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Feb. 4 (UPI) -- Some might argue the color of climate change is red -- the color that most often marks dramatic temperature increases on climate maps. But, according to a new study, global warming's real color is blue. As Earth's oceans warm, they will become more blue.
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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. Researchers also studied satellite images to better understand how different types of phytoplankton species absorb and reflect light.
Their analysis, detailed this week in the journal Nature Communications, suggests half of Earth's oceans will be bluer by the end of the century.
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.
"The model suggests the changes won't appear huge to the naked eye, and the ocean will still look like it has blue regions in the subtropics and greener regions near the equator and poles," lead study author Stephanie Dutkiewicz, a planetary scientist at MIT, told MIT News. "That basic pattern will still be there. But it'll be enough different that it will affect the rest of the food web that phytoplankton supports."
What the ocean looks like depends on the types of organisms and molecules floating near the surface. Water molecules absorb most of the light spectrum, reflecting only blue light. As such, the ocean appears blue. Phytoplankton produce chlorophyll, which absorbs much of the spectrum but reflects green light.
In places with large phytoplankton booms, the ocean appears greenish blue.
Scientists have previously tried to measure chlorophyl levels as a proxy for climate change's warming effects on the ocean. But chlorophyl is just one of many variables that influence the ocean's color. Natural climate variability can also alter chlorophyl levels, limiting its value as a measure of climate change's impact on the planet's oceans.
For the new research, scientists decided to study changes in the oceans' spectral signatures using satellites images.
After building their ocean model, which simulated how global warming's effects on temperature, acidification, currents and mixing will impact the metabolism and proliferation of different phytoplankton species, researchers incorporated their spectral analysis to simulate the impacts of shifts in phytoplankton communities on the ocean's color.
The research team found their model's predictions matched the spectral signatures measured by satellites.
According to the model's predictions, global warming will continue to alter the biochemical makeup of the world's oceans in ways that visibly alter its coloration. Subtle changes are already happening, and by 2100, the color shifts will be much more apparent -- a sign of global warming's significant ecological impacts.
"There will be a noticeable difference in the color of 50 percent of the ocean by the end of the 21st century," Dutkiewicz said. "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."
