Climate Change Has Shifted Colour Of Over Half Of World’s Oceans: Study

New Delhi: The colour of over 56 per cent of the world’s oceans, larger than Earth’s total land expanse, has changed significantly over the last two decades and human-caused climate change is likely the driver, according to researchers. These colour changes, subtle to the human eye, cannot be explained by natural, year-to-year variability alone, the researchers from the Massachusetts Institute of Technology (MIT), US, and other institutes write in their paper published in the journal Nature.

Ocean colour, a literal reflection of the life and materials in its waters, in regions near the equator was found to have steadily turned greener over time, indicating changes in the ecosystems within the surface oceans.

Also Read: Engage, Educate And Empower: The Three Es To Discuss Climate Change With Children

The green colour of the ocean waters comes from the green pigment chlorophyll present in phytoplankton, the plant-like microbes abundant in upper ocean. Scientists are, therefore, keen to monitor phytoplankton to see their response to climate change.

However, the authors of this study showed through previous studies that it would take 30 years of tracking chlorophyll changes before climate-change-driven trends would show, because natural, annual variations in chlorophyll would overwhelm those influenced by human activities.

In a 2019 paper, study co-author Stephanie Dutkiewicz and her colleagues showed that monitoring other ocean colours, whose annual variations are much smaller than those of chlorophyll, would convey more clear signals of climate-change-driven changes and that they might even be apparent in 20 years, rather than 30. Lead author B. B. Cael of the National Oceanography Center, said,

It’s worth looking at the whole spectrum, rather than just trying to estimate one number from bits of the spectrum.

Mr Cael and team then statistically analysed all the seven ocean colours recorded by satellite observations from 2002 to 2022 together. He initially studied the colours’ natural variations by seeing how they changed regionally in a given year.

He then observed how these annual variations changed over two decades.

To understand climate change’s contribution to all these changes, he used Dutkiewicz’s 2019 model to simulate the Earth’s oceans under two scenarios – one with greenhouse gases and the other without them.

The greenhouse-gas model predicted changes to the colour of about 50 per cent of the world’s surface oceans in under 20 years – close to Mr Cael’s conclusions from his real-world satellite data analysis.

This suggests that the trends we observe are not a random variation in the Earth system, said Mr Cael.

Dutkiewicz, senior research scientist in MIT’s Department of Earth, Atmospheric and Planetary Sciences, said,

This is consistent with anthropogenic climate change. I’ve been running simulations that have been telling me for years that these changes in ocean colour are going to happen. To actually see it happening for real is not surprising, but frightening. And these changes are consistent with man-induced changes to our climate.

Also Read: Climate Nears Point Of No Return As Land, Sea Temperatures Break Records: Experts

(This story has not been edited by NDTV staff and is published from a syndicated feed.)

NDTV – Dettol have been working towards a clean and healthy India since 2014 via the Banega Swachh India initiative, which is helmed by Campaign Ambassador Amitabh Bachchan. The campaign aims to highlight the inter-dependency of humans and the environment, and of humans on one another with the focus on One Health, One Planet, One Future – Leaving No One Behind. It stresses on the need to take care of, and consider, everyone’s health in India – especially vulnerable communities – theLGBTQ population,indigenous people, India’s different tribes, ethnic and linguistic minorities, people with disabilities, migrants, geographically remote populations, gender and sexual minorities. In wake of the currentCOVID-19 pandemic, the need for WASH (Water,SanitationandHygiene) is reaffirmed as handwashing is one of the ways to prevent Coronavirus infection and other diseases. The campaign will continue to raise awareness on the same along with focussing on the importance of nutrition and healthcare for women and children, fightmalnutrition, mental wellbeing, self care, science and health,adolescent health & gender awareness. Along with the health of people, the campaign has realised the need to also take care of the health of the eco-system. Our environment is fragile due to human activity, which is not only over-exploiting available resources, but also generating immense pollution as a result of using and extracting those resources. The imbalance has also led to immense biodiversity loss that has caused one of the biggest threats to human survival – climate change. It has now been described as a “code red for humanity.” The campaign will continue to cover issues likeair pollution,waste management,plastic ban,manual scavengingand sanitation workers andmenstrual hygiene. Banega Swasth India will also be taking forward the dream of Swasth Bharat, the campaign feels that only a Swachh or clean India wheretoiletsare used andopen defecation free (ODF)status achieved as part of the Swachh Bharat Abhiyan launched byPrime Minister Narendra Modiin 2014, can eradicate diseases like diahorrea and the country can become a Swasth or healthy India.