To reach net zero emissions by 2050, global emissions must be cut faster and deeper than the world has yet managed. But even then, some hard-to-treat sources of pollution in aviation, agriculture and cement making may linger for longer than we would like.
It will take time for clean alternatives to arrive and replace them, says Cameron Hepburn, Professor of Environmental Economics, University of Oxford and Steve Smith, Executive Director, Oxford Net Zero, University of Oxford.
In an article titled ‘Climate change: six priorities for pulling carbon out of the air’, Hepburn states that means the world also needs to find and ramp up ways of taking CO2 out of the atmosphere to stabilise the climate. Just meeting the UK’s net zero target is likely to require the removal of 100 million tonnes of CO2 a year, similar in size to current emissions from the country’s largest-emitting sector, road transport, but in reverse. The UK government’s announcement of 31.5 million pounds (USD 44.7 million) in support for research and development of carbon removal is welcome.
And while trials of new tech will help, there are many social issues that need to be tackled if removing greenhouse gases is to succeed. Done right, carbon removal could be the perfect accompaniment to emissions cuts, bringing the climate back into balance. Done badly, it could be a dangerous distraction.
Greenhouse gases can be removed from the atmosphere in several different ways. CO2 can be captured by plants as they grow or absorbed by soils, minerals or chemicals, and locked up in the biosphere, oceans, underground, or even in long-lived products such as construction materials (including timber or aggregates), the expert says.
These stores vary in size and stability, and methods for getting carbon into them vary in cost and readiness. Trees, for instance, are literally a shovel-ready way to soak up carbon with many additional benefits. But the carbon they store can be released by fires, pests or logging.
Storing CO2 underground offers a more stable reservoir and could hold 100 times as much, but methods of injecting it from the air are expensive and at an early stage of development. Nevertheless, a raft of innovations, competitions and start-ups are emerging.