Assessing the limits of GGR effectiveness: webinar video

In the first webinar of the GGR programme’s lunchtime webinar series, Professor Simon Tett from the University of Edinburgh presented insights from the MERLiN (Metrics for Emissions Removal Limits) research project which has been assessing the limits of Greenhouse Gas Removal (GGR) effectiveness.

GGR would be essential in a scenario in which we ‘overshoot’ a safe level of CO2 in the atmosphere. The use of GGR to reduce this overshoot implies there will be a period where emissions will be higher than the figure required to meet target temperatures before the removal of greenhouse gases at a later date.

It is expected that climate change impacts resulting from this overshoot and later recapture pathway will be different to impacts associated with pathways in which no recapture is required. This disparity in impacts sets boundaries on GGR’s contribution and MERLiN aims to determine these limits.

Prof. Tett presented findings from two papers, reporting on issues around carbon accounting and the consequences of emissions overshoot.

Accounting for net carbon emissions

Carbon accounting represents one of the major challenges of effective integration of greenhouse gas removal. Researchers from the MERLiN project conducted a literature review to help establish what is needed to reliably account for net carbon emissions. From this they identified several important considerations in carbon accounting. These include the importance of the baseline, the type of life cycle analysis approach, the permanence of carbon storage and the need to apply the reality principle i.e. account for carbon emissions and removal when and where they occur.

Consequences of Emission Overshoot

Professor Tett also presented findings from the modelling of the impacts of emission overshoot. For this the research group used two scenarios – one that represents the ramping up of emissions based on the current situation and one that is a control scenario with indefinite zero emissions.

Using the FAMOUS climate model, the researchers have investigated the effects of a large positive and negative pulse of CO2. They estimated that there would be a rapid response in surface temperature and a slow response in sea level, where the longer the overshoot the larger the rise. The results imply that when there is an emissions overshoot and GGR, it is not possible to return to the same climate as before and that, if we do allow an overshoot, we will pay the sea level price as well as the continuing cost of climate change.

The webinar is the first of a series that the GGR programme is running through March and April. For more information on the other seminars read the news story

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.