CO2, CH4, N2O and SF6 emissions compared

This article from The Conversation compares the contribution to global heating of several of the emissions that humans create, including the gas SF6 that leaks from electrical insulation used in all forms of electrical transmission, from both renewable and non renewable sources.

SF₆ is a man-made, colourless, odourless gas and is indeed the strongest greenhouse gas in the Earth’s atmosphere. On a per molecule basis, SF₆ is approximately 23,500 times more effective at trapping heat than CO₂ and lasts in the atmosphere for about 1,300 years. SF₆ is an effective electrical insulator for circuit breakers and switches (collectively known as switchgear) and helps prevent accidents and fires. Switchgear is leaky and inevitably emits some SF₆ to the atmosphere. Renewable energy installations require more switchgear in the electricity grid than fossil fuels, because it takes more solar panels and wind turbines to produce the same electrical output as a single coal power station. So as renewable power generation grows, emissions of SF₆ to the atmosphere should grow too.

The global concentration of atmospheric CO₂ today is about 410 parts per million, whereas the global concentration of SF₆ is only about 10 parts per trillion. In other words, there is 41 million times more CO₂ in the atmosphere than SF₆. But since SF₆ is 23,500 times stronger at trapping heat than CO₂, doesn’t this still mean it’s a bigger problem than CO₂ for the climate? CO₂ is actually a very weak greenhouse gas and is much less efficient at trapping heat compared to other greenhouse gases, such as methane (CH₄) and nitrous oxide (N₂O). The reason why CO₂ has the largest impact on the climate is partly because, like SF₆, it is very long-lived. But mostly, it is because there is so much more CO₂ in the atmosphere than other greenhouse gases (except for water vapour, which is not the main driver of anthropogenic climate change because it is so short-lived).