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.