Scientists have been able to determine the carbon footprint for 13,000 cities across the world for the first time. They were able to find that smaller cities that are overlooked during other studies also share some of the blame primarily taken by the largest cities in the world.
They found that the top 100 cities can have a large impact on the amount of carbon in the atmosphere.
Carbon Footprint Of 13,000 Cities
Researchers from Norway, Japan, Sweden, and the United States published a paper in the journal Environmental Research Letters that shows the carbon footprints of cities worldwide. Lead author of the study Daniel Moran from the Norwegian University of Science and Technology says that the top 100 highest-footprint cities are responsible for around 20 percent of the global carbon footprint. Moran says that this number could be lowered if local governments are able to tackle the carbon footprint issue.
They were able to focus on specific urban areas due to their outsize carbon footprint compared to size. Researchers used economic data that determined their outsized role in the process. Economists tout that 60 percent of global GDP is generated by only 600 urban centers. These urban areas also have 54 percent of the global population and are responsible for 70 percent of global energy use.
Scientists used a model that showed that income is a strong predictor of a city's carbon footprint. People in larger cities will have more disposable income, are able to take a trip to a country that requires airplane travel, and may also be able to own a car. Researchers also used previous data that estimated carbon footprints for 31,000 U.S. ZIP codes along with state and province results for the European Union, the UK, China, and Japan. Spending patterns were also factored in the model that researchers used.
Results Of The Study
To define cities for the study, researchers used the European Union model that defines a city as a contiguous densely populated area. Scientists found that carbon footprints are concentrated in a smaller number of dense, high-income cities and affluent suburbs. They also found that 41 of the top 200 cities are in countries that have low carbon emissions such as Senegal, Egypt, and Peru.
Researchers found that in 98 of the 187 countries that were studied, the top 3 largest urban areas are responsible for more than one-quarter of those countries' carbon emissions. Scientists also found that decarbonization measures such as limiting nonelectric vehicles and requiring 100 percent renewable electricity would be able to reduce emissions substantially.
The authors published the list of the top 500 cities from the study.