One third of the world’s remaining safe carbon budget could be determined by urban policy decisions in the next five years.

The C40 Cities Climate Leadership Group (C40) announced a new report today, which demonstrates that urban policy decisions before 2020 could determine up to a third of the remaining global carbon budget that is not already ‘locked-in’ by past decisions.

Existing research has shown that investing in low carbon infrastructure in the next five years will be four times less expensive than building high carbon infrastructure now, and then having to replace it in the future. Mayors and local leaders in power today thus have a major role to play in determining whether or not we have a cost-effective and, therefore, realistic path to a climate safe world.

“This report provides hope for the future because it shows that we don’t just have to rely on the outcome of the critical COP21 Treaty negotiations, but that mayors and city leaders in office right now have the opportunity to protect a large share of the world’s carbon budget,” said C40 Chair and Rio de Janeiro Mayor Eduardo Paes. “The report calculates that moving from a business as usual scenario to low carbon urban development across all the world’s cities would save 45 Gt CO2 by 2030 – equivalent to eight times the current emissions of the United States.”

Scientists have previously calculated that we can emit a ‘carbon budget’ of just 1,000 Gt C02 without creating an unacceptable risk of run-away climate change, and that much of this budget may be locked-in by investments such as fossil fuel power stations, highways and energy-hungry buildings that have already been made.

Previous research has suggested that decisions about the remaining infrastructure will be taken in the next five years, by 2020. Fortunately, new analysis shows that a third of the decisions will be made in cities, meaning local leaders in office right now, many of whom have already demonstrated leadership on climate change, can grasp the opportunity to move on to a low-carbon path.

To read the press release, click here

A full technical paper by C40 and the Stockholm Environment Institute (SEI) was also published today: "Keeping cities green: Avoiding carbon lock-in due to urban development". To read the technical paper, click here.