Environmentalists sometimes have an uneasy relationship with cities. Because they concentrate a lot of people and economic activity in relatively small places, they also concentrate a lot of negative environmental effects. All that concrete, all that energy being consumed, the kilometres of malls and highways and subdivisions! It can’t possibly be good, can it?
As it turns out, cities can be quite environmentally friendly. The same factors that make cities economically efficient – the ease of interacting with others in a dense environment and the economies of scale that arise in large, well-connected places – can also make them environmentally efficient.
However, there are large variations in environmental efficiency within and between cities. Cities which offer better housing and transport choices tend to have much lower per-capita carbon emissions – a fact highlighted by a 2011 study of carbon emissions in 100 cities:
- In the United States, the emissions per person in Denver are double those of people in New York, which has a greater population density and much lower reliance on private vehicles for commuting.
- In Toronto, residential emissions per person in a dense, inner city neighbourhood with a high quality public transport system are just 1.3 tonnes of carbon dioxide equivalent, compared to 13 tonnes in a sprawling distant suburb.
Auckland’s Low Carbon Action Plan presents some of this data in a fascinating infographic:
Interestingly, Auckland doesn’t come out too bad on this comparison. We’re nowhere near as efficient as Vancouver, Stockholm, or Copenhagen, but we are in the same ballpark as moderately efficient North American cities like New York and Seattle. This is probably down to our high share of renewably generated electricity, as well as our relatively short commutes.
But can Auckland become more environmentally efficient, or will it grow in a way that causes it to lose its edge? In order to get a sense of this, I took a look at variations in carbon emissions from commutes within New Zealand’s three largest cities.
The maps below presents some preliminary estimates of carbon emissions. They’ve been calculated using the Census journey to work data presented in my recent Location Affordability Index paper, which allowed me to identify how far people were travelling to work and what mode of travel they were using, as well as some supplementary assumptions and estimates from several sources (e.g. EECA, NZTA). [I will put together a working paper on the analysis when my work at MRCagney permits!] Lighter yellows reflect lower average annual carbon emissions from commute trips, while darker blues represent higher emissions.
A few first thoughts about these findings:
- These maps really show the power of proximity. People near the centre of the city tend to travel shorter distances to work, on average, because they’re closer to more jobs. This is obviously good for commuters – which is why house prices are so high in Ponsonby and Mount Eden – but it’s also great for the environment.
- They also demonstrate the importance of transport choices. Commute emissions in Wellington suburbs tend to be much lower than in similarly-situated Auckland suburbs, because many Wellingtonians can choose between driving, an efficient electric train system, a frequent bus network, and relatively good walking and cycling.
- Lastly, these maps highlight the perils of urban growth. Suburbs at the fringe of the city are much less environmental efficient than suburbs closer in. For example, moving from Mount Eden to Flat Bush could be expected to raise your commute emissions by one ton a year. (And leave you sitting in traffic for that much longer!) This is a particular challenge right now in Christchurch, where satellite towns with long commutes have absorbed households displaced by the earthquakes.
Of course, as a coastal city Auckland has some strong incentives to reduce its carbon emissions: