Last week I wrote about how difficult it is going to be to keep within 1.5 degrees of warming, and how it is only possible if we actively remove CO2 from the atmosphere. That’s a relatively new idea for climate change world, which has been focused almost entirely on how to reduce emissions. And if we’d started sooner and moved faster on reducing emissions, it would have been enough.
That’s still a priority, but because we’ve delayed so long, we’ve now made things more difficult for ourselves and we need negative emissions technologies. Here are four options. There are several more, but these are the easiest ones. They don’t require any new technological breakthroughs. They don’t rely on geo-engineering, and they’re all things that we ought to be doing anyway.
- Reforestation – by far and away the most obvious solution for drawing CO2 back out of the atmosphere is a programme of extensive reforestation. In Britain, we could combine this with a rewilding programme and return large areas of land to the trees, including much of the Scottish highlands. But this should be global. Since there are always many good reasons to plant trees, this is the best place to start.
- Wetlands – as I described in the summer, salt marshes and mangrove swamps are great at sequestering carbon, as the plants draw CO2 out of the air as they grow and then lock it away in very stable soil systems. We should conserve the ones we have, and restore and extend these ecosystems further if we want to get them working for us to reduce the atmostpheric CO2. While we’re at it, wetlands help to protect coastal regions against floods and act as a buffer during storms and tsunamis. They’re also rich in biodiversity.
- Wood – when a tree grows, it absorbs carbon. That is then released if the wood is burned, or as it rots away naturally. So if we make things out of wood, the carbon is safely preserved. An oak dining table is a form of long term carbon storage. Provided it is sustainably harvested, we could work towards negative emissions by using more wood as a building material or for quality furniture. If the wood we use is displacing CO2-intensive materials such as cement, that’s even better.
- Soil – CO2 can be sequestered in the soil, but intensive farming tends to deplete and dry out topsoil and reduce its capacity to do so. Low-till farming techniques reduce erosion and can help to rebuild the stock of micro-organisms and fungi that produce healthy soil. We have everything to gain from doing this anyway, since we need to restore depleted soils to maintain food production. Rebuilding soil would also reduce the need for fertilisers, which would help to reduce nitrogen pollution, improving water quality and aquatic biodiversity.
Those are four negative emissions strategies. I’ll cover some others next time, but what these four all have in common is that there are multiple benefits to all of them. They are restorative, actively improving the land and undoing the damage of past unsustainable behaviour. We can get started on these immediately, and the world would be better for it.
If we want to move quicker, there are other ways to draw CO2 out of the atmosphere. Some of them are more controversial, but if we keep on delaying, we’ll have to resort to those too. And I’ll write about those next time.
The Earthbound Report 
hi jeremy,
did you see this article about soil not absorbing carbon https://www.theguardian.com/environment/2016/sep/22/soil-carbon-storage-not-the-climate-change-fix-it-was-thought-research-finds
I hadn’t seen that, no – thanks. It’s not an article about soil not absorbing carbon though. It’s about it’s carbon absorption capacities being overestimated. It can and does absorb carbon, and we should definitely do it. It just doesn’t get us off the hook the way some might have hoped.
There are limits to all these measures. I will send through the resent research when I get a moment but global reviews suggest maximum realistic (ie once other land use for food, biodiversity, biofuel, urban expansion etc) global per annum potential of carbon sequestering is about 1/10 of carbon emissions produced from per annum burning fossil fuels. In other words stopping fossil fuel burning is still, by far, the main game. Sadly, very little chance we will stay within 2 degrees, let alone 1.5
I agree entirely, and I’ll be looking at the limits and objections to negative emission technologies later in the series. In some ways it reminds me of the debate around climate adaptation a few years ago, where some people were saying that was a distraction from the real business of reducing emissions. Ultimately, we need both, and we’re going to need negative emissions technologies too eventually.
The best interventions, incidentally, aren’t competing with CO2 reductions – like low till agriculture or reforestation. There are multiple reasons to go for those.
Just to follow up above comment see link below for good summary of evidence on limits with links to science
https://theconversation.com/putting-carbon-back-in-the-land-is-just-a-smokescreen-for-real-climate-action-climate-council-report-65475
ref soil carbon – some people maintain that grazed pasture, managed the right way, can be a significant carbon sink – with many other benefits into the bargain. Graham Harvey (agriculture story editor on The Archers, former Farmers Weekly journalist and co-founder of the Pasture-Fed Livestock Association) has written about this in ‘Grass-fed Nation’, for example. Any views/reactions? Are these pasture champions onto something, or perhaps over-stating the case??
The science is on their side, as I understand it, depending on where you are in the world and how you manage the pastureland.There’s the carbon cost of meat or dairy production to offset from the carbon storage, but the main downside is that its a very land intensive way to raise animals. That comes with a steep opportunity cost in some places – raising sheep on a hill may prove carbon negative, but planting it with trees would be a whole lot better.
In a world in which people ate an appropriate amount of meat, ie very little, this is how you’d want to raise it and it could be a carbon neutral or possibly carbon negative activity.
Concrete is phenomonly energy intensive. Wonderful, miraculous material. BUT tbe energy input requires vast amounts of fossil fuels and yet more heat.
I haven’t seen later posts since this, 2016, but where is population reduction, free vasectomies and related critical items?
Enjoyed your article about 4 ways to remove CO2 from the atmosphere. I wonder if there are some trees that do better than others in this regard. Thanks, Kathy
I’ve wondered that too, and have tried to find out. Apparently it’s almost impossible to run controlled experiments because you need mature trees in the right places, with identical exposure to pollution, etc. I’ve heard of a couple of people working on it, including one study in progress at my local university, but no conclusive results yet beyond conventional wisdom.
A few pointers I’ve heard are that evergreen trees are better than deciduous, because they’ll clean the air better all year round rather than just in summer. Shrubs and hedges can be just as effective, since you want the tree as close as possible to the source of pollution. If we’re talking about cars then that’s at tailpipe level. The position of trees is also important. Too many trees that overhang the road can actually trap pollution at ground level and stop it being dispersed in the wind.
If I get some good information at some point on specific tree species, I’ll pass it on!