Open Letter on the Summary Report for Urban Policymakers: What the IPCC Special Report on Global Warming of 1.5° Means for Cities

Open Letter on the Summary Report for Urban Policymakers: What the IPCC Special Report on Global Warming of 1.5° Means for Cities

Photo credits: @c40cities.

Dear Colleagues:

We are a group of sustainability-focused city-networks, associations and NGOs and international organisations working in and on cities worldwide. We want to draw your attention to a summary produced for urban policymakers, which condenses the latest science published by the Intergovernmental Panel on Climate Change (IPCC) on limiting global warming to 1.5°C.

A New Summary for Urban Policymakers

The Summary for Urban Policymakers is a comprehensive summary for all those working on urban issues that makes it clear that the only pathways that cities and regions should aim for is to constrain global warming to 1.5°C rather than 2°C.

We are standing at a crossroads in 2018. We are not on track to limit warming; in fact, current nationally determined contributions under the Paris Agreement will lead to warming of between 2.9 and 3.4°C by the end of the century. This will have huge implications on water and food security, living standards and human health and will have grave implications for our generation, and all generations to come

The science is clear – to stand a good chance of achieving 1.5°C, we must reduce our global CO2 emissions to zero within the next two decades. We must also dramatically reduce other pollutants, such as methane and black carbon. The gravity of the situation cannot be underestimated; each year we fail to get started on these emissions reductions, the window to reach zero emissions on a 1.5°C pathway is reduced by two years. At the same time, we must rapidly invest in helping our citizens, businesses and infrastructure to thrive in a changing climate.

What Can You Do?

We need to pursue aggressive strategies to limit warming to 1.5°C, while preparing our towns, cities and regions for warming of 2°C or more.

There are six areas where city, state and regional governments can focus to unlock a 1.5°C safer future. These are: urban energy systems, buildings, transport and urban planning, green infrastructure, sustainable land use and water management. Action in these areas will bring considerable co-benefits including improved public health and reduced air pollution.

All departments and levels of government must work in an integrated way to enable the urban transition required. No one actor can do this alone. This is particularly true when it comes to energy grid decarbonization and the availability of finance, where national governments have an especially important role to play.

We call upon higher emitting cities, states and regions to focus on rapid and far-reaching decarbonization and the protection of infrastructure and economic assets from predicted climatic changes.

We call on lower emitting cities, states and regions to recognize the human risks posed by climate change and to put in place strategies to improve climate resilience and limit future growth in emissions.

Why Act Now?

According to the latest science, we have less than a decade to peak our emissions. This means a complete transformation of all human systems on earth. Without this, achieving the Sustainable Development Goals and maintaining the development progress we have made to date will become increasingly difficult.

To continue to deliver development and quality of life for your citizens, responding to climate change will need to be integrated into everything you do. Every strategy, policy, project and financing mechanism will need to be 1.5°C compatible. We stand by you and offer our support to aid you in the transition to a low-carbon, climate resilient world.


Cities Alliance
Climate Alliance
C40 Cities Climate Leadership Group
Global Covenant of Mayors for Climate & Energy
United Cities & Local Governments (UCLG)
WRI Ross Center for Sustainable Cities
WWF One Planet City Challenge*
* WWFs One Planet City Challenge assesses cities’ against recommended emission reduction trajectories for 1.5°C, and guides them to big impact action

Supported by the following cities that advised the Summary for Urban Policymakers process:

Ajuntament de Barcelona (Spain) 
Buenos Aires Ciudad (Argentina) 
City of Melbourne (Australia)
Frederikshavn Municipality (Denmark) 
City of Seoul (South Korea)


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