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New Research Shows Cities Have The Potential To Reduce Annual Greenhouse Gas Emissions By 8 Gigatons By 2050 Over Current National Targets

Impact of Climate Efforts by All Cities Would Be Equivalent of Cutting World’s Annual Coal Use by More Than Half

Taking Cities’ Potential into Consideration Would Help Nations Set Far More Aggressive Targets to Fight Climate Change Than They Have Thus Far

UN Special Envoy for Cities and Climate Change Michael R. Bloomberg and C40 Cities Climate Leadership Group (C40) Chair and Rio de Janeiro Mayor Eduardo Paes today announced new research that shows that if all cities took on aggressive new efforts to reduce building, transportation and waste energy use, they could potentially reduce annual greenhouse gas (GHG) emissions by an additional 3.7 Gigatons (Gt) CO2e by 2030 over what national policies and actions are currently on track to achieve. By 2050, cities could cut annual GHG emissions by 8.0 Gt CO2e over what national policies are currently on track to achieve, the equivalent of cutting annual global coal use by more than half. Cumulatively, cities have the potential to reduce emissions by more than 140 Gt CO2e by 2050.

Special Envoy Bloomberg’s Report to the Secretary-General, which includes this new research in partnership with C40 and the Stockholm Environment Institute, underscores the importance of including cities’ climate efforts as nations set GHG reduction targets to prevent the world’s temperature from rising more than 2 degrees Celsius above pre-industrial levels, as part of the United Nations’ climate negotiations in 2015.

This also marks the first time all cities’ collective potential to reduce global GHGs has been quantified. The findings show that when city governments implement policies to reduce emissions from sectors they can control – namely, transportation, buildings and waste – their impact is significant. Cities, therefore, can help their nations achieve higher GHG targets and bridge the gap between current national commitments and those needed to prevent the global temperature rise, as nations agreed under the UN’s 2010 Cancun Agreement.

“Cities are key players in the global fight against climate change – and this research measures, for the first time, the huge difference they can make together,” Special Envoy Bloomberg said. “Despite the progress they are making, and their potential to do much more, cities are rarely included in national climate plans. This research can help change that – and encourage nations to set higher goals for reducing emissions – by showing how much their cities can contribute.”

Because mayors hold the executive powers to influence the local policies that most impact urban energy use and associated GHG emissions – like building energy standards, urban planning and public transit – cities are positioned to make major contributions towards more aggressive national and international targets to fight climate change.

According to the research, in order to realize this potential, the worlds’ cities must take new, even more aggressive actions. The research identifies the sectors and actions where mayors have the greatest control and which offer the most significant opportunities for urban GHG reductions.  They are the following:

  • Building energy efficiency standards for new urban buildings;
  • Building energy retrofits for existing urban buildings;
  • Aggressive energy performance standards for urban building lighting and appliances; and
  • Transportation mode shifts and transit efficiency for city residents

“From Rio to Seoul, mayors are not waiting to take decisive action to combat global climate change and prepare for the ill effects it will bring,” said Mayor Eduardo Paes. “We are forging ahead with innovative solutions that make our cities better, safer places to live and work. Leading mayors are setting the example for the rest of the world, and this new research shows what could be achieved if all cities and our national governments now followed suit. ”

This report was released today at the United Nations’ Climate Summit in New York City to drive home the major role cities are already playing in reducing global greenhouse gas emissions.  In conjunction with this research, the UN Secretary-General Ban Ki-moon, Special Envoy Bloomberg, and the world’s preeminent city networks – C40, ICLEI – Local Governments for Sustainability (ICLEI) and the United Council of Local Governments (UCLG) – launched a global Compact of Mayors.

The Compact is the world’s largest effort to drive more aggressive city climate actions and reaffirm existing targets, through public, annual reporting of cities’ GHG data. Under the Compact, cities will use a newly-standardized measurement system that is similar to the format used by nations under the UN’s 1997 Kyoto Protocol. Through this, cities will voluntarily meet the same requirements proposed for the international climate negotiations.

Other city-based initiatives launched at the Summit today included two new initiatives from national governments and the private sector to help cities finance investments in sustainability – the City Climate Finance Leadership Alliance and the City Creditworthiness Partnership.

About the Special Envoy
Michael R. Bloomberg is an entrepreneur and philanthropist who served three terms as Mayor of New York City, from 2002 through 2013.  In 2014, U.N. Secretary-General Ban Ki-moon appointed Bloomberg to be Special Envoy for Cities and Climate Change, where he is focusing on helping cities and countries set and achieve more ambitious goals for mitigating and adapting to climate change.  To learn more about the Special Envoy’s work, please visit:

About C40 Cities Climate Leadership Group (C40)
The C40 Cities Climate Leadership Group (C40) is a network of large and engaged cities from around the world committed to implementing meaningful and sustainable climate-related actions locally that will help address climate change globally. C40 was established in 2005 and expanded via a partnership in 2006 with President William J. Clinton’s Climate Initiative. The current chair of the C40 is Rio de Janeiro Mayor Eduardo Paes; the 108th Mayor of New York City Michael R. Bloomberg serves as President of the Board. To learn more about the work of C40 and our Cities, please visit, follow us on Twitter @c40cities and like us on Facebook at

Bloomberg Philanthropies, Benita Hussain, +1 212 205 0318,

C40 Cities Climate Leadership Group, Marie Scott Poulsen, +44 (0) 7476390339,