In 2015, the world united in its effort to reduce greenhouse gas (GHG) emissions by signing the Paris Agreement. As a crucial part of the Agreement, mitigation allows each country to identify its own commitments to GHG reduction, measured by each country’s priorities and concerns. And while the belief that bigger, denser cities are greener has largely driven mitigation policies and strategies, two researchers from Finland believe otherwise. In 2011, Finnish researchers Seppo Junnila and Jukka Heinonen published a study that argued against the widespread belief that cities are environmentally more sustainable since they produce less carbon emissions than their suburban and rural counterparts.

The researchers argue that the situation might be reversed by studying four different urban structure -related lifestyles in Finland. “This is mainly due to the higher income level in larger urban centers, but even housing-related emissions seem to favor less urbanized areas,” the study reads.

Carbon emissions are heavier in cities like Helsinki.

Street in Helsinki. CC: Benjamin Horn.

“We have done further research around the issue in Finland since 2011 and all our findings support the argument that GHG gains from reduced driving in denser settlements are compensated by elevated emissions from other sources,” Heinonen tells progrss. Heinonen, who is a professor at the Faculty of Civil and Environmental Engineering at the University of Iceland, has conducted four studies on the subject in collaboration with fellow researchers since 2011.

In 2013, he, along with a number of researchers, released a study that shows that living in denser contexts is more consumption-oriented. The paper analyzed the urban form–lifestyle relationships in Finland together with the resulting GHG implications, employing both monetary expenditure and time use data to portray lifestyles in metropolitan, urban, semi-urban, and rural areas. The researchers found that the more urbanized area types associated with more GHG emission-intensive lifestyles. For example, residents of more urbanized areas are found to buy more clothes and electronics. Additionally, consumption was found to increase in all kinds of leisure services parallel to the degree of urbanization, while in less urbanized areas, daily life was much more home-centered.

In 2016, Heinonen, Junnila, and two other researchers found in another study that larger family sizes and sharing among the family reduces the carbon footprints in suburban areas. The study found that the more members there are in the household, the bigger benefits – in monetary, environmental and social terms – are within reach when sharing GHG-intensive commodities such as heating energy, electricity, and car fuel. However, linking to the 2013 study, consumption and leisure goods are harder to share than necessities, even within a household. Therefore, a household with a smaller size would more likely lead to higher negative impacts on the local environment.

Carbon emissions produced by cars is dominant in Helsinki.

Cars in Helsinki. CC: Ralf Smallkaa

In 2017, the researchers conducted another study showing a strong rebound effect for not possessing and operating a car following the monetary saving. The study analyzes the changes in the carbon footprints of six different types of urban zones within the Helsinki Metropolitan Area: the central pedestrian zone, the fringe of the central pedestrian zone, intensive public transport zone, public transport zone, car zone, and the pedestrian zones of subcenters.

The results of the study reveal that the average carbon footprint decreased by seven percent from 2006 to 2012, despite the one percent increase in expenditure, which is encouraging since expenditure alone cannot explain the decline. The study found that emissions caused by housing energy consumption and motor fuel consumption are the ones that decreased the most. Driving-related emissions decreased the most in public transport zones and the pedestrian zones of subcenters; this is because, in these zones, there was a shift from car use to public transport. Furthermore, policies promoting cycling and walking – rather than density – may have decreased driving.

A 2018 study (e-mailed to progrss prior to publication) argues that effective mitigation policies are difficult to form and might need to be different for different types of areas. The researchers write that studies concerning the effect of urban structures on GHG emissions usually focus on ground transport. However, they argue that these studies fail to capture the rebound effects of consumption, widely acknowledged in economics.

Reducing emissions from driving also reduces expenditure on driving, and the released funds are often largely reused on other forms of consumption. While the average rebound for reduced driving is low, the study’s results show that the average rebound for giving up car ownership and driving entirely is quite high. This means that reduced driving reduces emissions effectively but the effect of giving up car ownership is not always as effective.

“The main policy implications are that the policy measures should be directed even more strongly towards car use instead of car ownership, and towards highly energy-efficient cars or cars using alternative low-carbon power technologies. Taxation is likely to be the best policy instrument to do this,” their conclusion reads.

Carbon emissions produced by cars in London seem to be lower than other British suburban areas.

Street in London, one of the cities Dodman studied. CC: City.and.Color

In 2009, The International Institute for Environment and Development Researcher David Dodman published a study that argued quite the opposite, lifting the burden of carbon emissions from cities. “An analysis of emissions inventories shows that – in most cases – per capita emissions from cities are lower than the average for the countries in which they are located,” the study reads. Dodman argues that high densities and large population concentrations brings a variety of advantages for meeting human needs and for environmental management.

However, in his conclusion, Dodman stresses that his paper doesn’t argue against the need for real mitigation strategies or shifting to renewable energy. In fact, he writes that there is actually no fundamental link between urbanization and high levels of greenhouse gas emissions. What is clear from his study is that, well-planned, well-managed cities can play a central role in helping to mitigate against climate change. “This does not necessarily entail increasing densities (particularly in low- and middle-income countries) but, rather, an awareness of broader issues of the urban form and urban structure,” he argues.

All the studies conducted by Heinonen and his colleagues are specific to Finnish urban and rural areas, and can hardly be taken to reflect the situation in other countries – particularly low- and middle-income ones. “Elsewhere, it could be that the positive impact of higher density is compensated by other emission sources than driving to a lesser extent,” Heinonen tells progrss. However, returning back to his argument, there is evidence that in general the same mechanisms apply elsewhere as well.

“Density policies are likely to dominate city development in the future as well,” Heinonen says. “It should also be emphasized that our argument is not that looser development would be preferable, but that we should not expect density policies to lead to GHG mitigation without other strong mitigation actions.”