Solved – How the world’s great cities are fixing the climate crisis

three cyclists cycle in the centre of Ljubljana in Slovenia
Reading Time: 6 minutes

Last week I finished the book ‘Solved’ by David Miller, former mayor of Toronto from 2003-2010. David Miller is now Managing Director of the C40 Centre for City Climate Policy and Economy. The book is a collection of examples of practical solutions to limit emissions at city level.


The C40 is a group of big city mayors who strongly believe they can take climate action much faster than federal or provincial governments can. C40 ( is financed by a number of wealthy donors from the German government to the wealthy Brennickmeijer Family foundation to a not for profit Danish group with an interesting source of funding (large numbers of smaller donors from what I understand) and many others. You can read more about C40 on their website.

Solved – David Miller

David’s book is called ‘Solved’, with the subtitle: “How the world’s great cities are fixing the climate crisis”. That is probably a bit optimistic, but the book is packed with positive examples: it is nice to read that certain issues such as waste, energy, emissions do get addressed.

In these days of climate doom, it is a surprisingly uplifting book. David has divided his book in several chapters, such as Energy and Electricity, Existing Buildings, New Buildings, Public Transportation, Personal and Other Transportation and Waste.

Numerous examples of climate action in ‘Solved’

If you are an urbanist or wannabe urbanist, you will recognise lots of examples from social media, presentations and other books, such as the Velib bike share system in Paris and Montreal’s Bixi bikes, the bus system in Curatiba in Brazil, the car free Sundays in Bogota (I should mention here that Ottawa’s car free Sundays pre dates Bogota’s) and Barcelona’s superblocks. It is encouraging to read that a city like Shenzhen introduced no less than 16359 electric buses by 2017 already, while Ottawa just ordered its first batch of 350 buses in 2022.

Retrofitting the Empire State Building

I found it particularly interesting to read in the New Buildings chapter that New York City has introduced stricter regulations than the New York State does. By using a carrot and stick approach, the city has tackled some serious CO2 emissions. There are several examples of retrofitting buildings in his book and it is encouraging to read about retrofitting the Empire State building: retrofits were saving USD 2.8 mln in operating cost in 2013 as a bonus (after serious investments obviously). The owner replaced all 6514 windows, added insulation, replaced meters and added sub metering; mechanical systems were replaced and better monitoring introduced. That is just one example. In New York, a dense city, like Tokio, buildings rather than transportation are the big source of greenhouse gas emissions.

Reducing waste

Another example I really appreciated reading in the Waste chapter in ‘Solved’ was how Slovenia’s Ljubljana deals with its garbage. At HansontheBike’s home, we try to minimise waste by being careful what we buy (‘reduce’). For example, we don’t buy food in clamshells anymore even when it is 50% off (which is hard to resist for the frugal Dutchman). We try to choose products that use recyclable paper packaging and we forgo plastic bags at the vegetable section. We also started to buy toilet paper in paper packaging, rather than the large amounts of plastic it comes in.

A small milk bag is sitting at the curb. The suburban front yard is covered with about 3 ft or 1 meter of snow. There is two weeks of waste in the bag and it weighs 363 grams
Two weeks of waste (363 grams) is all we had these last two weeks. And the two weeks before. And the two weeks before.


Waste Watch Ottawa

We buy some products at the Bulk Barn (bring your own bags or containers) and I refill (‘reuse’) our shampoo and dishwash soap at the zero waste NU store in Old Ottawa East. you pay a bit more, but really, per round of dishwashing, we’re probably talking a penny more. The only garbage left is basically some plastic from cheese bricks, tooth paste tubes etc. Other than occasional bigger items, our garbage is reduced to usually about 200 grams per week in our two person household. It is not that difficult really.

Central recycling in Ljubljana (photo: Ljubljana Tourist Office wih permission)

I found Ljubljana’s example so inspiring that I am copying a bit from that chapter in David’s book ‘Solved’, hoping that it’s OK. Ljubljana even cancelled plans to build an incinerator.

From ‘Solved’:

Ljubljana’s waste reduction

Ljubljana, Slovenia, is an excellent case study of what can be done, moving rapidly from recently starting separated waste collection to building a foundation for an economy that effectively reuses products rather than throwing them out – an idea known as a circular economy.

Ljubljana is the capital of Slovenia and has overseen a transformational change in the way it deals with waste. Separated waste collection began only in 2002, but by 2014, the city was diverting more than 60 percent of its waste to recycling and composting facilities.

A cobblestone market square in Ljubljana. Three cyclists cycle in the middle of the square. On both sides are historic buildings in white and yellow.
Downtown Ljubljana (photo: Ljubljana Tourist Office with permission)

Even its total per capita waste generation is impressive: the annual per person output of waste in 2014 was a mere 167 kilograms (368 pounds), while the European average was 475 kilograms (1,047 pounds) and the US average an astonishing 743 kilograms (1,68 pounds). Waste reduction and diversion was so effective that in 1014 the city scrapped its plans to build the country’s first waste incineration plant.

Ljubljana has worked closely with the public waste-management company Snaga to develop strategies to achieve zero waste. Once curbside pickup of separated recycling and compost was established in 2013, Snaga began to reduce the frequency of garbage pickup.

A narrow cobblestone street in Ljubljana is filled with planters. The planters ahve evergreens,  climbing plants, and flowers. There are white benches along the buildings. There is a church at the end of the street.
Downtown Ljubljana (photo: Ljubljana Tourist Office with permission)

Across the city, recycling and compost is picked up two to three times more frequently than garbage. This initially led to complaints, opponition, and packed garbage containers. Through education campaigns on sorting, open discussions of the reasons for the changes, and videos showing how those packed garbage containers were full of recyclable and compostable substances, the public mood eased, and the changes were accepted.

In Ljubljana, hazardous waste, large items, metals, textiles, e-waste, and other materials are collected in collection centers scattered across the city. Recognizing that these centers may not be convenient or accessible to all residents, mobile collection units are sent out to the neighborhoods twice a year to pick up there Items.

Free pickup of bulky items can be arranged. A recent measure in densely populated centers is pay-per-use pricing for disposal of garbage and compostable materials. Access to recycling bins remains free.

A cobblestone square in Ljubljana. A cyclist with long dark blond hair on a bike share bike poses in the middle of the square. There are red flowers in the baske on her bike. Other people are walking in the square.
Downtown Ljubljana (photo: Ljubljana Tourist Office with permission)

The city’s focus has now shifted to waste reduction and the building of a circular economy. By promoting leasing instead of buying, services instead of products, and sharing instead of ownership, the city saw an opportunity to reduce waste and build a more livable city.

A “Get Used to Reusing” campaign was launched and later adopted nationally. This was supported with the establishment of a reuse center, a clothing e-library, bike-sharing and electric car-sharing services, a library of things (for borrowing tools, sports equipment, etc.), exchange depots, a Repair Cafe, and a public company that makes paper towels and toilet paper from milk and juice packaging.

Snaga, the waste-management company, even furnished its offices with upcycled and reused furniture. At the industrial level, they encourage symbiosis: where waste from one industry is used as raw material for another local company. Ljubliana is showing the world how a shift in thinking can lead to the elimination of nearly all waste.

A wide side walk has young trees and several large umbrellas in Ljubljana. Several people are sitting on foldable wooden chairs under the umbrellas. the sun is out. There are planters with geraniums.
Downtown Ljubljana (photo: Ljubljana Tourist Office with permission)

As a result of these efforts, the city won the European Commission’s Green Capital Award in 2016 for waste management. The city is building on this success by focusing on ambitious goals reducing the amount of residual waste to 60 kilograms (132 pounds) per person annually by 2025, and to 50 kilograms (110 pounds) by 2035. It plans to increase the diversion rate to 78 per cent by 2025 and 80 per cent by 2035, with an ultimate goal of zero waste- the first European capital to aim for zero waste.

Ljubljana makes an interesting study for a North American audience: we often seem to assume that we have all the answers and, implicitly, that other parts of the world – developing nations, Eastern Europe, Africa – must learn from us. As shown in this case, the learning is often a two-way process.

From: Solved – How the world’s great cities are fixing the climate crisis by David Miller

If you’d like to read more on Ottawa’s waste, you may want to check out volunteer run Waste Watch Ottawa.

David’s book ‘Solved’ is available at the Ottawa Public Library:

Planning to visit Ottawa for some cycling? Check out my collection of cycling routes that mostly follow pathways.


  1. Great report of these real world examples, Hans!
    Did you share them with our City of Ottawa city councillors?

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