Cities are often blamed as the biggest producers of greenhouse gases - a worry as the world urbanizes - but planning can help
LONDON (AlertNet) – Cities are often blamed as the biggest producers of greenhouse gases, a concern for efforts to curb climate change as the world becomes increasingly urbanized.
But a new study shows wide differences in carbon emissions from cities and neighborhoods around the world, and suggests that thoughtful urban planning as cities expand could play a big role in limiting carbon emissions.
“How urban areas expand in the next 30 years has big implications for whether we reduce emissions or not,” said David Satterthwaite, an urban specialist at the London-based International Institute for Environment and Development and editor of the journal Environment and Urbanization, which will publish the new study in April.
The driving-oriented U.S. city of Denver, for instance, has greenhouse gas emissions of 21.5 tonnes per capita each year, but Porto Alegre, a pleasant, well-run southern Brazilian city with a life expectancy similar to cities in Europe or North America, emits just 1.5 tonnes of carbon per capita.
In part that’s because Brazil gets much of its power from hydroelectric plants. But Porto Allegre’s compact design and good public transportation appear to have played a key role in holding down emissions, Satterthwaite said.
In fact, Porto Alegre’s emission levels are similar to those in many less-developed major cities in South Asia – New Delhi, Dhaka and Colombo among them – which suggests that well-designed urbanization may help curb emission increases even as consumption levels and electricity use expand.
“Cities worldwide are blamed for most greenhouse gas emissions but many cities have very low emissions,” said Daniel Hoornweg, a specialist on cities and climate change with the World Bank and lead author of the study, “Cities and greenhouse gas emissions: moving forward.”
DENSITY, TRANSPORT ACCESS ARE KEY
So what do cities need to focus on to hold down emissions while growing and raising levels of development? Creating a relatively dense structure, putting in place good public transportation systems and ensuring residents can walk or bicycle to many services they need without having to drive or even take public transport, Satterthwaite said.
Study data from Toronto show neighborhoods with such design have emissions 10 times lower than other parts of the city, Satterthwaite said.
More than half of the world’s population today lives in urban areas, and urban zones produce more than 71 percent of the world’s energy-related greenhouse gas emissions, according to the International Energy Agency. That percentage is expected to rise to 76 percent by 2030, according to agency estimates.
Those numbers suggests “cities are the optimum scale for … action on climate change mitigation,” says the new study, which looks at emissions from 100 cities in 33 nations.
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