoplankton are small, microscopic plants that float through the water column, due to their ability to absorb and reflect light, communities of phytoplankton affect the color of the ocean.

"And it will likely be one of the earliest warning signals that we have changed the ecology of the ocean". "So it's a complicated process, how light is reflected back out of the ocean to give it its color".

"The nice thing about this model is, we can use it as a laboratory, a place where we can experiment, to see how our planet is going to change", Dutkiewicz says.

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. "It could be potentially quite serious". 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.

What's more, Dutkiewicz observed that this blue/green waveband showed a very clear signal, or shift, due specifically to climate change, taking place much earlier than what scientists have previously found when they looked to chlorophyll, which they projected would exhibit a climate-driven change by 2055.



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