This year several governments announced that their countries will be carbon neutral by 2050. This is a cheap promise, as the target is so far in the future that it doesn’t commit them to do anything significant now, but even if the commitment would be real, one may wonder how probable it is that the target will actually be reached, and whether it will be enough. These are two different questions, of course, and I will try to (provisionally) answer them in turn.

Is carbon-neutrality by 2050 possible?

Some kinds of carbon emissions are relatively easy to bring down – others are not. It is not unlikely that in industrialized countries the vast majority of passenger cars will be electric by the end of the 2030s, for example, but to what extent the same is achievable for road freight transport is more doubtful, and other kinds of transport will be even more problematic. Commercial flight (both cargo and passengers) will never be carbon neutral, and while ocean transport could in principle return to sail, it is not likely that transport companies are actually willing to rely on wind (and certainly not on wind alone).

Even if much energy use becomes electricity-based, that electricity has to be generated somehow, and the transition to green energy appears to be much slower than needed. Power plants are typically built to provide electricity for at least 40 years, and worldwide many new fossil-fuel-burning power plants continue to be built or are scheduled to be built in the near future. If the last scheduled fossil fuel power plant is finished in 2030 (which is implausibly early), then that would commit us to carbon emission from that plant to approximately 2070, unless it would be scrapped halfway its normal operational lifespan, which is unlikely for financial reasons.

An additional problem is that it is not immediately clear whether “green” sources of energy can be sufficient to meet our (excessive!) energy needs. We’re already close to the limit for water power, for example. Wind and solar can both be significantly expanded, but both require resources that are either quite energy-intensive or relatively scarce (or both). This is a problem that I have addressed before in The Lesser Dystopia. Perhaps, I was overly pessimistic when writing that article, but even a much more optimistic estimate suggests that it is unlikely that alternative sources of electric energy can ever be sufficient to provide the amount of electricity we are consuming now.

But even if a complete transition to green electricity is possible by 2050, and all transport infrastructure would be electric by then, there still are a number of other sources of carbon emissions that need to be addressed. Roughly 12% of greenhouse gas emissions result from agriculture, for example, and about 30% is related to manufacturing industry and construction. The use of concrete and cement in construction alone is responsible for approximately 7% of CO₂ emissions. Consequently, becoming carbon neutral by 2050 also means abolishing concrete (and replacing it with a suitable alternative) by 2050. And it requires a complete overhaul of the agricultural sector. Neither of these goals would be easy to achieve. There is no good substitute for concrete on the horizon, and the only way to make agriculture carbon neutral would be to abolish all livestock farming. Aside from the fact that it is unlikely that everyone is willing to switch to a vegan diet, an even bigger problem might be that agriculture is dominated by a relatively small number of very large firms.

When most people think of agriculture, they think of small farms, but reality is different.

Today, it is estimated that there are approximately 608 million farms in the world, and most are still family farms. However, the largest 1% of farms operate more than 70% of the world’s farmland and are integrated into the corporate food system, while over 80% are smallholdings of less than two hectares that are generally excluded from global food chains.1

Moreover, even many of the small(ish) farms have their hands tied behind their backs by contractual obligations to suppliers of seeds and buyers of their products. Consequently, agriculture – and food production in general – is dominated by a handful of very large corporations, which are not very likely to give up their profit-maximizing and world-destroying formula for something less profitable and less destructive.

All of these considerations point toward the same conclusion: carbon-neutrality by 2050 is very unlikely. One may even wonder whether we’ll ever voluntarily reach carbon-neutrality. (Of course, massive and widespread societal collapse would eventually result in something close to carbon neutrality, but it is the very point of emission reductions to avoid that scenario.) Unless we suddenly find a way to capture carbon from the atmosphere and store it in some other form. That, however, is extremely unlikely for another reason: it would require magic. For reasons explained in The Lesser Dystopia, capturing carbon to achieve carbon neutrality would require us to bend or break the laws of physics. It is for reasons like this that a bet on carbon capture technology has been called “magical thinking” in an editorial in Nature.2

So, in conclusion then, despite (empty) promises, carbon-neutrality by 2050 will almost certainly not be reached.

Is carbon-neutrality by 2050 enough?

Let’s say that despite the foregoing, we do actually manage to achieve carbon-neutrality by 2050. Then, what would the effect thereof be?

It is impossible to give an exact answer to that question for a number of reasons. First of all, virtually every aspect of climate science involved in producing such estimates works with large uncertainty margins. But perhaps even more important than that is that different trajectories towards carbon-neutrality would result in very different total greenhouse gas emissions. Rather obviously, the later we start with bringing CO₂ emissions down, the more we will emit over the three decades between now and 2050.

Currently, global annual emissions are close to 50 gigatonnes CO₂-equivalent. Let’s compare three different scenarios of bringing that down to 0 in 2050. The three different (colored) lines in the following figure show these three different trajectories. The blue line results in a total of 775 Gt, the red line in a total of 766 Gt, and the orange line in a total of 1131 Gt.

Three trajectories towards carbon-neutrality by 2050.

Since not much is happening yet in terms of emission reductions, we’re obviously not on the blue line, so that is not a realistic scenario. The red line is – more or less – the most optimistic trajectory, while the orange line represents a more “pessimistic” scenario. Even more pessimistic scenarios start with a further increase in carbon emissions before the line finally starts descending.

Note (March 2, 2022)

In an earlier version of this article, these calculations underestimated natural carbon sequestration, and thus overestimated atmospheric carbon increases (i.e. the ppm numbers). Because of that, the predicted temperature increases were also much too high.

The 766 Gt of CO₂ equivalent emissions of the red scenario lead to roughly another 45 ppm of atmospheric CO₂; the orange line leads to almost 70 ppm. Right now, we’re at approximately 415,3 so that will lead to between 460 and 485 ppm mid century. (If we take into account that certain emissions are very hard to reduce for technological and/or economic reasons, the actual number will almost certainly be significantly higher. In this section we’re assuming that it is actually possible to reach carbon-neutrality in 2050, however.)

What these numbers mean in terms of warming can be inferred from the recent refinement of the “climate sensitivity” measure by Steve Sherwood and colleagues,4 discussed before in this blog. Climate sensitivity is the expected average global temperature increase due to a doubling of atmospheric CO₂ from pre-industrial levels of 280 ppm to 560 ppm. In 1979 this was estimated at 1.5‑4.5°C, and that range remained unchanged until earlier this year when a refined measure of 2.6‑3.9°C was published. This means that there is a 66% chance that the planet will be warmed up that much if we double atmospheric CO₂ (relative to the pre-industrial standard of 280 ppm); the 95% likelihood range is 2.3‑4.7°C, and the median expected temperature increase is 3.1°C.

Even the “pessimistic” scenario (i.e. the orange line) remains well below 560 ppm. It would lead to approximately 2.2°C of warming. The optimistic scenario would lead to a slightly smaller temperature increase – somewhere around 1.9°C. (Realistic scenarios probably far exceed the higher number. If residual emissions and other obstacles are taken into account 3°C or even more seems much more likely.)

Even 2°C or more of average global warming would have devastating effects on large parts of the planet – for a summary of the effects of +2°C, see The 2020s and Beyond – and may very well be sufficient to set off the cascade of societal collapse described in A Theory of Disaster- Driven Societal Collapse and How to Prevent It and in On the Fragility of Civilization.

What is even more concerning, however, is that this number puts us awfully close to the expected range of many major tipping points. Although the classic study on tipping points by Timothy Lenton and colleagues suggests that it would require warming in the range of 3 to 5°C to trigger most tipping elements in the Earth system, according to Sybren Drijfhout and colleagues’ inventory of tipping points recognized by the IPCC (in 2014) about two thirds of those are triggered at temperature increases below 3°C.5 If we pass such tipping points, this will lead to fundamental changes that cause further temperature increases, which may trigger further tipping points. One of the most worrying of these is permafrost melting because melting permafrost releases methane, but also rots away itself, putting more carbon in the atmosphere, leading to more warming. Such tipping points are not runaway effects, however – they do not lead to unlimited warming (even if additional warming due to passing one tipping point leads to passing another). Rather, they add additional warming on top of the warming that is directly caused by us. In other words, if we warm up the planet by roughly 2°C, there is a high likelihood that “natural” processes add some further warming, it may be just half a degree or less, but it could very well lead to 3°C (or even more in less probable scenarios). In Our Final Warming, Mark Lynas has described in detail what the effects of 1 to 6°C of warming are, dedicating a chapter to each degree.6 The chapter titled “3 degrees”, describing the effect of +3°C can be summarized in one word: devastating.

The answer to the question whether carbon-neutrality by 2050 is good enough, then, is clear as glass: No. If we want this planet to remain hospitable to something approaching civilization, then carbon neutrality by 2050 is not nearly good enough

Concluding remark

It turns out that the promise of carbon-neutrality by 2050 isn’t only empty and cheap, but is unlikely to be kept, and even if it would be kept, would result in overheating the planet way beyond acceptable levels.


addendum (May 21, 2022)

A series of attempts to get a more realistic prediction of how much carbon we are going to emit and how much warming that will cause suggests a median value of average global warming of 3.3°C (67% confidence interval: 2.3 ~ 5.0°C). The models resulting in this prediction also suggest that a greater contribution to carbon emission reduction will be made by social and economic collapse than by policy and other peaceful means. For further details, see episode 8 in the Stages of the Anthropocene – Revisited series.


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Notes

  1. W. Anseeuw & G.M. Baldinelli (2020). Uneven ground: land inequality at the heart of unequal societies (Rome: International Land Coalition), p. 10.
  2. Nature editorial (2018). “Negative thinking”, Nature 554 (22 February), p. 404.
  3. See www.co2.earth for the most recent number, but notice seasonal fluctuations.
  4. Steve Sherwood et al. (2020), “An assessment of Earth’s climate sensitivity using multiple lines of evidence”, Review of Geophysics 58.4: e2019RG000678.
  5. Timothy Lenton et al. (2008), “Tipping Elements in the Earth’s Climate System”, PNAS 105.6: 1786-93. Sybren Drijfhout et al. (2015), “Catalogue of Abrupt Shifts in Intergovernmental Panel on Climate Change Climate Models”, PNAS: E5777-86. See also: Will Steffen et al. (2018), “Trajectories of the Earth System in the Anthropocene”, PNAS 115.33: 8252-9.
  6. Mark Lynas (2020), Our Final Warning: Six Degrees of Climate Emergency (London: 4th Estate).