Carbon dioxide has long been regarded as the primary driver of climate change and, in 2013, the global concentration of carbon dioxide in the atmosphere hit 400 parts per million for the first time in recorded history at an observation station in Hawaii. Even more alarming than passing the 400 parts per million carbon dioxide threshold has been the rate that carbon dioxide emissions have been increasing. Between 2005 and 2014, the atmospheric growth rate for carbon dioxide was 2.11 parts per million per year, which outpaced the growth rate of any other decade in recorded history.
While the 2015 United Nations Climate Change Conference in Paris signaled that the great majority of the world’s leaders are at least aware of the problems that increased greenhouse gas emissions will have on our planet, the data cited above suggests the international community may be doing too little too late. The Paris Agreement, which was the global agreement regarding how to address climate change that resulted from the 2015 conference, would require zero net anthropogenic greenhouse gas emissions by 2050 at the very latest to avoid a global warming of 2 degrees Celsius. While there were 180 states that signed the Paris Agreement, only 23 of those states have ratified the agreement and none of the top emitters of greenhouse gases have ratified it. Efforts to address climate change have also stalled out in the United States. President Obama’s efforts to utilize to the Clean Air Act to regulate greenhouse gases was stalled by the Supreme Court this year when it granted a stay pending a decision by the U.S. Court of Appeals. The Republican Party has walked backwards on the issue and have repeatedly called into question the very existence of climate change and have asserted that the party would completely forbid the Environmental Protection Agency from regulating carbon dioxide emissions. Obviously, climate change is a complex problem both in terms of defining the impacts and identifying solutions. However, it is the later problem that is flummoxing both the international community and the United States government. The world is still operating and developing on an intensive diet of fossil fuels and marshalling the requisite resources and political will to reverse that course will be a Herculean task.
However, while climate change is an international problem, impacts are often felt locally. For example, as extreme rainstorms become more intense and more frequent, it will be Detroit residents’ basements that flood. This reveals one of the more unique aspects of climate change: it is often a local problem that ultimately requires a global solution. As the international community and federal government continue to struggle to craft an effective global solution, many local governments are realizing that local solutions need to be created for the local problems that are being causes by climate change.
One key problem that is becoming an increasing focus in Detroit is stormwater management. Detroit’s sewer system is one of the largest in the country. The city’s wastewater treatment plant not only services Detroit, but also 127 other communities in the metro-Detroit region. All told, the plant treats approximately 650 million gallons of waster water per day. All of the waste water that arrives at the treatment plant gets there via a combined sewer system that contains everything from raw sewage, industrial waste water, and storm water runoff. This means everything from what you flush down your toilet to the rain water running down the street goes to the same sewage system. When Detroit’s enormous waste water treatment plant is overwhelmed by the amount of sewage flowing to it and is unable to process it, a problem occurs. Either the untreated sewage that contains everything from your toilet to the storm water on the street is discharged into the Detroit River or Rouge River, floods the basements and streets of Detroit, or both.
For decades, Detroit has struggled to manage its sewer system, specifically during periods of heavy rain. As depicted in the picture above, Detroit streets and basements regularly flood during periods of heavy rain due to the sewer system’s insufficient capacity to handle the large amounts of stormwater. As extreme rain events become more intense and more frequent due to climate change, flooding may become more frequent and more severe. Comprehensively updating Detroit’s sewer system would involve tearing up streets and installing new sewer lines. Unfortunately, this solution is financially infeasible for Detroit and many other older cities. However, an alternative approach utilized by Detroit and many other cities has been to invest large sums of money in green infrastructure. While green infrastructure can mean many different things, for the purposes of this blog post it is essentially a project which seeks to reduce the amount of stormwater that goes into the sewer system and instead keeps it within the natural hydrologic cycle. Common examples include rain gardens and installing permeable pavement rather than impermeable pavement.
In 2013, the Michigan Department of Environmental Quality mandated that the Detroit Water and Sewage Department develop and implement a Green Infrastructure Plan for a 37.5 square mile area in Northwest Detroit. This plan is required by the permit that the Detroit Water and Sewage Department is required to obtain under the Clean Water Act in order to operate its water treatment facility. In addition to the Plan requirement, the permit also requires the Detroit Water and Sewage Department to spend, on average, $3 million per year until 2019 and an average of $2 million dollars per year between 2019 and 2029. All told, the Detroit Water and Sewage Department is required to spend $50 million on green infrastructure development over a course of 20 years. While the City has started to develop some green infrastructure projects, most of its activity to date has taken the form of planning.
Another large problem that Detroit struggles with that is perhaps more well-known is its problem with vacant land. When considered together, the problems of excessive stormwater and vacant land may seem oxymoronic. If a lot is vacant and only consists of an unmanaged lawn and no structure, one might think that any water that falls on that lot permeates into the soil. However, an analysis of the soil of vacant urban lots suggests that they may be part of the storm water problem as well. Considering that most vacant lots in urban areas once had structures on them, the soil that exists on vacant lots is usually very compact which limits the amount of stormwater that can filter into the ground. Fortunately, one of Detroit’s most ubiquitous solutions for vacant lots may also be one of its most ubiquitous solutions for storm water management. While not always referred to as green infrastructure, traditional urban agriculture that involves working with existing soil, adding compost, and planting fruit trees and vegetable crops is a very effective way to reduce stormwater runoff from vacant lots. In fact, a recent study found that tilling soil and adding compost alone can reduce stormwater runoff from a vacant urban lot by 65%. Another study found that every vacant land in Cleveland that is converted for agricultural use provides $103,185 in benefits to local residents. Ecological benefits, primarily in the form of reduced stormwater runoff, accounted for 65%, while 33% was a direct monetary benefit to the farmer and 3.22% was a benefit to surrounding property owners in the form of increased property values.
Clearly urban agriculture has a role to play in Detroit’s effort to reduce the amount of stormwater that is entering its sewer system. However, obstacles do exist. First, best management practices that focus on utilizing urban agriculture to reduce stormwater runoff must be developed. Questions of how to design an urban farm or which crops to select to maximize reductions in stormwater runoff remain largely unanswered. Second, and perhaps most importantly, cities such as Detroit must recognize urban agriculture as green infrastructure and integrate it into green infrastructure planning. As mentioned above, Detroit is obligated to contribute $50 million to green infrastructure development. Many of Detroit’s urban farms and gardens typically lack access to start-up funds. If even a small percentage of the $50 million that Detroit is obligated to spend for green infrastructure were utilized to help urban farms and gardens overcome the financial burdens of starting a new urban farm or garden, Detroit would not only be reducing stormwater runoff, but it would be helping local businesses turn vacant lots into food production sites that provide a multitude of benefits to the community.