Sourced from the BBC
With many countries struggling to cut their carbon, new data suggests that major cities are making substantial strides to stem their emissions.
Twenty-seven cities, including Warsaw, Barcelona and Sydney, saw CO2 peak in 2012 and then go into decline.
As well as moving to green energy, the cities have provided affordable alternatives to private cars.
Emissions declined by 2% every year on average, while their economies expanded by 3% annually.
The C40 Cities group is an umbrella organisation that co-ordinates the climate change activities of 96 major urban centres around the world.
Back in 2015, their research showed that if the planet was to keep to the lower, 1.5-degree-Celsius target agreed in the Paris climate pact, then major cities would have to peak their emissions of CO2 by 2020 at the latest.
This new analysis by the group shows that 27 of these cities saw their emissions peak by 2012 and then fall over a five-year period. Those emissions are now at least 10% lower than at their zenith.
The 27 who peaked and cut their carbon are: Barcelona, Basel, Berlin, Boston, Chicago, Copenhagen, Heidelberg, London, Los Angeles, Madrid, Melbourne, Milan, Montréal, New Orleans, New York City, Oslo, Paris, Philadelphia, Portland, Rome, San Francisco, Stockholm, Sydney, Toronto, Vancouver, Warsaw, Washington DC.
According to C40, the cities have cut carbon while their economies and populations have grown.
The key steps taken include decarbonising the electricity systems, optimising energy use in buildings, providing cleaner and affordable alternatives to cars, and cutting waste while increasing recycling.