Sucking carbon out of the air is no magic fix for the climate

For many areas of life, near-zero emissions by 2050 is an attainable goal, but there are other areas where zero emission is impossible.
For many areas of life, near-zero emissions by 2050 is an attainable goal, but there are other areas where zero emission is impossible.

THE Arctic is on fire, hot on the heels of the latest scorching European heatwave. As the impact of the climate crisis mounts, more and more people are asking: how can we control this beast we have created? The scientific answer is fairly straightforward: reduce the amount of greenhouse gases added to the atmosphere to zero. The sooner that’s done, the lower the stabilized temperature and the fewer devastating climate impacts we must face.

The world signed up to this in the Paris agreement, agreeing to “pursue efforts” to limit global warming to 1.5C (Celsius) above pre-industrial levels, while committing to keep the rise “well below” 2C. To have just a 50 percent chance of meeting, the 1.5C means halving global emissions over the next decade and hitting “net zero” emissions by about 2050. That means every sector of every country in the world needs to be, on average, zero emissions. That’s electricity, transport, industry, farming, the lot.

For many areas of life, near-zero emissions is an attainable goal. We could refit our homes and use electric-powered transport from low-carbon energy sources. Energy from the sun, wind and waves could power societies worldwide. But there are some areas where zero emission by 2050 is impossible. There will, for example, always be some emissions from the farming needed to feed more than 10 billion people this century, and there is no sign of flying long-haul on an electric plane any time soon.

The answer to this is to remove carbon dioxide from the atmosphere, using “negative emissions technologies.” By sucking carbon out of the atmosphere – at the same rate as it is being added – we can reach zero emissions. Whatever the shape of society in the future, a stable climate will require some working negative emissions technologies. They will be an indispensable tool to mop up the hard-to-eliminate emissions.

The UK is betting on bioenergy with carbon capture and storage, BECCS, where carbon is removed from the atmosphere by crops or trees as they grow. This biomass is then burned in a power station to generate electricity, and the waste carbon dioxide is pumped far underground into old oil and gas reservoirs or saline aquifers. A second approach is to restore or enhance processes that naturally remove carbon dioxide from the atmosphere. Forest restoration removes carbon by storing it in trees, and soils can also take up carbon, for example, if crushed silicate rocks are spread on to them, enhancing a natural chemical process.

With a range of options, we might think that negative emissions mean that climate change can be tackled, and tackled fast. But evidence that these technologies can work at a small demonstration scale is causing the opposite. Negative emissions are treated as a “get out of jail free” card – a license to keep emitting and clean up the mess later with new technologies. Politicians and their advisers love them, because they can announce a target such as 1.5C while planning to exceed it, with temperatures hopefully clawed back later in the century through negative emissions.

While it is true that some negative emissions technologies are practically feasible at modest scales, this knowledge encourages both magical and mendacious thinking. We all want a magic bullet that solves the climate emergency, but negative emissions technologies are not it. Of course, it makes no sense to be against these technologies in principle. Investment in them is needed, as hard-to-mitigate emissions will need removing from the atmosphere, and some options such as forest restoration bring many additional benefits. But we should recognize the dual role they also play in encouraging a delay to the action we need to take: rapidly ending the use of fossil fuels. (The Guardian)


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