Sustainable BuildingsRetrofittingDecarbonising Cities to Reverse Climate Change

Decarbonising Cities to Reverse Climate Change

Karl Dickinson
Karl Dickinson
Change matters. It takes courage. As a writer - and citizen - I am inspired by stories of those who challenge the 'we've always done it this way' attitude. We can do better - it's time to listen to those who go against the grain.

Cities emit seemingly endless cascades of greenhouse gasses. Carbon dioxide is the number one offender. Rectifying this is pivotal to halting global warming and preventing irreversible climate damage. But decarbonising cities at a mass scale is an unprecedented task with an unforgiving deadline. So, how can it be achieved? What are the major players in our fight for a temperate future?

There’s a word you’ll read a lot on innovation. If we’re going to save the world as we know it from, well, ourselves, we need to change, learn from mistakes, adapt, and nail those sustainable solutions. Never is this more pertinent than in our fight against carbon.

CO2 is unquestionably making the planet hotter and destabilising weather systems. Consequences to the natural world aside, we’re having to futureproof cities for harsher times ahead – including retrofitting potentially many millions of older properties. Decarbonising cities can relieve the pressure. In this article, we’ll explore the possibilities for depleting dioxide.


If this term is new to you, think of it like this: for every force, there is an equal and an opposite – in the case of planet-choking emissions released by burning fossil fuels, the pushback is decarbonisation.

In short, this is the process of reducing the amount of CO2 in the atmosphere by cutting down on and extracting emissions. It’s important, because carbon dioxide is one of the most harmful greenhouse gases and it hangs around for centuries. Accounting for three quarters of all GHGs, it’s a puzzle ripe for solving.

Industry (24.2%), transport (16.2%) and electricity production (5.8%) are carbon big-hitters. Yet, operational use of buildings churns out an astounding 28% of global CO2 emissions, with another 11% from construction and building materials. That really puts the necessity of retrofitting inefficient properties into context.

Is Decarbonisation Realistic?

Fossil fuels are being burned like they’re going out of fashion. Well, they are – these days it’s only boardrooms of corporations that rake in profits who see a sexy side to these pollutants. It’s no coincidence that oil was once considered ‘black gold’. But coal, oil, and natural gas are running out, anyway. Prepping the grid with alternatives now saves us from problematic power failures of the future.

It’s no unobtainable dream. “Globally, renewable energy generation doubled in the five years to 2020”, according to The Conversation. Prices for “solar electricity fell almost 20% in the first six months of 2020 alone” and wind power is now so cheap that the economic benefit of nuclear power stations is no longer a tenable argument.

Siddharth Sareen, Associate Professor in Energy and Environment at the University of Stavanger, researches the governance of energy transitions. He cited “two activists getting elected onto the board of Exxon” – a petrochemical company, no less! – as a significant shift in attitude for big business. Shell, similarly, committed to becoming net zero by 2050. There’s a long way to go, though. Despite this improving mentality, “we’re still building out new coal thermal plants even though solar would be cheaper”. And cleaner. And longer-lasting.

Reliance on an Alliance

Decarbonisation has its advocates. The Carbon Neutral Cities Alliance (CNCA) is an international partnership of 22 cities with the most ambitious CO2 commitments of any urban spaces on the planet. Interim Director of the Alliance, Trude Rauken, explained how these cities are “taking on a task that nobody has done before”: member cities are aiming to be carbon neutral within this decade, “in record time”, and carbon positive by 2050.

CNCA’s modest membership roster offers these cities an intimacy that facilitates transparent dialogue. From Yokohama to Minneapolis, and from Adelaide to Rio de Janeiro, the CNCA supports trailblazing cities across continents to develop, implement, share, and learn from policies that tackle carbon pollution head-on. Trude reflected that “we know that they will be able to move faster together and develop better policies if they are able to exchange”. Ultimately, other cities will benefit from adopting the concepts that are proven to work, and we’ll all benefit.

Cities Reversing Climate Change – The Three Pillars of Decarbonisation

We can learn a lot from CNCA’s approach. Its work comprises of three branches: policy investment, peer-to-peer learning, and communications, training, and support.

Transcending politics, CNCA’s only agenda is decarbonisation. There’s no posturing; each city is recognised for their specialities. Members benefit from peer-to-peer learning – webinars, online training sessions, workshops, etc. For example, CityChangers from Stockholm joined a Vancouver city council meeting virtually to pass on their experiential wisdom in tackling transport issues. This support led to Van City approving a new Transport Pricing Game Changer action plan, introducing congestion charging to disincentivise car use. Often the challenge is not the public acceptance of change, but convincing decision-makers internally to take the plunge.

“Communications training is critical, both to talk to your citizens but also to talk to your departments. Getting all other departments on board in the climate action work is as big of a challenge and an often-overlooked challenge”.

Experimentation, too, paves the way for ever-more impactful solutions. But this is costly, and it places stress on limited resources. Plus, “you’re not quite sure about how they’re going to play out” so there will be failures. As city budgets are public money, this risk can be hard to justify. While philanthropic funding is primed for backing innovative ideas, according to Trude “only 2% of philanthropic funding actually goes to climate work”.

CNCA’s former Innovation Fund underpinned policies or “solutions that might turn into policies”. A $25,000 grant supporting Vancouver’s Centre of Excellence for Net Zero Buildings led to the development of a carbon-neutral building code now adopted at the city, province, and potentially federal level. Decent progress can emerge from even relatively modest cash injections.

Similarly in Oslo, funding led to the implementation of a clean construction programme. This formed on the back of exploring options for zero emission or renewable-powered non-road machinery (e.g. snow ploughs) and how savvy procurement can prioritise tech with lower emissions.

A small grant allowed San Francisco to test the market for Energiesprong’s quick retrofit model in the Bay Area. The pilot was a success: “Two years later, that resulted in a much larger grant from the California Energy Commission to support the rollout in other counties.”

Decarbonisation, it seems, really does rely on innovation. We just need to give it room to thrive. CNCA’s new Game Changer Fund runs on that notion, bankrolling radical policies already identified to work. Unlike its predecessor, this fledgling fund “can support any city in the world that is poised for policy development, adoption implementation”. Lack of money is no longer an excuse for business as usual.

City Tricks for Reversing Climate Change

So, what do these tried and tested decarbonisation methods look like? Here are a few to whet your appetite.

No Drawback to Drawdown

As vegetation holds CO2, urban greening is a natural and aesthetic way to capture ambient carbon deposits. But let’s think more creatively. Chicago has paved cycle lanes with ‘smog-eating’ concrete. New tech is swallowing carbon from power stations before it’s released into the ozone and traps it within the earth. Through CNCA’s brokerage, Boulder helped Stockholm develop carbon drawdown mechanics using biochar – organic matter turned carbon negative through heating. We’re actually altering biology to turn our cities into active carbon sinks!

Carbon Tax

“A price on carbon helps shift the burden for the damage back to those who are responsible for it, and who can reduce it”, states the World Bank website. From industry to transport, plenty of EU countries impose a tax on carbon as a disincentive. Rates vary tremendously: wealthy countries like Sweden and Switzerland levy around 1,000 times the cost of the likes of Poland and Estonia. Whether this is a reflection of wealth or commitment to the cause is a question for another time. One constant is clear: polluters can choose to cut emissions or pay the price. It’s win-win, with lower carbon levels and supplements to central funding pumped into clean energy development.

On a city level, carbon offsetting for deliveries and manufacturing, and road taxes for the dirtiest engines are frequently used to put people off private vehicles. Between 2017 and 2021, congestion charging saw 44,100 fewer cars driving London’s streets each day. This only works if alternatives are available. When it comes to transport, London provides. Upping the ante, the Underground is set to be fully powered by net zero sources by 2030. Pressure is increasing the world over to electrify fleets of public busses, trains, and taxis.

Improve Building Efficiency

Carbon stores are big news! As a collaborative network, CNCA is very much led by the needs of its members. In 2018, seven cities wanted to address a single issue, and for Trude, it’s the hot topic in the retrofitting world: “Embodied carbon is often overlooked, but it actually constitutes right now about 11% of all global emissions.”

Zurich and Oslo had the field know-how. As for the other seven, “we gathered them on webinars and workshops, where we can help with technical experts, academia, other organisations”, from which a 52-page policy framework emerged. This can be adapted and adopted to suit locality needs. Helsinki, for example, “has just started a new initiative on energy efficiency consultants. They will give advice to members of the community that want to retrofit their homes or increase the energy efficiency of buildings”. The pace is picking up.

Speaking of which, in America cracks are appearing in the national PACE loan scheme. True to its name, the city that never sleeps isn’t resting on its laurels. New York City, Trude fairly speculates, is home to a million buildings, many needing retrofits. NYC’s Retrofit Accelerator programme, according to their website, exists to “provide free, personalized guidance to make cost-saving, energy-efficiency upgrades and reduce carbon emissions”. And financing. So, the frenetic city’s residents have the support they need to decarbonise one of the world’s biggest, most populated conurbations.

Harnessing Earth’s Energy

Renewables are clean and green. Cities are not short of roofs, so it stands to reason that microgeneration – building-centric electricity creation for personal use (generally through solar panels) – is on the increase. Wind, hydro, and geothermal power are also on the up, and technologies are improving at an almost exponential scale. We’re developing more efficient storage facilities for prosumers to save power for when it’s really needed. And we’re getting creative with new energy sources.

While only responsible for 2% of the world’s GHGs, hydrogen is a useful and popular fuel. While it doesn’t produce CO2 itself, the electricity used to extract it from water traditionally comes from fossil fuels. Green hydrogen serves the same purposes but is extracted using renewable electricity. As renewables become cheaper, so will green hydrogen. And it’s in a fairly inexhaustible supply.

Nature continues to provide answers. Biogas is essentially a by-product of decomposition. Food waste and other organic matter that’s broken down by microbes without the presence of oxygen (aka anaerobic digestion) produce a natural gas that’s useful for replacing carbon-based fuels. The big question is, though, when will these innovations become the mainstay? We’ve yet to see.

Equity – Why Does It Matter?

One thing Trude is quick to remind us of is that no decarbonisation measure should disadvantage already (disproportionately) disadvantaged groups. (Speaking of which, we have an article about that right here.)

Homes, manufacturing, and transport all need to cater for a city’s diverse communities and their respective needs. We need zero-emission transit networks, but they also need to be safe, fair, and accessible regardless of socioeconomics or which district in the city you live in.

How does this manifest in policy? Trude has some insights: “Making sure that the solutions that you develop and implement actually work for frontline communities and low-income communities.” That means, for example, not pricing low-income households out of mobility because they cannot afford to upgrade from a petrol to an electric vehicle.

Tech develops faster than society can keep up with. It’s not good enough in planning, Trude tells us, to just have an equality checklist, or making token efforts to speak to communities; it’s an empty gesture if their voices continue to be unheard and their needs continue to be underserved. Take a leaf out of the CNCA’s book which has made equity a scoring criterion for bids to the Game Changer Fund. It supports the development of climate justice governance tools, allowing individual municipalities to evaluate equity, inject it into their policies, or remedy where it falls short. “And then in our leadership training, we’ve also given a special priority for people who identify as minorities” to offer representation of often-overlooked communities in decision-making positions. Citizen empowerment is critical to decarbonisation.

Decarbonisation in a Nutshell

Humanity has a long hard slog ahead to becoming carbon neutral. Experimental ideas, game-changing policies, fear-free investment, and racing ahead with revolutionary methods have so far proven to be the formula for combatting ambient carbon. And there’s nothing stopping us from replicating and upscaling until we reach the ambitious targets we have to hit.

Municipalities would do well to follow CNCA’s example, too: the tried-and-tested model of communication, knowledge-sharing, investing in future CityChangers, and exchanging dialogue around failures and success. Who knows, if cities take inspiration from the CNCA cities soon enough, maybe we’ll be carbon positive by mid-century. With a stable climate and comfortable lifestyles to gain, why wouldn’t we put politics aside and at least try?

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