Secondary GHG Effects

Definition

A Secondary GHG Effect is an unintended change caused by a GHG Project Activity in GHG Emissions, removals, or storage associated with a GHG source or sink.

Project activities often produce changes in GHG emissions aside from their primary effects—and these are termed secondary effects. As with primary effects, these secondary effects are defined as a difference in GHG emissions between the GHG Baseline Scenario and the project activity. The baseline scenario used for estimating the secondary effects is the same as that identified for the related primary effect.

Secondary effects may be “positive” (e.g., involving a reduction in GHG emissions) or “negative” (e.g., involving an increase in GHG emissions). Secondary effects are typically small relative to a project activity’s Primary GHG Effects. In some cases, however, they may undermine or negate the primary effect. Therefore, it is wise to consider the type and magnitude of secondary effects before proceeding with rest of the GHG Project Protocol.

Secondary effects are classified into two categories:

• One-Time Effects: Changes in GHG emissions associated with the construction, installation, and establishment or the decommissioning and termination of the project activity.
• Upstream and Downstream Effects: Recurring changes in GHG emissions associated with inputs to the project activity (upstream) or products from the project activity (downstream), relative to baseline emissions.

Some upstream and downstream effects may involve market responses to the changes in supply and/or demand for project activity inputs or products. Only significant secondary effects, however, need to be monitored and quantified under the GHG Project Protocol. Whether a secondary effect is considered significant depends on its magnitude relative to its associated primary effect and on circumstances surrounding the associated project activity.

One-Time Effects

One-time effects are identified by considering whether the project activity will require any practices, processes, or consumption or production of energy or materials during its establishment and termination that will cause a change in GHG emissions unrelated to the primary effect.

For some types of projects, large one-time effects may arise during construction or establishment from the transportation of equipment, or manufacturing and use of cement used in construction. During the decommissioning or termination phase, the one-time effects to consider may be associated with off-site waste disposal and dismantling equipment.

One-time effects during the establishment phase can also be large for some land-use projects. For example, reforestation and afforestation projects often require the clearing of vegetation to prepare a site for planting. This results in GHG emissions from the machinery used to clear the site, as well as the release of stored carbon from the cleared vegetation and disturbed soils.

Issues and Challenges

• One-Time Effects concern secondary effects on emissions. Other unintended effects are outside the GHG protocol. See e.g. Do No Significant Harm Principle