Tropical waters have turned ‘green’ in colour

Recently, a study has indicated that Tropical Ocean waters are turning Green in colour due to alteration in phytoplankton communities.

• The green colour comes from chlorophyll, a pigment that helps microscopic plant-like phytoplankton make food.

Highlights of the study:

• According to the study, Climate change has altered the colour of 56 per cent of the world’s oceans.
• The southern Indian Ocean, in particular, has seen a significant colour change.
• The reason highlighted for the change in colour seems to determine the amount of carbon dioxide absorbed by the ocean.
• Currently, oceans absorbed 25 per cent of all carbon dioxide (CO2) emissions.
• The study also predicted that predicted that more than 50 per cent of the world’s oceans will shift in colour due to climate change by 2100.

Data collection and Procedure:

• They analysed data generated from the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Aqua satellite, which has been monitoring ocean colour for two decades between 2002 and 2022.
• The team then used to model to simulate two scenarios: one with the addition of greenhouse gases and the other without them.

How Oceans absorb CO2?

• The ocean absorbs carbon dioxide from the atmosphere wherever air meets water.
• Wind causes waves and turbulence, giving more opportunity for the water to absorb the carbon dioxide.
• Fish and other animals in the ocean breathe oxygen and give off carbon dioxide (CO2), just like land animals.

Tropical Oceans & Ecosystem:

• Tropical oceans encircle Earth in an equatorial region between the Tropic of Cancer (23.5° North latitude) and the Tropic of Capricorn (23.5° South latitude).
• The central portions of the Pacific and Atlantic Oceans and most of the Indian Ocean lie in the tropics.
• The warm tropical oceans play a critical role in regulating Earth's climate and large-scale weather patterns.
• Much of the planet's biological diversity resides in the tropics, and the global distribution of species and ecosystems depends on oceanographic and atmospheric processes that occur in the equatorial oceans.

Significance of Tropical waters:

• Tropical upwelling support huge populations of microscopic plants and animals called phytoplankton and zooplankton.
• Plankton, in turn, feed many species of fish and other marine life, and humans who depend on fish for food.
• Tropical fisheries account for about half of the world's fish catch, even though tropical oceans represent only 0.01 percent of Earth's ocean volume.
• Coral reefs are another well-recognized feature of tropical oceans.
• The seas surrounding tropical islands and low-latitude continental shelves away from major river deltas are ideal for coral reef formation.

Concerns:

• A change in colour due to an increase or decline in the population will impact organisms that feed on plankton.
• It will also change how much the ocean will take up carbon because different types of plankton have different abilities to absorb carbon dioxide.