I’ve been thinking a lot about negative carbon technologies lately. This could be because it looks more and more like we’re going to be needing a lot of negative carbon emissions in the coming decades. Even if everybody follows through on their pledges, the emission reductions agreed to in Paris could still take us to a 3.7 degree global temperature increase. If we’re going to keep the global temperature rise to below 2 degrees, it is looking more and more like we are going to have to take up the slack with something that is going to take carbon out of the atmosphere to compensate for everything we’ve been putting in.
This is not an ideal situation, because it turns out that it’s actually very difficult to take carbon dioxide out of the atmosphere at anything like the rate that will be required. CO2 is a very inert gas, which means that separating it out from the rest of the gases in the atmosphere requires a lot of energy. This leads to a lot of unanswered questions. How, exactly, do you go about taking carbon out of the atmosphere? Nobody has perfected any reliable technique yet, save for a few examples of biomass power generation with carbon capture and storage built in to it. Of course, we may well get over the technological hurdles, but that still leaves us with the fact that all of the techniques proposed thus far look like they’re going to be astronomically expensive. Wikipedia links to three studies assessing the costs of negative carbon technoloies. The estimates range from 54 euros (54 US dollars) per ton of CO2 captured, to $600 per ton. When you consider the fact that the carbon emissions of industrialised countries tend to be measured in gigatons, you see how big the problem is. Taking the United States as an example: To offset the 5.3 gigatons of carbon they emit every year at a cost of $600 per ton, it would cost $3.2 trillion, or about 20 percent of the entire US GDP. Even at the lower estimate of $54 per ton, it would cost $576 billion, or about 3 percent of their GDP.
The technology might get cheaper before we wind up having to use it. But what if it doesn’t? What if our only hope to salvage anything like a healthy climate is going to cost hundreds of billions of dollars, just to offset American emissions? Can we expect governments to spend that kind of money?
With today’s political values, the answer to that question is a resounding “no”. No country is going to spend up to 20 percent of its GDP on pulling carbon out of the atmosphere just because it might be a nice thing to do for future generations. But what if the situation becomes truly dire? How much money would a modern country be willing to spend on carbon mitigation if the world is being ravaged by drought, floods, hurricanes, heat waves, and famines? How much will the United States be willing to spend on pulling carbon out of the atmosphere when Miami starts to sink under the Atlantic ocean. To answer this, we have to look at how governments have spent their money in desperate circumstances in the past. So I did a bit of googling to find out the proportionate costs to the United States of the most expensive wars during the twentieth century. Here’s what I found:
- World War I: $344 billion, or 13.6% of US GDP at its peak in 1919.
- World War II: $3.1 trillion, or 35.8% of the US GDP at its peak in 1945.
- The Cold War: US military spending was between 5 and 10 percent of US GDP during the 1960s.
So it is possible to muster the political will to spend ten or twenty percent of a country’s GDP on a single cause if that cause is closely tied with self-preservation from fascist takeover or nuclear annihilation. The good news is that the percent of GDP that the United States spent on its wars during the twentieth century would in some cases be enough to offset its entire carbon footprint, even with a $600 per ton price-tag. If the cheaper estimates are more accurate, then you could do it with a level of spending comparable to what the Americans spent in the cold war.
The bad news is that this comes with a lot of caveats. Firstly, it isn’t exactly clear how even catastrophic climate change compares, on a socio-political level, with a world war. Maybe without a clear human enemy to fight, you can’t muster the same political will. Maybe catastrophic climate change will cause a world war, which will soak up all the resources that could otherwise be used to deal with the root of the problem. Secondly, we have to recognize that funds are not the only constraining variable we need to be talking about. It takes time to up-scale a new technology to the point that it can influence the atmosphere of an entire planet. And shortages of land, labour or raw materials might set a maximum amount of carbon we can sequester per year that is lower than we need. That’s to say nothing about the ethical concerns about negative carbon technologies.
This is just a very basic back-of-the-envelope musing about a topic that is in the climate change news a lot these days. Please don’t take a 1000 word blog post to be a thorough economic or historical analysis. If I were to make one substantive argument out of all this, it’s that in predicting how the climate crisis will unfold, we need to look at times in history when human politics, economics, and psychology has been under a lot more pressure than it is now. Perhaps that pressure can translate into real action. But we probably shouldn’t count on it.