Over 50% Of The World’s Oceans Have Turned Green In Two Decades Due To Global Warming

Scientists have made a surprising discovery about climate change by studying changes in the colour of the ocean. They expected to need several years of data to find indications of climate change through ocean colour, but they could detect them earlier than anticipated. The study’s lead author, B. B. Cael, an ocean and climate scientist, says we are impacting the ecosystem unprecedentedly.

The colour of the ocean can change due to different factors. One of these factors is the growth of green phytoplankton blooms fueled by rising nutrients. Scientists can measure the abundance of chlorophyll and the presence of living organisms like phytoplankton and algae by examining the sunlight reflected from the ocean’s surface.

The researchers analysed data from the MODIS sensor on NASA’s Aqua satellite to overcome the challenge of distinguishing climate change-induced changes from natural fluctuations. They examined trends in seven different colours of light emitted by the ocean instead of relying on a single wavelength traditionally used to track chlorophyll levels.

After studying two decades’ worth of MODIS data, the scientists identified significant changes in ocean colour, covering 56% of the Earth’s surface. These changes were most prominent in tropical and subtropical waters, where even slight long-term changes became more noticeable. Overall, the seas have been becoming greener over time.

The researchers compared their observations with a model that simulated the response of marine ecosystems to rising greenhouse gas levels. They found that the observed changes closely matched the model’s projections, providing strong evidence linking the changes in colour to climate change.

The exact cause of the ocean’s green tint is still uncertain, but it is unlikely to be solely due to rising sea surface temperatures. Nutrient distribution within the ocean may play a role. The researchers emphasise that ocean colour is an essential indicator of ecosystem dynamics.

NASA’s upcoming PACE satellite, launching in January 2024, is expected to revolutionise the measurement of ocean colour. Its advanced capabilities will provide valuable insights into the ecological implications of the observed trends in ocean ecosystem structure.

The study highlights the significance of understanding colour as an indicator of climate change and ecosystem health. The findings suggest that the impact of climate change on marine ecosystems may occur sooner than anticipated.

Reference: Nature, News18, The Guardian

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