Sticking with the optimists

By Mark Watts, Executive Director of C40

Early in the new year the Guardian newspaper asked some of the world’s most prominent scientists if it was still possible to prevent catastrophic climate change. The bleak assessment from all but one respondent was that it is not. One called it “on the fanciful edge of implausible”. This not only made for depressing reading, but also provided a marked contrast to the sense of determined optimism that pervaded C40’s mayoral summit a few weeks earlier. Gathered in Mexico City, mayors of the Steering Committee – C40’s elected leadership – voted unanimously to adopt a target of constraining global temperature rise to no more than 1.5 degrees Celsius above the pre-industrial average (the toughest goal of the Paris Climate Agreement), and to make it a condition of C40 membership that all cities have a plan to deliver their proportionate contribution towards this goal.

So who’s right – the scientists or the politicians? Perhaps this is not the right question to pose. It’s hard not to be scared by the data on climate change, but widespread pessimism among scientists stems in part from a lack of confidence that political leaders will deliver what is necessary. Some C40 mayors may share that concern with respect to their national governments, but they know first-hand what can be done at a city level and have confidence in a collective determination to utilise their own governmental powers in pursuit of securing a prosperous, inclusive, low-carbon future.

Moreover, the mayors of our Steering Committee were basing their political judgements in part on a new analysis, Deadline 2020, prepared by C40 and its research partner, Arup. Deadline 2020 attempts to set out a roadmap for what it is possible to achieve through the most ambitious urban climate action. A key finding of the report is that while staying below the 1.5-degree threshold will be incredibly tough, it is still technically possible.

Mark Watts presents the Deadline 2020 research at the 2016 C40 Mayors Summit in Mexico City

Importantly, the research shows that the remaining global carbon budget – the total amount of emissions humans can risk putting in the atmosphere and still keep global temperature rise below 1.5 degrees – is about 400 gigatonnes for the rest of the 21st century. Of this, C40 cities are allocated 22 gigatonnes.

At present, C40 cities emit 2.4 gigatonnes per year, so if they carried on at that rate the whole budget will be used up in less than a decade and by 2060, C40’s 90 cities alone will have used up the entire world’s carbon budget for the rest of this century.

If C40 cities are really to lead on delivering the Paris Agreement then we need to see a surge in climate action in the next few years. We need to 'bend the curve’ of the emissions graph so that instead of an anticipated 35% increase, emissions peak in 2020 and then start to fall sharply. That’s why we called the report ‘Deadline 2020’.

Every single city needs to take radical action to move to a new low-carbon development path, with wealthier cities taking 70% of actions between now and 2020; and lower income cities rapidly shifting to a low carbon development model so standards of living increase while emissions go down.  There is no time to waste, indeed in our model, 90% of all the action C40 cities need to take to put the world on a climate-safe path needs to have happened by 2030.

Deadline 2020 outlines what will need to have happened in cities in order to achieve these ambitious emissions reductions:

  • By 2020 nearly all C40 cities will have started building smart grids and energy storage, drastically reducing energy wastage.
  • By 2025 75% of buses in C40 cities will be electric or other zero carbon, and every part of the city will be supported by mass transit, so we’ll all be breathing cleaner air, enjoying quieter roads, and finding it easier to get around.
  • All new development will be transit-oriented by 2030 and no mayor will be giving planning permission for new, sprawling suburbs that can only be accessed by car.
  • At the same time, waste pricing mechanisms will discourage the throw-away society.  


This sounds like a huge transformation – and it is. But delivering on the Paris Agreement is in every cities’ self-interest. We already know from the work of the New Climate Economy that getting onto a low carbon development pathway will improve living standards faster and embed stronger and more sustained economic growth than the high carbon alternative. 


City leadership on climate change is essential, not least because the pledges made by presidents and prime ministers thus far would put the world on a path to between 2.5 and 3 degrees of warming. That is well within the zone that would spell disaster for large parts of the world and many C40 cities, and that is assuming that President Trump does not renege on the U.S.’s commitments.

Even as mayors, governors and business leaders are prepared to forge ahead, national commitments need to become more ambitious: if all are united on this issue we can make change that will resonate for generations. That was the message in an open letter to the incoming president from 70 U.S. mayors, initiated by Los Angeles Mayor and C40 Vice Chair Eric Garcetti.

The leadership of cities and mayors is critical and it’s the mayors in office right now who hold in their hands the power to put the world on a low carbon path. As we saw at the C40 Summit in Mexico City, mayors are currently much better placed to deliver collective global climate action than any other set of political leaders. They are already convinced that we will build a much better world if we can constrain global temperature rise to below 1.5 degrees – and they are acting upon it. 

The world’s scientists, whose clear, fact-based messages have been ignored by world leaders for twenty years, are right to be worried about the future. But there are some politicians with both real power and a determination to use it to tackle climate change. For now, I’m staying in the optimists’ camp and focussing on helping C40 mayors get on with the job of delivering a bright, climate-safe future. 

Read the full Deadline 2020 report here