Greenhouse emissions not attributable to cities alone - Study

BY EDMUND SMITH-ASANTE

A yet to be released study on greenhouse gas emissions for 100 cities in 33 nations has shown that the contribution of greenhouse gases to climate change cannot be attributed to cities on the whole.

The study, which was peer reviewed in the journal Environment and Urbanization published by Sage Publications and the International Institute for Environment and Development, has therefore urged policymakers worldwide to take a fresh look at the differences between greenhouse gas emissions from different cities, to identify new opportunities to mitigate climate change.

Commenting on the study which suggests policy tools that city governments can use to take action on climate change, lead author, Daniel Hoornweg, who is also lead urban specialist on Cities and Climate Change at the World Bank, said “Cities worldwide are blamed for most greenhouse gas emissions but many cities have very low emissions, as do many city dwellers in even the most industrialised countries.”

He added that “Differences in production and consumption patterns between cities and citizens mean that it is not helpful to attribute emissions to cities as a whole,” and that “Policymakers need a better understanding of the sources of emissions if they are to develop real solutions.”

Hoornweg and colleagues showed in the study that emissions per person per year vary from 15-30 tonnes of carbon dioxide equivalent in some cities in industrialised countries to less than half a tonne per person per year in various cities in South Asia.

The paper shows that emissions vary greatly depending on whether they are calculated according to what a city (or a citizen) produces or instead of what they consume.

“Lifestyles and consumption patterns are key drivers of greenhouse gas emissions in emissions in far off cities, as in the case of Western consumer demand for Chinese goods,” says Hoornweg. He expatiates that “From the production perspective Shanghai has high emissions but from the consumption perspective its emissions are much lower.”

Equally, a wealthy city where many inhabitants have a high-consumption lifestyle can have low per capita emissions from a production perspective, but very high emissions from a consumption perspective, the study infers.

Adding his voice to the outcome of the study, Dr. David Satterthwaite, editor of Environment and Urbanization and a senior fellow at the International Institute for Environment and Development, says; “This paper reminds us that it is the world’s wealthiest cities and their wealthiest inhabitants that cause unsustainable levels of greenhouse gas emissions, not cities in general.”

“Most cities in Africa, Asia and Latin America have low emissions per person. The challenge for them is to keep these emissions low even as their wealth grows,.” He stated. Further. 

Meanwhile, available data as follows, suggests that there is great variation within countries and even within 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.

There are also some surprising differences between cities in different parts of the world as follows:

• Many European cities have less than half the emissions per person of many cities in North America;
• Some successful and wealthy cities in Brazil have lower emissions per person than poorer cities in Asia and Africa;
• Emissions per person in London are lower than those in Cape Town, South Africa.

The paper will appear in the April 2011 edition of the journal but has been made available online this month of January and is available through the journal’s ‘on-line first’ facility.