By Chris Davey
This month, let’s have a quiz… how many of the following are effective at reducing the quantities of greenhouse gases (GHGs) now in the air? — “Tick any that apply”:
1. Solar panels
2. Wind generators
3. Wave or tidal power
4. Geothermal energy
5. Carbon capture and storage (CCS) and direct air capture (DAC, of CO2)
6. Afforestation / reforestation
7. Wetlands
8. Oceans
9. Rewilding
Notice that the question is about the greenhouse gases in the air right now, not in the future. (I’ve used the term GHGs, but mostly I’m talking about carbon dioxide; methane is also important.) This is because in order to stay at 2C warming above pre-industrial levels (as agreed at the Paris COP in 2015) we have to stop emissions now, and preferably begin the process of removing some of the GHGs floating around above us. Carbon dioxide hangs around for a long time, making the emissions cumulative. So the answer is… a bit lower down, in case you want to think about it a bit more!
PV solar panels on a house roof. Just generating renewable electricity? (Photo: Chris Davey)
Answer: those that can effectively remove carbon currently in the air… 6 – 9 inclusive. Now for a bit more detail.
CCS can capture and “bury” carbon from fossil fuel emissions as they occur, but it doesn’t affect the levels already in the air, so that’s clearly a ‘no’. DAC does remove carbon from the air, but does not currently exist at the scale required to make any significant difference. So DAC is ruled out for practical purposes, at least for the present.
“Plant some trees” is quite often used as the panacea for drawing carbon down from the air (“sequestration”). Now trees do of course take carbon out of the air to build their own structures; but we need the right trees in the right places; also, planting a forest is a better idea, not only because it’s obviously lots of trees, but it is a whole ecosystem, thus biodiversity is also boosted. So reforestation/afforestation is a great idea, and the ideal time for it is… say about 30 years ago. Oh dear, still better late than never. Let’s get reforesting/afforesting now.
Wetlands potentially sequester more carbon than forests – of course, we need both. But there’s now some concern that some wetlands may flip from being absorbers to emitters of carbon. Carbon Brief explain this here. This is a complex area (just one of many when it comes to our climate) depending on the type of wetland, and where in the world it is located. Of particular concern is the temperature rise in the wetland areas in the colder regions of the planet, the tundra. These hold pockets of methane frozen in the ground. As the temperature rises, these may melt and the methane is released if they do. This is shown dramatically in the excellent BBC documentary, Climate Change: the Facts (from 2019 but still relevant and available on iPlayer; go to about 40 minutes in to find this bit — better still, watch or rewatch the whole thing!).
There are many reasons for taking better care of our oceans. After all, much of what we throw away (and remember, there is no such place on Earth as the “away”) tends to end up in the sea, and because the oceans have become so polluted, they have lost some of their natural ability to draw down carbon. If we clean them up, they will take more carbon down from the air. Plastic pollution is a particular problem as it interferes with phytoplankton, which draw down carbon.
And so to #9, rewilding, which not only improves biodiversity, but can also make the land better at sequestering carbon. Full details at rewildingbritain.org.uk.
To sum up, renewables are wonderful. I get a kick from seeing all the wind generators and solar panels in Cornwall as I drive up the A30; and of course there are Cornwall’s geothermal projects — hydro, well, not yet… but renewables will reduce carbon emissions only when they replace fossil fuel electricity generation, not complement it. Mike Berners-Lee emphasises this in his new book (see below). For the atmosphere, it’s irrelevant how many solar panels and wind farm we have; all that matters is the levels of GHGs. So emission reduction must go hand in hand with the expansion of renewables.
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Sources consulted in the writing of this article include: A Climate Of Truth by Mike Berners-Lee (Cambridge University Press); rewildingbritain.org.uk; The Climate Book, created by Greta Thunberg (Penguin Random House); BBC iPlayer (for Climate Change: the Facts, presented by David Attenborough).
