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Benedict McAleenan is Senior Adviser, Energy & Environment at Policy Exchange.

I’m sorry to bring you bad news, but we’re about to completely blow the budget. We had planned to stay within no more than 1.5°C of global warming by the end of this century, but we’re about to hit that mark in 2040, if we don’t use all the tools available.

When we go beyond 1.5°C, things really get out of control. Permafrost thaws, releasing methane that worsens the rate of change (this has already begun). Polar ice caps lose their ability to reflect energy back into space, so things speed up again (also already underway). Greater evaporation causes a more humid atmosphere, again raising the heat.

If this was an asteroid heading for earth, we would be pouring resources into a hundred possible solutions, from simple nudges right through to high-tech warheads. But on climate we have so far not used an important secret weapon, and it’s time to get moving.

According to a report last week by McKinsey launching a new ‘Coalition for Negative Emissions’, we need to start deploying ‘Negative Emissions Technologies’ at scale. This are systems that can suck carbon dioxide out of the air and store it away. They include some very old techniques and some very new ones. Some can be used now at low cost (like tree planting), but other more technological solutions need investment now so we can use them before 2030 at megaton scale.

Restoring peatland and planting trees are the most obvious and least technical options, capturing carbon in tree trunks and sphagnum mosses for decades or hundreds of years – including, of course, in sustainably harvested timber. We need to start now, because these options take decades to deliver, though they are also the lowest cost in this range.

Moving up the technological scale, there’s ‘enhanced weathering’, where rocks are crushed to encourage them to absorb carbon from the air through chemical processes. They’re then spread over fields and beaches or ploughed into soil. Soil carbonation is also at the heart of another negative emissions technique: using waste to generate gas also creates a carbon byproduct known as ‘biochar’. The gas goes to heat homes or generate electricity, the carbon biochar is ploughed into soil, storing the carbon and boosting soil fertility.

Finally, there are the industrial players of negative emissions. Direct Air Carbon Capture and Storage (DACCS) and Bioenergy with Carbon Capture and Storage (BECCS) both suck carbon out of the atmosphere and either store it away or use it – although only the former is strictly negative emissions.

DACCS uses huge fans and filters to capture the carbon from the air, and the firm Carbon Engineering already has plans to build a DACCS plant in Scotland. BECCS lets trees and plants do the carbon capturing naturally, but then uses parts of those plants for energy production, capturing the emissions before they escape.

These are not uncontroversial solutions. Greta Thunberg calls them “unproven technologies”, and she casts such doubt because she thinks they are a fig leaf for oil companies. If we just suck the carbon out of the atmosphere, her thinking goes, then there will be less pressure to stop putting it there in the first place. Her solution is something called ‘Absolute Zero’, as opposed to ‘Net Zero’.

Net Zero means accepting that we can’t stop absolutely all carbon emissions by 2050 and using negative emissions to address the shortfall. Greta’s Absolute Zero means no aeroplanes if they’re not zero-carbon, no steel if it’s not zero-carbon, no exceptions for myriad fiddly details that are the reality of life.

Not only that, but this ‘unproven technology’ line is bizarrely luddite. If we accepted its logic, then we would be tying our hands behind our own backs. In climate terms, we’d have no wind turbines beyond those featured in the art of Monet. In pandemic terms, mRNA vaccines were unproven less than 30 years ago. Climate change is urgent enough for us to try the options available.

Yet the UK is a very small player in global GDP and in carbon emissions. Why should we invest in such moon-shot technologies as BECCS, DACCS and enhanced weathering? Why not leave it to the US and China, who both pollute far more than us? There are three special reasons for the UK to lead on negative emissions.

Firstly, this is a massive opportunity in a high-growth sector with the potential to sell our solutions around the world. As the saying in Silicon Valley goes, “the best way to make a billion dollars is to solve a problem for a billion people.” Countries around the world are signed up to targets for emissions reductions and they want solutions including electric cars, wind turbines and, yes, negative emissions. As Andrea Leadsom and Amber Rudd have pointed out for Policy Exchange’s COP26 programme, we have excellence in engineering solutions that we can sell to the world.

Secondly, as Policy Exchange’s Future of the North Sea report noted, we have some legacy assets that make us very well placed to do that. We have an oil and gas industry with world-leading expertise in transporting gases to and from geological storage sites, and it’s currently looking for a new role to play in the world. Not only that, but we’ve spent forty years emptying gas and oil from such storage sites in the North Sea and we can refill them with our unwanted carbon. That’s a facility we can also sell to others, creating jobs along the North Sea littoral.

Finally, we, as a nation, made a big contribution to climate change, even if it has been the by-product of huge contributions to global prosperity and progress. They’ve been two sides of the same coin, so it’s logical that we take the lead again in solving the next part of the problem.

We need negative emissions technologies to stave off climate change, that much is known. The Climate Change Committee has supported that view and Ministers have followed suit. They should stay the course by investing in a suite of these emerging technologies, but also support much greater deployment through market solutions, such as a market for negative emissions, which can eventually work within the UK’s new Emissions Trading System. Without these ‘unproven technologies’, the carbon budget will be blown and the targets of the Paris Agreement will be a pipe dream