Solving climate change would be "the most amazing thing humanity has ever done", says billionaire founder of Microsoft Bill Gates. By comparison, ending the pandemic is "very, very easy", he claims, according to the BBC.

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

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

Fifty-one billion is how many tonnes of greenhouse gases the world typically adds to the atmosphere each year. Net zero is where we need to get to.

This means cutting emissions to a level where any remaining greenhouse gas releases are balanced out by absorbing an equivalent amount from the atmosphere. One way to do this is by planting trees, which soak up CO2 through their leaves.

Gates' focus is on how technology can help us make that journey. Renewable sources like wind and solar can help us decarbonize electricity but, as Gates points out, that's less than 30% of total emissions.