One answer, in light of Mr Gore's decision to sell his Current TV channel to Qatar-financed Al Jazeera, is that it would cause sleepless nights for his new friends in Doha, who make their money by selling fossil fuels to the world. Their success had made them very, very rich – and also given Qatar the largest per capita carbon footprint in the world.

This inconvenient truth was omitted from the email announcing the deal, sent to Current TV staff on Wednesday by Mr Gore's partner in the broadcasting project, Joel Hyatt.

Mr Gore has long campaigned about the environmental damage done by fossil fuels (in the process earning a Nobel prize). Now he has first-hand experience of its economic benefits, after the Qataris reportedly paid around half a billion dollars for Current TV. Based on his reported stake of around 20 per cent, the former VP is expected to net around $100m (£60m) from the sale, a healthy gain on the $60m that Mr Gore and his partners are reported to have paid for the channel in 2004.

While it makes Mr Gore richer, the deal gives Al Jazeera a way to expand its reach in the US. Despite its record of awards and commendations for its international coverage, particularly during the Arab Spring, it has faced an uphill battle in convincing Americans that it is a legitimate news organisation, not a propaganda tool for oil-rich Gulf states or Islamist militants.