"We have a history of embracing transparency and disclosure," Fiona Wild, BHP vice president of sustainability and climate change, told a summit on Thursday.

Rather than greenwashing, BHP was guilty of "radical transparency", Dr Wild told the Carbon Markets Institute summit.

But she conceded it has become much more important that there is no misalignment in what you say and do.

"Offsets are a really important tool but we must reduce emissions first," Dr Wild said.

BHP has been active in carbon markets for the past decade.

A Forests Bond launched five years ago demonstrated there is a value in keeping forests standing, she said.

The bond provides a choice for investors to receive coupons in the form of carbon credits instead of cash coupons.

BHP is "going hard" on using renewable energy across its operations but replacing the diesel fleet is harder, she said.

BHP commitment's to reduce operational emissions, known as Scope 1 and Scope 2, by at least 30 per cent by 2030 and achieve net zero by 2050 was approved by shareholders at last month's annual meeting.

But the company has not made any promises on the Scope 3 emissions generated by its customers.

Dr Wild told the summit 90 per cent of BHP's Scope 3 emissions happen downstream, and BHP does not have operational control of what customers do with its products.

It's about shipping and steel production, so that's where BHP focuses its efforts, she said.

The Australasian Centre for Corporate Responsibility has said BHP's climate plan falls short of global rivals Rio Tinto and Glencore.

Rio Tinto is looking at a 50 per cent reduction in operational emissions by 2030 to get to net-zero emissions by 2050.

Anglo-Swiss resources giant Glencore has pledged to halve its total Scope 1, 2 and 3 emissions by 2035 and achieve carbon neutrality by 2050.

Glencore recognised last year that the wider value chain is a material part of the mining sector's carbon footprint.

Australian Associated Press