2024-10-03 23:02:16
A study links an unusual phytoplankton bloom off the coast of Madagascar to drought in southern Africa, an increasingly common phenomenon due to climate change.
They act as fertilizer
When vegetation dies from lack of water, wind can lift and carry unprotected soil particles thousands of miles. These dust particles can act as a fertilizer when they settle in seawater.
Dionisio Raitsosprofessor at the National and Kapodistrian University of Athens, and colleagues show that dust from drought-stricken southern Africa triggered a bloom of phytoplankton marina off the southeast coast of Madagascar from November 2019 to February 2020.
The team used standardized dust aerosol optical depth anomalies from the Copernicus Atmosphere Monitoring Service (CAMS) and aerosol optical depth in coarse mode on site retrieved from a nearby Aerosol Robotic Network (AERONET) station to quantify the density of atmospheric dust aerosols over the Madagascar area over time.
The results are published in PNAS nexus (1).
These blooms could absorb carbon dioxide from the atmosphere
Dust aerosol optical depth anomalies averaged in the region of the bloom was the highest ever observed during the 17 years that CAMS has collected data. This dust cloud coincided with heavy rain, which deposited the iron-rich particles in the sea, creating ideal nutritional conditions for the growth of phytoplankton. The authors identify multiple potential sources of these iron-rich dust aerosols in southern Africa, which has experienced high air temperatures drought between 2012 and 2020.
According to the authors, as the climate warms, further phytoplankton blooms caused by the same mechanism are expected, and these blooms could absorb carbon dioxide from the atmosphere.
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