Delegates at the annual United Nations climate conference were unable to reach a consensus on setting more ambitious targets to tackle climate change even after over two weeks of negotiations. United Nations Secretary General António Guterres called the outcome of the Madrid conference “disappointing”.

India, China and the United States were accused of pushing back on stronger language calling on countries to enhance their climate-action targets, according to The New York Times. The final resolution requires countries to put forward new climate pledges within a year, while richer countries will also have to show that they have achieved the targets they set for 2020.

The 25th edition of Conference of Parties, or COP25, was scheduled to end on Friday, but was extended for two days in the hope that delegates would reach an agreement.

The primary goal of the climate talks was to finalise the rules of operation for international cooperation on mitigating climate change through the instrument of carbon markets, a mechanism that would allow countries to trade emission reductions. This was not resolved and the discussion was postponed to COP26, to be held in December 2020 in Glasgow.

The final declaration merely called for fresh proposals for emission reductions by countries to be submitted by the time they meet next at the COP26.

Guterres tweeted: “The international community lost an important opportunity to show increased ambition on mitigation, adaptation and finance to tackle the climate crisis. But we must not give up, and I will not give up.”

The plans for a global carbon marketplace were first laid out under Article 6 of the Paris Agreement, a landmark deal aimed at strengthening global response to climate change, signed by 197 countries, which came into force in 2016. The Paris Agreement aims to limit the global temperature rise in this century to less than 2 degrees Celsius above pre-industrial levels. Article 6 is the last remaining portion of the Paris Agreement that needs to be negotiated. The article covers the issue of carbon marketplaces, which are currently regulated under the Kyoto Protocol, which ends in 2020.

The Kyoto Protocol of 1997 set internationally binding emission reduction targets. Under this, countries accumulated carbon credits for projects that led to emission reductions. China, Brazil and India accumulated a significant quantity of these. It was expected that developed countries that had committed to emissions cuts would buy these carbon credits, but the market for them crashed. As much as 85% of India’s credits remain unsold.

One of the debates at COP25 was over whether the carbon credits from under the Kyoto Protocol would carry forward into the carbon marketplace under the Paris Agreement. Developed countries argued for doing away with the previous credits and starting from scratch, while developing countries oppose this because the credits they acquired under the Kyoto Protocol would then become worthless.