In the United States, 14 of the 25 largest cities have committed themselves to achieving greenhouse gas reduction targets. This study shows that, as a group, the 25 largest US cities are more ambitious than the US national reduction target. If the 11 cities without reduction targets implement measures consistent with the NDC target, the additional reductions would add up to 30 MtCO2e, and only to 5 MtCO2e, if they do not.
What can we expect from the US cities without greenhouse gas commitments?
Around 190 countries submitted national reduction targets in the run up to the 2015 UNFCCC climate negotiations in Paris. However, not only countries are pledging greenhouse gas reduction targets, many cities have done so, as well. In the United States, the 25 largest cities, 14 of which have actually committed themselves to a certain reduction target, combined, could deliver between 95 and 125 MtCO2eq in greenhouse gas emission reductions by 2030, compared to a business-as-usual scenario.
But will the group of 25 cities deliver greenhouse gas reductions that go beyond the US nationally determined contributions (NDCs)? This analysis shows that the combined reduction target of these 25 cities is more ambitious than the US NDC target. The projected level depends not only on the ambitions of the 14 cities with emission reduction commitments — and whether they will actually deliver on their promise — but also on the expected measures taken by the 11 other cities without reduction commitments. If the 14 cities deliver on their promise, and the 11 cities implement measures consistent with the NDC target, the additional reductions to the NDC will be 30 MtCO2e. This number would decrease to 5 MtCO2e, if the 11 cities take a business-as-usual approach.
One important lesson from this study is that, to show the additionality of city reductions to the NDC target on a national level, all cities need to be taken into account, not only those with commitments. This would also hold for assessments of all sub-national and non-state actors (companies, civil society), while also paying attention to any overlap.