A recently released study conducted in the UK suggests that cities have the ability to absorb 10 times more carbon dioxide than previously expected.
The study was conducted due to “a need for reliable data to help establish and underpin realistic carbon emission targets and reduction trajectories, along with acceptable and robust policies for meeting these goals.”
Urban areas do not currently make up a large portion of the earth’s surface, but it is still important to study the effect they have on global warming. Only approximately four percent of the earth’s surface is urbanized, but the number is expected to increase as the population rises from a current seven billion this year to 9.5 billion by the middle of the century. Scientists have long known that forests have the ability to soak up carbon dioxide due to photosynthesis, but urban areas have never been thought to be “sinks,” or areas that can absorb CO2. The study points out that the capacity of urban areas to absorb carbon dioxide has never been thoroughly studied because of “the perception that urban ecosystems have limited ecological value because they are heavily modified by humans and relatively small in size.” The study sought to dispel this myth due to increasing rates of urbanization.
The study, which was conducted by British scientists in the English city of Leicester, measured the ability of the city’s parks, fields, and other green areas to absorb CO2. Leicester, which has a population of 300,000 living in 28 square miles, was found to be able to absorb 231,000 tons of carbon dioxide, which is 10 times more than previously thought. The amount of carbon dioxide the city can absorb is equivalent to the yearly emissions of 150,000 sedans. A “vegetation survey” was conducted prior to the study, which recorded the types of vegetation in the city (i.e., herbaceous vegetation, shrubs, gardens) and whether they were publicly or privately owned. This helped the researchers determine the carbon dioxide absorbing capabilities of the city. The study also took into account the amount of trees and their density, which helped calculate their biomass and carbon storage abilities.
The study points out that urban “sinks,” while not a solution to global warming, do have the ability to minimize the impacts. Urban sinks are especially effective if the city has a large number of trees, which soak up more carbon dioxide than grass and shrubs. In Leicester, most of the publicly-owned land consists of lawns. The study points out that if 10% of the lawns are planted with trees, the capacity of the city to store carbon will rise by 12%. Trees provide numerous benefits to urban areas; in addition to storing carbon dioxide, they also provide shade while lowering temperatures.
The study encourages governments to protect carbon storage and lists the numerous benefits, including climate regulation, reduction of air and water pollution, decreasing surface water runoff, creating recreational opportunities, improving human health, and providing a habitat for various species. By improving upon urban areas, the effects of global warming can be minimized, which provides benefits both for the human and animal populations as well as the environment they live in.
The study coincides with the UK’s recent promise to cut carbon emissions by 80% by the year 2050. The study’s authors point out that “local governments are central to national efforts to cut carbon emissions, although the reductions required at city-wide levels are yet to be set.” If local governments in the UK heed the results of this study, it will be possible to absorb CO2 simply by planting more trees, helping the government meet its goal of drastic carbon emission reductions. In a world that is becoming increasingly urbanized, this most recent news is a small glimmer of hope that it is still possible to minimize the impacts of global warming, even with a rapidly growing population.
Photo Credit: health.utah.gov/enviroepi/activities/EPHTP/TrackingStates/new_york_city.jpg