Subject: Climate Change

Why in the News?

Scientists have coined a new term, “thirstwave”, to describe spikes in evaporative demand, where a warmer atmosphere draws more water from plants, soil, and trees.

What is Evaporative Demand?

• Definition: Evaporative demand is the measure of how much water the atmosphere can potentially absorb from land, plants, and water surfaces if there is unlimited water available. It tells us how “thirsty” the atmosphere is.
• Nature of Measurement: It is not about how much water is actually lost but how much could be lost if water was fully available. It depends on weather conditions, not the amount of water in the soil.
• Standard Metric: The most widely used metric to quantify this is Standardized Short-Crop Reference Evapotranspiration (ETos)—which assumes a 12 cm grass surface with unlimited water availability.
• Impact of Global Warming: As global warming increases atmospheric heat, evaporative demand also rises, making the air more “thirsty”.

• Key Features:

• • Simplified Model: ETos simplifies evapotranspiration by assuming fixed vegetation properties and only variable weather conditions.
  • Indicators of Stress: An increase in ETos indicates higher temperatures, lower humidity, faster wind, and stronger solar radiation.
  • Effect on Soil and Crops: Rising evaporative demand leads to more rapid drying of soil and plants, even with ample irrigation.
  • Agricultural Relevance: This directly affects irrigation scheduling, crop productivity, and climate-resilient farming strategies.

What is a Thirstwave?

• Origin: “Thirstwave” is a newly coined term (2025) by Meetpal Kukal and Mike Hobbins to describe three or more consecutive days of extreme evaporative demand.
• Definition: A thirstwave is a period of sudden and intense increase in evaporative demand, caused by hot, dry, and sunny weather. It means the atmosphere becomes extremely “thirsty” and starts pulling water rapidly from soil, plants, and water bodies, even if they already have limited moisture.
• Distinction from Heatwaves: Unlike heatwaves, thirstwaves account for multifactorial stress, combining temperature, humidity, wind, and solar input.
• Thirstwave in India: There is no dedicated data yet on thirstwaves in India, but researchers are beginning to investigate, especially in South Asia’s climate-vulnerable zones.

Why in the News?

A new study from the University of Plymouth has revealed that over 21% of the global ocean has significantly darkened in the last two decades.

What is Ocean Darkening?

• Ocean darkening refers to the reduction in sunlight penetration into the ocean’s upper layers, known as the photic zone (up to 200 meters deep), where sunlight drives photosynthesis and supports marine biodiversity.
• This process is measured using the diffuse attenuation coefficient (Kd 490), which tracks how quickly light diminishes as it passes through seawater.
• The photic zone is essential for phytoplankton productivity, oxygen generation, marine food chains, and the regulation of global climate.

Recent Report Citing Ocean Darkening:

• A new study by researchers from the University of Plymouth, published in 2024, titled “Darkening of the Global Ocean”, revealed that 21% of the global ocean has significantly darkened from 2003 to 2022.
• Key findings:
  • 9% of the ocean saw a drop of more than 50 meters in light penetration—equal to the area of Africa.
  • 2.6% experienced a loss exceeding 100 meters in photic depth.
• Affected Region: The study found the Arctic, Antarctic, Gulf Stream, and North Sea among the worst affected regions.
• Causes:
  • Algal blooms from nutrient runoff in coastal areas.
  • Warming seas, altered plankton dynamics, and changing ocean currents in open ocean zones.

Implications of Ocean Darkening:

• Ecosystem Disruption: Light-dependent species, such as Calanus copepods, are being pushed into shallower zones, increasing predation and competition.
• Loss of Habitat: The shrinkage of the photic zone could be one of the largest marine habitat losses ever, affecting fish stocks and biodiversity.
• Climate Feedback Loop: Reduced photosynthesis in oceans could weaken the ocean’s role in carbon sequestration and oxygen production, worsening climate change.
• Threat to Global Fisheries: The contraction of productive zones affects fish populations, jeopardising fisheries and food security.
• Scientific Concern: Researchers warn that this hidden crisis could fundamentally alter marine ecosystems if not urgently addressed.

Why in the News?

A new ETH Zurich study warns that under the Shared Socioeconomic Pathway (SSP) 5-8.5 scenario, warming could make cyclones more intense and hit unusual regions with greater damage.

About SSP5-8.5 and Cyclone Risks:

• Scenario Summary: SSP5 shows rapid economic growth fuelled by fossil fuels.
• Radiative Forcing: SSP5-8.5 implies 8.5 W/m² of energy, compared to about 2.7 W/m² today.
• Climate Target Gap: To limit warming below 2°C, forcing must stay around 2.6 W/m².
• Cyclone Projections: Using the CLIMADA (climate adaptation) AI model, scientists studied past cyclone patterns and projected risks from 2015–2050.
• Ecoregion Types:

1. 1. Resilient: Often affected, but recover quickly
   2. Dependent: Moderately impacted and adaptive
   3. Vulnerable: Rarely hit but slow to recover

• Findings:
  • Time between severe cyclones in resilient areas may drop from 19 to 12 years.
  • East Asia, Central America, and the Caribbean will face stronger, more frequent cyclones.
  • Madagascar, Oceania, and the Philippines will face unprecedented cyclone activity.

Impact on Mangroves and Coastal Ecosystems:

• Mangrove Risk: By 2100, up to 56% of global mangroves could be at high to severe risk.
• Most Affected Region: Southeast Asia, with 52–78% of mangroves at risk.
• Other Scenario Impact (SSP3-7.0): Even under less severe warming, 97–98% of protective mangroves in Southeast Asia could still face critical threats.
• Environmental Concern: These losses would severely weaken coastal protection, biodiversity, and carbon storage.

Why in the News?

India participated in the 20th session of the United Nations Forum on Forests (UNFF20) held at the UN Headquarters, New York, reaffirming its commitment to the United Nations Strategic Plan for Forests (UNSPF) 2017–2030.

About United Nations Forum on Forests (UNFF):

• UNFF was established in 2000 by the UN Economic and Social Council (ECOSOC).
• It aims to promote sustainable forest management and global forest policy coordination.
• It holds annual sessions at UN Headquarters:
  • Technical discussions in odd years
  • Policy-level dialogues in even years
• It has universal membership — includes all UN Member States and relevant forest-related agencies.
• India is a founding member and plays an active role in shaping forest policies.
• The UN Strategic Plan for Forests (UNSPF) is the guiding framework for achieving global forest goals by 2030.
• The 19th UNFF Declaration secured high-level political commitment for forest conservation.

Key Highlights of UNFF20:

• India reaffirmed its commitment to Voluntary National Contributions (VNCs) under the UNSPF (2017–2030).
• It reported an increase in forest and tree cover to 25.17% of its geographical area.
• National efforts included the Aravalli Green Wall, a 7.86% rise in mangrove cover, 1.55 lakh hectares afforested under the Green India Mission, and 1.4 billion seedlings planted under the Ek Ped Maa Ke Naam campaign.
• India invited countries to join the International Big Cat Alliance (IBCA) for big cat conservation.
• It urged support for outcomes of the Country-Led Initiative (CLI) on forest fire management held in Dehradun (2023).
• In a high-level panel, India presented findings on carbon sequestration, water services, biodiversity, and tools like System of Environmental Economic Accounting (SEEA) and Millennium Ecosystem Assessment (MEA).
• It stressed the need to mainstream ecosystem valuation in forest policy.

Why in the News?

To channel investments into clean-energy projects and climate-resilient infrastructure, the Finance Ministry has released a draft document titled ‘Framework of India’s Climate Finance Taxonomy’.

What is a Climate Finance Taxonomy?

• A CFT is a classification system that defines which economic activities qualify as climate-friendly or sustainable investments.
• It helps investors, financial institutions, and policymakers channel funds into low-emission and climate-resilient projects.
• It acts as a safeguard against green-washing, where non-sustainable initiatives are falsely labelled as green.
• It supports the mobilization of finance necessary to achieve global climate goals, including Net Zero targets.
• It offers a structured decision-making framework to ensure that investments deliver measurable environmental benefits.

About India’s Draft ‘Climate Taxonomy’ (May 2025)

• The Finance Ministry released the draft ‘Framework of India’s Climate Finance Taxonomy’ to help meet India’s Net Zero by 2070 goal while maintaining energy access.
• It categorizes activities as:
  • Climate Supportive Activities: Those that reduce GHG emissions, enable adaptation, or promote clean tech R&D.
  • Climate Transition Activities: Those that encourage gradual progress, especially in hard-to-abate sectors like steel, iron, and cement.
• It aligns with the national vision of ‘Viksit Bharat 2047’.
• It includes key sectors such as power, mobility, buildings, agriculture, food, and water security.
• The framework was first announced in the Union Budget 2025.

Global Context and Negotiation Relevance:

• A standard taxonomy is critical in global forums like the Conference of Parties (COP) to resolve disputes over climate finance commitments.
• Developing nations, including India, advocate for grants and technology transfers, while developed countries often include private investments in their finance counts.
• At the Baku Climate Conference, developed countries pledged $300 billion annually by 2035, far below the $1.35 trillion required.
• India’s taxonomy aims to provide a clear benchmark for climate-related financial flows, promoting transparency, credibility, and trust in international climate funding.

Why in the News?

On Earth Day, April 22, the Food and Agriculture Organization (FAO) launched the Accelerating Innovative Monitoring for Nature Restoration (AIM4NatuRe) Initiative aimed at accelerating nature restoration.

About the AIM4NatuRe Initiative:

• AIM4NatuRe is a global initiative launched by the FAO aimed at enhancing countries’ ability to monitor and report ecosystem restoration efforts.
• With £7 million (approximately USD 9.38 million) from the United Kingdom, the initiative will run from 2025 to 2028, focusing on restoring 30% of degraded ecosystems globally by 2030, in alignment with the Global Biodiversity Framework (GBF).
• Key aspects:
  • Utilizes advanced technology and data frameworks for ecosystem restoration monitoring.
  • Targets restoration across forests, wetlands, grasslands, marine ecosystems, and agricultural landscapes.
  • Integrates Indigenous knowledge in restoration efforts.
  • Develops tools like the Framework for Ecosystem Restoration Monitoring (FERM) and builds a unified global dataset for transparency.

Key Stakeholders:

• FAO: Leads the initiative, providing tools, data, and frameworks to support restoration.
• UK: Provides financial backing and focuses on helping countries achieve the 30×30 target.
• Indigenous Communities: Contribute traditional knowledge and participate in restoration efforts.
• World Resources Institute (WRI): Supports global restoration initiatives, including the Kham River Restoration Mission in India.
• Convention on Biological Diversity (CBD): Shapes the biodiversity framework for monitoring progress on 30% ecosystem restoration by 2030.
• World Bank: Provides funding and technical expertise for financing and implementing ecosystem restoration.

Why in the News?

A new global initiative called ‘Revive Our Ocean’ was launched with the goal of scaling up effective, community-led marine protected areas (MPAs) to boost marine conservation efforts.

About the Revive Our Ocean Initiative:

• It is a global effort to enhance marine ecosystem protection through community-led Marine Protected Areas (MPAs).
• It was launched by David Attenborough, Dynamic Planet, and National Geographic’s Pristine Seas to scale up MPAs, empowering coastal communities to lead conservation efforts.
• The goal is to protect 30% of the world’s oceans by 2030, aligning with the Kunming-Montreal Global Biodiversity Framework (KMGBF).
• Initially focused on 7 countries: UK, Portugal, Greece, Turkey, Philippines, Indonesia, and Mexico, using successful MPA models.
• It emphasizes economic benefits of MPAs, such as generating €16 million annually from diving tourism in Medes Island, Spain.