BP has become the biggest oil and gas company to promise a cut in its carbon emissions to net zero by 2050.

Bernard Looney, BP’s new chief executive, said today that it was “no longer enough” to provide reliable and affordable energy, it had to be cleaner too. “For BP to play our part and serve our purpose, we have to change,” he said in a statement. The company said it would need to “fundamentally transform” itself to meet its new net zero ambition.

However, the pledge does not cover emissions produced when oil and gas is burned by the firms’ customers, which amounts to BP’s biggest contribution to climate change.

The company also made no promise to rein in hydrocarbon exploration and production over the next decade, which is expected to increase significantly .

It is also unclear how and when BP might transition into renewables. The company said today that it would increase the share its $16bn-plus annual spending outside of oil and gas over time, but gave no figures or dates. The company came 7 ^th in a recent ranking of oil companies’ investments in low carbon projects.

Campaigners said key questions were not answered. “How will they reach net zero? Will it be through offsetting? When will they stop wasting billions on drilling for new oil and gas we can’t burn?” said Charlie Kronick at Greenpeace UK, in a statement.

Repsol of Spain last year became the first oil and gas company to set a net zero goal . More details on how BP will deliver its ambition are expected in September.