Hopes for sustainable jet fuel not realistic, report finds

"There's an under-appreciation of how big the energy problem is for aviation. We are still many years away from zero pollution flights," he said. 

"But it's true that the industry has been slow to pick things up. We are now trying to find solutions, but we are working at this problem and realizing it's a lot harder than we thought. We are late to the game. We are in the dark ages in terms of sustainability, compared to other sectors."…

https://www.theguardian.com/environment/article/2024/may/14/sustainable-jet-fuel-report

Opinion | Why Medicare and Social Security Are Sustainable - The New York Times

So no, Social Security and Medicare aren't inherently unsustainable, doomed by demography. We can keep these programs, which are so deeply embedded in American society, if we want to. Killing them would be a choice...

https://www.nytimes.com/2023/02/21/opinion/medicare-social-security.html