Fast-depleting global carbon budget
The global carbon budget, translated into a quantifiable cap on the release of CO2 emissions to the atmosphere has emerged as a thorny climate policy discourse bristling with perplexities. IPCC, The Intergovernmental Panel on Climate Change, estimates that to have a 66 per cent chance of limiting global warming to 1.5 degrees Celsius, we can emit no more than 250–300 gigatons of CO₂. Scientific assessments demonstrate that at current emission levels, the remaining carbon budget will likely be exhausted in the next five years, i.e. by 2030, raising the alarm bell for the countries to accelerate their decarbonisation efforts. However, it is worrisome to see that despite a fast-depleting carbon space, the global climate policy actions by countries presented through NDCs collectively fall far short of the global targets. Scientific studies on climate change indicate that close to 50 per cent of total carbon dioxide emissions are removed by natural carbon sinks such as plants and oceans. However, the threat emanates from the gradual declining efficiency of these natural sinks to absorb the CO2 emissions from the atmosphere. There are reinforcing effects of having a high quantity of carbon dioxide in the atmosphere and consequent high negative impacts on the sinking ability of nature and conversely.
Gap in the legal backing to the global carbon budget
While ‘carbon budget’ as a scientific concept has received global recognition, it has not really translated into globally actionable legal binding targets so far either in the form of an agreement or treaty. Though, the nationally determined contributions (NDCs) declared under the Paris Agreement and the five‑year Global Stock Taking (GST) exercises hint at collective limits on the temperature rise thereby indicating an indirect cap on the carbon budget. However, neither of the global climate goals has provisions for allocating an enforceable budget scheme. Nevertheless, there are some patchy and sporadic efforts undertaken at some individual country level in this direction. For instance, countries like the UK and Ireland have already integrated it into national climate Action plans. The UK’s Climate Change Act necessitates the Government of UK to set a carbon budget and makes it a legally binding policy goal with a five-year limit on greenhouse gas emissions. Similar targets are also set for Ireland.
While the magnitude of the global carbon budget is built on the scientific consensus on its assessment and evaluation, the challenge lies in the mechanism and rationale of allocating the available budget across countries. While various allocation approaches are debated worldwide such as allocation based on historical emissions, egalitarian principles, national sovereignty, and allocation based on capabilities, however, none of them has received any common consensus and are mostly limited within scholarly circles. In this context, developing countries strongly assert whether the principle of ‘common but differentiated responsibilities’ be unleashed as an approach for carbon budget allocation where all countries share the obligation to tackle climate change; however, those who emitted more in the past and have more resources should shoulder a greater share of the burden.
Global carbon budget and implications for India
For a country like India, which is home to the world’s largest population and a rapidly growing economy, equity in the allocation of the remaining global carbon budget is not just desirable, it becomes imperative. With per capita emissions significantly lower than developed nations, India must be afforded the developmental space to peak responsibly without being unfairly constrained by a budget already consumed disproportionately by the industrialised world. The United States has emitted around 400 billion tonnes of CO₂ since the Industrial Revolution, accounting for about 25 per cent of all historical emissions. The European Union (EU) is not far behind, contributing roughly 22 per cent of cumulative emissions. China, which industrialised later but on a massive scale, is the largest emitter today, yet its cumulative share since the 1800s is about 11 per cent, roughly half that of the U.S. In contrast, India’s cumulative contribution is only on the order of 3–4 per cent of global emissions. In other words, India accounts for approximately four per cent of global CO₂ emissions, yet it hosts over 17 per cent of the global population. Even looking at current emissions on a per-person basis, the gap is striking. The average Indian emits approximately two metric tonnes per person per year, compared to the United States at over 14–15 tonnes, China nearly eight tonnes, and the EU at around 6–7 tonnes per year. In fact, the global average is about 4.8 tonnes per person, which means Indians emit less than half the world. Another way to put it: an average Indian emits in an entire year what an average American might emit in about six weeks.
India must push for a more equitable carbon budget allocation framework, grounded in:
Per capita emissions equity: Recognising current and cumulative emissions on a per-person basis.
Developmental needs: Accounting for access to energy, industrialisation needs, and poverty levels.
Population weighting: Reflecting demographic realities in budget distribution models.
Historical responsibility: Allocating less budget to nations that have already emitted far beyond their fair share.
This argument should not be seen as obstructionist in the global climate policy orders. On the contrary, India is already leading on several climate fronts, from the creation of the International Solar Alliance (ISA) to the acceleration of green hydrogen policy and development and afforestation drives. But to maintain credibility and traction, the global system must create room for just growth, not just net-zero targets.
The global carbon budget is not just a scientific threshold; it is a geopolitical battleground. For India, the stakes are existential. The nation needs time, space, technology, and trust to fulfil its development potential without breaching planetary boundaries. That means developed nations must decarbonise deeper and faster, freeing up space for emerging economies to climb the development ladder sustainably.
The writers are respectively research scholar, Department of Policy and Management Studies (DoPMS), TERI School of Advanced Studies, New Delhi and associate professor and head, TERI School of Advanced Studies, New Delhi