Last month at Breakthrough’s Ecomodernism 2019 conference, UCSB’s Professor Leah Stokes presented two graphs — quickly dubbed “the narwhal” — visualizing the sheer magnitude of the clean-energy buildout needed for the United States’ electric grid to meet climate goals set by former Democratic presidential candidate Jay Inslee.
Climate mitigation is often portrayed as a predominantly subtractive process in which we remove fossil fuels from our energy landscape and replace them with clean alternatives. But this egregiously understates the task. The world will need vast additional quantities of electricity in the next decades as population grows and as standards of living continue to rise.
In other words, the real challenge for curbing climate change is both subtractive and additive — namely, replacing existing fossil fuels while providing enough new clean power to meet greatly increased future demand. It’s the additive challenge — the difficulty of meeting energy needs of tomorrow that dwarf those of today — that will overwhelmingly decide whether our future is low-carbon.
While the clean power we have today makes up about one-third of global electricity generation, this amounts to a mere 7% of what we would need by 2100 to limit warming to 2°C or better. To match projected electricity demand over the 21st century, new clean power would need to come online 2 to 3.5 times faster than the historical installation rate of all electricity infrastructure — both fossil and clean — between 1985 and 2018.
To demonstrate the scale of the challenge, we took Dr. Stokes’ approach and generated global-scale “narwhal plots,” shown below. They visualize a challenging century ahead for human electricity generation, which must expand by five-fold while simultaneously decarbonizing.
Our data combines historical electricity use with societal scenarios outlined through the IPCC’s Shared Socioeconomic Pathways (SSPs). The SSPs depict different alternative future worlds in which population either stabilizes or continues growing, or where technology progresses or stagnates. Each pathway considers a range of emissions scenarios, from cases of strong climate mitigation, to cases reflecting “no policy” or “business as usual” futures. Our analysis uses the “business as usual” SSP2 pathway, focusing on the SSP2 2.6 and 1.9 scenarios that successfully limit warming to 2°C and 1.5°C respectively.
We limit our scope to the electricity sector since it is more than sufficient to make the point. Achieving ambitious climate targets means not just replacing carbon-emitting generation, but massively expanding the electricity sector to support large numbers of electric vehicles, decarbonization of other industries, and more. In the SSP2’s MESSAGE model, for instance, the percentage of global primary energy demand met by electricity generation increases from 20% to around 50%.
So, what kind of clean electricity deployment rates would we need to triumph against climate change?
To meet the 2°C target, our annual clean electricity deployment rate would need to more than quintuple by 2040, rising from the 2013-2018 rate of 1.3 EJ/yr to 7 EJ/yr — an ambitious rate we would need to maintain through the end of the century. This would give us 70% clean electricity by 2040, climbing to nearly 100% by 2060.
Even more titanic efforts must materialize to maintain warming at below 1.5°C, with similar clean-energy targets met at least a decade earlier. The planet must double clean electricity installation to 4 EJ/yr over the 2020s, increase this to 6-7.5 EJ/yr by 2030, and maintain that pace for forty years through 2070. Clean electricity constitutes >90% of all global electricity by 2040.
Are there differences between climate models? Certainly. For example, in 2100, the share of wind generation within total clean electricity ranges between 14.6% and 42.8% across 1.5°C scenarios and between 12.1% and 55.5% for 2°C scenarios. Nuclear power varies between 3.8% and 43.2% of clean electricity in 2100 for 2°C scenarios, with nuclear generation growing consistently over time in some models while peaking in the mid-21st century and falling in other cases.
The important thing to note, however, is that the bottom line doesn’t change — every scenario involves large-scale, rapid buildout of clean electricity generation. The final electricity mix and the technological paths traveled might differ, but the ultimate outcome is identical: the same fifteen-fold increase in clean electrical power to a total of 500 exajoules per year.
This need to account for future growth applies to the entire range of the global economy, not just the electricity sector. Worldwide emissions from both air travel and marine shipping are projected to at least triple by mid-century, for instance, and progress in decarbonizing both industries has lagged. Other categories like heavy industry are at similar risk of expansion without readily available, low-carbon energy alternatives.
As we contemplate this intimidatingly steep slope — this high ramp protruding upwards like a narwhal’s horn from the water’s surface — we must accordingly prioritize rising future energy demand, even as we take steps toward decarbonization today.
Every future gigaton of carbon matters, and so we must climb the hill, steep as it is.