Rob Jackson has a dream: to restore our atmosphere to the way it was before humans started tampering with it.
It makes him a somewhat unusual climate scientist. For many, the focus is on slowing global warming to 1.5°C above pre-industrial levels, the most that experts say we can handle without disastrous results.
Prof Jackson sees 1.5°C as arbitrary. People "don't understand why those numbers are important or what they mean", he says.
Instead, he is inspired by the idea of restoring and repairing our world, in the way we might think about endangered wildlife or precious artwork.
"When we see grey whales, grizzly bears, bald eagles, we're looking at life and a planet restored, and my goal for the atmosphere is the same," Prof Jackson told The National.
In a new book, Into the Clear Blue Sky, the Stanford University professor and chairman of the Global Carbon Trust offers a suite of solutions.
Prof Jackson calls the book a "repair manual" that can help us cut our carbon footprint and, if that fails, claw carbon dioxide and methane back from the atmosphere.
Drawing on trips around the world to see green solutions in action, he sees the ideas as "a chance to go from climate despair to climate repair, for any person who cares about the planet".
Cutting emissions
Prof Jackson's first message is, he admits, an uncomfortable one for an American: people in rich countries should use less and drive less.
The author has an all-electric home, after high pollution readings inspired him to buy heat pumps and an induction hob.
"Friends don't let friends buy gas," a fellow environmentalist tells him.
A chapter on electric vehicles takes us aboard a hydrogen-powered ship, the Energy Observer, after we join Prof Jackson on a zero-emission motorcycle.
Electric vehicles "are taking off not just because people want to buy something that doesn't pollute the air", he said.
"They're taking off because they're faster, cheaper to operate and better products."
He recognises those incentives are not there in every field, though, and "personal choice will not do the job we need" in making steel and heavy industry.
The book takes us to a green steel plant in Sweden, where hydrogen is used instead of coal, but concludes that a carbon tax is needed to make this viable.
Prof Jackson says he is excited by work on changing the diet of cows, whose belching is a key source of methane emissions.
Methane is a potent greenhouse gas, but unlike carbon dioxide it does not linger for centuries in the atmosphere.
That means Prof Jackson's restoration dream could, in methane terms, come true in his lifetime.
"If we had a magic wand and stopped emitting methane today, the atmosphere would return to normal in 10 or 15 years," he said.
"There are more than a billion cows on the planet now. So you can do two things. You can eat less beef, you can consume less dairy. We can change our diets.
"Or we can change the cow diets by adding feed additives that reduce methane emissions. I'm excited about research in that area."
Methane emissions can be cut by fixing pipes, too. But Prof Jackson ends this chapter on a more downbeat note after mapping leaks in New York, Boston and Washington. Some have been there for years.
Then there are chemicals known as CFCs, or chlorofluorocarbons, which have been cut back to protect the ozone layer but are also greenhouse gases.
We hear of a crackdown in China after banned emissions were traced there.
Greenhouse gas removal
If you want to restore the atmosphere, you will also need to deal with the carb on dioxide that is already up there.
Any mention of capturing and removing carbon can raise eyebrows among environmentalists, who tend to see it as an excuse not to cut emissions.
"I share suspicion about greenhouse gas removals. The most important thing we can do is to keep greenhouse gas pollution from entering the atmosphere," Prof Jackson says.
"But we've left climate action for so long, delayed action so long, that we've left ourselves no choice but to try and remove some of the gases in the atmosphere."
A chapter on carbon capture warns of concerns over carbon dioxide storage sites being foisted on to socially deprived areas.
But burning biofuels and storing their carbon dioxide underground is a relatively cheap way of getting to negative emissions, the book says.
We visit Iceland where captured carbon is turned into stone, a process that occurs over centuries in the Earth's oceans but can be sped up industrially.
In Finland we learn how restoring peatlands once drained for forestry will remove carbon from the air, even as they release methane because of microbial activity in wet conditions.
That leads us to removing methane, a fairly new field that Prof Jackson is exploring, but he is unsure whether it will work.
"It's very hard to remove a dilute gas like methane from the air. It's like searching for a needle in a haystack," he said.
Reducing methane emissions in the first place is preferable.
Nonetheless, he believes microbes, catalysts and chemicals that could claw back methane are worth exploring now before it is too late.
"One thing I'm concerned about is we're already seeing signs of natural systems beginning to increase emissions," such as wetlands in Africa and South America and melting permafrost in the Arctic, Prof Jackson said.
"We have no technology that allows us to address an increase in natural emissions, so methane removal may be the only tool that we have.
"I want to work to try and develop that tool now, before we need it – or figure out that it's not possible."
Into the Clear Blue Sky: The Path to Restoring Our Atmosphere, by Rob Jackson, is published by Allen Lane.
