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Scientists backed by the Swiss government warn that widely accepted global scenarios for reducing carbon emissions to avoid dangerous climate change in reality pose a 60-80 percent probability of breaching the 1.5 degrees Celsius (C) ‘safe limit’ agreed by world nations under the 2015 Paris Agreement. Their new preprint paper published in March, which is currently under review with the journal Environmental Research Letters, finds that only a “fast and complete” global renewable energy transition led by solar power to be accomplished before 2030 can reduce this probability to a more acceptable level of around 20 percent.
The vast majority of decarbonization scenarios put forward by the UN’s Intergovernmental Panel on Climate Change (IPCC) and the UN Environment Program, especially those which are consistent with actual current levels of carbon emissions, point toward the 60—80 percent probability of breaching the 1.5°C safe limit. The IPCC has called for emissions to be halved by 2030, with a net zero target for 2050. Even when the more ambitious IPCC decarbonization scenarios are taken into account, the scientists find that: “All the IPCC scenarios violate the 1.5°C peak heating target” with a probability between 40 percent and higher than 80 percent. “Such high probabilities of violation would be considered unacceptable in other areas, like engineering or public health,” write the co-authors Harald Desing and Rolf Widmer of the Swiss Federal Laboratories for Material Science and Technology in Switzerland. “Growing understanding of the Earth system suggests that peak heating beyond 1.5°C may be an existential threat to the biosphere and therefore also humanity,” they explain in their paper. “Transitions that exceed this vital threshold with a high probability expose future generations to substantial risks without their prior consent.” Although some residual probability might still be acceptable for society, they say, by tolerating high probabilities between 40 and 80 percent the current climate discourse “exposes future generations to unprecedented risks without their prior consent.”
To illustrate the urgency of climate action, the paper shows that even if carbon emissions were to remain constant at 2018 levels, there would be a 66 percent probability of depleting the remaining carbon budget before 2028. Of course, carbon emissions continue to rise every year and are forecast to increase this year by as much as 5 percent.
However, while this sober warning suggests that the “existential threat” of dangerous climate change beyond the 1.5°C limit is baked into prevailing decarbonisation plans, the paper also shows that a rapid transition to a solar-based renewable energy system can dramatically reduce this risk. But we need to act fast. The paper uses the concept of Energy Return on Investment (EROI)—a measure of the amount of energy used to extract a certain quantity of energy from any given resource—to assess the prospects of such a transition. The speed of action would require a temporary increase in fossil fuel emissions above current levels “for the sole purpose of accelerating the growth of renewable energy capacity” and switching off the “fossil engine” before 2030. “The solar engine grows fastest, when the fossil engine’s output is not replaced by solar energy during the transition… but is increased to utilize all available idle capacity,” says the paper. “Consequently, fossil CO2 emissions will temporarily increase during the transition but will be reduced to zero as soon as the solar engine can replace the fossil engine.”
Lead author Harald Desing told Motherboard that: “The fast transition would need to commence beginning of next year or end of 2021 and… would be complete anywhere in between 2024 and 2028.” Although this is far faster than all conventional decarbonization scenarios, it is the only feasible way to reduce the probability of breaching the 1.5C limit to a genuinely safer level.
Desing explained that such a rapid global solar transition would create further new possibilities for decarbonization due to the potential for clean electrification of key sectors: “The fastest possible transition is achieved by investing all overcapacity we have in today’s fossil energy system in building the solar system. And given the fast exponential growth, the size of overcapacity built into the solar system doesn’t matter that much… This indicates that solar overcapacity is fast to obtain… having a negligible effect on the climate but opening unprecedented possibilities.” Recent peer-reviewed research by Columbia University engineer Marc Perez has shown that overbuilding solar capacity—aiming for 100 percent if not more—creates a level of surplus solar energy which can be used to top off the grid, producing electricity some 75 percent cheaper. Perez found that if the US, for instance, operated an overcapacity solar-dominated grid with limited wind power and energy storage, it could generate a constant source of electricity even cheaper than today’s conventional production without intermittency problems.
Overbuilding solar to ‘switch off’ the fossil engine
The Swiss paper thus confirms that while building out the global renewable energy system will entail exploitation of carbon intensive resources, if deployed correctly this can pave the way for shifting all further societal activities including the manufacturing of renewable energy systems onto the new solar-based power system: “Fossil fuel use should be increased temporarily with the sole purpose to build the solar engine as fast as possible to subsequently switch off the fossil engine forever,” the paper concludes. “As solar overcapacity is fast to build, we see two main advantages,” said Desing. “First, it reduced the need for storage capacity. Storage is energetically expensive as it either has high embodied energy, for example, battery, and has a low turnaround efficiency, for instance for synthetic fuels.” Second, he said, solar overcapacity can then provide the clean power to sustain direct air capture and storage (DACS) technologies to drawdown further carbon from the atmosphere. “Stabilizing the climate in the long run, it is necessary to reduce the atmospheric CO2 concentration down to below 350ppm. Solar overcapacity is ideal for this task, operating DACS during peak sun hours and summer, when idle capacity is available.” The new research has been funded under the Sustainable Economy National Research Program (NRP) run by the Swiss National Science Foundation. NRPs are administered by the Swiss Federal Council, the seven-member executive council that constitutes the federal government of Switzerland.
Two years ago, Desing’s team at the Swiss Federal Laboratories for Material Science and Technology released a paper published in the peer-reviewed Energies journal which attempted to calculate the “global appropriate technical potential”—the actual quantity of energy that could be produced for societal use given realistic environmental, land-use and other constraints—of a solar-dominated renewable energy system. They found that such a system, if deployed properly with sufficient overcapacity, could generate vastly more energy than the existing fossil fuel-based industrial energy system. Their study took into account the need to remain within earth system boundaries while also accounting for demand for chemicals and materials. It found that the technical potential incorporating solar installed across the built environment as well as the world’s deserts would be as high as 71 terawatts (TW) of clean electricity annually, “which is significantly larger than the current global energy demand”. Currently global energy consumption is around 17.7 TW, which according to Desing is equivalent to 6.7 TW of electricity.This is orders of magnitude higher—more than ten times as much—as current levels of energy consumption, and leaves large quantities of electricity “which can then be transformed into e-fuels and heat where necessary.” Even without deserts, Desing told Motherboard, solar concentrated on the built environment alone would still contribute 22 TW of electricity, which is a huge three times higher than current equivalent energy consumption.Desing and his team conclude that this means there is “sufficient renewable energy potentially available to increase energy access for a growing world population as well as for a development towards increasingly closed material cycles within the technosphere”—that is, to devote more energy toward the ‘circular economy’ through increased recycling of raw materials and electrification of industry. If the Swiss team’s data is correct—and they have expressed 99 percent confidence in their calculations—a solar transition by 2030 could not only avert the worst risks of dangerous climate change by switching off the age of fossil fuels forever, it would usher a new age of clean energy abundance unleashing “unprecedented possibilities” for human civilization.