By Jon C
The UK Office of Budget Responsibility estimates that the UK getting to net zero by 2050 will cost about £320 billion pounds.
Here is a graph of the United Kingdoms (estimated) annual carbon dioxide emissions from 1850 to 2022 in Gigatonnes (Gt) (Figure 1).
The graph shows that the UK has cut its emissions by half since its peak around 1975. A lot of the emissions reductions resulted from UK manufacturing moving overseas in response to rising energy and labour costs. This has hollowed out the manufacturing sector of the UK economy, destroying high-skill, high pay jobs (so these skills are lost to the UK now) and quite a few communities as well. But, the costs (financial and other) might be worth it, if reducing the United Kingdom’s carbon dioxide emissions would have a meaningful impact on global warming.
Figure 2 (below) shows the UK’s emission in comparison to those of the rest of the world over the same period of 1850-2022. The UK’s emissions are shown in yellow and the rest of the World in red.
As can be seen, the UK’s reduction hardly shows above the base line on the graph and has had little measurable effect on changing the levels of CO2 emissions over the years.
The IPCC (International Panel on Climate Change) claims that the sum total of all the emissions (thus, in effect, the area under the graphs) has raised global surface temperatures by about 1.4°C .
Comparing the two lines gives us the first clue that the UK’s contribution to Global Warming / Climate Change is basically negligible.
To estimate how much difference the UK sacrifices will make, let us assume that we will reach zero emissions by 2050, at that estimated cost of £320 billion – and remember this is likely to be an under-estimate, almost all large scale publicly funded schemes have cost over-runs.
The UK emits about 0.4Gt p of CO2 per year at present. If we assume a linear fall in carbon dioxide emissions this means an average of 0.20 Gt per year for the period 2024-2050, which is 26 years or a total of 5.2 Gt saved over the period. But let’s make the assumption that more of the drop-off occurs sooner and take a (generous) figure of 6.0 Gt as the amount saved (this, in effect, makes the UK “carbon neutral” by 2030 for the period 2024-2050).
Restating the assumption: the UK saves 6.0 Gt of CO2 by 2050. This will reduce the concentration of CO2 in the atmosphere by 0.41 ppm (as will be shown later).
In 2024 the CO2 concentration was 423.6 ±0.5 ppm. Note the error on the data, ±0.5 ppm, this means that the reduction of CO2 from the UK going to zero emissions would fall within the error range of the current value. In other words the effect of any reduction in global carbon dioxide from the UK could not be determined.
That should be our second clue that whatever we do in the UK, the effect will simply not be measurable. The UK moving to “net zero” or even “zero” emissions will have no significant effect on global temperatures.
However, using data from the IPCC we can calculate the (theoretical) effect of the UK’s move to net zero.
The total mass of the atmosphere is approximately 5.1×1018 kg , or 5.1 million Gt.
1 part per million (1 ppm) of that is 5.1 Gt.
However, carbon dioxide is a ‘heavy’ gas, with a molar mass (44g/mol) roughly 1.5× that of the “average” molar mass of atmosphere (~29 g/mol). As a result 1 ppm of CO2 in the atmosphere is thus equivalent to 7.7 Gt of CO2.
Currently, approximately 50% of emitted CO2 remains in the atmosphere, while the rest is absorbed by oceans and land. One consequence of increased carbon dioxide levels has been an increase in plant growth around the globe – the world is greening as a result of higher levels of carbon dioxide.
So a 1 ppm decrease in atmospheric CO2 requires the removal of ~14.4 Gt of CO2 emissions. And the UK change of ‒6.0 Gt of CO2 converts to a 6.0/14.4 = 0.41 ppm decrease in atmospheric CO2.
Using Copernicus’ estimate of an annual increase in atmospheric carbon dioxide of 2.4 ppm and if we assume that no other Country follows the UK then by 2050 the concentration might be as high as 423.6 + 2.4×26 = 486 ppm, up from the baseline pre-industrial value of 275 ppm, an increase of 77%.
According to the IPCC, a doubling of CO2 is projected (by a mid-range estimate) to increase global temperatures by 3.0°C, an 77% increase would then be a warming of 3×0.71 = 2.3°C.
The Uk’s reduction of 0.41ppm represents a reduction of 0.41/486 = 0.00084 or 0.084%.
Thus the reduction in global temperature due to the UK going to zero emissions would be reduction of the 2.43°C by: 2.43×0.00084 = 0.0020°C.
A more optimistic scenario could be taken. Let’s assume that the rate of increase of CO2 halves overall, so by 2050 the concentration will be 423.6 + 1.2×26 = 455 ppm, a change from the pre-industrial base of 275ppm of 65% and a projected warming of 2.0°C.
In this case the reduction in CO2 due to the UK going to zero carbon is: 0.41/455 = 0.00090.
And the reduction in temperature is: 2.0×0.0009 = 0.0018°C.
These numbers are literally too small to reliably measure with any instrument existing today. Thus, assuming the UK reaches net zero by 2050, the effect on the global climate will be entirely negligible.
Note that there are more complex, and accurate, ways of calculating the theoretical temperature reduction, for example those involving what is known as “radiative forcing” and “climate sensitivity”. By this method, in all the examples I have seen the temperature reduction is less than that calculated above (though of similar irrelevant magnitude).
Further, there are a lot of assumptions in all these calculations, so the results from any analysis are estimates at best and speculation at worst.
Thus a valid question to ask is this. If it will cost 320 billion pounds to reach net zero emissions by 2050, for no measurable effect on global warming or climate change, is this a sensible use of the money, or could the money be better spent on things other than ‘net zero’?
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