We’re Getting a Clearer Picture of the Climate Future — and It’s Not as Bad as It Once Looked
Photo: NASA/The LIFE Picture Collection via Getty Images
For once, the climate news might be better than you thought. It’s certainly better than I’ve thought.
You may not have noticed it, amid the flood of bad news about the “Emissions Gap” and the collapse of the COP25 climate conference in Madrid, but over the last few weeks a new narrative about the climate future has emerged, on balance encouraging, at least to an alarmist like me. It is this: As best as we can understand and project the medium- and long-term trajectories of energy use and emissions, the window of possible climate futures is probably narrowing, with both the most optimistic scenarios and the most pessimistic ones seeming, now, less likely.
That narrowing contains both good and bad news — what was recently the best to hope for now seems vanishingly unlikely, and what was the worst to fear much less likely, too. But let’s start with the good news, since there is typically so little of it.
A few weeks ago, the International Energy Agency released its annual World Energy Outlook 2019. The IEA is not known to be optimistic, at least to climate advocates, who have, for years, mocked its projections for future renewable growth: Every year, the agency basically predicts a plateau for renewable use, and every year renewables keep dramatically growing. This made the most noteworthy prediction in this year’s report even more so. According to the IEA report, given only current carbon policies, which nearly everyone studying climate considers terribly weak, the world is on track for as little as 2.7 degrees Celsius of warming by 2100 — about one and a half degrees less warming than is suggested by the U.N.’s IPCC reports in what is often referred to as the “business as usual” “RCP8.5” scenario.
Now, bear with me, because this is going to get a bit technical, but, I promise, it really does matter. That RCP8.5 scenario is one of four included by the IPCC in their last major assessment report, in 2014, to model possible paths forward — the worst one, tracing the highest arc of emissions and warming outcomes this century. It has shaped a lot of scientific research conducted in the interim; a very common approach is for a particular paper to highlight projected climate impacts in a low-end emissions scenario (either 1.5 degrees or 2 degrees Celsius) and a high-end one (somewhere in the neighborhood of 4 degrees), then describe the low-end outcome as the climate future “if we achieve the goals of the Paris accords” and the high-end one as “business as usual.”
Those deep in the weeds always knew there was something misleading about that characterization, but especially in the aftermath of that IEA report, a very public conversation began, especially on “climate Twitter,” outlining the deep — and perhaps fatal — problems with using RCP8.5 in that way. To begin with, all of the four climate scenarios in the IPCC report were originally devised as “business as usual” scenarios, because none of them reflect meaningful climate policy. Instead, they represent a variety of different no-policy futures, each reflecting different assumptions about the way the world’s energy systems and economies will evolve over the next decades. And the assumptions about those factors which are baked into RCP8.5 seem, by the year, more and more implausible — chiefly that global coal use, which is growing slowly, would dramatically increase over the rest of the century. Given that China is still opening new coal plants, and much of the developing world has yet to reach levels of prosperity where energy use explodes, some growth in coal is probably inevitable, perhaps even dramatic growth. But by 2100, RCP8.5 would require 6.5 times as much global coal use as we have today. That may be possible, given how much we don’t know about the path developing nations in south and southeast Asia and sub-Saharan Africa will take. But given recent drops in renewable pricing, and the positive signs for coal decline in the developed world, as a prediction about energy use RCP8.5 is probably closer to a “worst case,” outlier scenario than anything it would be fair to call “business as usual.”
To be clear, the IEA report only measured emissions from energy use, which is not at all the whole picture when it comes to emissions. RCP stands for “representative concentration pathways,” and theoretically climate feedback loops and other natural processes could deliver those carbon concentrations even if coal use fails to grow at the predicted rate. And it is also the case that some climate impacts are already as bad or even worse than RCP8.5 imagined they could be—arctic ice melt, for instance, including in Greenland, where the ice sheet is melting seven times faster than it was in the 1990s. Plus, the IEA only projects out to 2040, leaving large uncertainties about what would come in the second half of the century. But in a remarkably insightful paper published by the Breakthrough Institute on Wednesday — “in a right and just world, this would be the most high-impact piece of climate writing of the month of December,” the Niskanen Center’s Joseph Majkut said on Twitter — Zeke Hausfather and Justin Ritchie modeled the remainder of the century based on some very conservative assumptions. In one scenario, they assumed emissions would peak in 2040 and hold steady rather than decline until 2100; in the other, they assumed emissions would steadily grow from 2040 until the end of the century. They ran those emissions figures through the IPCC’s own basic temperature-calculator and found “that transitions in the global energy system over the past decade mean that a conservative business-as-usual projection of current trends in the energy system continuing is now likely to lead to warming of around 3C by 2100.” Further, while they acknowledge a higher-emissions world than the IEA projects is possible, they conclude that “it may be possible under an optimistic business-as-usual case to have as little as 2.5C warming by the end of the century, though anything below that is very unlikely to happen in the absence of policy given the rate of emissions reductions required.”
I’ve spent the last few weeks trying to wrap my head around all of this, speaking with energy analysts and climate scientists (including Hausfather) about just what these projections mean for our understanding of where we are headed. Nearly every one has told me the IEA projections, while limited in ways, nevertheless represent a more plausible projection of the medium-term energy future than is contained in RCP8.5. Most — though not all — told me that they did not see RCP8.5 as a plausible scenario, even in the absence of meaningful climate policy. Honestly, this surprised me; while objections to RCP8.5 have been around for a decade or more, those who view it skeptically now seem to outnumber those who see it as useful—at least as a vision of a “business as usual” future.
That’s the good news. But it is not, in the end, simple good news. To begin with, there is not corresponding good news in all the other sectors of emissions—agricultural, transportation, industry. Additionally, the single-figure of 3C is a little misleading, since it is only a median projection, as the Breakthrough authors fully acknowledge; their analysis actually finds, using the IEA projections, a range of possible warming levels, from 1.9C to 4.4C (the high-end figure ultimately not very different from RCP8.5’s projections). On top of which, a next generation of more advanced models are currently being developed to better predict what amount of temperature rise would result from certain emissions levels, and while the models are by no means speaking in unison, a concerning proportion of those that have been released show that the climate could be considerably more sensitive to emissions than previously understood—meaning we could find ourselves in a better place, emissions wise, this century, and still end up in roughly the same place we thought we would, when we were expecting higher emissions. (Or perhaps, in theory, even a worse place.)
But the worst news from recent calculations is not about how much we should be lowering our high-end estimates for what amount of warming is possible, but that we have to simultaneously raise our floors. As this animation usefully shows, we are practically already at the limit of our “carbon budget” for 1.5 degrees Celsius:
The math — ten years left at current emissions — is actually bleaker than it might seem at first, since running through ten years at the current rate would only land us at 1.5 degrees if, immediately thereafter, we went all the way to zero, never again emitting another ounce of carbon, let alone a gigaton, of which we are today producing, from industrial processes and fossil-fuel burning, 37 each year. A gigaton is a billion tons. Which makes not just 1.5 degrees but, I think, 2 degrees, for all practical purposes out of reach. As a reminder, this is a level of warming that the IPCC has called “catastrophic” and the island nations of the world have described as “genocide.”
This may all seem dizzyingly complicated on-the-one-hand-and-on-the-other inside baseball climate talk. But four big takeaways suggest themselves—to me, at least.
The first is that, for all of our earned confidence in the present state of scientific understanding of climate change, there is enormous uncertainty about human response to the challenge of warming. There is a reason the IEA sunsets its projections at 2040—it’s because projecting things further out is, ultimately, a foolish game. Energy projections as recent as the pre-fracking 2000s are already very much out of date; even more so for those made during the 1970s and 1980s. Projecting what global energy use will be in the year 2100 is the equivalent of trusting projections made in 1940 about where we are today.
This is especially problematic because, ultimately, that range of inputs — how much carbon we put into the atmosphere over the next decades — is the major determinant of warming levels. We can know, with pretty good if not absolute confidence, that putting X amount of carbon into the atmosphere will produce Y amount of warming on a timescale of a century, say. But just how much is, ultimately, a matter of very gestural guesswork. Whether China’s coal use grows slowly, plateaus and then drops slowly, or drops precipitously over the next two decades—that is not something it is even possible to know, really, though we can guess. Even less possible is knowing whether the next wave of developing nations — India, Indonesia, much of sub-Saharan Africa — will follow the patterns of energy use of the nations just ahead of them on the economic growth. If coal use grows in other parts of the world as dramatically as it did in China in the 1990s and 2000s… well, there are billions of people in those parts of the world, and a rapid energy expansion there could conceivably bring us a lot closer to RCP8.5 than the IEA (or Breakthrough) suggest.
Perhaps a sixfold increase in coal use seems implausible, globally. But even a steady trajectory of coal emissions — new use in the developing world counterbalancing the growth of renewables elsewhere — would be quite bad, if it extended for decades. The IEA predicts it will remain stable, at least for the time being. Exxon, for its part, predicts no decline in carbon emissions from the energy sector through 2040—and no point, at all, where they reach zero. (By the way, a little-noticed 2018 methane leak at an Exxon plant in Ohio was recently found to have released more of the powerful greenhouse gas than the entire oil and gas industries of many countries.) The second takeaway is that anyone, including me, who has built their understanding on what level of warming is likely this century on that RCP8.5 scenario should probably revise that understanding in a less alarmist direction. Scientists who are studying particular impacts should probably stop using RCP8.5 as a stand-in for “no policy” or “business as usual” climate trajectories, and certainly stop describing research that does use it as reflecting a “business as usual” world. We could still get to an RCP8.5-like situation, theoretically, but it is pretty unlikely, and would probably require a departure from the blithe stumbling-down-our-current-path-blindly pattern of the last few decades. This is all, absolutely, cause for optimism, even if it is optimism in the face of great uncertainty. (In climate, we’ll take what we can get.)
The third takeaway is that anyone who sees a world of 3 degrees warming — or even 2.5 degrees — as a positive or happy outcome has a pretty grotesque, or at least deluded, perspective on human suffering. At just two degrees, the U.N. estimates, damages from storms and sea-level rise could grow 100-fold. Cities in South Asia and the Middle East that are today home to many millions of people would be so hot during summer heat waves, scientists have projected, even going outside during the day could mean risking heatstroke or heat death. The number of climate refugees could pass 200 million, according to the U.N., and more than 150 million would die from the impacts of air pollution alone. North of two degrees, of course, the strain accumulates and intensifies, and while some amount of human adaptation to these forces is inevitable, the scale of adaptation required at even two degrees begins to seem close to impossible.
The fourth is that these findings do not, actually, make it look easier to get to “safe” levels of warming—say 1.5 degrees, or even, for that matter, 2. All future emissions paths are charted from the present forward, of course, not from some projected scenario backward. And the state of things is in the present tense is really quite dire—new emissions records every year. To stay safely below 2 degrees, we would still need to roughly halve our carbon output by 2030 and zero it out entirely by 2075, as the U.N. warned last October in its “Doomsday” report. Neither of those tasks look any easier today than they did six months ago, since in fact the world is still moving in the wrong direction, growing our emissions and making more radical future cuts necessary with each passing day. According to the UN’s Emissions Gap report, we now need to cut emissions by 7.6 percent per year every year for the next decade, globally, to hit the Paris targets—a rate faster than any single nation has ever achieved in any single year, pursued globally, including by many countries with populations collectively in the billions pursuing high-energy prosperity for the very first time.
How we respond to these challenges — decarbonization but also the climate impacts brought about by delay — is, of course, another uncertainty, perhaps the most significant one. And even in a year of dramatic political mobilization on climate, on this question, personally, I’ve been growing more concerned that one major response among the world’s well-off, at least, will be normalization, compartmentalization, and continued complacency.
In the spring, I spent some time reporting on life in California under the threat of wildfires—traveling to Los Angeles expecting I’d be seeing a glimpse of our climate future, a city buckled under with climate anxiety, but which I found ultimately to be a journey through normalization and compartmentalization. One woman I met had personally lived through nine fires, a fact I thought about a lot in the months that followed, whenever I found myself considering the problem of climate normalization. But over the last few weeks, I’ve been thinking more about another encounter, one that followed a climate panel I’d just participated in. After the discussion, I was cornered by a middle-aged businessman, who assured me that despite what I might think, he did believe in climate change, then asked, in an almost conspiratorial tone — seeking, it seemed, a kind of a secret answer — “How bad is it going to be?”
It was a bit of a confusing question, after ninety minutes of conversation on stage—a conversation he’d chosen to attend and paid attention to, he pointed out, which he suggested was a self-evident sign that he took the issue seriously.
“Well,” I began, “at just two degrees of warming, which is basically a best-case scenario, it’s been estimated that 150 million people would die from air pollution—”
“But out of 8 billion,” he said quickly, cutting me off and smiling strangely.
“Right,” I said, “I don’t think human extinction or total civilization collapse is likely, though the pressures are going to get pretty intense and we don’t really know how societies will respond. But even if they respond pretty well—I mean, 150 million is 150 million. That’s a lot of people. That’s dying at the scale of 25 Holocausts.”
“But out of 8 billion,” he repeated, like he’d caught me in a trap. At which point I understood what he’d actually meant by the question he’d posed, and why it was so important to him to get a precise answer. What he was asking was not, how bad is it going to be. What he was asking was, how bad is it going to be for me?
The tragic thing was, in learning about 150 million deaths from air pollution, which were today concentrated in India and China and would likely grow in other areas of the developing world in the future, he seemed to have gotten the comforting answer he was looking for: not that bad, relatively speaking. He smiled again and walked away. I didn’t have the chance to tell him that, just in 2017, pollution killed 197,000 Americans.