Climate change is one of the greatest challenges of our time. Since the 1970s, the Great Lakes region has been warming at a rate of 0.4°F per decade and average winter temperatures are rising at a rate of 0.9°F per decade.1 By the end of the century, when scientists consider ‘business as usual’ scenarios with consistent growth in greenhouse gas emissions, summers in the Midwest may be more like the current summers in Arkansas or Mississippi.2 The latest science from the Intergovernmental Panel on Climate Change (IPCC), the U.S. Environmental Protection Agency (U.S. EPA), the U.S. Global Change Research Program, and a host of other research institutions, shows that climate change will increase the frequency and intensity of extreme weather events such as heat waves, droughts, and floods in the Midwest, as well as degrade air and water quality.3 These impacts threaten ecosystems, economic activities, public health, and infrastructure.
Responding to climate-related risks and joining global efforts to mitigate climate change involve adjusting current policies and decision-making at a variety of scales. The Detroit Climate Action Collaborative (DCAC), a multi-stakeholder group convened by Detroiters Working for Environmental Justice (DWEJ), is leading efforts in the City of Detroit to initiate policy reform and drive actions to reduce greenhouse gases, to increase the city’s climate change preparedness, and to seize opportunities for cost-savings that come from energy efficiency improvements. The Detroit greenhouse gas (GHG) inventory is a resource that facilitates climate-smart decisionmaking that leads to a healthy, vibrant Detroit.
This GHG inventory quantifies Detroit’s citywide emissions from calendar years 2011 and 2012. The inventory accounts for the anthropogenic GHG emissions of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O)4 and follows methods determined by U.S. EPA guidance and ICLEI Community and Municipal Protocols to model emissions from available activity data. These data were collected from a variety of sources, including DTE Energy, Southeast Michigan Council of Governments (SEMCOG), U.S. EPA, Federal Transit Administration’s National Transit Database, and various departments within the City of Detroit municipal government.
The inventory is organized into the following activity categories: energy use from buildings and facilities, passenger cars, trucks, and on-road freight, public transportation, and municipal vehicle fleets; industrial processes; solid waste landfill disposal and incineration; and wastewater treatment. Carbon dioxide sequestered or removed from the atmosphere by land use, specifically by Detroit’s trees, is estimated but reported separately (i.e., these emissions are not included in citywide totals), as directed by current inventory protocols.
Detroit’s total citywide emission calculations include emissions from the city’s municipal government operations, which are also reported and analyzed in a distinct municipal government inventory section of the report.
In general, GHG emissions are modeled using the parameters of annual activity data (such as electricity use) and emission factors (the per unit GHG intensity of the corresponding activity). For both the citywide and municipal inventory analyses, a variety of activity-specific models, data, and emission factors were used—all of which (along with corresponding complexities and limitations for each activity) are explained in detail in the methods presented in the inventory report and appendices.
Results from 2011 and 2012 show that citywide emissions were nearly equal, with approximately 10.6 million metric tons (million t) of carbon dioxide equivalents (CO2e) emitted in both 2011 and 2012.5
Because emissions values (and their proportional composition) were nearly identical across the two analysis years, most of the analyses in the report present 2012 emissions for simplicity. However, complete 2011 results and figures are included as appendices to the report.
In 2012, 63% of Detroit’s citywide emissions (6.7 million t CO2e) were a result of electricity and natural gas used in buildings and facilities within the city limits; these buildings and facilities include residential, commercial and institutional, and industrial customers of DTE Energy, the city’s primary utility company. Electricity use in the city contributed 45% to 2012 citywide emissions, due in part to DTE Energy’s fuel mix, which consists of more than 75% coal.6
Detroit’s citywide emissions per person or per capita emissions (15.2 t CO2e/person) were approximately 27% less than the United States average per capita emissions (20.7 t CO2e/person) in 2012.
Detroit’s per capita emissions are lower than both the national and State of Michigan7 averages in this comparison. The difference can be attributed in part to the fact that inventory accounting standards and available data for national and state-level inventories tend to be more comprehensive (in the GHGs, activities, and emission sources included) than those of local GHG inventories. While the 2012 per capita emissions in Detroit are lower than those reported by the State of Michigan in 2002, Detroit, as a more urbanized area, may still have relatively higher and more concentrated amounts of commercial and industrial activity, as well as greater energy demand, than many other areas of the state. Accordingly, when comparing and differentiating these local, regional, and national inventories it is important to carefully examine the potential differences in methods and drivers of emissions at different scales of analysis.
In a comparison of fourteen select North American cities, Detroit’s total 2012 citywide emissions (10.6 million t CO2e) fell below the sample’s average (14.8 million t CO2e). While the cities selected for this comparison have some similarities, it is important to keep in mind that their inventories, populations, and infrastructure are all quite different from one another. They have, for example, conducted inventories for a range of different years and have used different geographic boundaries, assumptions, protocol resources, and methods than the City of Detroit analysis. As a result, this comparative analysis is only meant to provide a high-level view of the range of emissions contributed by different cities and Detroit’s relative position in this sample.
Other Citywide Key Findings
- Approximately 41% of emissions from stationary sources, such as buildings and facilities, are concentrated in four of Detroit’s thirty Zip Codes (these high-emitting Zip Codes are 48217, 48209, 48211, and 48226);
- The Commercial and Institutional end-use sector—which includes retail goods and services, non-profit agencies, and academic institutions—accounted for more than 50% of the buildings and facilities total emissions in 2012;
- Passenger car, truck, and on-road freight contributed 98% of total citywide transportation emissions. The municipal government vehicle fleet and public transportation vehicles contributed only 2% of citywide transportation emissions;
- Two industrial process facilities, the Air Products and Chemicals Inc. hydrogen facility and the Marathon Petroleum Co. petroleum refinery, are responsible for 3% of total citywide emissions; and
- Carbon sequestration from tree canopy cover—estimated to be slightly more than 0.07 million t CO2e annually—is relatively small compared to the citywide emissions total (i.e., less than 1% of that total). Nonetheless, this supplemental land use analysis is of great interest to Detroit stakeholders, who are particularly interested in land use mitigation strategies, given the city’s size, the amount of vacant land, and the potential for cobenefits to climate adaptation and public health goals from urban forests.
Municipal Inventory Key Findings
- City of Detroit’s municipal government operations accounted for 11% (1.18 million t CO2e) of 2012 emissions.
- In 2012, four City of Detroit departments (Detroit Water and Sewerage Department, Detroit Public Lighting Department, Detroit Department of Public Works, and Greater Detroit Resource Recovery Authority) were responsible for 93% of City of Detroit’s municipal emissions.
Conclusions and Next Steps
A coalition of community, government, private sector, and academic leaders are in the early stages of developing a strategy to address climate change and incorporate climate change mitigation and adaptation into long-term planning decisions in the City of Detroit. Adaptation and mitigation choices in the near-term will affect the risks that climate change imposes locally throughout the coming century. This report, in analyzing the GHG emissions of the City of Detroit, identifies key activities and sectors at both citywide and municipal operations scales that contribute the largest relative amounts of GHG emissions. Drawing from the results, activities can then be targeted for improvement and mitigation.
The City of Detroit GHG inventory supports ongoing work in Detroit that seeks to establish emissions reduction and energy efficiency targets. It also encourages the development of both implementation strategies and a system to conduct future inventories in order to benchmark progress over time.
Improving the inventory process, conducting regular inventories, and incorporating these inventory results into decision-making will be critical for evaluating progress toward emissions reductions targets and for identifying cost-savings opportunities in the future.
As a result, in order to continue to build momentum around this work and to improve future inventory processes, the project team recommends that DCAC and the City of Detroit prioritize the following:
- Conduct citywide and municipal GHG inventories at regular time intervals to monitor and to evaluate progress toward emissions reductions goals and impacts from policy changes;
- Collaborate across organizations and departments to facilitate efficient, accurate, and timely data collection for tracking activities and emissions;
- Consider measurable climate mitigation, efficiency improvements, and climate adaptation actions synergistically.
To produce the first inventory of Detroit’s GHG emissions, the project team spent more than a year gathering and analyzing data and consulting with more than 50 organizations in and around the city. Once a preliminary inventory report was completed in April 2014, the project team continued to engage with the Detroit community and DCAC in order to strengthen the impact of this work, by verifying GHG inventory results presented in this preliminary report with additional support from the University of Michigan Center for Sustainable Systems, undertaking a report review and vetting process, and hosting a presentation and discussion of inventory results with data contacts and DCAC stakeholders.
Next steps in the DCAC process include beginning to share inventory results more broadly through publicly available materials, presentations, and stakeholder meetings. In addition, materials developed by this project will assist in the development of future Detroit GHG inventories, the continued reporting by the City of Detroit to the Carbon Disclosure Project, and ultimately the development of a comprehensive Detroit Climate Action Plan.
1 UCS (2009)
2 U.S. Global Change Research Program (2009)
3 IPCC (2013), U.S. EPA. (2013a), U.S. Global Change Research Program (2013)
4 The anthropogenic GHGs hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6) were not included in this analysis based on current protocol and data availability.
5 While this approximately 1% increase (about 0.07 million t CO2e) in total citywide GHG emissions was found between 2011 and 2012, it is important to keep in mind that this difference (or its directionality) may not be significant in reality, given the precision and comprehensiveness of data, methods, and models used.
6 DTE Energy (2014)
7 A GHG inventory completed for the State of Michigan by the University of Michigan Center for Sustainable Systems presents statewide emissions from 2002 (Bull et al. 2005). Michigan has not updated its inventory since this time. It is important to keep in mind the difference in the inventory analysis years and that the state’s emissions per person may have changed since the analysis cited here was performed.