Do you live in a city? Chances are you’re one of the four billion or so people who do – just over half the total global population, and inching steadily to almost a third by 2050. Having lived in London, I know that it can feel like most of them are jammed into the same train carriage as you every day.

Cities are on the rise – upwards and outwards. Today, there are at least 28 mega cities with populations of more than 10 million, and in less than 15 more years the tally will be somewhere north of 40. This growth will be most significantly defined by three countries – India, China and Nigeria – which, on their own, will account for 37 per cent of the projected growth of the world’s urban population by 2050.

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Whether you’re a City Slicker or a Rural Ranger, there’s no doubting it’s going to get a whole lot more crowded on planet Earth. Feeding, housing, transporting and caring for a growing urban population means that cities are taking out far more than they are putting in – the figures show that urban settlements are both the biggest consumers of global energy and the biggest producers of global carbon emissions. In short, the cities so many of us call home are steadily putting us on a one way track towards climate change, unless we do something about it.

Thankfully, the clarion call for action is ringing loud and clear across the cityscapes. Cities100 reveals that nestled amongst the world’s cities are some of the most progressive, exciting, and transformational solutions for climate action. From Addis Ababa to Wuhan, these solutions show how local governments around the world are taking the necessary steps to mitigate and adapt to climate change – and you may have read about lots of them already. Solutions just like the biomass plant in Stockholm that looks set to put the Swedish capital into a fossil-fuel free future by 2050, and the district cooling system in Hong Kong’s Kowloon East which has already reduced CO2 emissions by 56,100 metric tonnes whilst making it a resilient low-carbon community.

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So far, so sustainable – but look beneath the skyline and there’s something even more important going on. We know that the impacts of climate change are not distributed equally or fairly, and that people living in cities – particularly in low-income countries – are disproportionately affected by the burden of the changing climate. There is a parallel and equally challenging problem relating to inequality which is highest within large cities, leading to large disparities in income and inclusion from one area of a city to another. When considered together, these systemic challenges can initially appear overwhelming, but they actually present a unique opportunity. Climate adaptive and resilient cities allow for sustainable economic development and expanding access to basic services, such as housing and health, for large numbers of people. Simply, the solutions which lessen the burden of climate change on vulnerable urban communities can also provide them with the many benefits climate action can present.

This means I am filled with hope when I look to cities like Mexico City, which has created a new park as a way of reducing heatwaves whilst providing new business opportunities for locals, or Tshwane where a cooperative of 25 small farms is securing food and energy supplies for generations to come. Or Washington DC where a low-cost bike-share scheme helps ensure that healthy, green transport is available to everyone.

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With COP22 underway, and the ratification of the Paris Agreement, we need to celebrate, promote and scale city solutions like never before. Cities100 shows just how often cities act, in nimble, collaborative and smart ways that do not rely on the will of national governments. It also shows that cities are responding and adapting to the impact of climate change whilst simultaneously creating valuable benefits for their economies, communities and citizen’s health.

So here’s to the cities making life greener and fairer for us all. And if that just happens to include more inclusive and sustainable transport options that make my train carriage a little less busy every morning, all the better.

Cities100 is a mission shared by Sustainia, C40 and Realdania to find the 100 leading city solutions to climate change. Read the publication here, and follow the conversation online using #Cities100

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