Can carbon offsetting help to reduce global warming?

It is now widely accepted that global greenhouse gas emissions need to decrease as quickly, and as much, as possible to avoid dangerous climate change. We are using carbon offsetting as a way of reducing the impact of some of the emissions from everyday activities such as heating our homes, flying on holiday or business trips.

However, as Dr Vicky Pope, Head of Climate Change Advice, explains, carbon offsetting could give a false sense of security that we are tackling climate change and, although useful, is no substitute for directly reducing carbon emissions.

Recent work from the Met Office has shown that when a carbon offset scheme stops, the carbon is released straight back into the atmosphere. If this takes place before the carbon is naturally removed from the atmosphere any benefit is lost very quickly, resulting in the very warming that was trying to be avoided.

Good offset schemes act to remove the amount of CO₂ emitted and aim to do this over the whole lifetime that carbon will remain in the atmosphere. The Department of Energy and Climate Change (DECC) has recently introduced a quality assurance scheme, to help individuals and businesses choose a scheme that generates genuine and permanent CO₂ savings — critical in talking climate change well into the future. However, as the website points out, carbon offsetting is no substitute for actually reducing our emissions.

The Met Office has shown that carbon offsetting can only be fully effective if it has an impact that lasts as long as the original carbon emissions. This is very difficult to achieve for carbon dioxide, because it lasts so long in the atmosphere — currently around 100 years. If the trees are chopped down, or the renewable energy project is replaced by a more traditional energy project, then the carbon dioxide will be released straight back into the atmosphere — whether it is after one, ten or even fifty years — and the benefit will be lost very quickly over a few years. This could risk even larger impacts of global warming because of the speed of change. Ecosystems and people will find it harder to adapt if temperature rapidly increases.

Many offset schemes can not guarantee that they will remain in place for the long timescales needed to offset the original carbon emissions. Forests are under increasing pressure from the need to supply food, and, even more, from growing biofuels. Forests are also at increasing risk from climate change. As the climate continues to warm, the Amazon, in particular, is likely to dry out and start to die back. This puts additional risks on offsetting schemes that rely on planting trees. An alternative is the establishment of green technology in developing countries. However, it is essential that the technologies are workable, maintained for the long-term and would only have taken place because of the funding from the offset scheme.

Short-term carbon offsets on their own give a false sense of security as they are effectively masking long-term climate change and can be seen as a ‘get out of jail free’ card, giving permission for people to not change their behaviour. Carbon offsetting remains a useful way of reducing the impacts of some of the emissions from everyday activities that we cannot avoid, but only as part of other measures to reduce our carbon footprint.