Greenhouse Gas Emissions "101"

A few things I learned last week at the ECO Canada GHG Emissions Management Training Program:

1. Climate change has been correlated to changes in Greenhouse Gas quantities in the Earth's atmosphere, which traps (absorbs) more of the Sun's radiation and causes an increase in average global temperatures.

2. In addition to natural greenhouse gases ("GHG") such as water vapor and ozone, increasing amounts of carbon dioxide ("CO2"), methane ("CH4"), nitrous oxide ("NO2") and fluorinated gases ("HFC", "PFC", "SF4", "NF3") have contributed to the problem of global warming. The increase in these GHG's is attributed to human-caused activities, including the combustion of fossil fuels.

3. Greenhouse gas lifetimes vary, from 10-12 years for CH4 to hundreds of years for CO2 and fluorinated gases. Consequently, global warming will continue beyond the end or reduction of GHG emissions.

4. Each GHG has its own characteristic Emissions Factor ("EF") which describes the rate of emissions released (also referred to as emission intensity).

5. Each GHG also has its own Global Warming Potential ("GWP") which according to the EPA "is a measure of how much energy the emission of 1 ton of a gas will absorb over a given period of time, relative to the emission of 1 ton of carbon dioxide (CO₂). The larger the GWP, the more that a given gas warms the Earth compared to CO₂ over that time period. The time period usually used for GWPs is 100 years." The benchmark used is CO2, which has been assigned a GWP of 1. By comparison, CH4 has a GWP of 28 and NO2's GWP is about 265. Thus, a tonne of CH4 emissions has the same effect as 28 tonnes of CO2 over a 100 year period.

6. To calculate the overall impact of GHG emissions, the EF is multiplied by the GWP to come up with a CO2e (i.e. CO2 equivalent) value.

7. Tracking and reporting of GHG emissions are categorized as Scope 1, Scope 2 and Scope 3. Scope 1 emissions are direct emissions that occur within the defined boundary of a business ("inside the fence") and under the control of the company. Scope 2 emissions are associated with indirect sources, such as inputs for the business (eg. electricity). Scope 3 emissions are outside of the physical boundary of the business and not under the company's control (eg. waste generated by business, staff commuting & travel).

8. While companies meeting a minimum threshold of emissions must track and report their Scope 1 & 2 GHG emissions, tracking of Scope 3 is still optional. Some companies track and report Scope 3 emissions in order to incentivize them in developing better (i.e. lower GHG) products and services. This has resulted in "Extended Producer Responsibility" initiatives by companies like Nike and Apple to reduce the amount of products going to landfills as waste.