CALCULATe emissions

When comparing online calculators, the difference in emissions output should not differ significantly from one calculator to another; however, there are a few reasons as to why differences may occur. Some calculators may use different criteria to calculate emissions. Variations in individual behavioural estimates, accounting for radiative forcing, and uplift factors can also affect the carbon emissions output.

Another reason may be that some calculators could be out-of-date since emissions factors are updated every year.

We recommend that when determining the accuracy of an online calculator, you only use calculators that:

• provide sources for emissions factors – including the date published
• use radiative forcing and account for an uplift factor

Ostrom Climate’s online flight and car emissions calculators are created by our analyst team based on The Greenhouse Gas Protocol: A Corporate Accounting and Reporting Standard, Revised Edition, as it is the industry standard. We also ensure that we are using the most up to date emissions factors in all of our calculations, which can be found below:

• C. Best Practices Methodology for Quantifying Greenhouse Gas Emissions, 2022; https://www2.gov.bc.ca/assets/gov/environment/climate-change/lg/lgcap/2023/bc_best_practices_guidance_on_quantifying_ghg_emissions.pdf
• National Inventory Report (Parts 2 and 3) 1990-2021: Greenhouse Gas Emission Sources and Sinks in Canada (2023); https://publications.gc.ca/site/eng/9.506002/publication.html
• Natural Resources Canada – Comprehensive Energy Use Database, 2020; https://oee.nrcan.gc.ca/corporate/statistics/neud/dpa/menus/trends/comprehensive_tables/list.cfm
• UK Government’s GHG Conversion Factors, 2023; https://www.gov.uk/government/publications/greenhouse-gas-reporting-conversion-factors-2023
• eGRID Summary Tables 2021, US EPA; https://www.epa.gov/egrid/summary-data
• Government of Canada Fuel Consumption Ratings, 2023; https://open.canada.ca/data/en/dataset/98f1a129-f628-4ce4-b24d-6f16bf24dd64

Emissions factors are multipliers that enable one to calculate the amount of greenhouse gases produced from an activity. We work to ensure that the emissions factors in our calculator are up-to-date, such that we can provide the most accurate and detailed representation of your carbon footprint. Most emissions factors are updated annually, but some government agencies do not update factors every year, which is why you’ll see sources as old as 2020 in the list above.

The IPCC’S “Aviation and the Global Atmosphere” report also recommends that a radiative forcing factor being included, and the UK Government recommends that an uplift factor also be used when calculating flight emissions. Condensation trails (contrails) may also impact these calculations.

What is radiative forcing?

The IPCC defines Radiative Forcing (RF) as “a measure of the importance of a potential climate change mechanism. It expresses the perturbation or change to the energy balance of the Earth-atmosphere system in watts per square metre (Wm­^-2). Positive values of radiative forcing imply a net warming, while negative values imply cooling.”

The IPCC has also indicated that the location of emissions from aircrafts is a further driver for climate change, “Aircrafts emit gases and particles directly into the upper troposphere and lower stratosphere where they have an impact on atmospheric composition. These gases and particles alter the concentration of atmospheric greenhouse gases, including carbon dioxide (CO­₂), ozone (O₃), and methane (CH₄); trigger the formation of condensation trails (contrails); and may increase cirrus cloudiness—all of which contribute to climate change.”

https://www.ipcc.ch/site/assets/uploads/2018/03/av-en-1.pdf

What is an uplift factor?

The uplift factor adds 8% to emissions based on distance flown, due to aircraft stacking (circling), and the fact that some routes are not direct (e.g., due to weather conditions, or flying around international airspace, etc.).

What are contrails?

During flight, airplanes’ engines produce condensation trails (contrails) from their exhaust, putting out a thermal blanket of linear clouds made up of ice particles. While they only last in the atmosphere for a short time, they have a direct impact on climate change.