Net zero

Background and evolution

Climate science shows that global temperature rise is roughly proportional to the total amount of carbon dioxide emitted over time. Warming will only stop when net CO2 emissions fall to zero. The IPCC Special Report on Global Warming of 1.5°C (2018) found that limiting warming to 1.5°C requires global net CO2 emissions to reach zero around 2050, and to about 2070 for 2°C.

Following that report, many countries and corporations announced net-zero targets. Unlike older targets expressed as percentage cuts from a base year, net zero is an end point. India, at COP26 in Glasgow, announced a five-part "Panchamrit" commitment, with net zero by 2070 as its long-term goal, while arguing that developed countries should reach net zero well before 2050 because of their historical responsibility.

Key features and provisions

• Gross emission cuts: the bulk of the work, via clean electricity, electrification of transport and heating, efficiency, and cleaner industry.
• Residual emissions: some, from cement, steel, aviation or agriculture, are hard to eliminate.
• Removals: natural sinks (forests, mangroves, soils) and technologies (direct air capture, bioenergy with carbon capture).
• Offsets: buying credits from projects elsewhere; their quality and permanence are often debated.
• Scope of gases: some targets cover only CO2; others all greenhouse gases.
• Interim targets: credible plans have milestones for 2030 and 2040.