More than 2,500 cities worldwide have formally issued plans to cut carbon emissions since late 2014, as Reuters reported. And many of these local targets are more ambitious than those set by governments under the global climate accord signed in Paris in December 2015.

This is leading to tensions with national governments about who controls policy over green energy, transportation or air pollution, according to the article. In Oslo, for example, municipal authorities are pushing to more than halve the city’s greenhouse gas emissions within four years. The ambitious plan includes car-free zones, fossil-fuel-free building sites and higher road tolls.

But the deputy mayor is now accusing the Norwegian government of delaying Oslo’s plans for new road tolls on diesel cars during rush hour after it called for a national computer system for environmental road tolls – even though Oslo is the only city that wants one.

On the other side of the globe, Sydney is at odds with the Australian government over its plans to generate more electricity locally without paying high charges for using the national grid. According to the city’s mayor, the city generates energy through its solar initiatives but has to pay “the same charges as a remote coal or gas station that exports its power hundreds of kilometres”. Canberra has dismissed these concerns, saying that local generation network credits would be too costly to implement, explains Reuters.

According to a 2016 study, climate plans by cities and regions could cut an extra 500 million tonnes of annual greenhouse gas emissions by 2030 beyond cuts pledged by governments. “The benefits are very local in cities,” explained Niklas Höhne at the NewClimate Institute think tank in Germany.