by Sanghyun Hong, 5th October at 11:00 AM

We, human, have known the anthropogenic climate change since 1896, or at least more than 70 years now. The Intergovernmental Panel on Climate Change was formed in 1988, and the first assessment report was published in 1990 followed by the series of meetings and agreements including the Kyoto protocol, and the Paris agreements. After the series of the meetings which wasted a valuable time to respond, we came up with an agreement that the global mean temperature increases need to be limited to or below 2 °C within this century, or 1.5 °C, if possible [1].

Although it is a little bit late, we are doing something to reduce greenhouse-gas emissions, aren’t we? We are installing on-shore and off-shore wind farms, large-scale and rooftop solar photovoltaics (i.e., solar panels), solar thermal power plants, and even expensive batteries. For example, Germany spent $222 billion on renewable energy subsidies between 2000 and 2016 [2-4]. Germany increased solar photovoltaic capacities by 40.6 GWe, wind capacities by 43.5 GWe and biomass capacities by 7.3 GWe. As a result, the greenhouse-gas emissions from electricity generation increased by 12 Mt CO2-eq during the period. Eventually, Germany will miss its greenhouse-gas emission reductions target by 2022 by a large margin [5].


Wait, something is not correct. Why do we emit more greenhouse-gas emissions when we build more renewables? The answer is simple. When you have an apple and an orange, if you replace an orange with another orange, you still have an apple and an orange. Germany replaced a large-scale zero-emission source (i.e., nuclear power) with small-scale zero- or low-emission sources (i.e., wind, solar, bioenergy). But if we keep replacing it, at some point, renewable sources will replace coal and gas too? And we still have time to reduce greenhouse-gas emissions by increasing the share of renewables right? This is an argument of some, if not all, anti-nuclear and renewable advocates. Can renewables replace nuclear and fossil fuels before it is too late?

A short answer is ‘NO’, and the long answer is ‘NEVER’. Globally, 25,081 TWh of electricity is being consumed in 2016. 16,320 TWh is from fossil fuels (e.g., coal, oil, gas), 4,170 TWh from hydroelectric power and 2,606 TWh from nuclear power. All other non-hydroelectric renewables provide < 1,990 TWh. Since 2000, the total production increased by 9,559 TWh which were mostly provided by the increases in the fossil fuel generations (additional 6,362 TWh). Nuclear power has not been changed significantly (2,590 TWh in 2000). If this trend maintains, it is highly likely that fossil fuels will be major sources of electricity in the foreseen future. Moreover, electricity is just a small part of the problem. We easily forget that electricity is only a quarter of the total final energy demand. The other three quarters are heat demand, oil consumption for transportation, direct use of fossil fuels for industry including agriculture and manufacturing. We don’t have a clear plan about how to decarbonise the other three quarters. Oh, my bad. We almost forgot to add the potential energy demand growth of developing countries yet. The economic growth of developing countries can increase the global energy demand by more than three folds [6].

The important question is do we have a chance to meet the global mean temperature target? If we are to meet the 2 °C target, what we need to do? Is the 1.5 °C target even worth to mention? According to a study recently published by Raftery, et al. [7], the global temperature increases are likely between 2.0 and 4.9 °C (median: 3.2 °C). We have a very small chance (5%) that the global mean temperature increases will be limited below 2 °C, and the lower target (1.5 °C) is not a practically possible option. Another study confirms that we must accept the difficult reality that we will never be able to reduce our greenhouse-gas emissions within the given timeframe [8]. Even if we include non-renewable options such as nuclear power and carbon capture and sequestration, it is very difficult to decarbonise the entire energy production (not just electricity, but the whole energy use) in a decade or two.


Until recently, reducing greenhouse-gas emissions from human activities, in particular energy activities, have been the focus of climate change mitigation studies. We now have to accept that two other technological options including negative emissions (i.e., direct air capture) [9,10], and geoengineering [11,12] should be on our discussion table. Negative emission technologies are becoming cheaper but still quite expensive and inefficient in capturing CO2 from the air [11,12]. Geoengineering has regulatory barriers and can cause international conflicts over the control of the Geosystems, and its adverse impacts are largely uncertain yet [11,13].

We are living in the world full of uncertainty. We don’t know what combination is the economically feasible, and socially and environmentally acceptable. We don’t know the exact consequences of climate change. Only one thing is certain: climate will change, and we will suffer from what we have done to it. It is quite clear that our ‘Plan A: Reducing greenhouse-gas emissions’ has been failed and it will not achieve what it supposed. Although we don’t have a planet B, fortunately we do have a ‘Plan B: Preparing the high carbon future’. It is time to put the ‘Plan B’ on the table.

(All posts are personal reflections of the blog-post author and do not necessarily reflect the views of all other DEEP members).

  1. Spencer, T.; Colombier, M.; Sartor, O.; Garg, A.; Tiwari, V.; Burton, J.; Caetano, T.; Green, F.; Teng, F.; Wiseman, J. The 1.5°C target and coal sector transition: at the limits of societal feasibility. Climate Policy 2018, 18, 335-351.
  2. Reed, S. Germany’s shift to green power stalls, despite huge investments. https://www.nytimes.com/2017/10/07/business/energy-environment/german-renewable-energy.html (9 October 2017).
  3. Unnerstall, T. How expensive is an energy transition? A lesson from the German “Energiewende”. Energ Sustain Soc 2017, 7, 38.
  4. Kreuz, S.; Müsgens, F. The German Energiewende and its roll-out of renewable energies: An economic perspective. Front. Energy 2017, 11, 126-134.
  5. Amelang, S. Germany to miss climate targets ‘disastrously’: leaked government paper http://www.climatechangenews.com/2017/10/11/germany-miss-climate-targets-disastrously-leaked-government-paper/ (12 October 2017).
  6. Clarke, L.; Edmonds, J.; Kim, S.; Lurz, J.; Pitcher, H.; Smith, S.; Wise, M. Documentation for the MiniCAM CCSP Scenarios. Battelle Pacific Northwest Division Technical Report, PNNL-16735 2007.
  7. Raftery, A.E.; Zimmer, A.; Frierson, D.M.W.; Startz, R.; Liu, P. Less than 2 °C warming by 2100 unlikely. Nature Climate Change 2017, 7, 637-641.
  8. Figueres, C.; Schellnhuber, H.J.; Whiteman, G.; Rockström, J.; Hobley, A.; Rahmstorf, S. Three years to safeguard our climate. Nature News 2017, 546, 593.
  9. Williamson, P. Emissions reduction: Scrutinize CO2 removal methods. Nature News 2016, 530, 153.
  10. Tollefson, J. Sucking carbon dioxide from air is cheaper than scientists thought. Nature 2018.
  11. Zhang, Z.; Moore, J.C.; Huisingh, D.; Zhao, Y. Review of geoengineering approaches to mitigating climate change. Journal of Cleaner Production 2015, 103, 898-907.
  12. Wigley, T.M.L. A Combined Mitigation/Geoengineering Approach to Climate Stabilization. Science 2006, 314, 452-454.
  13. Corry, O. The international politics of geoengineering: The feasibility of Plan B for tackling climate change. Security Dialogue 2017, 48, 297-315.



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