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30 cities say their greenhouse gas emissions have peaked

Austin, Athens, Lisbon and Venice are the latest major cities to have ‘peaked’ their greenhouse gas emissions, meaning they won’t rise any further and are now falling.


Scientists have calculated that global greenhouse gas emissions must peak by 2020 in order to limit global temperature rise to 1.5°C, in line with the Paris Agreement.


New analysis, published ahead of the C40 World Mayors Summit this week, finds that 30 of the world’s largest cities, representing more than 58 million citizens, have now reached this milestone.


The 30 cities are: Athens, Austin, Barcelona, Berlin, Boston, Chicago, Copenhagen, Heidelberg, Lisbon, London, Los Angeles, Madrid, Melbourne, Milan, Montréal, New Orleans, New York City, Oslo, Paris, Philadelphia, Portland, Rome, San Francisco, Stockholm, Sydney, Toronto, Vancouver, Venice, Warsaw and Washington, D.C.


Michael Doust, Programme Director, Measurement and Planning at C40, explained more about the methodology for calculating and tracking peak greenhouse gas emissions: "We [C40] do this calculation on behalf of C40 cities. Our definition of peaking is that a city must have reduced [its] greenhouse gas emissions over a five-year period or longer and achieved at least a 10 per cent reduction compared to its peak emissions.


“We require a minimum of three GHG emissions inventories, and the latest emissions inventory must not be older than five years. These criteria ensure that a peak has not been reversed and that it is indicative of a long-term trend (as opposed to being due to inter-annual variabilities).”


“The 30 cities that we are announcing as having peaked in fact reached peak emissions in 2014 or before but we can only now confirm this,” he added.





C40 is a network of the world’s megacities committed to collaborating to address climate change. C40 analysis shows that since reaching peak emissions levels, these 30 cities have reduced greenhouse gas emissions by an average of 22 per cent. Copenhagen, the host city for this year’s C40 World Mayors Summit, has reduced emissions by "up to 61 per cent".


Copenhagen has reduced emissions by up to 61 per cent since reaching peak emissions levels.


Examples of notable progress made by C40 cities over the last decade include:

  • 82 cities have implemented cycle hire schemes, compared to 13 in 2009
  • There are over 66,000 electric buses on the streets of C40 cities, compared to fewer than 100 in 2009
  • 24 cities have committed to achieving 100 per cent renewable electricity by 2030, compared to four in 2009
  • 18 cities have banned or restricted single-use, non-recyclable plastics, compared to two in 2009
  • 17 cities have restrictions on high-polluting vehicles that cover a significant part of the city, compared to three in 2009




”The C40 cities that have reached peak emissions are raising the bar for climate ambition, and at the same time exemplifying how climate action creates healthier, more equitable and resilient communities,” said Mark Watts, executive director of C40 Cities.


“But this is nothing to win medals for - emissions across the whole world need to stop rising and start falling within the next year if we are to keep global heating below 1.5 degrees.”


C40 also announced the launch of its C40 Knowledge Hub, an online platform bringing together insights, practical experiences and tested climate approaches from cities around the world.


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