In the ocean (electric) blue

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Green and brown island in dark blue ocean with bright blue swirls and long white cloud

Green and brown island in dark blue ocean with bright blue swirls and long white cloud. Sources: European Space Agency / Scientific American

The world’s most abundant form of life—plankton—makes the electric blue swirls in this image of the North Atlantic Ocean off Ireland. This massive bloom is an annual springtime phenomenon.

Also known as the “grass of the sea,” plankton are microscopic marine plants at the base of the ocean’s food chain—all marine life directly or indirectly depend on them for survival. They also play a vital role in sucking carbon dioxide out of the Earth’s atmosphere through photosynthesis—like their terrestrial counterparts—and by influencing ocean circulation to let denser, cooler water that has absorbed CO2 sink to the bottom of the sea.

While invisible to the naked eye as individuals, collectively their chlorophyll creates a bright blue tint, which can be seen from space. The European Space Agency’s satellite Envisat took this image with an instrument called a Medium Resolution Imaging Spectrometer, a device that breaks light down into constituent wavelengths (i.e. colors), providing detailed information to create images like this one.

Scientists fear that climate change might reduce these blooms, which could not only threaten the survival of all marine life, but also result in the loss of a key carbon dioxide removal system, thus adding more greenhouse gases to an already overtaxed atmosphere.