Solving climate change would be "the most amazing thing humanity has ever done", says the billionaire founder of Microsoft Bill Gates.

By comparison, ending the pandemic is "very, very easy", he claims.

Mr Gates's new book, How to Avoid a Climate Disaster, is a guide to tackling global warming.

Don't underestimate the scale of the challenge, he told me when we spoke last week.

"We've never made a transition like we're talking about doing in the next 30 years. There is no precedent for this."

Fifty-one billion is how many tonnes of greenhouse gases the world typically adds to the atmosphere each year.

Mr Gates' focus is on how technology can help us make that journey.

Renewable sources like wind and solar can help us decarbonise electricity but, as Mr Gates points out, that's less than 30% of total emissions.

We are also going to have to decarbonise the other 70% of the world economy - steel, cement, transport systems, fertiliser production and much, much more.

We simply don't have ways of doing that at the moment for many of these sectors.

TH