To his possible horror, or more likely indifference, we’re saving a seat for Zeke Hausfather at the denier table. To be sure, he’s long been a go-to alarmist for the media. But lately he’s been putting on the brakes, including this vital if apparently casual post: “There is a lot to worry about with climate change, but ‘runaway’ feedbacks are not one of them.” Exactly, we say, donning our historian’s mortarboard. It’s all too common to read online comments like this one about a chart based on 800,000 years of Pleistocene ice cores: “Climate deniers keep posting ice-age graphs as if they weaken the case for CO2. They do the opposite. If tiny orbital changes can help flip the planet when amplified by feedbacks, that’s evidence of a high-gain climate system – not a low-sensitivity one. CO2 is part of the amplifier stack.” The what? What we actually know about Earth’s climate is that it changes constantly, making alarmists like Al Gore the real “deniers”. But while it does strange stuff, and often does it at speeds that make recent decades and even centuries look unusually stable, what it doesn’t do is run away. The point is so obvious it hardly needs stating, but state it we must.
When it was far hotter than today, it didn’t surge into “boiling” or “scorching”, it kept fluctuating. And when it was far colder, mercifully, it didn’t get stuck. (We’re talking geological time here, because long before the dinosaurs there were ice ages and even we think “snowball Earth” phases that lasted tens of millions of years.) But clearly a great many of the feedback mechanisms are “negative”, tending to damp down rather than amplify external or even internal shocks to the system. So all those people saying CO2 won’t warm the planet much, but the warming it does cause will feed back through water vapour and turn the place into a pizza oven are mistaken. (Those who think CO2 is going to do the heavy heating are just ignorant.) Which does leave the question why there’s “a lot to worry about with climate change” so, as noted, we’re saving him a chair for when he works through that one. We even have doughnuts.
The delusion that the climate is brittle, that its current delicate stable state can easily be shattered by minor perturbations, generally only in the direction of runaway heating, is extremely widespread. Hence MSN passes on a The Daily Digest panic that “Large methane leaks will cause a brutal rise in global temperatures”. The accompanying photo of steam from a power plant really ought to get people’s guard up, especially as the story itself eventually refers to methane as an “invisible pollutant”. But the key point is that if trace quantities of methane were capable of triggering a runaway warming they would have done it by now. It’s not as though humans were more careful with the stuff 50 years ago.
MSN also passes on a 2022 pro-nuclear TED talk that claims “8.7 million deaths a year from fossil fuels - yet we fear nuclear power”. Does any sane person believe if fossil fuels disappeared tomorrow 8.7 million fewer people would die annually? There really needs to be more of a filter here. And Hausfather really is trying.
In the post quoted above, he was drawing attention to an article by Andrew Dessler on “The Climate Brink”, a Substack whose name rather implies ominous tipping points. But the actual piece took issue with James Hansen’s longstanding belief, apparently, that a bit more CO2 will send Earth’s oceans into the atmosphere and the place will end up like Venus. And it includes a bit of math about feedback loops that concludes, appropriately:
“As long as f remains below 1, each pass through the feedback loop contributes less warming than the last, and the infinite series converges to a finite total. But when f reaches 1, every pass contributes the same warming as the one before – the series never converges, and the total warming becomes unbounded. This is a runaway climate.”
Which is all fine and good and simply creates the issue of calculating whether f, the strength of whatever feedback you’re looking at, is indeed below 1 or not. (Which, parenthetically, we know to be true of extra CO2.) And here Dressler makes a very common-sense observation:
“We know our current climate is stable – we add warming every year, and the climate hasn’t run away.”
OK, we don’t “add warming”. We add a small percentage of CO2 to the natural carbon cycle. Whether it actually causes any warming at all is highly speculative, since we’re not sure of our temperature measurements given gaps in coverage even now and basically coverage in gaps once you go back even half a century, the Urban Heat Island Effect and so on, and we certainly don’t know how much natural warming would have occurred as the planet emerged from the Little Ice Age if neither James Watt nor Henry Ford had ever drawn breath. But let us not get distracted by that point, at least not here.
What matters is that “We know our current climate is stable”. Not static, of course. But stable. Dressler then goes into some Venus scenarios to show how absurd they are, and then tries to salvage some ruin from the lack of catastrophe with:
“As Jim Hansen has argued, what we should really care about is warming sufficient to break the things that matter to us — ecosystems, infrastructure, food and water security, human lives. We’re already seeing bad things happen to those — with only 1.5°C of warming. Climate change is affecting us right now, without any runaway greenhouse in sight. That alone should be more than enough motivation to limit future warming as much as we can.”
What these “bad things” are he does not say, since extreme weather is not increasing but crop production is, along with human longevity and at least physical well-being. But if they want to sidle over to our table taking small steps, let them.
By contrast, the amplifier stack guy is a ranter. It’s bad enough for him to say “CO2 is part of the amplifier stack” when looking at data that shows that temperatures have cycled up and down, mostly down, for hundreds of thousands of years, rises in CO2 leading to drops not runaway anything. And worse for him to dismiss orbital changes that cause glaciations to start and stop over and over as “tiny”. The Earth is actually big, and the sun bigger. And their interactions have produced what seems to be a fairly regular cycle of temperature increases and decreases for millions of years, albeit not all of which triggered glaciations. (Real scientists are still debating whether it’s a 100,000 year cycle, a 41,000 year cycle, a 21,000 year cycle or some mix of them, with enough internal variability that not all proto-glaciations make it.) Despite these famous flippy feedback amplifier things, which instead of destabilizing the system bounce right off it.
