Youth activists walked out of the UN climate talks in Madrid in protest on Friday evening as negotiations went into overtime, with countries locked in arguments over the creation of a global carbon offset trading mechanism. Holding signs that read, “Bad politicians ruin the planet”, about 100 young people who had been attending the talks marched from the building and formed a roadblock in front of the conference centre. The move came as the 197 countries that signed up to the 2015 Paris climate accord appeared to be deadlocked, with no resolution in sight as the annual climate negotiations that were due to end on Friday stretched into the weekend.

One of the sticking points has been what to do with leftover carbon credits that were created under the 1997 Kyoto protocol, as negotiators try to agree the framework for a new global carbon trading market that would allow countries to exchange credits for emissions reductions. Laurence Tubiana, an architect of the 2015 Paris climate accord, pointed to the US, Brazil and Australia as the biggest obstacles to reaching a productive conclusion for this year’s talks.

Brazil and Australia are seeking to hold on to old carbon credits that were generated under the Kyoto protocol and carry these forward into the new regime.

Meanwhile, the US is preparing to withdraw altogether from the Paris pact, and will formally pull out completely in November 2020.  “What we’re feeling is the dissonance between what’s happening outside in the street … and how this process [the climate talks] can incorporate that,” said Ms Tubiana.

She added that it was essential to get the new system for carbon credits right – singling out Australia as a particular laggard, as it seeks to apply past credits to its future emission performance.