Humanity sometimes finds it is easier to buy its way out of guilt or trouble. Take climate change, for example. As greenhouse gas emissions keep rising and the impacts worsen, the clamour to tackle our carbon sins gets ever louder – and the marketing spin ever more creative. This is where carbon offsets come in. These are often sold as a way to pay someone to reduce emissions caused by that taxi ride, that plane trip to an exotic destination or even electricity usage. Each offset represents a tonne of carbon dioxide (CO2) – the main greenhouse gas – that is either removed from the air, by planting trees for example, or not emitted in the first place.

These days, there are thousands of projects around the globe that aim to tackle climate change by hoovering up excess CO2 from the air or keeping it locked away – for instance, protecting a big patch of rainforest from being cleared for oil palms, cattle ranching or logging. Many of these projects are legitimate and are regularly audited. And many do a lot of good. Projects that bring much cleaner cookstoves to poor villages, for instance, cut air pollution (and carbon emissions) and reduce respiratory illnesses. Others bring renewable energy to places without power. Rainforest preservation projects in Indonesia, Africa and the Amazon keep the forests standing, improve livelihoods and also save many animal species.