BHP says it may need to rely on carbon offsets for a long period to solve the problem of “fugitive” emissions that escape from its open-cut mines, despite Fortescue chief Elizabeth Gaines’ warning that long-term reliance on offsets could leave companies vulnerable to soaring carbon offset prices in the future.

BHP has switched some of its assets – such as Chilean copper mines – to renewable power, and its sustainability vice president Fiona Wild said the company was working with vehicle manufacturers to ensure a substitute for diesel-powered trucks was available by the time a big replacement of its mining fleet was due later this decade.