Climate Change and the International Response

The single greatest environmental challenge of our age is climate change, the warming of the whole planet caused by human activity. The atmosphere belongs to everyone, so no nation can solve it alone. Countries have therefore come together in a series of global agreements. Understanding the science, the impacts and the international response is essential for environment and current-affairs questions.

The Earth is kept warm by the greenhouse effect: certain gases in the atmosphere (chiefly carbon dioxide, methane and nitrous oxide) trap part of the heat the Earth radiates back to space. A natural greenhouse effect is essential for life.

The problem is that human activity has sharply increased these greenhouse gases. The main sources are burning fossil fuels such as coal, oil and gas, clearing forests, and industry. More greenhouse gases strengthen the effect and trap more heat. This causes global warming: a steady rise in the Earth's average temperature.

Carbon dioxide, methane and nitrous oxide are not the whole story. Three other agents also warm the atmosphere:

• Water vapour: the most abundant natural greenhouse gas in the atmosphere.
• Sulphur hexafluoride (SF6): an industrial gas used in electrical equipment, and one of the most potent greenhouse gases known.
• Soot (black carbon): fine dark particles from incomplete burning. Soot is not a gas, but it warms the air by absorbing solar radiation.

Agriculture is a leading source of greenhouse gases. Flooded rice paddies cut off the oxygen supply to the soil. In these anaerobic (oxygen-free) conditions, soil microbes produce methane. The nitrogen fertilisers applied to the same fields release nitrous oxide from the soil. Rice cultivation is therefore the most important human-made source of both methane and nitrous oxide. Other major methane sources are coal mining, domestic animals (which release methane during digestion, a process called enteric fermentation) and natural wetlands.

A hidden methane danger lies in methane hydrates: ice-like deposits of methane locked in the permafrost of the Arctic tundra and under the seafloor. Global warming might thaw these stores and trigger a large release of methane. Once in the atmosphere, methane oxidises into carbon dioxide within a decade or two, so its warming effect is intense but short-lived.

Industry adds its own large share. The cement industry alone accounts for more than 5% of global carbon dioxide emissions. In cement manufacturing, silica-bearing clay is mixed with limestone. During the production of clinker, the limestone is heated and converted into lime. This chemical step, called calcination, releases carbon dioxide. The calcination reaction, not just the fuel burned in the kiln, explains why cement emissions are so high.

India's per-capita carbon dioxide emissions are about 2 tonnes a year, far above the 0.5-tonne figure sometimes quoted. India ranks second in the Asia-Pacific region for carbon dioxide emissions from fuel combustion. Within India, electricity and heat producers are the largest source of carbon dioxide emissions.

One feedback of rising carbon dioxide is positive for plants. Carbon fertilization means increased plant growth caused by the increased concentration of carbon dioxide in the atmosphere. Plants build tissue from carbon dioxide during photosynthesis, so more of the gas can speed their growth. The term refers to this growth effect alone, not to warming, ocean acidification or adaptation.

Global warming drives a chain of harmful impacts across the planet:

• Melting glaciers and polar ice, which raises the sea level and threatens low-lying coasts and island nations.
• More frequent and severe extreme weather: heatwaves, droughts, floods and storms.
• Disruption of agriculture and water supplies, threatening food security.
• Loss of species and habitats that cannot adapt fast enough.

These impacts fall hardest on poor countries and communities, who have done least to cause the problem.

Heat itself can become a direct threat to survival, separate from flooding or cyclone risk. Humans cool themselves by sweating: perspiration evaporates from the skin and carries body heat away. The wet-bulb temperature measures heat and humidity together. It is the lowest temperature to which air can be cooled by evaporating water into it. Above a wet-bulb temperature of about 35°C, evaporative cooling fails. Humans and animals can no longer shed body heat through perspiration, and even healthy people resting in the shade cannot survive prolonged exposure.

Scientists also project what happens if warming exceeds about 3°C above pre-industrial levels. Two outcomes stand out:

• Land becomes a carbon source: the terrestrial biosphere, the world's land plants and soils, tends to flip from absorbing carbon to releasing it.
• Widespread coral mortality: most coral reefs die off across the oceans.

Some predictions overshoot the evidence. Wetlands would not all permanently disappear, and cereal cultivation would not become impossible everywhere. Statements claiming such total, universal losses are wrong.

The world responded by building scientific and diplomatic institutions:

• The Intergovernmental Panel on Climate Change (IPCC) is the body that assesses the science of climate change, producing reports that guide policy.
• The United Nations Framework Convention on Climate Change (UNFCCC), agreed at the 1992 Rio Earth Summit, is the global treaty under which nations negotiate. Its members meet each year at the Conference of the Parties (COP).

A key principle of the UNFCCC is "common but differentiated responsibilities". All nations must act. But the rich nations caused most past emissions, so they must do more.

Two landmark agreements came out of this process:

• The Kyoto Protocol (1997) set binding targets for developed countries to cut their greenhouse-gas emissions. It applied mainly to the rich nations.
• The Paris Agreement (2015) went further: all countries, rich and poor, pledged to limit global warming to well below 2°C (aiming for 1.5°C) above pre-industrial levels, each setting its own national targets.

India is an active participant. It stresses climate justice and the right of developing nations to grow. India is also expanding renewable energy.

The Kyoto Protocol was adopted in 1997 and entered into force in 2005. The developed countries that took binding targets are listed as Annex-I countries. The term comes from the UNFCCC, which groups its parties in annexes; developing countries are non-Annex-I.

Kyoto's lasting innovation was a set of market mechanisms:

• Clean Development Mechanism (CDM): lets a developed country fund an emission-reduction project in a developing (non-Annex-I) country and earn credits in exchange. The developing host gets investment and clean technology.
• Carbon credits: a credit is awarded to a country or firm that reduces its emissions below its assigned quota. The formal Kyoto unit is the Certified Emission Reduction (CER). Both carbon credits and CERs originate from the Kyoto Protocol.
• Trading: credits are bought and sold at prices determined by the market. No UN body, including UNEP, fixes their price.

Credits are counted in tonnes of carbon dioxide equivalent because the gases differ in potency. Methane, for example, has a much higher global warming potential than carbon dioxide, so cutting one tonne of methane earns more credit.

Carbon markets are expected to be among the most widespread tools in the fight against climate change. When governments auction emission permits or sell credits, the market transfers resources from the private sector to the State.

A related fiscal tool is the carbon tax, a direct levy on emissions. New Zealand was the first country in the world to propose a carbon tax for its people.

Three details about the Paris Agreement are tested often:

• Entry into force: the Agreement was adopted in 2015 but was not signed by all UN members at its inception. It entered into force in 2016, once enough countries had ratified it. Membership grew over time.
• Climate finance: developed countries pledged to mobilise $100 billion per year from 2020 to help developing countries. The figure is $100 billion, not $1,000 billion.
• Article 6: this article sets out the principles of carbon markets under the Agreement, and it also promotes non-market approaches between countries for meeting climate targets. This dual role is why Article 6 features so often in negotiations and in the news.

Mitigation means acting to reduce greenhouse-gas emissions at the source. It is distinct from adaptation, which means adjusting to the warming that is already unavoidable. Mitigation runs through every sector of the economy, from how goods are made to how roads are built.

A powerful mitigation idea is the circular economy. In a circular economy, materials are reused, repaired and recycled instead of being used once and thrown away. This reduces the demand for fresh raw materials and cuts wastage in the production process. Both effects together lower greenhouse-gas emissions, because extracting and processing virgin materials is energy intensive.

Mitigation also shapes everyday engineering choices. In rural road construction, certain materials and methods are preferred because they carry a smaller carbon footprint:

• Copper slag: an industrial by-product reused in road layers, which avoids fresh quarrying.
• Cold mix asphalt: asphalt laid without heating, which saves the large energy cost of hot mixing.
• Geotextiles: polymer fabrics that strengthen the road bed and reduce the need for cement.

By contrast, hot mix asphalt and Portland cement are energy intensive and add to emissions, so they are avoided where greener options exist.

Economists support mitigation policy with the Social Cost of Carbon. It is a measure, in monetary terms, of the long-term damage done by emitting one additional tonne of carbon dioxide in a given year. Governments use this figure in cost-benefit analysis to judge whether a climate policy is worth its price.

A carbon sink is any reservoir that absorbs more carbon than it releases. Natural sinks remove a large share of the carbon dioxide humans emit. The most important is the ocean: microscopic phytoplankton absorb carbon dioxide through photosynthesis, pulling it out of the lower atmosphere. Carbon dioxide does not escape into the outer stratosphere, and it is not removed by being trapped in polar ice. The ocean's living pump does the work.

Several other natural stores matter for the exam:

• Blue carbon: the carbon captured by oceans and coastal ecosystems such as mangroves, seagrasses and salt marshes.
• Tropical peatlands: waterlogged soils of partly decayed plants. The Congo Basin holds the world's largest tropical peatland (the Cuvette Centrale), storing roughly three years' worth of global fossil-fuel emissions. Its destruction would be a global climate disaster.
• Soil carbon: farming methods influence it. Zero tillage, which avoids ploughing, preserves soil organic matter and stores carbon. Contour bunding and relay cropping are useful soil and water practices but do not directly sequester carbon.

Beyond natural sinks, engineers are building carbon capture and sequestration (CCS) technologies that pull carbon dioxide out of smokestacks or the open air and lock it away:

• Geological storage: injecting captured carbon dioxide into abandoned and uneconomic coal seams, depleted oil and gas reservoirs, deep saline formations, or old mines as carbonated water.
• Direct Air Capture (DAC): machines that strip carbon dioxide straight from ambient air. The captured gas can be sequestered, used in plastic production and food processing, or combined with hydrogen to make synthetic low-carbon aviation fuel.
• Enhanced rock weathering: spreading finely ground basalt rock on farmland, where it reacts with and absorbs carbon dioxide.
• Ocean alkalinity enhancement: adding lime to seawater so the ocean can absorb more carbon dioxide.

Treaties are only part of the global response. A web of initiatives, coalitions and tools now drives climate action, and the examiner loves to test who runs what.

Initiatives under the UN system include:

• REDD+ (Reducing Emissions from Deforestation and Forest Degradation): a UN programme that pays developing countries to protect forests. Well-designed REDD+ protects biodiversity, strengthens forest resilience and reduces rural poverty at the same time.
• Momentum for Change: Climate Neutral Now: an initiative of the UNFCCC Secretariat that promotes voluntary climate neutrality.
• Common Carbon Metric: a UNEP-supported standard for assessing the carbon footprint of building operations around the world.
• Climate and Clean Air Coalition (CCAC): a voluntary partnership open to all countries, not a G20 body. It targets short-lived climate pollutants: methane, black carbon and hydrofluorocarbons (HFCs).
• New York Declaration on Forests (2014): first endorsed at the UN Climate Summit, it sets a voluntary, non-binding timeline to end forest loss. Governments, big companies and indigenous communities endorsed it. India was not among the original signatories.
• COP28 Declaration on Climate and Health: a non-binding pledge to decarbonise the health sector. India refrained from signing it, fearing that decarbonising the health sector could compromise the resilience of its health-care system.

The European Union runs its own climate architecture. The Global Climate Change Alliance is an EU initiative giving technical and financial support to developing countries so they can build climate change into their development policies and budgets. The Nature Restoration Law is an EU law with binding targets to restore degraded ecosystems. The Net-Zero Industry Act, approved by the European Parliament, boosts clean-technology manufacturing within the EU. The EU's carbon-neutrality target year is 2050, not 2040.

Non-government bodies supply the data and networks:

• Climate Action Tracker: a database created by a coalition of research organisations that monitors countries' emission-reduction pledges.
• The Climate Group: an international non-profit that builds large business and government networks. It launched EP100, which gathers companies, including Indian firms, committed to energy efficiency, and it serves as secretariat of the Under2 Coalition of sub-national governments.
• Greenhouse Gas Protocol: an international accounting tool, developed by the World Resources Institute and the World Business Council for Sustainable Development, that helps governments and businesses quantify and manage their emissions.
• Greendex: an annual survey by the National Geographic Society and GlobeScan measuring environmentally sustainable consumer behaviour across countries. India topped the 2009 score.

Climate action costs money, and developing countries cannot bear the burden alone. A set of dedicated funds channels finance from rich nations and multilateral banks to climate projects:

• Green Climate Fund (GCF): established under the UNFCCC to assist developing countries with both adaptation and mitigation. It was not founded by UNEP, the OECD or the development banks.
• Global Environment Facility (GEF): serves as the financial mechanism for several environmental treaties, including the Convention on Biological Diversity and the UNFCCC. It funds projects; it does not conduct scientific research itself.
• Forest Carbon Partnership Facility: a global partnership of governments, businesses, civil society and indigenous peoples. It gives countries financial and technical help for their REDD+ efforts. It does not fund university research.
• BioCarbon Fund Initiative for Sustainable Forest Landscapes: a fund managed by the World Bank to promote low-emission land use and forestry.
• Nature Solutions Finance Hub for Asia and the Pacific: launched by the Asian Development Bank (ADB) to mobilise money for nature-based solutions in the region.

The exam trap in this area is attribution. Match each fund to its parent: GCF to the UNFCCC, GEF to the conventions it finances, the BioCarbon Fund to the World Bank, and the Nature Solutions Finance Hub to the ADB.