Has anyone factored in atmospheric heat added by all that concrete in New Yorks urban heat island verses the lower heat signature of cities with fewer skyscrapers and larger numbers of trees per square mile?
While a sprawling city like Atlanta may have a larger carbon foot print per capita because of added commuting distance than NY, I?ll bet Atlanta has triple the number of trees per square mile.
Beyond retaining less heat than millions of tons of concrete, should those trees be considered a built in carbon offset?
It is a complex calculation when you look at the big picture.
Cities are places of great efficiency, innovation, and — especially in dense cities — energy savings. But cities shouldn’t let all that get to their head. According to a new UN report, cities around the world are not doing enough in the fight against climate change.
The report, “Hot Cities: battle-ground for climate change” from the United Nations Human Settlement Program, or UN-HABITAT, shows that while the world’s cities only cover 2 percent of global land area, they account for a staggering 70 percent of greenhouse-gas emissions.
“Cities are responsible for the majority of our harmful greenhouse gases. But they are also places where the greatest efficiencies can be made. This makes it imperative that we understand the form and content of urbanization so that we can reduce our footprint,” said Joan Clos Executive Director of UN-HABITAT. “Understanding the contribution of cities to climate change will help us intervene at the local level. With better urban planning and greater citizen participation we can make our hot cities cool again.”
It’s a humbling report, but there’s hope. Cities have the ability to make changes that can quickly affect millions of people. If you think about a city that’s smart about public transportation, they have the ability to take millions of cars off the road. Here are some other factors, that the report cites, which influence CO2 emissions in urban areas:
- A city’s geographic situation — influencing the amount of energy required for heating, cooling and lighting;
- Demographics — the size of the population influences the demand for space and services;
- Urban form and density — sprawling cities tend to have higher per capita emissions than more compact ones;
- The urban economy — types of economic activities and whether these emit large quantities of greenhouse gases;
- The wealth and consumption patterns of urban residents.
Of course, cities don’t have control over some of these factors. But when they recognize the factors they can control the impact can be profound.
Take New York City, for example. It’s a wealthy city located in a wealthy country. However, because of high population density and a vast public transportation network, it’s able to keep its annual CO2 emissions per capital down to 7.1 tonnes. Compare that with a less dense Washington D.C. which emits 19.7 tonnes of CO2 per capita each year. And while that’s still lower than the average in the U.S. — 23.9 tonnes — the world will need more cities like New York if cities are going to have a positive impact on climate change.
Photo: Chang’r/Flickr
[Via Grist]
