The decision this week by European leaders to fast-track ratification of the Paris Agreement on Climate Change is historic.
It is now certain that less than one year will have passed from the beginning of the COP21 climate negotiations in December 2015 to the moment when the Paris Agreement will come into force.
These weeks and months are when the nations of the world stared over the precipice of catastrophic climate change and chose to act. By standards of international diplomacy, the ratification of the Paris Agreement has been remarkably swift.
Leaders of the many nations who have ratified the deal deserve our praise and gratitude.
From the biggest emitters, China, the United States and the European Union, to the smallest Island nations that are most at risk from the effects of climate change, each has recognized the scale of the threat we face and acted with commendable speed.
After 20 years of waiting for an inter-governmental agreement to tackle climate change it is fantastic that nation states are now moving so rapidly to bring it into international law.
There is no time to waste because the next years are crucial. Global greenhouse gas emissions must peak by 2020 and then fall rapidly.
The next step is for countries to put forward national emissions plans that are as ambitious as the aspiration of the Paris Agreement. Almost none are at present.
Fortunately, mayors of the world’s great cities have also been using the months since December 2015 to ramp up climate action.
This determination to act by mayors is consistent with more than a decade of international leadership on climate change before the Paris Agreement, through powerful networks like the C40 Cities and common platforms for declaring commitments like the Global Covenant of Mayors.
At the height of the COP21 climate negotiations, Paris City Hall hosted more than 1,000 mayors and city leaders at the Climate Summit for Local Leaders.
This local and global display of commitment by mayors was instrumental in showing national leaders negotiating to secure the Paris Agreement that they were far from alone.
Throughout 2016 cities have continued to deliver concretely ambitious climate action.
Last week, Paris confirmed the pedestrianisation of the right bank of the Seine, building on its world famous cycle hire scheme to further creating a city that prioritises sustainable transport.
This summer, Rio de Janeiro hosted the most ecological Olympic and Paralympic Games in modern history with new light railway lines, 150km of rapid bus lanes, and hundreds of kilometres of bike lanes that are creating a mass transit revolution in the city.
Mexico City is taking decisive action to create a clean and efficient transport network, through the growth of its Bus Rapid Transport as well as the subway systems, while creating cycling infrastructure.
This includes cycle lanes, bike parking and a public bike share system, all integrated to the city’s transport card.
One of reasons that city leaders have been particularly bold is because we work together. Through networks like C40 we are learning from each other in delivering, so that success gets copied quickly and replicated around the world.
The cost of innovation is reduced and we are all able to learn from inevitable mistakes.
Cities will prove it again during the C40 Mayors Summit 2016 in Mexico City from 30 November – 2 December 2 where the most world’s most influential mayors, representing 650 million citizens will work together and present their common goals for a sustainable future, one year after COP21 in Paris.
Cities are leading the way to make the Paris Agreement concrete for citizens, but as mayors, we cannot do it alone. We welcome the leadership of national leaders in committing to the Paris Agreement but now we call on Presidents and Prime Ministers of every nation to empower their cities.
C40’s research shows that one third of the remaining global ‘safe’ carbon budget could be locked-in by urban policy decisions taken just between now and 2020.
Supporting mayors to be able to take the most far-sighted decisions on, for example, land-use planning, transport infrastructure, and building codes, could be the single most efficient way for nations to kick-start their commitments under the Paris Agreement
For example, mayors of the world’s great cities have identified sustainable infrastructure projects, innovative policies and carbon cutting initiatives, but yet too often they are not able to deliver on their ambitions because they lack access to finance.
National governments must now help mayors and cities by devolving authority over finance for sustainable infrastructure.
In parallel, international financial institutions must grant cities direct access to green funds and lending mechanisms to finance their ambitious climate plans.
Our responsibility is huge and citizens reminds us of this every day. If today is a moment of great hope, we must never forget that the hard work of making the Paris Agreement a reality has only just begun. Cities are ready to help in getting the job done.
Anne Hidalgo is Mayor of Paris, Eduardo Paes is Mayor of Rio de Janeiro and Miguel Ángel Mancera is Mayor of Mexico City