We are (almost) all committed to combatting climate change by achieving net zero greenhouse gas emissions by 2050, the UN-set target which is now enshrined in UK law. But that is different from achieving absolute zero emissions.
“Net zero” means as much greenhouse gases (mainly carbon dioxide) are taken out of the atmosphere as are put in. While most human activities – primarily burning fossil fuels – emit carbon dioxide, there are other activities that produce “negative emissions”, taking carbon dioxide out. Indeed, nature left to its own devices is carbon negative – since life started 3.5 billion years ago, it has been sucking CO2 out of the atmosphere and burying it underground as gas, oil, coal, and carboniferous rocks such as chalk and limestone. Since the advent of the industrial revolution, mankind has been reversing that process, taking 3 trillion tonnes of carbon from underground and emitting it into the atmosphere, increasing the amount of CO2 in the air by nearly 50%, exacerbating the greenhouse effect.
Negative emissions are a key part of the world’s strategy to tackle climate change. They are recognised by the UN’s International Panel on Climate Change and the UK’s Committee on Climate Change as an essential part of reaching net zero. There are some activities where it will be impossible to reduce emissions to zero, so we need negative emissions to offset them.
Last week, in my role as Chair of the All Party Parliamentary Group on the Environment, I hosted the Parliamentary launch of the Coalition for Negative Emissions, a new global group set up to champion taking carbon dioxide out of the atmosphere and capturing it in the biosphere (life on earth) or burying in the geosphere (in geological formations far underground).
Nature-based solutions are the more straightforward part – planting trees, restoring peat bogs and salt marshes, and restorative farming practices. But then there are negative emissions technologies - carbon capture and storage (CCS - taking CO2 out from the chimneys of power stations), and direct air capture (taking CO2 out of the atmosphere). The UK’s Drax power station is burning biomass (wood pellets) and aiming to use CCS to become 70% carbon negative.
As was clear at the parliamentary launch, some environment groups have concerns that need to be answered. The technology has been shown to work, but is new, and hasn’t been developed at scale. Biomass is controversial – it clearly needs to be proven to be done in a way that is verifiable and sustainable, not leading to the destruction of nature. Of less concern now is the carbon escaping from under the ocean – it stayed there as natural gas and oil for hundreds of millions of years without getting out.
Negative emissions are not a solution by themselves and must not be used as an excuse not to curb emissions in the first place. They must be shown to be robust and do what they claim. But they are a potential useful tool in getting our emissions back in balance - and we should use every tool we have.