Hoesung Lee’s speech (IPCC president), from the IAEA conference, about nuclear and climate

Hoesung Lee’s speech (IPCC president) from the IAEA conference


Excellences and dear colleagues,
I wish to thank very much the IAEA for organizing this very timely and important conference.
Nuclear power currently supplies about 11% of the world’s electricity. Today’s output, as you know very well, is lower than it was a decade ago. Ten years ago, when there was no Paris agreement, the world global temperature was not as high as today’s one degree C above pre-industrial levels. 10 years ago, when the world did not have the benefit of having IPCC’s special report on 1.5 degrees, we didn’t know at the time the differential impacts of global warming of 1 degree C, 1.5 degrees C and 2 degrees C and its policy implications.
Four years ago, at the December 2015 COP-meeting in Paris, the countries invited IPCC to provide a special report on the very important aspects of 1.5 degrees and the impacts of keeping the warming to 1.5 degrees as well as the compatible mitigation pathways to achieve that global warming.
Now, one of the key conclusion is that, as was very often mentioned in this conference as well as also before this conference, it is feasible to limit the global warming 1.5 degrees C. Considering that the world is already experiencing warming, it implies that it is feasible to achieve a limited warming of close to 0.5 degrees C. It is feasible. But more important message is that limiting that warming to 1.5 degrees C comes with the opportunities for clean economy, job creation, better jobs, innovation and great potential for achieving sustainability.

We analyzed 21 models, globally available, and we came up with the conclusion that to limit 1.5 degrees C global warming, the global net anthropogenic CO2 emissions must reach net-zero around 2050. That must be accompanied by very deep reductions in non- CO2 emissions as well. Obviously, emission reductions of that scale and speed require a very rapid transition in energy, industry and consumption. Emissions in all of these sectors must be virtually eliminated, net-zero, within a few decades. Achieving this will require a wide portfolio of mitigation options and a significant upscaling of investments in those options. The transitions required to realize this emission reduction are clearly unprecedented in terms of scale but not necessarily in terms of speed.
The benefit of limiting warming to 1.5 degrees C is lower climate related risks to ecosystems, health, livelihoods, food security, water supply, human security and economic growth.
Now, what is the implications for the energy sector transition? We have so much relied on fossil fueled energy systems the last 100 years. Reducing energy sector CO2 emissions to 0 by 2050 involves three broad strategies. One is energy efficiency improvement, the second is increased electrification and, [thirdly], decarbonization of electricity supply. As I said before, we examined 21 models available and those 21 models provided by the scientific communities a total of 85 emission pathways consistent with 1. 5 degrees C.

Looking at energy efficiency first. Efficiency is reflected in the data of the global primary energy supply. Across these 85 pathways modelled pathways of 1.5 degrees C implies that the medium primary energy supply declined from 582 exajoule in 2020, the next year, to 503 exajoule 2030, in 10 years, and then 581 exajoule in 2050. These projections are, of course, uncertain – let me say this very clearly – uncertain. And the range increases as they go further into the future. For 2050 the range is 289 to 1012 exajoule. In short, over the next 30 years global energy primary energy supply could grow at a rate of 1.9% or decline at a rate of 2.3% per year. But the medium projection is no growth of primary energy supply to 2050. Stabilizing primary energy for the next 30 years while the global population and income rises is possible only with significant improvements in the efficiency of energy production, transformation, distribution and final use.

Now, secondly, about electrification. The electricity share of global energy use is projected to more than double. Generally known that electricity is more versatile than fossil fuels and in most energy use more efficient. Based on median values of 89 1.5 degrees C pathways, electricity share as primary equivalent of total primary energy arises from 19% in 2020 to 43% in 2050. As usual the ranges across the pathways are very large, over 3 decades, but in every case global electricity consumption rises. The rate of growth varies between 0.5% and 5% per year. This is the range.

Thirdly, about decarbonization. Increased electrification reduces emissions only if the power comes from non-fossil sources. Fossil fuel share of electricity generation declines from 63% to 22% within the next 30 years and this is based on median results of 89 pathways. Non-biomass renewables offset this decline of fossil generation and most of the increased supply. Over 30 years their supply increases from 25 exajoule to 137 exajoule, that is an average annual growth rate of 5.9%.

Now finally about nuclear power. In most 1.5 degrees C pathways, nuclear power contributes to the decarbonization of electricity supply over the next 30 years. Based on, again the median results of these 89 pathways, nuclear power increases from 11 exajoule in 2020 two 23 exajoule in 2050 – an average annual growth rate of about 2.5%. There are large variations, however, in nuclear power between models and across pathways. The pathway with minimum nuclear power assumption anticipates output of only 3 exajoule in 2050 – about 30% of the 2020 output. While the pathway with maximum reliance on nuclear power estimates 116 exajoule on nuclear power on that year – a tenfold increase from 2020. One reason for this large variation is that the future development of nuclear can be constrained by societal preferences, assumed that narratives underlying the pathways. A second reason for the variation is the technology assumptions built into the models. For example, only 7 of 21 models we analyzed includes advanced small modular reactor designs as possible technologies. In addition to electricity generation, nuclear energy contributes to mitigation of other GHG missions in many pathways. Nuclear process heat is an option in 6 of the 21 models used to generate the emissions pathways.

Clearly, 1.5 degrees C pathways are consistent with everything from negligible nuclear power to a tenfold increase in nuclear power over the next three decades. The opportunity exists. The challenge is how much of the opportunity will you be able to catch up? Time is critical, so the share of the opportunity you capture will depend on the speed at which nuclear technology can be deployed.

In summary, human activity has already led to 1 degree C increase in global average temperature. It is still possible, though, but challenging, to limit the global average temperature increase to 1.5 degrees Celsius – the goal of the Paris agreement. To meet that goal will require the global net anthropogenic CO2 emissions to be reduced to net- zero by 2050 and that human induced emissions of other GHGs be reduced to zero shortly thereafter. The strategies for reducing energy related CO2 emissions are robust and well known: very ambitious efficiency improvements, increased electrification and decarbonization of electricity supply.

The available models indicate that this can be done using widely different mixes of technologies including pathways with much greater and with very limited use of nuclear power. In short, there is considerable potential as well as uncertainty for nuclear power. Obviously, we don’t and cannot know what technologies will be available over the next 30 years and how they will perform. The challenges for nuclear power are to be a cost- effective alternative to other non-fossil generation technologies and to deploy nuclear power much faster than in the past. I wish you success in meeting these challenges because climate needs all the help it can get.

Thank you very much for your attention.

French translation here

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  1. Ping : Discours du président de la Conférence de l’AIEA, Hoesung Lee, Président du GIEC – Science en Francais

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