Imagine (or maybe you don't need to) that you hanker after the safari trip of a lifetime in sub-Saharan Africa. A 17-day tour beginning at the iconic Victoria Falls, passing through Zimbabwe, Zambia, Malawi and Tanzania, taking in some of the continent’s most wildlife-rich national parks, and ending on the lush island of Zanzibar.

It’s just what you’re looking for – now you just need to raid the piggy bank or win the National Lottery.

The tour is run by an adventure travel group called Intrepid, that offsets the carbon emissions generated by the trip. In this case, that’s 18kg of carbon dioxide (often called CO2 equivalent or CO2e) per person per day, so a grand total of 306kg of CO2e.

Great, you think – not just the experience of a lifetime, but a guilt-free one, too.

But isn’t offsetting a con, you wonder? An analysis published last year, for example, found that 90 per cent of rainforest offset credits approved by the world’s leading certifier were worthless, arguably bringing the whole industry and concept down.

Intrepid, of course, would dispute this. Its global environmental impact manager, Susanne Etti, says Intrepid follows the rigorous Oxford Offsetting Principles and insists that any projects it invests in have benefits beyond carbon removal. “We ask if they provide employment or education, or whether there is a benefit to local biodiversity,” she explains. “Restoring ecosystems is a really big driver for us.”

Previously, Intrepid invested in a lot of wind energy projects, but now it is mainly reforestation, with a particular focus on India and Papua New Guinea. Artificial carbon capture and storage – a more controversial tool in the fight against climate change – is too expensive at the moment, Etti says.