On Friday, I published a column exploring what I see as a likely narrowing of the window of possible climate futures this century. It’s kicked up a bit of dust which, I think, obscures the meaning of the column... nymag.com/intelligencer/… (1/x)
(Or, what I hoped, and thought I managed, to say in it.)
That narrowing is a function of two things: the rosiest possible futures and the bleakest ones *both* looking a bit less likely.
Over the last couple of days, I've wondered what the reaction would have been if I had opened with the first part: that catastrophic warming is, for all intents and purposes, inevitable.
Scientists used to say to me that achieving 1.5 degrees Celsius of warming was “technically possible within the laws of physics”—an acknowledgment that, practically speaking, it was impossible, though perhaps a worthy goal for advocates hoping to move the goalposts.
They are now beginning to say the same about 2C.
2C is not a good outcome. It is not a tolerable outcome. It is not a conscionable outcome. It will probably produce suffering unprecedented in human history.
You can find the horrors almost everywhere you look in the scientific literature, but a brief rundown appears in my article:
At 2C, damages from storms and sea level rise grow 100 fold. Cities in South Asia and the Middle East get some hot in summer that simply going outside risks heatstroke and heat death...
150 million additional people would did of air pollution, and perhaps the world would have perhaps hundreds of millions of climate refugees.
This is not good news by any standard of morality or humanity. It is catastrophic news.
It is also, I think, an unavoidable future—a best-case future. Which is why I want to reiterate that my column is not an argument against alarmism or for complacency of any kind.
It is also not an argument against considering worst-case scenarios, like those I covered in my 2017 article, most of which described warming impacts that would arrive at 4C or 5C—temperatures very much still within the realm of possibility this century.
It is not even an argument for optimism—or, rather, is only an argument for optimism when judging by the absolutely terrifying standards we’ve allowed ourselves to sleepwalk into possibility.
By those standards, I do think the likely future is a little “better” than I thought six months or a year ago. But that does not mean I believe considerably worse outcomes are impossible, or not worth considering. Only that the chances they happen have shrunk somewhat.
This is good, of course. But it is not a reason to be satisfied, or complacent, at all.
As I write at some length in the piece, projections for the end of the century are dominated by uncertainty about human action, about which we know much less than we know about the climate system.
But given what we do know, the path we are on today probably takes us to an emissions level that suggests warming of about 3C rather than 4.5C (as the IPCC’s RCP8.5 scenario suggested).
But that is merely a median projection. The uncertainty is significant, and just our uncertainty about emissions produces a range of outcomes from...about 2C to about 4.5C.
It is also a projection based on a whole lot of guesswork about the future of human economic development, particularly about patterns of growth in the developing world.
To assume the future will follow this path precisely is as foolish as assuming energy projections from the 1940s would hold today. Or to assume the same about those from the 1960s and 1970s — projecting a nuclear age quickly crowding out dirty energy within a generation.
The bottom line is: we don't know with very much certainty how much coal will be burned in the year 2075, though we do know we have enough of it on hand to produce well more than 4.5C, if we burnt it all.
Better guesses today suggest less coal use is likely than might have seemed true ten years ago. But that doesn't make high-end estimates impossible, just relatively less likely.
And this is all just concerning the trajectory of energy emissions, and does not take into account agriculture and land use and all other sectors.
And while a new, lower estimate of projected energy use gives a median warming projection of ~3C, the range of ~2C to ~4.5C suggests it could also produce considerably more warming than that, even holding other factors constant.
They will not necessarily stay constant.
As I note in the piece, certain feedback loops, such as methane release from northern latitudes and the decreasing albedo effect due to arctic ice melt, are already unfolding faster than expected, making warming worse. Others may kick in soon, making extreme warming likelier.
It is also the case, as I note in the piece, that a set of next-generation climate models have begun to surface, and, on balance, they suggest that the climate system is more sensitive to emissions that the previous generation.
If they are right, it means that the same amount of emissions would produce more warming and/or that less emissions could produce roughly the same amount of warming.
These models are still cooking, and it's not clear what to make of them in totality yet. But it is worth keeping in mind that the last time there was even as much carbon in the atmosphere as there is today, sea levels were 60 feet higher and there were trees near the south pole.
We are going to be adding a lot more carbon to the atmosphere from here, no matter what course we take.
But the amount matters enormously—the difference between a world of 3C and a world of 2.5C is tremendous. And taking radical action now is our best protection against the possibility of worse-than-anticipated warming of, say, 4C.
It is also the best protection we can offer to those around the world already suffering immensely, from impacts at just 1.1C—catastrophic Australian wildfires, producing air quality almost 100 times above the safe level, deadly flooding in India, to name just two...
In other words, in the big picture, there is no good news, just shades of bad news.
I'll happily take a business-as-usual median projection of 3C warming this century rather than a business-as-usual projection of 4.5C, as I imagine anyone who cares about these things would.
But if you think a likely future of 2.5C+ is an argument for complacency or against alarmism, you have, as I write in the piece, a pretty grotesque perspective on human suffering and justice. (x/x)
