_ Dr. habil. Sebastian Lüning. Berlin 26 July 2021.*
Climate policy is a particular challenge for everyone involved. Dealing with a variety of uncertainties, enormous interdisciplinarity, a high degree of internationality and time scales, sometimes beyond one’s own lifespan, is unusual and difficult. It is still unknown whether or when affordable carbon-free base load energy sources, energy storage and CO2 storage facilities will be available on a large scale. At the same time, the scientific understanding of the climate continues to develop and is much less dramatic today than it was a decade ago. There is now much evidence that the warming effect of CO2 is in the lower half of the uncertainty range of 1.5-4.5 ° C per CO2 doubling cited by the Intergovernmental Panel on Climate Change. The assumed CO2 climate damage is correspondingly lower. In general, earlier damage calculations seem to be very inflated and not very robust, since the climate models used in the determination have turned out to be unrealistic in many respects, so that the calculations can only be given little confidence.
In view of the still lacking solutions for carbon-free energy carriers and storage, CO2 pricing in the electricity generation sector will currently primarily stimulate the switch from coal to natural gas, with natural gas only causing half as many CO2 emissions per unit of energy generated compared to coal. The planned phase-out of coal in Germany by means of a ban will de facto make market-based management via additional CO2 taxation superfluous in Germany. At the European level, the common CO2 avoidance target will be achieved cost-effectively with the existing emissions trading system.
The main task of politics should now be to stimulate progress in energy technology with the help of research funding. Complete decarbonization remains an illusion until technical substitute solutions are available. Even sharp CO2 pricing cannot enforce this technical breakthrough, as is clear from the example of long-term nuclear fusion research. Concentrating on what is currently realistically feasible should have priority, especially when considering Germany’s international competitiveness.
Climate policy requires a sense of proportion. Political decision-makers should not allow themselves to be driven emotionally by blatant catastrophe scenarios that, on closer inspection, turn out to be excessively exaggerated. Measures should not only be ecologically sustainable, they should also be socially and economically sustainable. Unfortunately, the public climate discussion is currently in extreme imbalance and is dominated by a few actors in the media. The silent majority of the specialist colleagues go unnoticed. It would be important that politicians create more public forums in which even controversial climate science issues can be discussed soberly and openly with the participation of all scientific opinions.
In the course of global industrialization and the use of fossil fuels, the carbon dioxide concentration in the atmosphere has now risen to its highest level for 800,000 years. At the same time, the temperature of the earth has increased by almost one degree in the last 150 years. The exact quantitative proportion of man-made and natural climate factors in this warming is still unclear and is linked to the only imprecisely known climate effect of CO2, the so-called CO2 climate sensitivity. In its first climate report in 1990, the Intergovernmental Panel on Climate Change (IPCC) assumed a warming amount of 1.5-4.5 ° C per doubling of CO2. This very large area of uncertainty with a factor of 3 has not decreased to this day, despite great research efforts. While a best estimate of 3.0 ° C was given in earlier IPCC reports, the IPCC dispensed with this information in its last overall report (AR5) because no consensus could be reached among the researchers involved. The range of possible temperature developments accordingly ranges from “controllable” to “catastrophic”. There is now much evidence of a value for CO2 climate sensitivity in the lower half of the spectrum. In particular, the range of 1.6-2.2 ° C has many supporters in the professional world (e.g. Lewis and Curry, 2015; Mauritsen and Pincus, 2017; Mauritsen and Stevens, 2015; Otto et al., 2013).
In accordance with the environmental precautionary principle, some leading industrialized countries are currently endeavoring to significantly reduce their greenhouse gas emissions, as set out in the Paris Climate Agreement of 2015. The world’s largest CO2 emitter, China, on the other hand, is allowed to increase its CO2 emissions further up to 2030 and then reduce them again. In the past 20 years, China tripled its annual CO2 emissions to more than 9 gigatons today (Fig. 1). For comparison: the entire EU currently emits 3.5 gigatons per year. Around the world, 1,600 coal-fired power plants are currently being built or expanded in 62 countries. It is clear that only joint international efforts can bring about a noticeable reduction in global CO2 emissions. Going it alone nationally is at the expense of international competitiveness and ultimately brings hardly any benefit to the atmosphere. Global trading in emissions certificates would be the order of the day.
Figure 1: Development of CO2 emissions since 1965, broken down by country and regions
Source: BP Statistical Review of World Energy 2018.
Any attempt at political control with regard to national energy generation must comply with the principle of sustainability. Changes not only have to meet ecological requirements, but also have to be socially and economically sustainable. First of all, climate protection leads to higher costs and has to be accepted by the population. The current burden on electricity customers due to the EEG alone already amounts to more than 27 billion euros per year, and there are also burdens from the eco-tax in the area of mobility.
The economically most effective control for avoiding CO2 occurs via market-based mechanisms that are intended to stimulate all those involved in the market to reduce emissions where it is cheapest and most efficient. The most suitable is the international emissions trading, an instrument that was introduced into law in the EU in 2005. If a CO2 emitter exceeds its maximum quantity, it can flexibly buy additional freely tradable emission rights, whereby the price is variable and is determined by the demand. The certificate price has now risen to over 20 euros / t (Fig. 2). Separate CO2 taxation is not necessary, as every European avoidance target can be achieved cost-effectively with emissions trading (Weimann, 2019). In the medium to long term, however, global emissions trading would be desirable.
Figure 2: Development of the CO2 price per ton in European emissions trading
From Weimann (2019).
A number of countries have introduced national CO2 taxes. These are mainly countries that have little or no lignite and hard coal production, which means that the measure is correspondingly easy for them. These include, for example, France, Sweden, Switzerland and Slovenia. The large coal producer Australia abolished the carbon tax introduced in 2012 in 2014. Germany is currently still the world’s largest producer of lignite and benefits from domestic energy sources. For this reason, the decision of the current government coalition was very wrong to introduce a national CO2 tax, This will reduce international competitiveness and cause another cost explosion. The CO2 tax should be binned in the future. German customers, together with Denmark, are already paying the highest electricity prices in Europe. Several large oil and gas companies such as Shell, ExxonMobil, BP, Total, Eni or Equinor are campaigning for the introduction of national and international CO2 taxation. The companies are suppliers of natural gas, which emits only half as much CO2 per unit of energy generated as burning coal. Natural gas is an important transition energy carrier for the global energy transition, as there is currently no other low-carbon energy carrier in sight that would be available in large quantities and at affordable prices and that is also base-loadable and storable. In addition to climate protection, the oil and gas companies naturally have a great interest in taking over coal’s market share. The companies hope for long-term planning security for their investments in cost-intensive gas projects.
The most extreme political interference in energy production is bans. Unfortunately, Germany has made use of this twice in the recent past. First of all, it was decided to shut down the nuclear power plants without any country in the world having followed this radical step. This was followed by the recommendation of the Coal Commission to phase out coal-fired power generation. Such legally enforced prohibitions have a strong planned economy character and are difficult to reconcile with the market economy approach. The consequences of the higher energy costs and the threat to the competitiveness of jobs particularly affect employee households in Germany. The parallel exit from nuclear power and coal also represents a questionable national solo effort, which seems strange in a world that is growing ever closer together. Ultimately, the economic aspect must also not be disregarded. Replacing domestic lignite with expensive imported natural gas, electricity imports or even more expensive renewable energy sources plus exorbitantly high storage costs will result in additional costs in Germany. Other coal countries have not taken this step and will probably not take it in the foreseeable future either. The impending ban on coal in Germany will also make the introduction of a national CO2 tax superfluous for the foreseeable future, as the coal ban does not require additional market-based stimulation of a switch from coal to natural gas.
Recognizing technological and physical realities
An important cornerstone of any energy policy must be security of supply at acceptable prices. It is good to have ambitions in developing renewable energies, especially because the reserves of oil, natural gas and coal are finite and a large part of them also has to be imported. In all ambitious efforts, however, current technological possibilities as well as physical realities must also be recognized. Due to the high volatility of renewable energies, a base load-capable energy system must be kept in place, which can take over the entire energy supply for Germany for days at times of limited wind and solar supply (during so-called dark slacks). Since there are currently still no suitable forms of energy storage that could “save” overproduced green electricity in sufficient quantities into the future, conventional energy sources have to secure the base load until a technological solution is found. Politicians are therefore well advised to intensively promote research efforts in the search for suitable ones, e.g. in the field of hydrogen or “green gases”, and to set well-dosed innovation incentives.
The large-scale replacement of conventional base load energy can, however, realistically only be fully approached in a meaningful way when affordable replacement technologies are available. Long-term political planning over many decades should therefore be kept as flexible as possible and be based on an energy mix, with the possibility of being able to change at any time as soon as this is technically possible. Technical progress can only be stimulated but not forced. This is made clear by the example of nuclear fusion, which has been subsidized with large sums of money – rightly – internationally for decades, but has still not achieved a breakthrough. It would be important to keep this realism in mind when planning policy for the far future.
It goes without saying that it doesn’t make sense to fill the gap in the base load supply in Germany by importing electricity from abroad. Germany’s pioneering role is well meant and intended as a role model, but remains ineffective for the global climate if other major emitters do not follow suit (Lomborg, 2016). In this respect, Germany should avoid dangerous overconfidence and increasingly seek international solutions (BDI, 2017). Going it alone on a national level will only lead to a relocation of fossil power generation and emission-intensive production to locations in non-CO2 taxed countries (carbon leakage, “gray emissions”).
Divergent interests and competitive imbalances in international negotiations should not be overlooked. The beneficiaries of decarbonization will propose a sharper pace out of pure national interest. These include, for example, Norway, Russia and Qatar, which are important supplier countries for natural gas, as well as France, which secures a very large proportion of its electricity generation from nuclear power.
Amount of climate damage caused
Determination of climate damage
With the help of computer models, the amount of damage caused to society by greenhouse gas emissions and the resulting climate change is estimated. In a recent study, the Federal Environment Agency came to a climate damage value of 180 euros per ton of CO2 (UBA, 2018). Three years earlier, Edenhofer (2015) had reported a value of US $ 150 per tonne of CO2. Ricke et al. (2018) even assume a global median of US $ 417 per tonne of CO2. The damage, also known as the “social cost of carbon”, is usually estimated using one of three models (DICE, FUND, PAGE) , in which the physical fundamentals are combined with economic aspects (Fig. 3) (Carbon Brief, 2019). The “climate module” contained therein represents a greatly simplified climate model, which in turn is calibrated with more complex climate models (NAP, 2017). The quality of the damage assessment is therefore directly dependent on the quality of the climate models.
Figure 3: Conceptual structure of a climate module for calculating CO2 damage
Source: NAP (2017)
Climate models with severe deficits
A large number of studies in recent years have shown that climate models still have enormous deficits, so that the level of climate damage estimated from them is fundamentally subject to great uncertainties. This became clear again only recently when the IPCC suddenly increased the remaining CO2 budget by 420 gigatons of CO2 as part of its special report on the 1.5 degree target, after the “CO2 clock” had actually expired according to earlier information in the 5th climate status report and should be zero (MCC, 2018). In this way, the world population was granted a further 10 years of CO2 emissions “overnight” before the 1.5 degree warming mark would be exceeded. According to calculations by Millar et al. (2017) the remaining CO2 budget could be even higher and cover 20 years (Klimaretter.info, 2017). Such forecast weaknesses do not exactly help to strengthen confidence in the IPCC models.
The attribution of the warming observed so far since the beginning of industrialization is similarly uncertain. The recent IPCC special report on the 1.5 degree target assumes that the warming is entirely of anthropogenic origin. In contrast, a climate report published almost at the same time in Switzerland gives significantly more space to natural climate factors, which could have caused up to half of the warming observed in the country over the past 100 years (CH2018, 2018). When asked how the anthropogenic and natural components of global warming were distributed in industrial times, the well-known Kiel climate researcher Prof. Mojob Latif stated in a newspaper interview in 2012: “It’s a mix of both. It is clear that humans are responsible for more than half of the rise in temperature since the beginning of industrialization” (Neue Osnabrücker Zeitung, 2012).
The climate models also revealed weaknesses in forecasting over the past 20 years, although none of the models had forecast the sharp slowdown in warming from the turn of the millennium. Santer et al. (2017) located part of the missing warming in natural ocean cycles, which was apparently underestimated in the models. Even after subtracting this component, there is still a residue of unrealized heat, the cause of which is still unclear to the authors. Santer et al. (2017) assume that the climate forcing systems show systematic weaknesses in the model equations. Major deficits in the climate models are now also evident in the aerosols. A 35-strong suspended matter research group led by Florent Malavelle was able to show that the cooling effect of sulfur dioxide aerosols is much lower than assumed in common climate models (Malavelle et al., 2017). As a result, the warming effect of the CO2 must now also be corrected downwards, since the sulfur dioxide had an important cooling function for excess heat from the CO2 in earlier models.
Probably Germany’s best-known climate modeler, Prof. Jochem Marotzke from the Max Planck Institute for Meteorology in Hamburg, warned in a recent paper that even painful efforts to reduce CO2 may hardly have any impact on the climate in the next two decades (Marotzke, 2019 ). Using climate models, Marotzke simulated the global temperature profile up to 2035 and used a conventional emission profile (scenario RCP 4.5) and a politically reduced emission scenario. His conclusion: There is a high probability that no difference will be noticeable, since natural climate variability has the upper hand in these time scales. Marotzke sees a major communication challenge facing the scientists, for which politicians should of course also prepare.
The climate models also show major problems with precipitation. According to DeAngelis et al. (2015) the current models systematically overestimate the increase in global precipitation by 40 percent. Other authors also criticize the enormous discrepancies between simulated and real observed rain trends (e.g. Bartlein et al., 2017; Bothe et al., 2019; Coats et al., 2016; Jin and Wang, 2017; Prasanna, 2016; Saha et al., 2014; Yuan and Zhu, 2018), so that climate damage calculations based on models cannot be robust either.
Incomplete validation of the climate models
The climate prognoses up to the year 2100 are based on theoretical climate simulations. To ensure the reliability of the simulations, the corresponding climate models must first be calibrated against the known climate development. The models must show in a so-called backward modeling (English: Hindcast, History Match) that they can reproduce the measured or paleoclimatologically reconstructed temperature history. While the warming of the last 150 years can usually be represented by the models without major problems, the pre-industrial warming phases could not be reproduced satisfactorily so far. The Intergovernmental Panel on Climate Change (IPCC) frankly admits this in its last climate report with regard to the Medieval Climate Anomaly (MCA) (Chapter 5.3.5 in IPCC, 2013). The poor reproductive performance of the climate models for the time before the Little Ice Age was noted and criticized in numerous specialist publications (e.g. Büntgen et al., 2017; Marcott et al., 2013; Zhang et al., 2017).
On closer inspection, however, it is hardly surprising that the models cannot reproduce the pre-industrial natural climate fluctuations. In the simulations, the influence of natural climatic factors is already approaching zero (Fig. 4). At most, the pre-industrial simulations are allowed a certain amount of unsystematic noise. In view of the significant systematic temperature fluctuations in pre-industrial times, there are many indications of a classic approach error in the modeling. In view of the inadequate calibration of the climate models for the pre-industrial warm phases, results from the climate simulations should be treated with extreme caution until the enormous discrepancies are finally resolved.
Fig. 4: The importance of anthropogenic and natural climate factors assumed by the IPCC, expressed as radiative forcing during the industrial era (1750–2011). WMGHG = well mixed greenhouse gases. Figure from IPCC (2014).
Lower climate sensitivity
The greenhouse gas CO2 has a warming effect. However, the exact amount of warming is still poorly known and has been assumed by the IPCC since its first climate report in 1990 in the range of 1.5 4.5 ° C per CO2 doubling. The climate modules used for calculating CO2 damage omit the lower possible range of CO2 climate sensitivity (ECS) and only cover the range of 2.0-4.5 ° C per CO2 doubling (Carbon Brief, 2019). This artificially inflates the damage sums. This is all the more regrettable, as there are now many indications that the real warming value of CO2 is probably located exactly there in the lower part of the spectrum. In particular, the range of 1.6-2.2 ° C has many supporters in the professional world (Lewis and Curry, 2015; Mauritsen and Pincus, 2017; Mauritsen and Stevens, 2015; Otto et al., 2013). However, most of the damage is calculated in the models for the upper ranges of the CO2 climate sensitivity, since the damage distribution is distributed non-linearly and generates damage with skew symmetry, especially at high temperatures (Carbon Brief, 2019; Schleussner et al., 2016).
Respected climate scientists such as Reto Knutti and Gabriele Hegerl seem to be preparing the public for the upcoming downward revision of the value of CO2 climate sensitivity and declare that climate protection efforts should definitely be continued even at lower values (Knutti et al., 2017). This is only correct in principle, because it should not be disregarded that lower values drastically reduce the level of damage and there is more time for more sustainable planning of the measures to be taken.
Climate policy is a particular challenge for everyone involved. Dealing with diverse uncertainties, enormous interdisciplinarity, high internationality and time scales beyond one’s own lifespan is unusual and difficult. It is still unknown whether or when affordable carbon-free base load energy sources, energy storage and CO2 storage options will be available on a large scale. At the same time, the scientific understanding of climate continues to develop and is much less dramatic today than it was a decade ago. In the meantime, there are many indications that the warming effect of CO2 is more in the lower half of the uncertainty range of 1.5-4.5 ° C per CO2 doubling named by the Intergovernmental Panel on Climate Change. The assumed CO2 climate damage is correspondingly lower. In general, earlier damage calculations seem to be overly inflated and not very robust, since the climate models used in the determination have turned out to be unrealistic in many respects, so that the calculations can only be given little confidence.
In view of the still lacking solutions for carbon-free energy carriers and storage, CO2 pricing in the electricity sector will currently primarily stimulate the switch from coal to natural gas, with natural gas only causing half as many CO2 emissions per unit of energy generated compared to coal. The planned phase-out of coal in Germany by means of a ban will de facto make market-based steering via additional CO2 taxation superfluous in Germany. At the European level, the common CO2 avoidance target can be achieved cost-effectively with the existing emissions trading system.
The main task of politics should now be to stimulate progress in energy technology with the help of research funding. Complete decarbonization remains an illusion until technical substitute solutions are available. Even sharp CO2 pricing cannot enforce this technical breakthrough, as is clear from the example of long-term nuclear fusion research. Concentrating on what is currently realistically feasible should have priority, especially considering Germany’s international competitiveness.
Climate policy requires a sense of proportion. Political decision-makers should not allow themselves to be emotionally driven by blatant catastrophe scenarios which, on closer inspection, turn out to be excessively exaggerated. Measures should not only be environmentally sustainable, but also be socially and economically sustainable (Lomborg, 2016). Unfortunately, the public climate discussion is currently in an extreme imbalance and is dominated by a few actors in the media. The silent majority of the specialist colleagues go unnoticed. It would be important that politicians create more public forums in which even controversial climate science issues can be discussed soberly and openly with the participation of all scientific opinions.
*About the author:
Sebastian Lüning studied geology / paleontology at the University of Göttingen. He obtained his doctorate and habilitation in this subject at the University of Bremen. Lüning received study prizes for the preliminary diploma, doctoral thesis and habilitation. During his postdoc time he worked on ecological oxygen starvation situations during the history of the earth. Lüning has been working full-time in the conventional energy industry since 2007. The topic of climate change is dealt with exclusively in a private capacity, in continuation of his many years of full-time research activities. This research is completely independent and has not been commissioned or funded by the industry. In 2012, Lüning and Fritz Vahrenholt published the book “The Cold Sun”, in which they advocated greater consideration of natural climate drivers. Many of the points of criticism proposed at the time have now been recognized by climate science, e.g. the systematic role of the 60-year ocean cycles, the originally excessive cooling effect of the aerosols and the divergence between real and simulated climate development. One of the scenarios presented in the book describes a CO2 climate sensitivity of 1.5 ° C, which corresponds to the lower end of the IPCC range of 1.5-4.5 ° C. The technical discussion of the last few years indicates that this low scenario could very soon become capable of consensus. Sebastian Lüning is associated with the Institute for Hydrography, Geoecology and Climate Sciences (IFHGK) in Switzerland and worked as an official reviewer on the IPCC special reports on the 1.5 degree target as well as on the oceans and the cryosphere. More information at www.luening.info.
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