Study suggests that global warming can be kept to 1.5°C, but only if 17 of the biggest emitters step up

A recent study offers a glimmer of hope for meeting the Paris Agreement goal of limiting global warming to 1.5 degrees celsius. But there’s a catch: major emitters, including the European Union, the United States, and China, need to go beyond their current carbon reduction commitments. According to researchers from Stockholm University and other institutions, these nations have a huge role to play in avoiding the worst effects of climate change.

The researchers propose a new metric called "additional carbon accountability" to measure just how much extra each country should contribute toward cutting or offsetting emissions. It doesn’t just look at emissions within a country’s borders but also considers how much it finances carbon reduction or removal outside its territory.

Thomas Hahn, lead author from Stockholm University, explained the study’s aim: "The ambition of this article is to suggest opportunities to enhance climate fairness and close the mitigation gap in the real world, based on the Paris Agreement."

Who bears the biggest responsibility?

The study found that some of the world’s wealthiest and most industrialized nations are the ones with the highest per capita "additional carbon accountability." At the top of this list are the United Arab Emirates, Russia, Saudi Arabia, and the United States, meaning these nations bear a larger share of responsibility to help keep global warming within 1.5°C above pre-industrial levels.

The researchers also noted that high-income countries generally have "large carbon debts." This means they’ve historically emitted a lot and therefore should contribute more to climate solutions. Upper-middle-income countries, like China and Iran, also have high projected emissions and need to tighten their targets for future reductions.

How "additional carbon accountability" is calculated

The researchers arrived at these figures by analysing each country’s share of the remaining 1.5°C carbon budget, taking into account per capita emissions since 1990. Then they looked at each country’s current "carbon debt" — essentially the difference between their overall carbon footprint and their efforts to reduce it—and combined this with their future emissions targets. The result? An "additional carbon accountability" number that shows how much each country needs to do beyond its existing commitments.

The European Union, for example, has already pledged to reach a 2030 emissions reduction target and net-zero by 2050. But to align with the 1.5°C goal, the study suggests it would need to remove an additional 48 gigatonnes of CO₂ or finance similar reductions beyond current targets in other countries. China’s additional accountability is 150 gigatonnes, while for the US, it’s 167 gigatonnes.

Moving beyond fossil fuels

One clear takeaway from the study is that transitioning away from fossil fuels is crucial to staying within the global carbon budget. By shifting to cleaner energy sources, these high-emitting nations can significantly lower their carbon debt and stay within the limits necessary to prevent dangerous climate impacts.

The study authors stress that wealthy, historic emitters like the EU and the US should prioritise paying down their carbon debts. As co-author Robert Hoglund of Marginal Carbon AB in Sweden put it, "Our results highlight that meeting the 1.5 degrees Celsius target to a large extent is reliant on large historic emitters like the EU and the US paying off their historic carbon debts, and countries with plans for future large emissions, like China and Iran, setting stricter reduction targets."

(With inputs from agencies)