New research finds that Verra’s buffer pool for REDD projects is way too small
“The numbers aren’t actually based on any science, as far as anyone can tell.”
Fires present a serious threat to forests. As the climate crisis worsens, that threat increases. In 2024, the area of tropical primary forests lost hit a new record. And almost half of the destruction was caused by fire.
But forest carbon offset schemes fail to take this threat into account.
James Dinneen, an environmental reporter at New Scientist, wrote last week that,
Many of the forest-based carbon-offset schemes certified by the world’s largest carbon registry, Verra, may be at risk of becoming useless due to wildfires or other disturbances releasing the carbon they store back into the atmosphere.
Forest carbon projects (which include industrial tree plantations) set aside “buffer pools” of unsold carbon credits, which are a sort of insurance if the forest is destroyed by wildfire, insects, drought, storms, illegal logging, or illegal mining operations.
Buffer pools are not big enough
Dinneen is reporting on a recent study published in Global Change Biology. The study is titled, “Current Forest Carbon Offset Buffer Pool Contributions Do Not Adequately Insure Against Disturbance-Driven Carbon Losses”. The authors are: William Anderegg of the University of Utah; Anna Trugman of the University of California, Santa Barbara; and German Vargas, Chao Wu, and Linqing Yang — the last three of the University of Utah.
The study found that buffer pools are not big enough to address the risks of forests being destroyed. Lead author William Anderegg told New Scientist that “The numbers aren’t actually based on any science, as far as anyone can tell.”
Predictably enough, Verra defended its current approach to buffer pool sizes. A Verra spokesperson told New Scientist that Verra’s decisions about the size of buffer pools are “grounded in a robust science-based risk assessment”.
Verra’s spokesperson added that few of the 76 million carbon credits currently in the buffer pool have so far been used. “Its effectiveness is demonstrated by the way the buffer pool has been maintained over time, even amid the risk of reversals,” Verra’s spokesperson told New Scientist.
But this approach completely fails to take account of the fact that the as the climate crisis intensifies the risk of forests going up in smoke will massively accelerate.
It also fails to take account of the increased droughts and fires in the Amazon, that are bringing the Amazon rainforest ever closer to a dangerous tipping point.
Fossil fuels and forest offsets
Emissions from burning fossil fuels remain in the atmosphere for centuries or millennia. Forest carbon schemes are used to offset emissions from burning fossil fuels.
“If you’re going to try to lock up that carbon in a bunch of trees, you’re going to have to guarantee that the carbon stays there for a very long time,” Anderegg told New Scientist.
Anderegg was one of the authors of a 2023 study by the Berkeley Carbon Trading Project at the University of California, Berkeley. That study looked at 67 REDD projects on Verra’s registry and found “a mean of 2% contributions to the buffer pool to insure all natural risk categories”.
The authors used data from 125 tropical forest plots in several countries to ask the following questions:
Do existing buffer pool estimates conform with historical data-constrained models of tropical forest carbon cycle dynamics?
What buffer pool contributions would be needed to adequately insure different disturbance frequencies and severities, while accounting for a wide range in observed forest growth and mortality rates?
How does forest age affect buffer pool contributions within established forests?
The authors write that,
We find that the buffer pool contributions in Verra's risk tool are inconsistent with forest biomass trajectories from a validated stand development model in the large majority of disturbance scenarios, especially at moderate or high frequency or severity of disturbance that are increasingly likely under climate change. The inadequacy of the current buffer pool estimates is much larger for older forests, such as those likely to be enrolled in avoided conversion or improved forest management, but still substantial in established but younger forests.
The authors found that Verra’s buffer pool is far too small to guarantee permanence in almost all scenarios. In some cases, the buffer pool requirement is more than 11 times smaller than required.
“For these natural risks, [the buffer] needs to be at least double, maybe more than double, to be adequate,” Anderegg told New Scientist.
The authors conclude that, rigorous Nature-based Climate Solutions urgently need:
to ensure buffer pool contributions reflect carbon cycle science and are based on rigorous and publicly available scientific datasets,
to use external and rigorous estimates of disturbance probability and frequency that are standardized by a third party and not chosen by project developers, and
to ensure that any risk amplification or deduction factors are based on rigorous science as well.
The authors note that ways of funding Nature-based Climate Solutions that do not involve carbon offsets, are a “promising pathway because the uncertainty and rising risks to forest carbon durability are much less of a concern due to the decoupling of forest carbon from fossil fuel emissions”.
Thank you for your work