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how do phytoplankton influence global change
As previously stated, phytoplankton use carbon dioxide for photosynthesis. The larger the world's phytoplankton population, the more carbon dioxide gets pulled from the atmosphere, hence, the lower the average temperature due to lower volumes of this greenhouse gas. Scientists have found that a given population of phytoplankton can double its numbers on the order of once per day. In other words, phytoplankton respond very rapidly to changes in their environment. Large populations of this organism, sustained over long periods of time, could significantly lower atmospheric carbon dioxide levels and, in turn, lower average temperatures.

Phytoplankton as indicators of change
As described above, phytoplankton depend upon sunlight, water, and nutrients to survive. Physical or chemical variance in any of these ingredients over time for a given region will affect the phytoplankton concentrations there. Populations of this marine plant will grow or diminish rapidly in response to changes in its environment. Changes in the trends for a given phytoplankton population—such as its density, areal distribution, and rate of population growth or diminishment—will alert Earth scientists that environmental conditions are changing there. Then, by comparing these phytoplankton trends to other measurements—such as temperature—scientists can learn more about how phytoplankton may be contributing to, and affected by, climatic and environmental change.

To human eyes, the ocean appears as shades of blue; sometimes blue-green. From outer space, satellite sensors can distinguish even slight variations in color to which our eyes are not sensitive. Different shades of ocean color reveals the presence of differing concentrations of sediments, organic materials, or even phytoplankton—all of which can be measured by satellites.

Due to their pigment—chlorophyll—phytoplankton preferentially absorb the red and blue portions of the light spectrum (for photosynthesis) and reflect green light. So, the ocean over regions with high concentrations of phytoplankton will appear as certain shades, from blue-green to green, depending upon the type and density of the phytoplankton population there.

SeaWiFS Ocean ColorSeaWiFS Ocean Color
SeaWiFS Ocean ColorSeaWiFS Ocean Color

This sequence of SeaWiFS ocean color imagery shows the impact of the recent El Niño on the productivity of phytoplankton around the Galapagos Islands in the Pacific Ocean. The top left image was taken during the height of the 1997-98 El Niño, while the bottom right image was taken during the more recent La Niña. Note the gradually flourishing bloom of phytoplankton as the surface waters cool, allowing the deeper, more nutrient-rich waters to upwell. (Courtesy of the SeaWiFS Project)

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What are Phytoplankton?
What are phytoplankton?
How do phytoplankton influence global climate?
What is a coccolithophore?

Related Data Sets:
Ocean Chlorophyll (CZCS)
Biosphere (SeaWiFS)

Relevant Satellite Missions:
SeaWiFS
Terra

   
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