Counting the cost of decarbonising aviation

UK industry body Sustainable Aviation said the cost of decarbonising air travel was likely to push up ticket prices and put some off flying.
Measures such as moving to higher-cost sustainable aviation fuel will "inevitably reduce passenger demand", the group said.
However it added that people will "still want to fly" despite "slightly higher costs", the BBC reported.
Annual passenger numbers are still expected to rise by nearly 250 million by 2050, it added.
Sustainable Aviation is an alliance of companies including airlines such as British Airways, airports such as Heathrow and manufacturers like Airbus.
It said that sustainable aviation fuel (SAF) would be a key part of the industry's "journey to net-zero,” accounting for at least three-quarters of the fuel used in UK flights by 2050.
Heathrow Airport's director of sustainability Matthew Gorman - who chairs Sustainable Aviation - said this "green premium" will have "some impact on future demand" for air travel.
However, he added that the industry could still "grow significantly" as most people were "happy to pay a bit more to travel".
The Sustainable Aviation group argued the move to greener travel presents a big opportunity for the UK, which has the world's third-largest global aviation network.
Up to five new SAF production plants are planned for the UK, with the government investing in their development.
However, the group said it was concerned investors would be lured to the US and the rest of Europe by "significant" tax incentives, and the UK risked missing out.
Transport Secretary Mark Harper said: "This government is a determined partner to the aviation industry - helping accelerate new technology and fuels, modernise their operations and work internationally to remove barriers to progress.
"Together, we can set aviation up for success, continue harnessing its huge social and economic benefits, and ensure it remains a core part of the UK's sustainable economic future."