Scientists from MIT and the National Oceanography Centre, among others, have detected significant changes in the colour of the world’s oceans over the past two decades.
CHANGES IN ECOSYSTEM
Published in Nature, the study indicates that these colour shifts, covering 56% of the world’s oceans, cannot be attributed solely to natural year-to-year variability. The researchers found that tropical ocean regions near the equator have gradually become greener, indicating changes in the ecosystems within the surface ocean. Although the exact impact on marine ecosystems remains uncertain, the study suggests that human-induced climate change is a likely driver behind these changes.
Stephanie Dutkiewicz, a senior research scientist at MIT, expressed her concern and stated that the observed changes in ocean colour align with predictions made by climate change simulations. The study provides additional evidence of how human activities are affecting the planet’s biosphere on a global scale.
Ocean colour serves as a visual representation of the organisms and materials present in the upper layers of the ocean. The presence of ecosystems, particularly phytoplankton, which contain the green pigment chlorophyll, is reflected in greener waters. Phytoplankton plays a vital role in the marine food web and contributes to the ocean’s ability to capture and store carbon dioxide. The study underscores the importance of monitoring phytoplankton and their response to climate change.
CLEAR TREND
Previously, it was challenging to detect climate change-driven trends in chlorophyll concentrations due to natural variations. However, by analysing changes in other ocean colours, the researchers were able to identify a clear trend over the past two decades. The analysis of satellite data from the Moderate Resolution Imaging Spectroradiometer (MODIS) indicated a correlation between the observed trend in ocean colour and anthropogenic climate change.
The study highlights the potential for monitoring ocean colour beyond chlorophyll as a faster and more accurate method to detect climate change-induced changes in marine ecosystems. The researchers urge scientists to take these changes seriously, as they can affect plankton communities, the marine food web, and the ocean’s carbon uptake. The study serves as a reminder that the ocean is changing, and understanding these changes is crucial for the health of our planet.
