Contemporary Environmental Issues I: Biodiversity Loss, Climate Change, Ozone Depletion and Sea-Level Rise, International Efforts, the National Action Plan on Climate Change and Its Eight Missions, Adaptation, Energy and Food Security, and Carbon Sequestration and Carbon Credits

About 90% of the atmosphere's ozone lies in the stratosphere, where it absorbs ultraviolet-B radiation; a typical total column is about 300 Dobson units. Molina and Rowland warned in 1974 that chlorine from chlorofluorocarbons could destroy it catalytically, and in 1985 the British Antarctic Survey (Farman, Gardiner and Shanklin) reported the springtime Antarctic ozone hole, conventionally the area where the total column falls below 220 Dobson units. The hole forms each September and October because polar stratospheric clouds in the extreme cold of the polar vortex convert chlorine reservoirs into active forms, which destroy ozone as sunlight returns. Thinner ozone raises surface UV-B, increasing skin cancer and cataracts, suppressing immunity and harming phytoplankton and crops. Crutzen, Molina and Rowland shared the 1995 Nobel Prize in Chemistry for this work.

The Vienna Convention (1985) and the Montreal Protocol (1987), with its amendments, have phased out the production of almost all ozone-depleting substances. The 2022 WMO–UNEP Scientific Assessment of Ozone Depletion projected that, if current policies continue, the ozone layer will return to its 1980 values around 2066 over the Antarctic, around 2045 over the Arctic and around 2040 elsewhere. Because many ozone-depleting substances and their replacements are also greenhouse gases, the Protocol has been an effective climate treaty too, and its Kigali Amendment (2016) now phases down hydrofluorocarbons.

Sea level is rising because ocean water expands as it warms and because melting glaciers and ice sheets add water to the ocean. The Sixth Assessment Report found that global mean sea level rose by about 0.20 m between 1901 and 2018, and that the rate has accelerated, from about 1.3 mm a year in 1901–1971 to 1.9 mm in 1971–2006 and 3.7 mm in 2006–2018. Of the rise in 1971–2018, thermal expansion explained about 50%, glaciers about 22%, ice sheets about 20% and changes in land-water storage about 8%. It projected a further likely rise by 2100, relative to 1995–2014, of about 0.28–0.55 m under a very low emissions scenario and 0.63–1.01 m under a very high one, with more possible if ice sheets become unstable, and rise continues for centuries after emissions stop.

The consequences are coastal erosion, more frequent flooding from storm surges and high tides, saltwater intrusion into aquifers and farmland, loss of wetlands and mangroves where they cannot migrate inland, and, for low-lying small island states such as the Maldives and Tuvalu, a threat to their existence. In India the densely populated deltas, the Sundarbans above all, and low coastal cities are most exposed.

International efforts for environmental protection, taught with their dates in Unit VIII, run from the Stockholm Conference (1972) through the Montreal Protocol, the Rio Earth Summit (1992) with its conventions on climate, biodiversity and desertification, the Kyoto Protocol and the Paris Agreement (2015), to chemical treaties such as the Basel, Rotterdam, Stockholm (persistent organic pollutants, 2001) and Minamata (mercury, 2013) Conventions, and the agreement on marine biodiversity of areas beyond national jurisdiction adopted in 2023. Under the Paris Agreement each country sets its own nationally determined contribution; India's updated contribution of 2022 commits it to reducing the emissions intensity of its GDP by 45% from the 2005 level by 2030, to about 50% of installed electric power capacity from non-fossil sources by 2030 and to an additional carbon sink of 2.5 to 3 billion tonnes of CO₂e through forest and tree cover by 2030, and India has pledged net-zero emissions by 2070.

India's National Action Plan on Climate Change (NAPCC) was released on 30 June 2008 by the Prime Minister's Council on Climate Change. It rests on the principle that India's development and the eradication of poverty come first, and that climate action should deliver co-benefits for development; it organises action through eight national missions, and the states were later asked to prepare State Action Plans on Climate Change in line with it.

Mitigation reduces the causes of climate change, by cutting emissions or enhancing sinks; adaptation adjusts natural and human systems to actual or expected climate and its effects, to reduce harm or exploit opportunities. The IPCC describes risk as arising from the interaction of hazard, exposure and vulnerability, and vulnerability as depending on sensitivity and adaptive capacity. Adaptation in India includes heat action plans, the first in South Asia being Ahmedabad's in 2013; drought- and flood-tolerant crop varieties and the Indian Council of Agricultural Research's National Innovations in Climate Resilient Agriculture (2011); crop insurance; early warning of cyclones, which has sharply reduced cyclone deaths; mangrove restoration and coastal defences; and water harvesting. Adaptation has limits, and poorly designed measures can become maladaptation, such as sea walls that destroy the beaches they protect.

Energy security is commonly defined, following the International Energy Agency, as the uninterrupted availability of energy sources at an affordable price. India imports most of its crude oil, so price shocks and supply disruptions threaten its economy; it holds strategic petroleum reserves in underground rock caverns at Visakhapatnam, Mangaluru and Padur. Climate policy and energy security largely point the same way: domestic renewable energy, efficiency, electric mobility and green hydrogen reduce import dependence as well as emissions, although they create new dependencies, on critical minerals such as lithium and on grid flexibility to manage variable power, and climate change itself threatens energy supply through heat stress on thermal plants, cooling-water shortages and variable hydropower.

Food security, as defined at the World Food Summit of 1996, exists when all people, at all times, have physical and economic access to sufficient, safe and nutritious food that meets their dietary needs and food preferences for an active and healthy life; its four pillars are availability, access, utilisation and stability. Climate change threatens all four: terminal heat stress lowers wheat yields, erratic monsoon rainfall and droughts cut rain-fed output, pests and diseases spread, and extreme events disrupt supply. Rising carbon dioxide raises the photosynthesis of C₃ crops such as wheat and rice more than of C₄ crops such as maize, but it also lowers the protein, zinc and iron content of grain. India's National Food Security Act, 2013 entitles up to 75% of the rural and 50% of the urban population to subsidised grain. Sustainability demands that responses do not trade one goal against another, for example biofuel crops that compete with food, or groundwater-intensive irrigation that deepens water insecurity.

Carbon sequestration is the long-term removal of carbon dioxide from the atmosphere and its storage in another reservoir. Biological sequestration stores carbon in the biomass and soils of forests, grasslands and farmland, through afforestation, agroforestry, reduced tillage and biochar, and in "blue carbon" ecosystems, mangroves, salt marshes and seagrass beds, which bury carbon in waterlogged sediments. Geological sequestration, part of carbon capture and storage (CCS), captures carbon dioxide from power plants or industry, compresses it and injects it into deep saline aquifers, depleted oil and gas fields or unmineable coal seams, sometimes for enhanced oil recovery. Other approaches include bioenergy with CCS, direct air capture, enhanced weathering of silicate rocks, and ocean fertilisation, which is controversial. Biological stores are cheap but can be reversed by fire, felling or drought, a problem of permanence.

A carbon credit is a tradable certificate representing the reduction or removal of one tonne of carbon dioxide equivalent. The Kyoto Protocol created three market mechanisms, international emissions trading, joint implementation and the Clean Development Mechanism, whose certified emission reductions came largely from projects in India and China. The Paris Agreement's Article 6 provides for cooperation through internationally transferred mitigation outcomes and a new crediting mechanism under the UNFCCC. Voluntary markets, run by independent standards, serve companies offsetting emissions. Credits are only as good as their integrity: a reduction must be additional (it would not have happened anyway), measurable, verified, permanent and not counted twice, and must not simply shift emissions elsewhere, which is leakage. REDD+ rewards developing countries for reducing emissions from deforestation and forest degradation and for conservation and enhancement of forest carbon stocks.

India notified its Carbon Credit Trading Scheme in 2023 under the Energy Conservation Act, 2001 as amended in 2022, with the Bureau of Energy Efficiency as administrator, creating a domestic compliance market in which obligated entities meet emission-intensity targets and trade carbon credit certificates, alongside a voluntary offset mechanism. The separate Green Credit Programme, notified in 2023 under the Environment (Protection) Act, rewards voluntary environmental actions such as tree plantation. A worked conversion: carbon is reported either as carbon or as carbon dioxide, and since the molar masses are 12 and 44, one tonne of carbon corresponds to 44 ÷ 12 ≈ 3.67 tonnes of CO₂. A plantation of 10 ha fixing a net 3 tonnes of carbon per hectare per year therefore removes 30 × 44 ÷ 12 = 110 tonnes of CO₂ a year, worth 110 credits if it meets the integrity tests.