Sometimes it is easy to miss the forest for the trees – probably the most apropos analogy in the carbon offset world. To my point, a new scientific analysis questions one cornerstone of offsets – how nature-based removals actually relate to current or future emissions. The general assumption that 1 ton of current emissions is negated by 1 ton of nature-based removal/sequestration is simply – and meaningfully – wrong, according to the study. Bloomberg summarized the main point:
“It’s important to emphasize that land and oceans are drawing down past emissions. That means they cannot be relied on to also neutralize future emissions.”
This makes sense, but it isn’t generally acknowledged. Emissions of CO2 (and anything else) float around in the atmosphere for some time depending on many factors. CO2 hangs around for a long time. It is implausible that ambient CO2 removals selectively exclude “old” CO2 and only absorb new emissions that can be accounted for in offset calculations.
Myles Allen, professor of geosystem science at University of Oxford and one of the study’s authors, said “the flaws in accounting are so significant that they could be concealing another 0.5C rise.”
How do we address this? Well, it’s a hard nut to crack. The study’s authors suggest – as a starting point:
“land management categories should be disaggregated in emissions reporting and targets to better separate the role of passive CO2 uptake; where possible, claimed removals should be additional to passive uptake; and targets should acknowledge the need for Geological Net Zero, meaning one tonne of CO2 permanently restored to the solid Earth for every tonne still generated from fossil sources.”
But the logic here isn’t limited to nature-based projects – it’s relevant to any technology that removes CO2 from ambient air, such as Direct Air Capture (DAC). Those solutions also don’t have a way to exclude old CO2 molecules, ensuring only new ones are removed. Perhaps some project developers/registries do estimate old versus new CO2 in calculating tradable removal offsets intended to net out current or future emissions. At the very least, it is something to think about.
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