IPCC on How to Tackle Climate Change, Part 7: Beyond wind and solar, how must global energy systems change to limit warming?
-
- Published on April 11th, 2022
Limiting global warming to 1.5C or 2C would mean “rapid and deep” emissions reductions in “all sectors” of the global economy, says the latest report from the United Nations’ Intergovernmental Panel on Climate Change (IPCC). Instead, emissions have continued to rise – albeit at a slowing rate – and it will be “impossible” to stay below 1.5C with “no or limited overshoot” without stronger climate action this decade, says the new document, which forms part of the IPCC’s sixth assessment report (AR6). In this in-depth Q&A series, Carbon Brief unpacks the key findings of the latest report. (Read previous section here)
7. How must global energy systems change to limit warming?
The energy supply sector is the largest source of greenhouse gas emissions, accounting for some 20GtCO2e or 34% of the total in 2019, the report says. It states with high confidence:
“Warming cannot be limited to 2C or 1.5C without rapid and deep reductions in energy system CO2 and GHG emissions.”
This means it is “essential” to cut energy supply sector emissions in order to limit warming and, consequently, the energy systems of the future will be “very different”. It adds: “Achieving and responding to these changes presents an impressive range of challenges and opportunities.”
Some 4GtCO2e of the sector’s emissions are due to fugitive emissions from fossil fuel production, which are potentially “underestimated” and remain subject to a “high degree of uncertainty”.
However, the largest share – some 14GtCO2e – relates to the generation of electricity and heat. These emissions must be all but eliminated even as demand increases, it says, because all scenarios staying below 2C involve “increased electrification of buildings, transport and industry”.
(In scenarios limiting warming to 2C, electricity’s share of final energy increases from today’s level of 20% to at least 42% in 2050 and 60% in 2100, with even higher levels for 1.5C.)
While the challenge is large, the report says that a shift to low-carbon energy could save money, thanks to rapid cost reductions in key technologies over the past decade. (See: How much innovation and new technology is needed to hit climate goals?) It states:
“Unit cost reductions in key technologies, notably wind power, solar power, and storage, have increased the economic attractiveness of low-emission energy sector transitions through 2030. Maintaining emission-intensive systems may, in some regions and sectors, be more expensive than transitioning to low-carbon systems. Low-emission energy sector transitions will have multiple co-benefits, including improvements in air quality and health.”
These cost reductions mean that in “many parts of the world”, solar power is cheaper than electricity from fossil fuels and in “some” places below the cost of continuing to operate existing coal or gas power plants, the report says with high confidence. Similarly, it says that electricity from onshore wind is cheaper than from fossil fuels “in a growing number of markets”.
Moreover, the report says with medium confidence that evidence has emerged since the previous fifth IPCC assessment report (AR5) suggesting that “future energy transitions may occur more quickly than those in the past”.
One stumbling block highlighted by the report is the weight of emissions likely to be created by existing and currently planned fossil fuel infrastructure. It warns:
“Estimates of future CO2 emissions from existing fossil fuel infrastructures already exceed remaining cumulative net CO2 emissions in pathways limiting warming to 1.5°C (>50%) with no or limited overshoot (high confidence).”
Given the “long lifetimes” of these assets, they “may influence the rate of transformation substantially and lock societies into carbon-intensive lifestyles and practices for many decades”. It adds:
“Decommissioning and reduced utilisation of existing fossil fuel installations in the power sector as well as cancellation of new installations are required to align future CO2 emissions from the power sector with projections in these pathways.”
If warming is kept below 2C, fossil fuel resources and fossil fuel-related infrastructure “could” be “strand[ed]”, the report says, though it adds that the use of CCS, where available, “could allow fossil fuels to be used longer” and reduce the risk of stranding.
It says, with medium confidence, that the combined discounted value of these assets is projected to be around $1-4tn between 2015-2050 and “will be higher” if warming is kept below 1.5C. Coal assets would be most at risk this decade but oil and gas would be too, “toward mid-century”.
The report says that limiting warming to 2C or below “requires a rapid shift” away from coal use without carbon capture and storage (CCS), and will “require cancellation of new coal power projects and accelerated retirement of existing coal plants”. Opportunities for more rapid action this decade also include “limiting the construction of new gas-fired power plants”, it adds.
The Carbon Brief figure below shows how global CO2 emissions and primary energy supply from fossil fuels falls rapidly in scenarios that keep warming below 1.5C with no or limited overshoot.
Indeed, the report says that using “far less fossil fuel than today” is “fundamental” to limiting warming. Specifically, coal use falls to 75% below 2019 levels by 2030 and 95% by 2050 (black bars), while gas falls 10% by 2030 and 45% by 2050 (blue), and oil by 10% and 60% (red).
Reduction in CO2 emissions and primary energy supply from fossil fuels, % below 2019 levels by 2030 and 2050, in 1.5C scenarios with “no or limited overshoot”. Dots show the median value across relevant scenarios and bars show the 25th to 75th percentile range. Source: Adapted from IPCC (2022) Table 3.6. Chart by Carbon Brief using Highcharts.
Although there are many different pathways to keeping warming below 2C, the report points to a number of key characteristics that are shared across all such scenarios. These include:
- Electricity systems that produce no CO2 or remove it from the atmosphere;
- Widespread electrification including for “light-duty” transport, heating and cooking;
- “Substantially” lower fossil fuel use than today;
- Use of alternative “energy carriers”, such as hydrogen, bioenergy and ammonia, in sectors where electrification is not possible;
- More efficient use of energy than today;
- Greater integration between different parts of the energy system, such as heating, transport and electricity, as well as between regions;
- Use of carbon dioxide removal (CDR) to offset residual emissions.
These are illustrated in the figure below, which shows how the energy system changes under a range of scenarios from high warming (red bars) to those staying below 1.5C (blue). The figure shows global primary energy supply (top left) and contributions from fossil fuels (top middle), coal without CCS (top right), non-biomass renewables (bottom left) and biomass (bottom middle).
The report says that pathways successfully limiting warming “show reductions in energy demand” compared with current policies, through a “diverse set of demand-side interventions”. (See: How can shifting peoples’ demand for products and services cut emissions?)
At the same time, low-carbon energy sources increase rapidly in below-2C pathways, meeting 88% of primary energy supply (with a range of 69-97%) in 2100.
Renewable energy, including wind, solar and bioenergy, supplies 30-70% of energy in below-2C pathways and “clearly above 40%” for 1.5C, the report says.
It notes that while scenarios have been published with 100% renewable energy at a global scale, there is “debate in the literature on whether [this] is possible to achieve”. It adds:
“It is unlikely that all low-carbon energy systems around the world will rely entirely on renewable energy sources.”
Regardless of these debates, non-biomass renewable energy – primarily wind and solar – expands very fast in scenarios keeping warming below 1.5C with no or limited overshoot, as shown in the figure below (yellow bars). In contrast, 1.5C scenarios show greater variation in the adoption of nuclear and biomass energy, the report shows (purple and orange bars).
Increase in primary energy supply from nuclear, biomass and other renewables, % above 2019 levels by 2030 and 2050, in 1.5C scenarios with “no or limited overshoot”. Dots show the median value across relevant scenarios and bars show the 25th to 75th percentile range. Source: Adapted from IPCC (2022) Table 3.6. Chart by Carbon Brief using Highcharts.
The contribution of biomass has “absolute limits”, the report says. (See: How does land add to climate change and how can it help soak up CO2?)
It says with high confidence that nuclear “can deliver low-carbon energy at scale”, but that doing so “will require improvements in managing construction of reactor designs that hold the promise of lower costs and broader use”. It adds:
“[N]uclear power continues to be affected by cost overruns, high upfront investment needs, challenges with final disposal of radioactive waste, and varying public acceptance and political support levels (high confidence).”
In contrast to the rapid recent cost reductions and adoption of “modular” technologies, such as wind, solar and batteries, which have happened “much faster than anticipated by experts and modelled in previous mitigation scenarios”, the report says that nuclear energy and CCS has been “slower than…anticipated”.
Moreover, it says with medium confidence that evidence since AR5 indicates “small-scale technologies (e.g. solar, batteries) tend to improve faster and be adopted more quickly than large-scale technologies (nuclear, CCS)”.
Another important technology is CCS, with a “considerable amount” being used in the “majority” of below-2C scenarios, the report says. Notably, however, some of the 1.5C pathways highlighted by the report include little or no CCS. (See: What would it take to limit warming to 1.5 or 2C?)
Box TS.9 in the Technical Summary compares hydrogen to electrification in areas such as transport, heating and industry. It says:
“As a general rule, and across all sectors, it is more efficient to use electricity directly and avoid the progressively larger conversion losses from producing hydrogen.”
Box TS.9 in the Technical Summary compares hydrogen to electrification in areas such as transport, heating and industry. It says:
“As a general rule, and across all sectors, it is more efficient to use electricity directly and avoid the progressively larger conversion losses from producing hydrogen.”
Nevertheless, as Box 12.5 explains, there has been growing interest in the use of the fuel, with the word “hydrogen” appearing five times
more often in AR6 than AR5. It points to the use of hydrogen in sectors that are hard to decarbonise, such as parts of transport and industry, as well as for storage in low-carbon electricity systems.
The report also addresses a range of challenges for low-carbon energy systems to overcome. For example, it says that integrating large amounts of “variable renewable energy” (VRE), particularly wind and solar, presents “economic and technical challenges to electricity system management”.
These challenges “can be addressed” by using batteries, hydrogen and other storage, as well as greater “demand-side responses”, it says, meaning that “[e]lectricity systems powered predominantly by renewables will be increasingly viable over the coming decades”.
Furthermore, the addition of “flexible/dispatchable” generation technologies, such as gas, hydrogen or nuclear plants, can “enabl[e] more secure and cost-effective integration of VRE generation and end-use electrification”, the report adds.
While expansion of solar, wind and EVs will increase demand for critical minerals, the report says “there are alternatives” and that recycling can boost supplies. The report also gives short shrift to the idea that wind power is not low carbon, saying that “all wind power technologies repay their carbon footprint in less than a year”.
Finally, the report says that while climate change will alter hydropower output, bioenergy yields, the efficiency of fossil and nuclear power plants, and demand for heat and cooling, it “will not affect wind and solar resources to the extent that it would compromise their ability to reduce emissions”.
Next Section: How does land add to climate change and how can it help soak up CO2?
All sections:
- What is the Working Group III report?
- How have global emissions been changing?
- How do current policies and pledges compare to scenarios assessed by the IPCC?
- What would it take to limit warming to 1.5 or 2C?
- How can shifting peoples’ demand for products and services cut emissions?
- What impact can the food system and dietary choices have on emissions?
- How must global energy systems change to limit warming?
- How does land add to climate change and how can it help soak up CO2?
Authors:
Aruna Chandrasekhar holds an MSc in environmental change and management from the University of Oxford. She previously worked as a freelance journalist for a variety of publications, including the New York Times, Guardian, Scroll and Caravan.
Daisy Dunne holds a BSc in biology from the University of Bristol and a science journalism MA from City, University of London. She was The Independent’s climate correspondent from November 2020 to 2021. Prior to this, she was Carbon Brief’s science writer from 2017 to 2020.
Dr Simon Evans is our deputy editor and policy editor. Simon covers climate and energy policy. He holds a PhD in biochemistry from Bristol University and previously studied chemistry at Oxford University. He worked for environment journal The ENDS Report for six years, covering topics including climate science and air pollution.
Josh Gabbatiss covers climate and energy policy. Josh holds a BSc in zoology from the University of Bristol. He previously worked as science correspondent at The Independent and prior to that was a freelance journalist for a variety of scientific publications including New Scientist and BBC Earth.
Dr Zeke Hausfather is a climate science contributor for Carbon Brief. Zeke has masters degrees in environmental science from Yale University and Vrije Universiteit Amsterdam, and a PhD in climate science from the University of California, Berkeley. He has spent the past 10 years working as a data scientist and entrepreneur in the cleantech sector.
