To offset or not to offset? We asked three prominent climate scientists what they think of the murky world of offsetting.
Johan Rockström, the director of the Potsdam Institute for Climate Impact Research and chief scientist at Conservation International, which manages a number of carbon offsetting projects, says that offsetting can be valuable but only if companies are already cutting their carbon emissions by at least half each decade, from now to reaching net zero in 2050. They can buy offsets as an additional effort, beyond those reductions, but the offsets cannot be used as a substitute for those stringent emission-reduction requirements.
Rockström told the Guardian: “On the one hand, carbon offsetting is necessary, and has positive potentials of providing incentives and thereby generating much-needed investments, for example in nature climate solutions [such as forests]. On the other hand, there is a large risk of misuse of offsetting, if used (as often is the case) to compensate for the inability to follow the scientifically defined mitigation pathway.” He argues that a sound pathway requires cutting emissions by half each decade. This is now the requirement of the Science Based Target initiative (SBTi), which certifies whether companies are in line with the Paris agreement.
While companies should not use carbon offsets as a substitute for making real emissions reductions, they should still be encouraged to buy offsets, he argues. That is because the world is doing badly at keeping its existing forests standing, even though these are vital if we are to stay within 1.5C of global heating.
Only by ensuring that forests remain intact, by protecting the oceans so they can still act as a carbon sink, and by growing new forests and changing our agricultural practices so that soils store carbon instead of releasing it, can we hope to stay within a 1.5C limit.
Offsets, correctly managed, can help to achieve these goals, and therefore can be a wise investment for the good of the planet. “Carbon offsetting is important but can only be an additionality – we need to get off fossil fuels, and do carbon offsets,” he said.
Simon Lewis, professor of global change science at UCL, says carbon offsetting can bring benefits, particularly in funding forest protection, but with strong caveats.
“We are clearly not doing a good job of getting cash to our forests,” he says. “We need to think about that, particularly forests in the tropics – we should be funding these global assets. Ideally that should be separate from the carbon markets – through a levy on fossil fuels, or on international financial transactions, for example. But there are ways of funding forests through offsets. There should be a debate about all this.”
He said generating high quality credits was possible. “We want there to be more good credits that are really beneficial, and less scam credits. The problem with the carbon markets is that they’re a wild west, they’re unregulated.”
He said: “I think the carbon markets have a place, as we do not have other mechanisms, but they really have to be highly regulated, otherwise people are buying hot air, and things they don’t know the true value of. I think scientists are quite sceptical of the carbon markets.”
People should also look behind the carbon markets to the reasons why forests are under threat. “One of the biggest drivers [of forest destruction] is agriculture. So people should be eating less meat, as that would free up space for nature.”
Kevin Anderson, professor of energy and climate change at the University of Manchester, says that offsets are actively dangerous. “My take on offsets, even supposedly good ones, is that from a climate perspective they are worse than doing nothing.”
This is partly owing to the “rebound” effect, he says. Essentially, if people think their carbon-emitting activities are covered by offsetting, they have no incentive to really reduce their emissions, and this encourages the continuation and even expansion of high-carbon activities.
Think of flying – if you believe that your flights are carbon-neutral, you will continue to take more of them.
Another issue is the time lag between the emissions and the impact of the offset. Each flight you take is pouring carbon dioxide into the atmosphere, where it will continue to heat the planet, even though the trees you consider to be offsetting your journey are taking up to a century to grow.
For Anderson, there are also equity issues – offsets are often used to cover for high-carbon activities in richer nations, without really benefiting the poor countries they are often bought from.
Anderson says: “The timeframe for cutting CO2 associated with “pursuing … 1.5C” and “well below 2C” [the requirements of the Paris agreement] is now so tight that there is no emissions space for companies to use offsetting as a means of further locking in high-carbon activities, technologies, norms and practices, even under the heroic assumption that offsetting actually works. Put simply, we need to pull every mitigation level to its max level; there is no longer any give or flexibility in the system.”
He adds: “Trees, and temporary CO2 sequestration, are not an offset for an essentially permanent transfer of carbon from the lithosphere into the atmosphere.”
