[This post was written before the previous post on Development, Pollution and Emissions, and makes more sense if it goes before it]
I had thought that the idea of a carbon budget was easier to understand than emissions intensity. A carbon budget tells us that we can only emit so many tonnes of carbon, before the chance of going over 1.5 degrees centigrade becomes extremely high.
The idea of a carbon budget seems to tell us something straightforward: we can no longer afford to keep emitting Greenhouse gas emissions, and we have to stop soon if we wish to avoid serious climate change.
But this idea gets mired in difficulty and unclarity, largely because of disputes over modelling, and the tendency of people to take probabilities as hard categories. That is, that a 66% chance of avoiding 1.5 degrees, often seems to be taken as if meaning that if we manage to meet that budget then we won’t exceed 1.5 degrees. This assumption could be fatal. It may also not be clear that the more we exceed the carbon budget the worse events will get. Our wealthy people are used to renegotiating loans, getting deferrals, getting assistance and so on. Our politicians are used to blaming the other side for the deficit, ignoring their own, or issuing bonds or even currency, and things keep going. A human budget is rarely ever fixed. However, the carbon budget is not a budget which can be escaped, or put to one side.
Here we have someone at The Guardian:
Time is running out to meet the goals of the Paris Agreement and avoid catastrophic climate change. The 2018 special report of the Intergovernmental Panel on Climate Change (IPCC) “suggests a remaining budget of about 420 Gigatonnes (Gt) of CO2 for a two-thirds chance of limiting warming to 1.5°C.” …. Despite this stark warning, the world keeps emitting over 40 Gt of CO2 per year.
Since we have already drawn down over 120 Gt of CO2 from this carbon budget, we have now less than 300 Gt left. Combining the proved fossil fuel reserves reported in British Petroleum’s Statistical Review of World Energy with CO2 emission factors from the IPCC yields 3,600 Gt of CO2 emissions. This means that we can only afford to burn one twelfth of the fossil fuels we have already found. [Currently there is no sign of this happening]
The policy instruments that are currently being used across the globe to reduce CO2 emissions aren’t working. It is therefore time to ban fossil fuels.Geyer It’s unavoidable: we must ban fossil fuels to save our planet. Here’s how we do it. The Guardian 9 March 2021
This account does not include natural emissions, such as methane from thawing tundras or sea releases of methane as the ocean temperature warms and currents change, or the likely growing inability of natural carbon sinks to keep up the absorption – especially with growing deforestation and poisoning of the sea. So the situation is far worse than is being portrayed.
Then there is the probability problem mentioned earlier. The “two-thirds chance of limiting warming”. That is an estimate. We have no means of knowing if it is absolutely correct, as opposed to roughly correct, or not. We could have a 99% chance of avoiding the problem, and still be in the 1% range, in which factors make the temperature increase too great for stability. We might, on the other hand, be in the range of being ok, and people might bet on that unrealistically with enough incentive. In any case, a one third chance of going over 1.5 degrees, even if we beat the target, is not small.
The only accurate model of a complex system is the system itself, and we don’t know exactly what will happen until it happens. So we are left with a guess, and the high probability of bad results given that events seems to be getting worse rapidly – although people will acclimatise rapidly to the idea of circumnavigating the north pole, changes in temperature, raging bushfires: “They always happen”.
Furthermore, the figures do not seem easily stable. The ACT/Climate Change Council brochure “What is a Carbon Budget” factors in some of the figures, bypassed in the Guardian report:
The UN International Panel on Climate Change (IPCC) estimates7 [in 2013] that for at least a 66% chance of staying below 2°C, total GHG emissions must be less than 1000 billion tonnes of carbon.
We have already ‘spent’ about 585 billion tonnes (also referred to as gigatonnes) of carbon (Gt C), which reduces the remaining carbon budget to about 415 Gt C. Then we need to account for the other GHGs, principally nitrous oxide and methane. If we don’t reduce them at the same rate as we reduce carbon dioxide we’ll have less of the budget—about 210 Gt C less—to still ‘spend’. That leaves about 205 Gt C. The current rate of emissions of carbon dioxide is about 10 Gt C per year, so at present rates this remaining budget would be used by about 2040…..
As the Earth warms, the oceans and land are no longer able to absorb the same fraction of our carbon emissions that they can at lower levels of warming, an effect due to ‘carbon cycle feedbacks.’ Combining scientific estimates of this effect by two independent groups [9 , 10] indicates that the budget previously calculated must be revised downward by about 75 Gt C. This leaves a remaining carbon budget for keeping global temperature within 2°C at 130 Gt C.What is a Carbon Budget 2018 p.5.
So what do we emit? There is a big difference between 40Gt and 10 Gt. There is a similarity to the figures, but even so, the second model seems far more urgent, because it includes factors left out of the first.
However the models available to us apparently differ considerably, which is inevitable when modelling complex systems (to repeat: the only accurate model of a complex system is the system itself), and that is a problem for knowing how desperate we should be. We have to accept that we don’t know for sure – we only know in general that the situation seems bad. It is of course comforting to use the margin for error to assume we are better off than we are, and that seems to be the common response.
In dealing with complex systems we have to recognise that certainty is gone, and was only ever illusory in the first place.
This is an official summary article, which gets referred to frequently, and which I found incredibly confusing – I would suggest it was not written to be approachable. It was of no immediate use to me – although Forbes tells me it says:
The world has 8% of carbon budget left, which will be exhausted in the coming decade at current emission rates. Any rise beyond this budget would mean that average global temperatures would go over 1.5 deg C at the turn of the century which could lead to catastrophic changes.Shetty World Is Set To Exhaust Carbon Budget In 10 Years. Forbes 11 December 2020 [Emphasis added]
To be repetitious again: we may not have to exceed this budget to exceed a 1.5 degree increase in temperature. It is fairly likely before that level and gets more and more likely as we reach or exceed that level.
The same source says 34 Gt of CO2 were added to the atmosphere in 2020. They add that to increase the likelihood that:
average global temperature does not rise beyond 1.5 deg C by the turn of this century, global carbon emissions will have to be cut by 25% to 50% between 2020 and 2030, predict various climate models.Shetty World Is Set To Exhaust Carbon Budget In 10 Years. Forbes 11 December 2020
You will probably have noted that one of the sources quoted states, that factoring in all the other problems, we cannot emit more than a total of 130GtCO2 to keep temperature below 2 degrees increase. That implies we have to cut 34 Gt per year significantly now. This is a huge variance in how fast we should move. Again it is comforting to think we can get by at the high end of the emissions, and that is probably the approach that will be taken.
Further more, the article actually makes the elementary mistake of writing “to ensure that the average global temperature does not rise beyond 1.5 deg C…” This is rubbish, for the reasons we have previously discussed. People are routinely turning probabilistic statements into hard category statements probably to reassure themselves. Again we have differences in the models, some require bigger cuts, some may require lesser cuts. We need to ask ourselves and our governments and businesses, whether it is sensible to risk the lesser cuts being appropriate, because we are dealing with probabilities not certainties.
Carbon budgets seem to be used to reassuringly play down the problem.
However, despite these problems, carbon budgets can suggest useful and direct action, unlike carbon intensity figures which can hide how things are getting worse. So they probably are better tools than the intensity measures.
For example, the UKs new carbon budget (issued December 2020), clearly states:
Our recommended pathway requires a 78% reduction in UK territorial emissions between 1990 and 2035. In effect, bringing forward the UK’s previous 80% target by nearly 15 years.UK Sixth Carbon Budget
- Phasing out high Carbon options, such as cars, trucks and boiler heaters. “By 2040 all new trucks are low-carbon. UK industry shifts to using renewable electricity or hydrogen instead of fossil fuels, or captures its carbon emissions, storing them safely under the sea.” [The capturing is fantasy, and clearly dangerous, how would you know if these emissions were leaking? But the principle seems straight-forward.]
- UK electricity production should be zero carbon by 2035, largely through offshore wind. They should explore hydrogen.
- Curb waste. Lower air traffic. Farm, and eat, less meat.
- Transform agriculture. Plant Trees. Biofuels. [Biofuels seem largely a fantasy as well, in terms of emissions reductions, but who knows?]
Graphs indicate an aim for zero emissions by 2050. The Conservative government possibly thinks this is practicable. especially given that most sources report dramatic falls in the UKs Carbon emissions since 1990 , , although gas largely used for heating, is now likely to get in the way, and political opposition get boosted. The UK actual emissions reductions are also better than Germanys. If the recommendations are accepted, the UK will be aiming at emissions reduction, relatively quickly, whether quickly enough is another matter.
If they do accept the recommendations then they are going first. They are not waiting for others to catch up to make it fair. They are not worrying about others taking advantage of them, they are simply setting an example. This is how things get done.
Others will follow if it works.
To someone in Australia or the US, this probably all seems unbelievable. A right wing government is taking hard action without trying to pretend everything is ok, and nothing needs to be done. They are accepting responsibility and working towards a target. They are possibly even recognising that there will be problems, and not running away from those problems. Of course, in this part of the world, it is hardly ever reported.
On top of these kinds of actions, it also seems likely that we may need technological carbon removal, although bio carbon removal, stopping deforestation and starting ecologically sensitive reforestation, would be easier. Technological removal will be massively expensive, the carbon will be hard to store or reuse, and we don’t have it, at anything like mass use – but it might be worthwhile expending public research money on it, and keeping the patents in the public domain, to make it useable. As long as it is not used to allow more fossil fuel burning then it will help.
Carbon Budget or not, the basic practice all comes to the same simple points.
- No new coal mines. Now. No expansion of existing mines.
- No new gas. Now.
- No new oil. Now
- No new fossil fuel power stations. EVER.
- Electrify everything so it can be powered by renewables. Do the research to make this possible.
- Replace fossil fuel burning, import and export in your own country, with Renewable Energy by 2030, whether it hurts or not, and then worry about elsewhere. It will hurt if the transition is not well planned and the open market well and transparently regulated.
- If possible, agree on a uniform world carbon price, to help phase out fossil fuels.
- Help workers in the fossil fuel industry gain new well paying jobs.
- Help poorer countries get a renewable electricity infrastructure that does not belong to people overseas, so they don’t have to use coal, or get sold coal by countries wanting to exploit them.
- Lower all forms of pollution drastically.
- Lower the damage from extraction. Allow living resources to replace themselves.
Of course getting some countries to agree will be difficult, that is why you work in your own country first. But the more who do agree the easier it will be.
Even if this process causes a mess, which it probably will, it is better than the alternative, and we can solve the problems as we encounter them rather than declare it is all too hard in advance.