In the Permian Basin of Texas and New Mexico, the racing heart of the US shale oil boom, there is generally not too much soul-searching about the implications for the climate of their production. The availability of truck drivers and pipeline capacity for transporting the oil to market are much more pressing concerns. Occidental Petroleum, the fifth-largest US oil group by market capitalisation and the holder of the largest net acreage of drilling rights in the Permian, is an exception.

Like its rivals including ExxonMobil and Chevron, Occidental is one of the key participants in that production boom. In the past three years, it has more than doubled its Permian shale output, and it expects to double it again to 6 0 0, 0 0 0 barrels of oil equivalent a day in the next five years. But at the same time, the company is committed to reducing its carbon footprint.

‘Tm thinking about the long term for our shareholders, “Vicki Hollub, Occidental chief executive, told the Financial Times in Houston. “We believe if you’re not addressing these [climate] issues today, you’re going to be behind the game.”

Ultimately, she wants Occidental to be “carbon neutral”: capturing greenhouse gases equivalent to all the emissions arising from its operations, its supply chain and the use of the oil and gas that it produces.

“We feel like that’s the key to the sustainability of our business over time,” she said.  “If you don’t have that, you almost don’t need to be in operation.”