Topic 4a - Phytoplankton and climate

The story of oceans and climate would not be complete until we explore the impact of weather and climate on marine life. We also need to understand how ocean life, notably phytoplankton might modulate oceanic weather and climate, through their role in the global carbon cycle, and on the ocean heat budget.

One way that phytoplankton influence the oceans is through heating. Photosynthesis is quite inefficient, so much of the light absorbed by phytoplankton cells is released as heat.

Phytoplankton are also affected by climate. Changes in the heat content and distribution within the Earth system can change ocean circulation. This can alter the access phytoplankton have to light and nutrients. Warmer or colder temperatures may favour some species over others, and similarly may change the dynamics between predators and their prey (often phytoplankton).

Long-term ocean colour records, and ocean biogeochemical models can be used to understand these changes.

Featured Educators:

  • Dr Ewa Kwiatowska

Explore the data

EUMETSAT Oceans MOOC Data Viewer

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Don’t forget you can download the video and transcript with the links on the right.

Optional Further Reading


OCTS image of Sea Surface Temperature in Japanese Waters

Distribution of sea surface temperature observed on April 25, 1997 by the infrared band of Ocean Colour and Temperature Sensor (OCTS IR) onboard The Japanese ADEOS satellite

OCTS ocean colour image of Japanese waters

Phytoplankton (chlorophyll-a) concentration in Japanese waters observed on April 25, 1997 by visible near infrared band of the Ocean Colour and Temperature Scanner (OCTS VNIR) onboard the Japanese Satellite ADEOS.

Ocean colour of the Mediterranean taken by VIIRS instrument

VIIRS-SNPP four month composite images (2014 October through 2015 January) of Chlorophyll a concentration (top) and the spectral attenuation coefficient at 490 nm (bottom) processed using NOAA-MSL12 ocean color data processing system with the BMW option for the NIR reflectance correction algorithm

SeaWiFS Global average phytoplankton chlorophyll concentration

This SeaWiFS image of our world depicts the global biosphere—the ocean’s long-term average phytoplankton chlorophyll concentration acquired between September 1997 and August 2000 combined with the SeaWiFS-derived Normalized Difference Vegetation Index over land during July 2000.

Coccolithophore blooms

Sentinel-3 OLCI coccolithophore blooms

Phytoplankton swirl in the Atlantic ocean off the coast of Iceland on June 3, 2016. (NASA Worldview)

Cyanobacteria blooms

Sentinel-3 OLCI cyanobacteria blooms

Aquatic Microbiology
Biological Carbon Pump

Schematic explaining the concept of the biological carbon pump – how phytoplankton contribute to take-up and storage of atmospheric carbon dioxide.

Chlorophyll a concentration, globe

Sentinel-3 OLCI chlorophyll-a concentration early result
SeaWiFS Biosphere from 1997 to 2006

Chlorophyll a concentrations (mg/m3)

Sentinel-3 OLCI chlorophyll-a concentration early result. The dark blues have the lowest concentrations, followed by the light blues, then greens, yellow, and finally red which has the highest concentration of Chlorophyll a.

North West Borneo

Sentinel-3 OLCI sediment plumes off North West Borneo

Great Barrier Reef

Sentinel-3 OLCI sediment plumes / Great Barrier Reef ecosystem


Artist impression of Sentinel-3