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, keep in mind, 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 Energy projections as recent as the pre-fracking 2000s are already very much out of date; even more so for those made during the 1970s and 1980s.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 big that X turns out to be 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.) And we do of course have enough carbon on the planet to reach RCP8.5 , should we choose to burn it.
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, from earlier this fall, 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 90 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 2 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, smiling, 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 walked away triumphantly. I didn’t have the chance to tell him that, just in 2017, pollution killed 197,000 Americans.
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