Images & Animations
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Credit
Each year trillions of scaly, one-celled marine plants called coccolithophores slough off their microscopic plates, called coccoliths, and dump more than 1.5 million tons of limestone dust (calcium carbonate, or calcite) into the sea—the largest source of this material on Earth. This false-color image is the first data product of its kind: a map of monthly observations of calcite concentrations across the world's oceans collected by the Terra satellite. Values range from 0.1 to 20 milligrams of carbon (in the form of calcite) per cubic meter of sea water, with lower values in dark blue and higher values in white. Black indicates regions where no data were collected (usually due to persistent clouds), and dark gray is land surfaces.
Coccoliths reflect nearly all colors of sunlight, which mingle and appear white. Like other plants, coccolithophores use chlorophyll to absorb sunlight and convert it into energy. In particular, they absorb large amounts of dark blue light and reflect green. When coccolithophores are present in abundance, ocean waters turn whitish with a tinge of green. While these plants live in the upper layers of the ocean, the microscopic plates they create, known as coccoliths, have a huge impact on the atmosphere.
Coccolithophores should help the environment in the long term. Calcite is one part carbon, one part calcium and three parts oxygen (CaCO3). Each time a molecule of calcite is made, one less carbon atom is allowed to roam freely to contribute to greenhouse gases and global warming. Their short-term effect is more complex. The chemical reaction that makes the coccolith also creates a carbon dioxide molecule. While much of the gas is sucked back in by the coccoliths during photosynthesis, some may escape into the atmosphere and immediately become part of the greenhouse gas problem. At this time, scientists think the longer-term benefit outweighs the potential short-term problem.
Metadata
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Sensor
Terra/MODIS
