Climate Change Alters Ocean Colour

• 17 Jul 2023

For Prelims: Climate Change, Marine Ecosystem, Global Warming

For Mains: India's climate change mitigation initiatives, climate change impact on oceans

Source: DTE

Why in News?

Recently, a new study reveals that 56% of the world's oceans have experienced a change in colour due to climate change.

• Tropical waters, particularly the southern Indian Ocean, have turned green, indicating an increase in phytoplankton and marine life.

What are the Key Highlights of the Study?

• Long-Term Trends and Data Analysis:
  • Aqua Satellite Data:
    • Researchers analyzed data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Aqua satellite (NASA’s Earth Science satellite mission), monitoring ocean colour for two decades (2002-2022).
    • MODIS takes measurements in seven visible wavelengths (Light of different wavelengths produces different perceptions of colour).
  • Subtle Colour Changes:
    • Human eyes cannot detect subtle colour changes in the oceans, which may contain a mix of wavelengths ranging from blue to green and even red.
  • Green Waters and Phytoplankton:
    • The study finds that green-coloured water indicates the presence of phytoplankton, essential microscopic plant-like organisms.
      • Phytoplankton serve as the base of the marine food web, similar to plants on land, and play a crucial role in supporting marine life.
    • The colour of the ocean affects the amount of carbon dioxide absorbed by the oceans, with current estimates indicating that oceans absorb 25% of global CO2 emissions.
  • Role of Climate Change:
    • By comparing annual variations in ocean colour over the two decades, the study identified climate change as the primary factor behind the observed changes.
    • Using a model, researchers simulated two scenarios—one considering greenhouse gas emissions and the other without them.
    • The scenario accounting for greenhouse gas emissions predicted that colour changes could occur in approximately 50% of the world's surface oceans, aligning with satellite observations indicating a 56% shift to green or blue waters.
  • Implications for Marine Life and Conservation:
    • Impact on Organisms:
      • The green hue comes from chlorophyll, a pigment that helps phytoplankton make food. A change in colour due to an increase or decline in the population will impact organisms that feed on plankton.
    • Carbon Sequestration:
      • Different types of plankton have varying abilities to absorb carbon, potentially influencing the ocean's capacity for carbon uptake.
  • Regional Variability and the Need for Further Study:
    • The southern Indian Ocean exhibits significant changes in colour, while waters near India do not follow the same trend, potentially due to natural variability.
• Recommendations:
  • Researchers emphasize the need for individuals and policymakers to recognize the significance of these changes and take appropriate action to protect marine ecosystems.
  • Ongoing monitoring and further research are crucial to understanding regional variations and the full extent of climate change's impact on ocean colour.

What are India's Climate Change Mitigation Initiatives?

• National Action Plan on Climate Change (NAPCC):
  • Launched in 2008 to address climate change challenges in India.
  • Aims to achieve low-carbon and climate-resilient development for India.
  • There are 8 national missions forming the core of the NAPCC which represent multi-pronged, long term and integrated strategies for achieving key goals in climate change. These are-
    • National Solar Mission
    • National Mission for Enhanced Energy Efficiency
    • National Mission on Sustainable Habitat
    • National Water Mission
    • National Mission for Sustaining the Himalayan Ecosystem
    • National Mission for A Green India
    • National Mission for Sustainable Agriculture
    • National
    • Mission on Strategic Knowledge for Climate Change.
    • Nationally Determined Contributions (NDC)
    • National Adaptation Fund on Climate Change (NAFCC):
    • State Action Plan on Climate Change (SAPCC).
• Nationally Determined Contributions (NDC):
  • India's commitments to reduce greenhouse gas emissions and adapt to climate change.
  • Pledged to reduce the emissions intensity of GDP by 45% by 2030 from 2005 levels and generate 50% of electricity from non-fossil fuel sources by 2030.
  • Pledged to create additional carbon sink and achieve net zero emissions by 2070.
• National Adaptation Fund on Climate Change (NAFCC):
  • Established in 2015 to provide financial assistance to state governments for implementing adaptation projects in various sectors.
• State Action Plan on Climate Change (SAPCC):
  • Encourages all states and union territories to prepare their own SAPCCs based on their specific needs and priorities.
  • SAPCCs outline strategies and actions for addressing climate change at the sub-national level.
  • Aligned with the objectives of the NAPCC and the NDC.

UPSC Civil Services Examination, Previous Year Questions (PYQs)

Q. What are the consequences of spreading ‘Dead Zones’ on marine ecosystems? (2018)