Qantas Airways Ltd on Monday pledged to slash its carbon emissions to net zero by 2050, joining British Airways owner IAG as the industry's response to climate change activists gathers momentum.

"We're doing this because it's the responsible thing to do," Qantas' Chief Executive Alan Joyce said in a statement, calling climate change concerns "real".

IAG last month became the first major airline group to make the net zero by 2050 commitment, leading the way amid intense pressure from climate change activists such as Extinction Rebellion and teenager Greta Thunberg.

The high-profile debate has spurred increasing numbers of environmentally conscious travellers and investors, putting pressure on the aviation industry.

The broader industry has committed to halving emissions by 2050 compared to 2005 levels.

Qantas said it was looking to cap net emissions at 2020 levels and will invest A$50 million (US$34.3 million) over 10 years to develop sustainable fuel to help lower carbon emissions by 80% compared with traditional jet fuel.

Australia's national carrier has already experimented by flying a plane from Los Angeles to Melbourne using mustard seed biofuel.

"So we know the technology's possible," Joyce told Australian Broadcasting Corp. "It's to actually do it commercially and to do it on scale and not impact the other environmental concerns like taking away from food crops or increasing the cost of food crops. That's why it'll take some time to get there."

Qantas' pledge coincided with an outbreak of deadly bushfires along Australia's east coast, which experts have linked to climate change.

Qantas said it operates the largest carbon offset program in the aviation industry, with around 10% of customers choosing to offset their flights through conservation and environmental projects. The airline said it would now match every dollar spent on offsets, effectively doubling the number of flights offset.

Air France and British Airways last month said they would offset all emissions on their domestic flights from 2020.

'Flight Shaming'

Airline companies are finding it harder to ignore growing scrutiny of their climate change policies by investors.

Fund managers, pension funds, sovereign wealth funds and others are showing greater care when investing in companies, and have started limiting exposure to oil, gas and coal stocks.

In coordination with the International Air Transport Association, which represents nearly 300 airlines, the aviation industry is launching a campaign it hopes will counter a 'flight shaming' movement that has gained momentum as travellers become more concerned about their environmental impact.

The aviation industry has already cut carbon emissions from each plane traveler in half since 1990, largely thanks to more fuel-efficient aircraft.

Plane and engine makers are also working on plans for hybrid or all-electric engines to help lower emissions in the future.