Even if global greenhouse gas (GHG) emissions were cut to zero today, long-term impacts resulting from what has already been emitted will require carbon source control and a resiliency and adaptation strategy. Despite increasing awareness and the “eco-friendly” steps corporations have been taking in recent years, climate modeling projects indicate that maintaining current levels of GHG emissions will increase global mean temperatures from between 3.7°C to 4.8°C by the end of the century.

To address this, the Carbon Disclosure Project (CDP), World Resources Institute (WRI), World Wildlife Fund (WWF), and the United Nations Global Compact (UNGC) formed the Science Based Targets Initiative (SBTI), which promotes the adoption of credible, science-based GHG emission reduction targets. According to the SBTI, targets are officially “science-based” “if they are in line with the level of decarbonization required to keep global temperature increase below 2°C compared to preindustrial temperatures.” The initiative has developed a set of free, publicly available tools to encourage companies to adopt policies that will keep them on track to meet the emissions thresholds.

The transportation sector accounts for a significant portion of Scope 1 (Direct) global GHG emissions (see note 1). According to a report published by the co-founders of the SBTI, the transportation sector was responsible for 14 percent of the 49 Gt CO2e (see note 2) of global GHG emissions in 2010. The majority of transportation sector emissions are a result of the combustion of fossil fuels in internal combustion engines. The good news is that this gives the sector a high emission reduction potential, as technological advancement continues to provide us with alternatives to internal combustion engines. The Opportunity Agenda of America’s Pledge, released at the Global Climate Action Summit in September, names “accelerating electric vehicle adoption” as one of the ten high-impact opportunities to focus on.

In 2015, the founders of SBTI published The Sectoral Decarbonization Approach (SDA), an SBT implementation method, along with an Excel tool that companies can utilize to set science-based emission reduction targets. The global carbon budget, as calculated by the International Energy Agency, is 1,055 GtCO2 emissions from 2011 to 2050, 236 GtCO2 (22.4 percent) of which the SDA allocates to the transportation sector. The SDA allows transportation-focused organizations to work together, within a framework, to keep the sector allocation target moving forward.

The SDA recognizes five subsectors of transportation that vary in terms of activity level, emission reduction potential, and carbon intensity. Based on the SDA, even with an expected increase in activity in all transportation subsectors, the overall carbon emissions of the transportation sector have the potential to decrease significantly with a reduction in carbon intensity due to electrification. For example, the activity level of the light-duty road passenger transportation subsector (measured in revenue passenger kilometers) is projected to increase 79 percent from 2010 to 2050. Reducing carbon intensity 76 percent by 2050 will decrease emissions from 2.9 to 1.2 GtCO2 and keep light passenger transport in line with the 2°C scenario.

The International Energy Agency proposes three strategies to reduce the carbon intensity of this subsector: (1) avoid, which takes advantage of city planning to reduce the travel needs of the individual; (2) shift, which promotes and enables individuals to use more efficient transportation modes; and (3) improve, which encourages the adoption of energy-efficient technologies (specifically hybrid and electric vehicles). The transportation sector has a daunting challenge to make a difference in avoiding the global climate tipping point, but with the creation of the SBTI and its SDA, along with promising innovation in electric vehicle, hybrid, and battery technology, the 2°C pathway scenario is within reach.

To learn more about SBTI and other source reduction and adaptation strategies, please reach out to Breanna Sewell and Chris Easter.


  1. Scope 1 emissions are direct emissions from sources owned or controlled by the reporting company. They are the most straightforward to estimate and track, whereas Scope 2 emissions are indirect GHG emissions that are a consequence of the activities of the reporting entity.
  2. CO2e, CO2 equivalent, is a unit used to express the global warming potential of GHGs as a single figure, namely the equivalent amount or concentration of carbon dioxide.