climate change

The risks and opportunities of negative emissions

Over the last three weeks I’ve been looking at negative emissions, and the various ways to draw CO2 back out of the atmosphere. I’ve done it in three stages because it’s very important not to see negative emissions as one broad category of climate change action.

To recap, here are those three:

  1. Land management – the first type of negative emissions interventions we could use are land management techniques, such as reforestation, wetlands restoration, and soil stewardship. All three of those would have multiple benefits, and would be worth doing even without the carbon storage. There’s no downside. When you hear people waxing sceptical about negative emissions, as we’ll come to in a moment, remember that there are some techniques that are totally worth doing.
  2. Technologies – the second category is technologies that can draw CO2 out of the atmosphere, such as biomass generation with CCS, or artificial trees. So far these don’t quite make economic sense without a market for CO2, so they’re an expensive way to deal with climate change. It’s far cheaper to cut emissions that to emit CO2 and then capture it later. But we can’t rule these technologies out. We might need them later.
  3. Geoengineering – all geo-engineering is theoretical, simply because we’re talking about large scale interventions – seeding the oceans to absorb more carbon, or accelerating cloud formation. Some ideas are more useful than others, so even here it’s worth keeping an open mind, but generally speaking we’re talking about experiments that we should only be turning to in an absolute emergency.

There’s a bit of a debate about negative emissions at the moment. The proposed 1.5 degree target has forced scientists to look at more radical solutions, and it’s clear that short of some spectacular global epiphany, we’re not going to cut emissions in time to keep within 1.5 degrees of warming. To meet that target, we need to wrangle CO2 back out of the atmosphere.

Hence the sudden wave of interest, and while some of this is positive, there’s a real risk too. By championing carbon negative solutions, we might give the impression that there’s no urgency to carbon reduction. No need to stop driving or flying or eating meat, because the scientists tell us we can pull carbon out of the atmosphere later. This is a dangerous delusion for a number of reasons. For one thing, we can’t afford to delay carbon cuts. Putting it off risks pushing us past a tipping point and into runaway climate change. We don’t get to shuffle responsibility off to those who come after us, even though that’s what previous generations have done to us. As Kevin Anderson has argued, “the beguiling appeal of relying on future negative emission technologies (NETs) is that they delay the need for stringent and politically challenging polices today – they pass the buck for reducing carbon on to future generations”.

The other reason to be sceptical of negative emissions is that they can only ever be a small part of the overall solution. A report by Australia’s Climate Council found that “current annual carbon emissions from fossil fuels are ten times greater than the annual amount of carbon that could be stored by sustainable land carbon mitigation methods.” So all those no-brainer interventions around reforestation and so on could only offset a tenth of annual emissions. They are no substitute for decarbonisation.

Are they worth bothering with at all then? Yes, if you bear in mind that we need to reduce emissions by 90%. By that point 10% of global emissions suddenly looks a lot more useful. So land management for better carbon storage will make a real difference in getting us over the line into climate safety. And since habitat loss, flooding, and soil erosion are all problems in their own right, there’s every reason to look for holistic approaches.

As carbon negative strategies are argued back and forth, I’m reminded of the debate a few years ago around climate adaptation. We shouldn’t be discussing how to adapt to a warmer world, some argued, because it was a distraction from climate mitigation. The real business is to cut carbon, and anything else sounds like letting ourselves off the hook.

But of course we need both. We need to cut carbon every which way we can, but a certain amount of warming has already happened and more is locked in. We need to adapt to that, and it would be foolish not to plan ahead and build resilience into our cities, infrastructure, and agriculture. The same logic applies to negative emissions. Reducing carbon emissions is by far and away the biggest priority, but that doesn’t mean we can’t use any of other tools at our disposal.

When you hear or read about negative emissions then, bear in mind the risks. Ask if those proposing them are doing so because they can offset global emissions, or delay carbon cuts. Be sceptical of those voices. If negative emissions are being discussed as part of a broader programme of restoration, that’s less likely to be a distraction.


    1. Yes, there are a few people working on synthesizing liquid fuels from captured carbon. And then of course you then burn that fuel in a plane or a car, and release it all back into the atmosphere again. Better than fossil fuels, no doubt about that – but not carbon negative. If it can be done at a decent price, it would help to create a market for captured CO2 though, and that may be helpful.

  1. Planting more trees and restoring wetlands is all well and good, except that, with a fast growing population, many will argue we need the land to grow food, intensively. So we need to quickly cut the rate of population increase, non-coersively. Reducing unwanted pregnancies would be a good start that no-one should argue with.

    1. The place to focus on reforestation is uplands that aren’t suitable for food production, and that are either barren or used inefficiently as pasture. In Britain, the Scottish highlands are the biggest opportunity. Reforested areas can be rewilded, or they can be sustainably managed for forestry, so they don’t cease to be productive.

      I’m with you on population. Growth rates naturally peak with development, but there’s plenty of entirely positive things that we can do to bring population growth down faster.

  2. A thought-provoking article. I think negative emissions should be worked on discretely. The land management techniques are very useful for other issues as well, as you pointed out. If scientists and think tanks made those reasons the primary reason and kept the carbon balance in the background, we can avoid the complacency you talked about.

    1. Yes, and where it gets troubling is when negative emissions start being written into national strategies. No harm in working on them as part of our climate action, but we shouldn’t be depending on them for future cuts.

  3. I totally agree when you said that there is already warming in our planet and there is more that has been locked in. With that in mind, we should be doing our part in managing these emissions. I hope the big factories or companies would be more responsible for these and seek help from experts to keep their emissions lesser to keep our planet from deteriorating.

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