We face a climate emergency.
In Ghana, we see the impacts of climate change in the erratic rainfall that risks our food production and security. In Accra, flooding threatens the city's infrastructure and affects citizens' health and it is going to get much worse as global temperatures rise.
Ghanaians produce on average only half a tonne of carbon dioxide each, compared to nine tonnes for a South African or nearly seventeen tonnes for an American. But climate change is a global phenomenon.
Although we have smaller carbon footprints than most, the science now makes it clear: every country will need to choose low-carbon development to avoid a climate catastrophe.
Millions of students - in Ghana and around the world - are skipping school to draw attention to this crisis.
The United Nations has called upon world leaders to increase their climate ambitions and invest in solutions. And mayors, business executives and civil society leaders gathered in Copenhagen for the C40 World Mayors Summit this month to call for bold climate action in the world's cities.
In Ghana, emerging technologies and the lessons from the past now give us the ability to leapfrog over the polluting practices and inefficient systems that challenged earlier urban development and skip directly to more sustainable solutions - which both improve the lives of our citizens and position our country to thrive in the economy of tomorrow.
Cities have the potential to offer a high quality of life in a low-carbon way.
When people live more densely together, it is possible to provide basic services while using less land, less material and less energy. This could make services both more affordable and more sustainable - zero-carbon cities can work for people and the planet.
Across Africa, we are seeing solutions emerge from city governments.
Kampala is installing solar street lights that are cheaper to install and run than street lights connected to the electricity grid. Lagos has set up a low-cost Bus Rapid Transit system that provides dedicated bus lanes but does not involve fancy new bus stops that cost the Earth. Johannesburg has partnered with informal waste pickers to improve their livelihoods and expand recycling.
New research from the Coalition for Urban Transitions shows that national and city governments can cut 90% of emissions from cities using existing technologies - and that these low-carbon measures would generate money for the city.
Solar panels, more efficient lighting, public transport, better waste management and other low-carbon measures can actually generate a direct commercial return worth almost US $24 trillion by 2050.
The benefits are not just economic.
Making streets safer for cyclists and pedestrians doesn't just reduce emissions; it also saves lives by reducing traffic injuries and air pollution. Installing solar panels doesn't just provide a return: it generates the much-needed energy to power lights, refrigerators, radios and fans in our homes.
Ambitious climate action in cities offers a huge opportunity to deliver fairer, faster development. But city governments cannot realise these opportunities alone.
Why national governments?
A new report, Climate Emergency, Urban Opportunity, shows that national support and investment is needed to seize this opportunity, and boost living standards in Africa's fast-growing cities.
Worldwide, city governments have primary authority over only a third of potential emission reductions in cities. The remaining two thirds depend on action by or with national governments.
But of course, this analysis includes rich, long-established cities such as Cape Town, London and Tokyo. The situation looks very different in Africa. Cities such as Takoradi, Tamale or Wa have much less capacity to enforce building codes or finance new bus networks. In Ghana and our neighbours, partnerships between national and city governments are all important.
The partnership between the Government of Ghana and the Accra Metropolitan Assembly demonstrates the advantages of collaboration.
With the support of C40 Cities and the Land Use and Spatial Planning Authority (LUSPA), Accra is developing a robust climate action plan. The spatial plans and infrastructure investments will reduce flooding and enhance access to basic services while reaching net-zero emissions through clean energy, mass transit and better waste management.
The Ministry of Works and House and Ministry of Local Government are supporting the city government to develop another project called the Greater Accra Resilience Integrated Development Project (GARID), which is focused on flooding and waste management, along with a spatial plan for metropolitan coordination and management. The Ministry of Finance is working to secure international funding to implement it.
Both the Government of Ghana and the Accra Metropolitan Assembly recognise the importance of creating a compact, connected and clean city with healthy people and safe neighbourhoods. This is a model of partnership for cities across the continent.
Africa's cities will expand by half a billion people by 2050. We will have to find a different way of building and managing our cities if we are to meet their needs and avoid climate catastrophe.
City governments have critical roles to play, but they cannot do it alone.
We must work together to ensure our citizens are prepared to weather the challenges ahead.
Mohammed Adjei Sowah is Mayor of Accra and Hajia Alima Mahama is Ghana's Minister of Local Government and Rural Development
Any views expressed in this opinion piece are those of the author and not of Thomson Reuters Foundation.