By Becca Stock

“From this we may conclude that increasing pollution of the atmosphere [by greenhouse gases] will have a marked influence on the climate of the world.” This prediction is from an article by H.A. Phillips in Nature from 1882 (Rathi, 2016). This may be the first in a series of warnings from scientists regarding the impacts of greenhouse gases (GHG) on our global climate. Over time, more and more scientists began to measure emissions, track temperature, and model impacts to better understand climate change and make the case for climate action.

Figure 1: ICLEI USA’s Five Milestone Program for Systematic GHG Emissions Reduction.

Starting in the 1990s, some cities began understanding their role and responsibility to address climate change. These trailblazing cities began using models like the Five Milestone approach from ICLEI (Figure 1) to understand and address local emissions. The first step in this process is to develop a GHG inventory of emissions within the city by source – helping cities understand the major sources of GHG emissions in their community and allowing them to target reduction goals and strategies.

Locally, the City of Fort Collins developed its first GHG inventory in 1999. That inventory estimated the City’s total emissions in 1990 and showed that 96% of those emissions came from electricity, natural gas, and on-road transportation (City of Fort Collins, 1999). Later, the City established 2005 as the baseline year as it used the Five Milestones approach to develop its Climate Action Plan. In 2017, the City reported a 17% reduction of city-wide emissions below the 2005 baseline, which is significant progress toward the goal of 20% reduction by 2020. Clearly, this model can be an effective mechanism for facilitating GHG emissions reductions efforts.

Now, almost 30-years after ICLEI was established, emissions profiles of cities are much better understood, GHG accounting protocols are more developed, and the need for impact is much more urgent. Is the Five Milestones model still the most effective approach?

GHG emissions data are much more readily available from public sources, so a city can quickly develop a basic understanding of the magnitude and the relative contributions of their major emissions sources. Some of these resources include the following:

  • Cities LEAP – A resource developed by the US Department of Energy that provides estimated electricity, natural gas, and transportation fuel use for communities.
  • EPA FLIGHT – This tool shows reported emissions from any large facilities within a city’s boundaries, providing industrial emissions and in some cases waste or fugitive natural gas emissions.
  • eGrid – These data provided by the US Environmental Protection Agency show regional emissions factors for electricity emissions.
  • Environmental Insights Explorer – This tool is in development by Google to estimate city emissions from electricity, natural gas, and transportation based off Google maps data.
  • GHG inventory emissions calculations from peer cities.

A community can use a preliminary draft inventory from the resources above to establish emissions reduction goals and develop and prioritize strategies for reduction.  As consultants, it is our job to work with cities to help identify strategies that will not only reduce their GHG emissions (climate change mitigation), but also increase their ability to respond to and recover from climate change impacts (also known as climate change adaptation, resiliency, and/or adaptive capacity). By prioritizing strategies that have co-benefits in mitigation and adaptation, a city can work locally to increase its resiliency while contributing to the global effort to eliminate GHG emissions.

Figure 2: Suggested Revised Approach for Systematic GHG Emissions Reduction

Once these strategies have been identified, we refine the preliminary GHG inventory (Figure 2). Thoughtful inventory development allows a city to track the impact of each mitigation strategy on a cost per metric ton emissions reduction basis. Through this process, the inventory is not just an estimation of the city’s GHG emissions, it is also a tool to evaluate strategy effectiveness. This allows a city to close the loop on the plan-do-check cycle and discard strategies that are ineffective – maximizing resources to focus on those strategies with the largest emissions reduction impact.

Now that many cities are starting to see the effects of global climate change, we need to shift from measuring and documenting GHG emissions to diligent data-driven implementation of mitigation and adaptation strategies that will improve our communities’ and our world’s resiliency to the changes we are sure to see in the next few decades.


About the Author – Becca has a strong background in energy efficiency measures for industrial customers though her experience at the Colorado State University Industrial Assessment Center. Also, she has been involved in researching and designing a commercial refrigeration heat recovery system that successfully brought industrial energy efficiency principles to a small commercial scale. At Brendle group, she employs her expertise to assess and quantify energy efficiency opportunities for commercial and institutional customers. She also applies energy efficiency principles on a larger scale for climate action planning, greenhouse gas accounting, and community energy planning, as well as analysis of renewable energy feasibility across these projects.

Outside of Brendle Group, Becca puts her degree in Zoology to work volunteering at a local wildlife rehabilitation center.