The travel industry must stare the reality of its high carbon footprint in the face and stop pretending it can be offset.
The industry is at a decisive moment in how it deals with emissions and must ask itself whether a trip is really worth it and justifiable in sustainability terms.
Sustainability expert and author Mike Berners-Lee says the industry is at a "crunch point" in time, whatever way it looks at the climate emergency and the current solutions.
Speaking during the European Global Business Travel Association conference in Berlin, he shares that the carbon dioxide emission of an economy class long-haul flight to Hong Kong and back is about 3.5 tonnes, while a first-class return is about 14 tonnes.
"That's more than the average person's annual carbon footprint. We don't yet have the technology for putting long-haul big aeroplanes into the sky without burning through something like 100 tonnes of oxygen," he says. "It turns into about four times its weight in carbon dioxide and because it happens at altitude the effect is more or less something like double again what it would be if you just burned that fuel on the runway."
Berners-Lee says technologies such as hydrogen, ammonia or electric-powered planes are "a long way off, at least for long-haul flights" while sustainable aviation fuel is "okay, up to a point."
"Either you grow that fuel using plant-based material in which case you put huge pressure on the food and land system or you use renewable energy for it in which case that renewable energy is not being used for replacing the fossil fuel.
"However you look at it there is a crunch point. I'm not saying we shouldn't fly but we have to face facts that there is a carbon footprint associated with it."
Carbon offsetting is not the answer, he says.
"If you look at all the opportunities for planting - environmentally-friendly projects that meet other environmental and social criteria as well - what you find is that there is a total capacity for sequestering of 200 billion tonnes, the equivalent of about four years of annual global emissions through tree planting.
"The trouble is that it's almost a one-hit thing, once it's done it's done. There's no substitute for reducing the emissions in the first place, we also need to deploy all these nature-based solutions, it's not one or the other."
Moves travel can make to address carbon issues
The one solution that might not be finite, he adds, is direct air carbon capture and storage through mechanical means - but the cost of that is currently high at about $900 per tonne and the technology "drastically needs funding and scaling up."
As businesses strive for net-zero, Berners-Lee argues that the priority is to "cut emissions in line with what the science is saying needs to happen for your sector which is not zero in travel because of the flying but it is some reduction."
"You must include your supply chains and any negative emissions needs to pass strict tests on do they really happen? Are they permanent? Are they verifiable? Are they removing carbon? Is it environmentally sound, is it socially sound?
"A net-zero date is not a good measure of ambition because it depends on the circumstances of the business and in the travel business it is particularly hard to get to zero."
The climate emergency also needs to be seen within a bigger picture of what is happening in the world, according to Berners-Lee. He believes it is "one symptom of what's going on with humanity" and how our energy use has been increasing.
"Through our energy use humans have become more powerful and influential over the planet we are living on and suddenly we've reached this era where humans are the big thing affecting the ecosystem. We've become a big species on a small, fragile planet and it has implications for everything."
The world is dealing with the transition to more sustainable energy, the climate crisis, a biodiversity crisis as well as having to feed a rising population and also having to cope with plastics, pollution and disease threats, he adds.
And, all that comes on top of finding ways to reduce the impact of the travel and transport industry.
Some next steps
Berners-Lee argues: "The good news is that if you look at this from a science and technology perspective it's all doable. So, the real question is what would it take for humans to be solving these technically solvable challenges and that takes us on to a whole load of other domains.
"The importance of truth and trust in the world, new questions about what things it's still okay to keep growing, new constraints for humanity that we need to work within huge questions around inequality, and can we deal with climate change with the level of inequality that is going on between countries, questions of values that are playing out globally right now and huge questions for politics and the way we do politics at an international level."
Despite the gloomy outlook, Berners-Lee says he is more optimistic now than he was three years ago because the human race seems to have woken up to the reality of climate change.
He also says that business travel could be a force for good through the "international understanding and respect" that it brings.
"Some business travel is still absolutely vital for better international relations and fostering global compassion which we so need now so I would encourage you all to stick with the science, be creative in what the solutions are.
"Make every trip count in terms of the mind broadening experience it brings about, find a business model that somehow works with less energy and unfortunately is not the silver bullet that lets the flying industry off the hook. This is such a critical moment for humanity and the implications for all businesses are enormous."
* Check this panel session on climate change and sustainability from The Phocuswright Conference 2021 in the U.S.
Travel's Dilemma - Are We Making Our Mark or Leaving One? - The Phocuswright Conference 2021