Our thinking

No time to lose

13 September, 2024

The general idea behind reaching net zero is simple: reduce emissions as much as possible and rebalance any remaining emissions with removing carbon from the atmosphere. But a huge amount of complexity arises from the social and economic impact of all the decisions that need to be made to put this into reality.  

There are complex questions about where to focus emissions reduction efforts, with some emissions sources considered harder to abate than others. One often-overlooked element is how to prioritise when to reduce emissions. Frameworks such as the Science-Based Targets initiative (SBTi) are focused on the percentage reduction endpoint, while lifecycle assessments measuring emissions over a product or project’s whole lifespan condense emissions produced over long periods into a single point in time. 

A new report by Arup challenges the assumption implicit in calculation methodologies that the timing of emitting GHGs has no influence on their environment burden and asks how much we should value delaying emissions. It’s a fairly technical read, drawing on ideas from climate science and economics to explore the ‘time-value of carbon’ using three arguments: that delaying emissions buys time to prevent those emissions being produced at all, reduces their cumulative climate impacts, and allows us to value the welfare of today’s society higher than of the future’s. 

Each of these arguments has subjective elements and the authors suggest that reflecting these considerations into emissions calculations would complicate them too much. But nonetheless, it’s a valuable insight and opportunity to challenge the subjectivity and assumptions in how we calculate and model emissions, which – given how emissions calculations underpin the complex decisions around how to reduce emissions – is well worth giving some time to. 

By Patrick Bapty