Is this how to save the planet?

As is so often the case, Donald Trump expressed it perfectly. Hurricane Florence, which has brought major devastation to parts of the US this week, was 'one of the wettest we've ever seen, from the standpoint of water'. (You don’t believe he actually said it? Here’s the video.)

And yes, this from the man whose administration thinks it would be just great if the US burnt more coal. Perhaps you hadn’t noticed, but the current acting head of the US Environmental Protection Agency is a former coal industry lobbyist. You really couldn’t make it up, which is why I’m looking forward to the new Trump baseball caps going on sale: ‘Make Water Wetter Again.’

Remember the summer heatwave? Perhaps you don’t – our weather-related memories are notoriously short. And of course, here in the UK, it’s virtually stopped raining all together – at least until Storms Ali and Bronagh popped up out of nowhere -- unless you happen to remember the downpours of 2014, the heaviest in nearly two hundred and fifty years, which caused more than a billion pounds’ worth of damage.

Just a few days ago, the UN secretary-general António Guterres tried yet again to shake world leaders out of their complacency. ‘Climate change is the defining issue of our time, and we are at a defining moment. If we do not change course by 2020, we risk missing the point where we can avoid runaway climate change.’

Mark those words: ‘runaway climate change’. That’s what everyone wants to prevent, because it would spell disaster for future human existence – and that’s where net zero carbon emissions come in. It’s no good simply reducing the amount of carbon we spew into the earth’s atmosphere; we have to reduce it to such an extent that it no longer exceeds the amount of carbon we remove.

Early next month, the Intergovernmental Panel on Climate Change (IPCC), the internationally-accepted scientific authority on climate change, will publish a report making the case for net zero carbon emissions. Like everything to do with climate change, it is bound to be complex and full of scientific jargon. So here, stealing unashamedly from a series of invaluable briefing papers published this week by the Energy and Climate Intelligence Unit, is my attempt to steer a path through it. (Full disclosure: I am a member of the ECIU’s advisory board.)

First off, can it be done? Well, France, Norway, New Zealand, Sweden, Iceland and Costa Rica have already set themselves targets to get there by the middle of the century – and the tiny Himalayan kingdom of Bhutan is already carbon-negative, thanks to a population of just 800,000 and a requirement written into its constitution that at least sixty per cent of its land area must remain forested in perpetuity.

Why bother? Because, in the words of the ECIU: ‘Climate science is clear that to a close approximation, the eventual extent of global warming is proportional to the total amount of carbon dioxide that human activities add to the atmosphere. So, in order to stabilise climate change, CO2 emissions need to fall to zero.’

How can it be done? Well, pumping out less of the stuff is a good start, and not quite as impossible to achieve as the sceptics would have had us believe twenty or thirty years ago. In fact, according to the ECIU, ‘the UK has already made substantial progress on decarbonisation, having cut emissions by more than 40% since 1990 while posting 70% economic growth – on a per-capita basis, leading the G7 on both measures.’

OK, but zero? True, we’re never going to get rid of all greenhouse gas emissions, although there is a theory that by feeding cows seaweed, we could cut their methane emissions by 99%. Far easier to plant lots more trees, because trees absorb CO2, so the more there are, the more CO2 gets removed from the atmosphere. (So three cheers for the new National Forest that’s being planted in the English Midlands.)

Technology can help as well: for example, by generating electricity from burning plant material, and then capturing and storing the CO2 that’s produced underground. The danger, however, is that if we start growing substantial quantities of the plant material that would be needed for increased electricity generation, we might end up chopping down trees to make space for them. Which would sort of defeat the object ...

So it’s all fine in theory, but it’ll never be done? Not necessarily – the UK actually has a rather good record in this field, having come top in a recent global index charting G20 nations’ transition to a low carbon economy.

Personally, I reckon the chances of avoiding of ‘runaway climate change’ are on a knife-edge, but if the UK needs to find itself a post-Brexit role, how about Zero Emissions Champion? According to the ECIU, ‘there are now more than 390,000 jobs in low-carbon businesses and their supply chains … [and] the UK’s low-carbon and renewable-energy economy was worth £43bn in 2016.’

So it would be good for the economy, and it might just save planet Earth. What’s not to like?