Hundreds of people were arrested this week for taking part in protests organised by Extinction Rebellion, a group demanding that the UK set legally binding targets to reduce carbon emissions to net zero by 2025. The activists may not get their wish, but the Committee on Climate Change (CCC), which advises the UK government, is due to publish a report on 2 May that is expected to recommend a net-zero target for 2050.
This is, at least, an improvement on the UK’s current position, which is to cut carbon emissions by 80 per cent by the same date. When that goal was set a decade ago, the country was praised as a leader on battling climate change, but since then, many other countries have caught up. Lately, some have begun declaring plans to go further, faster.
The reason is simple: the science has moved on. A cut of 80 per cent was based on advice to limit global temperature rises to 2°C, the line previously considered the threshold for dangerous global warming. But as the Intergovernmental Panel on Climate Change (IPCC) , limiting warming to the safer level of 1.5°C requires the world to hit net-zero carbon emissions by about 2050.
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Christiana Figueres, former United Nations climate chief, says it is possible that the UK could adopt such a target in time for a key UN climate summit in September. “All countries need to recalibrate their decarbonisation strategies. To go to zero net in the UK is absolutely key,” she says.
The UK would not be the first to aim for net zero, but it could become one of the most credible. Observers think the country’s existing, legally binding framework and the oversight of the CCC mean it would be more likely to implement the target in law and meet it.
“There is much hope for the UK because, with the CCC, people would believe there is serious planning for net zero. Along with Sweden, it would be the most credible,” says Oliver Geden of the German Institute for International and Security Affairs, which advises the German government.
Hitting the target
A group of other European countries, including France, Sweden, Norway and Portugal, as well as nations elsewhere, such as Costa Rica, the Marshall Islands and New Zealand, all have plans to hit the target, some by 2050, some earlier.
“Most of the interest is in Europe. The clear leader in all of this is obviously Sweden because they’ve set a goal in law,” says Richard Black, director of the Energy and Climate Intelligence Unit, a UK think tank.
The Swedish Climate Act came into force last year, demanding net-zero emissions through an 85 per cent reduction in domestic greenhouse gas emissions by 2045. The remaining 15 per cent will need to come from other options – probably planting trees, removing carbon dioxide from the air or carbon offsets – which a Swedish government commission is examining.
Many of the other countries talking about net-zero plans are still making political declarations rather than legislating for targets. “We have more not-so-credible announcements than we have credible announcements,” says Geden.
Net-zero targets are appealing because they are simple, says Corinne Le Quéré at the University of East Anglia, UK, but there is no agreed definition of which emissions they actually mean. In particular, whether net zero means just CO2 or all greenhouse gases (see “What about methane?”, below), and whether it could be reached by buying carbon credits from other countries. Still, she says: “Not all net zeroes are the same, but all net zeroes are good.”
There is a good reason governments are talking about net zero, rather than about cutting emissions entirely. Solutions exist to cut emissions from energy and transport, such as through renewables and electrification of vehicles. But sectors such as farming will be difficult, if not impossible, to decarbonise.
Hence the emissions of some sectors will need to be balanced against one another to reach overall net-zero emissions, as Sweden is considering.
The option of carbon offsetting, where countries could choose to offset the final portion of their emissions, is appealing because cutting them could be too expensive or tricky at home. Offsetting might involve a reforestation scheme on the other side of the world, for example.
But that could end up just shifting, rather than solving, the problem. For one thing, planting trees is no guarantee of reduced emissions – they could be mismanaged, die or get cut down.
“When we burn fossil fuels, we are guaranteed to emit carbon. When we plant a tree, we are not guaranteed it will absorb emissions,” says Kevin Anderson of the Tyndall Centre for Climate Change Research in Manchester, UK.
And some say that the only way to be certain that emissions really are being reduced is to do it on your own territory, rather than having to rely on other countries.
“We have a moral responsibility to do as much as we can here [in the UK],” says Josh Burke at the London School of Economics.
So, do we have the technology to get to zero? In theory, yes. But many of the key tools are untested at large scales, in particular capturing and storing carbon emitted from power stations and industrial processes, and ways of directly removing CO2 from the atmosphere.
“We have all the tools on paper and in demonstrator form. What we don’t have is proven techniques for scale-up and financing them,” says Myles Allen at the University of Oxford.
Without ways to actively capture CO2 – effectively creating negative emissions to balance out the positive ones – it will be impossible to achieve net zero.
One of the most hopeful ideas is known as bioenergy with carbon capture and storage (BECCS), which involves growing plants to capture carbon, then burning them for energy and capturing the emissions. The overall effect should be a reduction in atmospheric CO2. BECCS features in many of the scenarios for getting to net zero, but many people are sceptical about whether it can work.
Another idea is sucking CO2 from the atmosphere with machines, using fans that direct air into units where chemical processes trap the carbon ready for some form of storage.
“We don’t know if these things will work at global scale. Yet the language we use makes these things seem real, like they exist,” says Anderson.
Then there are the sectors that are tricky. No one, not even Sweden, is talking yet about including emissions from international aviation in its net-zero targets. Flights account for about 2 per cent of global emissions today. But by 2050, the International Civil Aviation Organization by as much as 700 per cent.
One thing is clear: as the Extinction Rebellion protesters say, this an emergency. The longer that countries wait to set net-zero emission targets and implement the policies to get there, the harder it will be to get to zero. “The sooner they are adopted, the easier it’ll be,” says Figueres.
What about methane?
One question about net-zero targets is how they should balance different greenhouse gases. Methane, for example, has a more powerful warming effect than carbon dioxide, but is shorter-lived in the atmosphere and so has less of an impact overall.
Such accounting debates are important, but don’t change the fact that carbon emissions from fossil fuels are key, not methane, says Myles Allen at the University of Oxford. “It’s all a bit moot if we don’t get fossil CO2 to zero,” he says.
Some countries are considering including methane in their net-zero goals. In New Zealand, methane emissions from sheep and cattle make agriculture the country’s biggest emitter. Dave Frame at Victoria University of Wellington says methane looks likely to be included in the country’s future targets.
But he also warns against overlooking CO2. “One risk we do face is if we go hard after agricultural methane and don’t make enough progress on CO2,” he says.
