Two, Four, Six Degrees: You Choose

Bob WornanNews And Views0 Comments

In the Copenhagen Climate Accord of 2009, countries agreed that “deep cuts in global emissions are required… to hold the increase in global temperature below 2 degrees Celsius…” The “eleventh hour” agreement wasn’t accompanied by anything enforceable, nevertheless the 2°C objective became the international mantra, repeated by mostly richer countries’ governments.

With the passage of time and closer scrutiny, it’s become clear that the 2°C target is incompatible with global commitments. To make transition plans publically palatable, governments promoted them as vectors for growth, which in reality will put limits on growth and has further complicated the likelihood of a satisfactory outcome.

The following information has been inspired by Kevin Anderson’s YouTube presentation:

Kevin Anderson is a professor at the University of Manchester in the UK, and Vice President of the Tyndall Institute, also in the UK. With his colleague Alice Bows, Kevin’s work on carbon budgets have been pivotal in revealing the widening gulf between political rhetoric on climate change and the reality of escalating emissions. Anderson makes clear – without saying it – that scientists, who know better are supplying politicians with the message that they want to hear rather than the tough truth regarding the real numbers.

His work indicates that there is now little chance of maintaining the rise in global temperature to below 2°C, despite repeated high-level statements to the contrary. Moreover, Anderson’s research demonstrates how avoiding even a 4°C rise demands a radical reframing of both the climate change agenda and the glowing economic results that will accompany the transition.

Anderson’s methods, his data and his conclusions.

When speaking of achieving the 2°C target, Anderson says (2013) that CO2 emissions reported to (UK) government agencies are always underplayed. Let’s use his explanations to interpret the weaknesses of the assumptions shown in the following familiar graph.



  1. What are the current emissions?
    In 2006, the UK produced the Stern report, which was a well-funded high profile project. At the time, the report assumed a worldwide growth rate between 2000 and 2006 of 0.9% per annum. At that time, the real rate was already known to be 2.4% per annum! This was a 250% error and fundamentally changes the conclusions. Nevertheless, this error went unnoticed by the scientific community and the concerned NGOs.
  2. What is the growth rate until reaching a peak in CO2 emissions?
    Typically, annual growth rates of 1 – 2% are used, which are far below recent China and India real figures, and below the average worldwide figures. Using the real rates makes it very hard to get governments to accept the consequences.Nearly every government estimate was based on peaking between 2014 – 2016. According to Anderson, no one (meaning his academic colleagues) believed the figures were viable. Nevertheless, the 2016 figure was the one given to the UK government to construct their plans, simply because if the peak was later, their plans would become non-viable.
  3. When do emissions peak?
    Data was continually underestimated. One 2009 paper gave policy recommendations for the following year, as if recommendations were administratively, economically and physically possible to implement in such a short timescale. Another paper in 2008 said emissions had already peaked in 2005. Anderson jokes that mitigation would require a time machine.
  1. What reductions are viable?
    Typically, calculations use 2 – 4% / year, occasionally reaching 5%. These figures are based on economists’ assertions about compatibility with economic growth.
  1. Is there an emissions floor?
    Food production and associated methane are factors that will be hard to significantly reduce.
  1. Are negative emissions assumed?
    This means using geoengineering techniques to withdraw CO2 from the atmosphere. The UN’s Integrated Assessment Models, or IAMs, the principal tool used to guide government policy aiming at 2°C assume negative emissions.Some scenarios propose introducing negative emission technology as early as 2024 and others as late as 2070. The dates are calculated based on the estimated costs at the time. Of course, no one can seriously estimate geoengineering costs in 2070 or even know if the technology will work on the scale needed.Apart from reforestation (where?) the model often proposed is based on the combustion of biomass and carbon capture. Since biomass is also proposed for use in shipping, aviation, and possibly cars on a planet with some nine billion people, it’s impossible to know if anywhere near the required quantity will be available. If every model depends on this scenario and it doesn’t work, there is a big danger.
  1. What is the “emissions budget” (maximum quantity of accumulated CO2) to avoid exceeding 2°C?
    Before considering the numbers, we must keep in mind that CO2 in the atmosphere is cumulative. Last year’s CO2 is still there.The UN’s IPPC figures are generally considered reasonable. IPPC provides numbers that give the relative probability of success as follows for the period 2011 à 2100:
66% probability of 2°C limit 50% 33%
1000 Gt CO2 cumulative emissions 1300 Gt CO2 1500 Gt CO2

Now, let’s look at some numbers over the 2015 à 2100 period:

2011 – 2015 Energy CO2 already emitted 150 Gt CO2
2015 – 2100 Land use & Deforestation: 100 Gt CO2
2015 – 2100 Cement production: 150 Gt CO2
Total 450 Gt CO2
  1. Now, assume the non-OECD countries peak their emissions by 2025 (China says 2030, but hope to do better) and then begin a 6-8% per annum reduction.

By the end of the century, they will have emitted 700 Gt CO2, which when added to the 450 Gt above will have exceed the century’s 2°C CO2 budget!

To get the figures back on track, with a 50:50 chance of meeting 2°C, the OECD countries would have to achieve a 10% year-on-year reduction, as follows:

-40%  by    2018
-70%  by    2024
-90%  by    2030

These figures are totally impossible, and are incompatible with any form of economic growth.

  1. When will the poorer countries’ emissions overtake the richer countries?Accurately knowing this date is very important for the calculations because the poorer countries emissions are much more tightly linked to fossil fuels, especially coal. The sooner they overtake the richer countries, the more CO2 will be accumulating.

Here are some studies estimated dates:

University of Maryland 2013
Stanford University 2021
MIT 2023

The actual cross over date: 2006. In other words, before the reports were published! It seems even well known research centers don’t look too carefully for factual errors when they might complicate the 2°C scenario.

  1. Assumptions about developing “big” technology projects are naively optimistic.All scenarios that approach the desired temperature limits depend on some sort of massive technology implementation, such as “renewables’” anti-intermittence storage schemes (e.g. methanation (power à gas)), bioenergy carbon capture and storage (BECCS), new nuclear technology, etc. The positive effects of these cost-effective glitch-free developments magically appear in the models’ result’s virtually overnight. Engineers would consider this unrealistic.In some quarters (certainly in France), engineers are arguing that these technological challenges are so critical to future success, they should be implemented immediately for technical and economic validation before massively committing to this or that fossil fuel replacement. Locking ourselves today into a future cul-de-sac would be disastrous.


Today, mitigation actions not associated with growth are extremely difficult to get accepted by governments. The French climate effort, called “Energy Transition for Green Growth” is a typical example. Unfortunately, until societies are decarbonized, there will have to be reductions that are incompatible with growth and may well require several generations of “economic compression”.

In principal, it’s physically possible to imagine a 2°C limit, however there is very little likelihood that the necessary actions will be accepted within the very limited timescales available.

Policy is dominated by what’s familiar and positive sounding. Large reductions are always pushed off to future politicians to deal with. The first 2017 French presidential election “debate” has made that very clear.

Temperature rise limited to 2°C is highly unlikely, and 4°C brings us into an unknown future. The planet will be revolutionarily different.

Robert Wornan

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