Cutting what is hard to cut: hard to abate sectors, methane and carbon removal

Prelims and MainsCurrent affairs on this: Mitigation: industry, methane and carbon removal

Power can switch fuel, but steel, cement, aluminium and fertiliser emit carbon in the process itself: coke strips oxygen from iron ore, limestone gives up carbon dioxide when it is burnt to clinker, aluminium smelting eats electricity, and ammonia is made from natural gas. These are the hard to abate sectors, and their levers are hydrogen in place of coke, scrap in electric furnaces, substitutes for clinker, and capture of what cannot be avoided. Carbon capture takes the gas at the chimney and avoids an emission; carbon dioxide removal takes it out of the air, by trees, soil, biochar, bioenergy with capture, direct air capture or faster rock weathering, and every pathway to 1.5°C needs some of it. Methane is the fast lever: it warms about 80 times as much as carbon dioxide over twenty years and lasts about twelve, so cutting it cools within a decade.

• The sectors and their levers: steel, the blast furnace against the electric arc furnace and direct reduced iron with green hydrogen (the carbon lock in subject); cement, where about 60 per cent of emissions come from calcining limestone, answered by fly ash and slag in place of clinker; aluminium, where the answer is clean power; fertiliser, where green ammonia replaces gas. Shipping and aviation have their own regulators, the International Maritime Organization, with a net zero target around 2050, and the aviation offset scheme, the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA).
• Capture against removal: capture at a plant reduces an emission and is counted as mitigation; removal creates a negative emission and is counted against what has already been emitted. The methods in the figure differ in how long the carbon stays put, a tree for decades, biochar for centuries, a mineral for ever. India has a NITI Aayog framework for capture from 2022 and pilot projects, and no removal at scale.
• Methane: India's largest source is enteric fermentation in cattle and buffalo, then flooded paddy, landfills and leaks from oil and gas. The Global Methane Pledge of 2021 asks for a 30 per cent cut from 2020 levels by 2030; India has not joined, arguing that its methane comes from the livelihoods of small farmers and not from fossil fuel leaks, which is where the pledge's signatories can cut cheaply.
• Hydrofluorocarbons: the refrigerant gases that replaced ozone depleting ones warm thousands of times more than carbon dioxide. The Kigali Amendment of 2016 to the Montreal Protocol phases them down; India, which ratified in 2021, freezes in 2028 and cuts 85 per cent by 2047 against a 2024 to 2026 baseline, and the India Cooling Action Plan of 2019 is its route. This is the one climate treaty that runs under the ozone convention.
• Solar radiation modification, spraying aerosols into the stratosphere to reflect sunlight, would cool without removing any carbon, and has no governance; it is discussed as a risk, not a plan. Black carbon, soot from cookstoves, diesel and crop burning, warms by darkening snow and is cut by clean cooking rather than by climate policy.

Mains: India's mitigation problem is industrial, not electrical: power can switch to renewables, but steel and cement will double with the country's building, and the technologies that decarbonise them, green hydrogen and capture, are the costly ones, which is why India asks for finance and technology before it takes on absolute cuts.

See also: Steel: carbon lock in and the two routes · Methane from paddy · Biochar from crop residue · The colours of hydrogen · India's carbon market: the Carbon Credit Trading Scheme · Net zero 2070 and the National Action Plan on Climate Change · The four chemicals conventions, and India's noise limits