Category: Climate Change

Global climate basics

Global climate basics

Last time, I expressed extreme disappointment that fossil fuel executives had any role in leading the climate meeting COP28. This is a classic example of putting the the fox in charge of the hen house. The issue is easily summed up:

It’s difficult to get a man to understand something when his salary depends on not understanding it.

Upton Sinclair

Setting aside economic self-interest and other human foibles, it is clear from the comments that the science is not as clear to everyone as it is to me. That’s fair; I’ve followed this subject for half a lifetime, and it is closely related to my own field.

Stars are fusion reactors surrounded by big balls of gas; understanding how they work was a major triumph of 20th century astrophysics. We understand these things. Planetary atmospheres are also balls of gas; there is some rich physics there but the problem is in many ways simpler when they aren’t acting as the container for a giant fusion reactor. We understand these things. The atmospheres of Venus and Mars come up when teaching Astronomy 101, these planets represent opposite extremes of climate change run amok. From that perspective, Earth is a nice problem to have. We understand these things.

It is easy to get distracted by irrelevant details. No climate model is ever perfect, but that doesn’t mean we don’t understand what’s going on. The issue is basic physics, which has been understood for well over a century. Not only is the physics incredibly clear; so too is the need to take collective action to ameliorate the effects of climate change. The latter has itself been clear since 1990+ at least.

The temperature of a planet is the balance between heating by the sun during the day and re-radiation of that heat at night. The effectiveness of both depend on the properties of the planet. What is the albedo? That is, how much of the incident radiation is reflected into space without heating? Once heated, how efficiently can the heated surface cool by radiating energy to space?

If a planet has no atmosphere, it is a straightforward calculation to find the balance point. If the Earth had no atmosphere, the average temperature would be much colder than it is, about -18 C. Thankfully, we have an atmosphere. There is a natural greenhouse effect – nothing to do with human activity – that makes the actual average temperature more like +15 C. I, for one, am grateful for this. It also means that changing the composition of the atmosphere will change the balance point.

The bulk of Earth’s atmosphere is nitrogen and oxygen. These gases are transparent to the incoming optical radiation from the sun that heats the surface. They are also transparent to the outgoing infrared radiation that cools the surface. Despite composing the bulk of the atmosphere, they play basically zero role in the greenhouse effect. As far as climate goes, having only these gases in the atmosphere returns the same answer as the zero atmosphere case.

The natural greenhouse effect is entirely due to trace gases like water vapor and carbon dioxide. I note this because one reasonable-sounding falsehood that gets repeated a lot is that CO2 is a trace gas, so it can’t possibly make a difference. That’s like saying adding a small dash of poison to a beverage isn’t dangerous. Or that it makes no difference to draw a shade over a window. The shade may be much thinner than the glass of the window, but unlike the transparent glass, the shade is opaque. That’s the property greenhouse gases provide, even in trace quantities: they are opaque to the infrared radiation that is trying to cool the surface by escaping to space.

If we looked down on the Earth with eyes that saw in the infrared part of the spectrum where greenhouse gases trap heat, we’d wouldn’t see the surface of the planet. Instead, we’d see a hazy ball: the effective altitude in the atmosphere from which infrared radiation can escape to space. This isn’t a solid surface any more than the edge of a cloud is – to you and me. To the photons seeking escape, it is an effective barrier. Some don’t make it out.

The greenhouse gases are like a fog bank that has to be traversed before the heat carried by the infrared radiation can escape into space. If we add greenhouse gases to the atmosphere, it makes the fog bank thicker, effectively trapping more heat. At a basic level, the issue is that simple. The science is entirely settled; no one seriously* debates this. It has been known for over a century.

Article published in 1912 in the Braidwood Dispatch and Mining Journal, via the National Library of Australia

The leading greenhouse gas in Earth’s atmosphere is water vapor. You don’t need a fancy scientific instrument to detect this effect, just your own senses. High humidity leads to hot, sultry nights while low humidity allows rapid cooling. To feel this, visit a humid place like New Orleans and an arid one like the desert of the US west. These places feel very different at night even when their daytime temperatures are similar. The humid place cannot cool effectively because of the greenhouse effect provided by water vapor, and nighttime temperatures can remain unpleasantly high. In the dry desert, the temperature drops like a rock as soon as the sun sets, and it can get rather chilly even if it was baking hot all day long. I’ve personally experienced both conditions many times; the difference is stark and obvious.

The amount of water vapor the atmosphere can hold is a function of temperature, but on bulk it is always less than half a percent. That trace gas is nevertheless 100% of what you care about in the morning weather forecast, as it leads to rain, snow, sleet, hail, cloud cover, and all the other weather phenomena that makes life near the triple point of water interesting. Indeed, clouds increase the albedo of the planet, reflecting some of the incoming solar radiation, so water in the atmosphere prevents some heating as well as helping to retain warmth once heated. This is pretty much in balance, as the limit on how much water vapor the atmosphere can hold means that equilibrium is achieved on a short time scale: too much humidity, and it rains. The sources and sinks of H2O in the atmosphere balance out on short timescales readily perceptible to humans. It’s what we call weather.

The next most important greenhouse gas is CO2. That too has a natural level with sources and sinks. The issue that induces human-caused climate change is the extra CO2 we put in the atmosphere by burning coal, oil, etc. for the energy it provides. This does not balance out on a short timescale, so there is a cumulative effect on the climate, as anticipated in 1912.

Producing energy is a good thing; no one here is advocating that we stop doing this add return to living like cavemen. Heck, even cavemen had an environmental impact: they burned enough wood to blacken many a cave roof. Human activity has always left a mark; the problem today is that there are 8+ billion of us doing a lot more than making campfires. That adds up to a measurable change in the composition of the atmosphere.

The natural pre-industrial level of CO2 was about 277 parts per million (ppm). Here is a graph of the CO2 content of the atmosphere over the past few centuries, extending to back before the onset of the industrial revolution when our collective experiment in atmospheric physics got going. We know how much carbon we’ve burned (that’s economic activity with profits and receipts, we know this number quite well) and we can measure how much CO2 is in the atmosphere directly. They ramp up together.

Mass of CO2 in the atmosphere (in gigatonnes) since 1700. Modern measurements (blue line) come from the Mauna Loa observatory courtesy of the NOAA Global Monitoring Laboratory; older measurements (black line) come from the Law Dome Antarctic ice core data. The red line is the cumulative CO2 added to the atmosphere by human activity. I’ve added the pre-industrial value to this in the upper (thin) red line to show how it compares with the measured CO2 content.

There is lots that can be said about this plot. Just some basic points: the amount of CO2 in the atmosphere has gone up as we have burned coal and oil to generate energy. We have measurably changed the composition of the atmosphere we all breathe. The current CO2 content of the atmosphere is 424 ppm, which is much larger than the pre-industrial level of 277 ppm. That by itself ought to give one pause: we are conducting an uncontrolled experiment in atmospheric physics on a global scale. That seems like a bad idea, even if we didn’t understand heat propagation in the atmosphere, which we do.

Not only has the amount of CO2 in the atmosphere increased as we’ve burned things, it is accumulating. There are natural sinks, which is why the extra amount of CO2 in the atmosphere is less than what we’ve added: not all of it sticks around. Much of it has been absorbed by the ocean, which is acidifying as a result. But lots of CO2 persists in the atmosphere: the timescale for it to “rain out” is much longer than for water. It will take many decades and probably centuries to restore anything resembling equilibrium. We aren’t just adding CO2 to the atmosphere, we’re making a long-term investment in having it there. Future generations will have to contend with the consequences of what we’ve already done.

What have we already done? I’ve outlined the basic physics; let’s now check the predictions of one of the earliest forecasts. This is from a 1982 report generated by Exxon scientists:

Forecast atmospheric CO2 content of the atmosphere (upper line; left axis) and the corresponding temperature change (lower line; right axis). I’ve added current values for both CO2 (green) and the temperature anomaly (orange). Looks like they pretty much nailed it. Note also that the null hypothesis of no climate change, i.e., a constant temperature with increasing CO2 content, is strongly rejected.

The study made over forty years ago accurately forecast where we are today. These predictions have repeatedly been corroborated. Some models may miss minor details here and there, but the basic picture is crystal clear. Anyone who tells you otherwise has some fossil fuels to sell.

Enough has been written on this subject; I won’t suggest solutions nor delve into likely impacts. But there is absolutely no doubt that climate change is real and that we caused it. None. That this simple, plain fact is not obvious to everyone at this point is a credit to the power of disinformation and propaganda. The best course forward from here is debatable. Pretending like it isn’t a problem is straight-up reality denial.

+It has become a trope of wingnut politics in the U.S. that scientists only say climate change is real so they can get research grants. That’s ridiculous on many levels. One reason that such grants exist is that right wing politicians asked for more research. This was a delaying tactic employed in the early 1990s by then-president and oil magnate George H. W. Bush.

Fresh off the success of regulatory repair to the ozone hole problem in the late 1980s, it was reasonable to hope that we could start tackling the threat of climate change. This was a much bigger problem encompassing a broader range of human activity, but the basic science is far simpler than the atmospheric chemistry that threatened ozone. Industries that didn’t want to be regulated whined about that as usual, but no one seriously questioned the science. After the usual wailing and gnashing of teeth, appropriate regulatory action was taken, and it worked.

When it came to doing the same thing with the oil industry when an oil baron was president, well, harrumph harrumph, more research was needed. The first Bush was a Republican, but he wasn’t a backwards science-denying goon, so he offered to fund more research. It was an obvious delaying tactic, but the argument in favor of it was to make the case more convincing. So the science community was like, sure, the basic answer is already clear, but there are things that we could understand better, so we’ll do more research if that helps you to also understand the problem. But it hasn’t helped people who don’t want to understand to do so, and never will, because the problem is with them, not with the science. So now, thirty years on from Bush I, the same political party that demanded more research be done now routinely attacks scientists for doing the research they asked scientists to do.

Sorry, not sorry: just because you don’t like the answer science gives doesn’t make it wrong. It is well past time for climate denying snowflakes to stop having emotional meltdowns and grow up already.

*Sometimes it is asserted that the opacity of CO2 is already saturated, so adding more doesn’t matter. Yes on one, no on two. Even at saturation we can still make the fog bank thicker by adding more CO2 – just ask Venus. Indeed, we’re dang lucky that the CO2 bands are already saturated; if not for that, the response of the climate to adding as much CO2 as we have would be much stronger. If these features were not saturated the response would be linear instead of incremental, so the temperature would have already increased by about an extra 7 C, not the mere 1 C we’ve so far** accomplished.

**Just how much we’ve added depends on how you define “before.” Modern studies often seem to adopt the average temperature measured between 1980 and 2000, presumably because the data with which to do so are very good. This gives an increase since then around 1.1 C, which is a remarkable amount of growth in just a few decades: we’ve tipped the climate system out of anything resembling equilibrium hard and fast. Of course, the impact of human activity was already palpable before 1980, so the total change since the industrial revolution is closer to 1.5 C. We’re not quite to that arbitrary threshold yet, but I see no way to avoid blowing past it. Talk of doing so is predicated on giving us a half degree mulligan by defining “average” during a period that is not average. So if you think portrayals of the problem are exaggerated, it is actually already worse than generally depicted.

Cop28 president not even trying to hide his obvious bias

In 1986, I was a grad student at Princeton, working in the atomic physics lab of Will Happer. It was at a department colloquium that I first heard a science talk that raised serious concerns about our use of fossil fuels potentially impacting the climate. This was not received well.

People asked all sorts of questions, with much of the discussion revolving around feedback effects. Perhaps warmer weather from CO2 will result in higher humidity, making more clouds*, and reflecting more sunlight into space. It does not. What about ice cover? This is actually a positive feedback – as the globe warms, ice coverage is replaced by darker surfaces, leading to more absorption of the incident solar radiation. And so on.

I thought the speaker did a creditable job of answering the concerns raised, repeatedly making the point that most feedback effects would make things worse, not better. It was entirely new to me at the time; I didn’t have any context to judge the relative merits of the discussion. Prof. Happer is one of those remarkable people who seems to know a lot about everything. So, as I related before, I asked him. His immediate and harsh retort was

“We can’t turn off the wheels of industry, and go back to living like cavemen.”

I relate this story again because the same language comes up today in a story I saw in the Guardian:

The president of Cop28, Sultan Al Jaber, has claimed there is “no science” indicating that a phase-out of fossil fuels is needed** to restrict global heating to 1.5C, the Guardian and the Centre for Climate Reporting can reveal.

Al Jaber also said a phase-out of fossil fuels would not allow sustainable development “unless you want to take the world back into caves”.

COP23 article, 3 December 2023

This is exactly the same solution aversion that Happer displayed, using exactly the same language. It doesn’t address the actual question. It leaps ahead to the worst conceivable consequence, doesn’t like it, and so reverts to reality denial: We don’t want that to happen, so the evidence must be wrong!

We humans excel at reality-denial. It is not helpful. Rather than starting to deal with the problem of climate change thirty years ago – the science was already crystal clear by then – we’ve dug ourselves a much deeper hole. That’s not to say we should abandon all hope and revert to living in caves, but we do need to take serious and rapid steps to reform the ways in which we generate power. It is doing more of the same that risks sending us back into caves.

The quoted reaction to this assertion in the story is predictably tepid. The quote in the Guardian is “The comments were `incredibly concerning’ and `verging on climate denial’, scientists said.” As a scientist who is not directly involved with dealing with these people, let me be more blunt:

ARE YOU FUCKING KIDDING ME?

Al Jaber’s attitude isn’t verging on climate denial, it is the archetype of climate denial. Literally the same thing that climate deniers said in the 1980s. It expresses an attitude that was clearly wrong and dangerously backwards by the early 1990s. And this guy is the president of COP28? I say again

ARE YOU FUCKING KIDDING ME?

And who is this guy? The Guardian reports “Al Jaber is also the chief executive of the United Arab Emirates’ state oil company, Adnoc, which many observers see as a serious conflict of interest.” A conflict of interest? Really? Do you think? Again I say

ARE YOU FUCKING KIDDING ME?

This is obviously a conflict of interest, of the worst sort. His personal wealth, and the sovereign wealth of his nation, is entirely based on the production and sale of fossil fuels. Mitigating climate change means reducing our consumption of fossil fuels, which is a direct threat to the economic interests he represents. Talk about putting the fox in charge of the hen house.

I am impressed by how the moneyed interests have managed to slither their way into positions of consequence on discussions in which they have an obvious conflict. I guess money always finds a way in. But can we please stop being so polite that we fail to call out obvious bullshit wherever it crops up? It seems to be spreading at the rate of made-up conspiracy nonsense on that site formerly known as Twitter. We should stop putting up with it already.

*Ironically, SO2 pollution from ocean-going vessels does have this effect, and as these emissions have been cleaned up, we can see the effect in global temperatures. This is not to advocate for SO2 pollution! though injecting aerosols like SO2 into the stratosphere is one of geoengineering approaches that gets discussed. Before going down that path, the obvious first step is to stop pouring petrol on the fire by continuing to add CO2 to the atmosphere.

**We’re already committed to 1.5C. I see no conceivable way that we can curb emissions fast enough to avoid that. So I guess this statement is true, from a certain point of view – that of a liar. A less misleading statement would be that a phase-out of fossil fuels is necessary to prevent things from getting much worse than forecast for the 1.5C threshold.

Solution Aversion

Solution Aversion

I have had the misfortune to encounter many terms for psychological dysfunction in many venues. Cognitive dissonance, confirmation bias, the Dunning-Kruger effect – I have witnessed them all, all too often, both in the context of science and elsewhere. Those of us who are trained as scientists are still human: though we fancy ourselves immune, we are still subject to the same cognitive foibles as everyone else. Generally our training only suffices us to get past the oft-repeated ones.

Solution aversion is the knee-jerk reaction we have to deny the legitimacy of a problem when we don’t like the solution admitting said problem would entail. An obvious example in the modern era is climate change. People who deny the existence of this problem are usually averse to its solution.

Let me give an example from my own experience. To give some context requires some circuitous story-telling. We’ll start with climate change, but eventually get to cosmology.

Recently I encountered a lot of yakking on social media about an encounter between Bill Nye (the science guy) and Will Happer in a dispute about climate change. The basic gist of most of the posts was that of people (mostly scientists, mostly young enough to have watched Bill Nye growing up) cheering on Nye as he “eviscerated” Happer’s denialism. I did not watch any of the exchange, so I cannot evaluate the relative merits of their arguments. However, there is a more important issue at stake here: credibility.

Bill Nye has done wonderful work promoting science. Younger scientists often seem to revere him as a sort of Mr. Rogers of science. Which is great. But he is a science-themed entertainer, not an actual scientist. His show demonstrates basic, well known phenomena at a really, well, juvenile level. That’s a good thing – it clearly helped motivate a lot of talented people to become scientists. But recapitulating well-known results is very different from doing the cutting edge science that establishes new results that will become the fodder of future textbooks.

Will Happer is a serious scientist. He has made numerous fundamental contributions to physics. For example, he pointed out that the sodium layer in the upper atmosphere could be excited by a laser to create artificial guide stars for adaptive optics, enabling ground-based telescopes to achieve resolutions comparable to that of the Hubble space telescope. I suspect his work for the JASON advisory group led to the implementation of adaptive optics on Air Force telescopes long before us astronomers were doing it. (This is speculation on my part: I wouldn’t know; it’s classified.)

My point is that, contrary to the wishful thinking on social media, Nye has no more standing to debate Happer than Mickey Mouse has to debate Einstein. Nye, like Mickey Mouse, is an entertainer. Einstein is a scientist. If you think that comparison is extreme, that’s because there aren’t many famous scientists whose name I can expect everyone to know. A better analogy might be comparing Jon Hirschtick (a successful mechanical engineer, Nye’s field) to I.I. Rabi (a prominent atomic physicist like Happer), but you’re less likely to know who those people are. Most serious scientists do not cultivate public fame, and the modern examples I can think of all gave up doing real science for the limelight of their roles as science entertainers.

Another important contribution Happer made was to the study and technology of spin polarized nuclei. If you place an alkali element and a noble gas together in vapor, they may form weak van der Waals molecules. An alkali is basically a noble gas with a spare electron, so the two can become loosely bound, sharing the unwanted electron between them. It turns out – as Happer found and explained – that the wavefunction of the spare electron overlaps with the nucleus of the noble. By spin polarizing the electron through the well known process of optical pumping with a laser, it is possible to transfer the spin polarization to the nucleus. In this way, one can create large quantities of polarized nuclei, an amazing feat. This has found use in medical imaging technology. Noble gases are chemically inert, so safe to inhale. By doing so, one can light up lung tissue that is otherwise invisible to MRI and other imaging technologies.

I know this because I worked on it with Happer in the mid-80s. I was a first year graduate student in physics at Princeton where he was a professor. I did not appreciate the importance of what we were doing at the time. Will was a nice guy, but he was also my boss and though I respected him I did not much like him. I was a high-strung, highly stressed, 21 year old graduate student displaced from friends and familiar settings, so he may not have liked me much, or simply despaired of me amounting to anything. Mostly I blame the toxic arrogance of the physics department we were both in – Princeton is very much the Slytherin of science schools.

In this environment, there weren’t many opportunities for unguarded conversations. I do vividly recall some of the few that happened. In one instance, we had heard a talk about the potential for industrial activity to add enough carbon dioxide to the atmosphere to cause an imbalance in the climate. This was 1986, and it was the first I had heard of what is now commonly referred to as climate change. I was skeptical, and asked Will’s opinion. I was surprised by the sudden vehemence of his reaction:

“We can’t turn off the wheels of industry, and go back to living like cavemen.”

I hadn’t suggested any such thing. I don’t even recall expressing support for the speaker’s contention. In retrospect, this is a crystal clear example of solution aversion in action. Will is a brilliant guy. He leapt ahead of the problem at hand to see the solution being a future he did not want. Rejecting that unacceptable solution became intimately tied, psychologically, to the problem itself. This attitude has persisted to the present day, and Happer is now known as one of the most prominent scientists who is also a climate change denier.

Being brilliant never makes us foolproof against being wrong. If anything, it sets us up for making mistakes of enormous magnitude.

There is a difference between the problem and the solution. Before we debate the solution, we must first agree on the problem. That should, ideally, be done dispassionately and without reference to the solutions that might stem from it. Only after we agree on the problem can we hope to find a fitting solution.

In the case of climate change, it might be that we decide the problem is not so large as to require drastic action. Or we might hope that we can gradually wean ourselves away from fossil fuels. That is easier said than done, as many people do not seem to appreciate the magnitude of the energy budget what needs replacing. But does that mean we shouldn’t even try? That seems to be the psychological result of solution aversion.

Either way, we have to agree and accept that there is a problem before we can legitimately decide what to do about it. Which brings me back to cosmology. I did promise you a circuitous bit of story-telling.

Happer’s is just the first example I encountered of a brilliant person coming to a dubious conclusion because of solution aversion. I have had many colleagues who work on cosmology and galaxy formation say straight out to me that they would only consider MOND “as a last resort.” This is a glaring, if understandable, example of solution aversion. We don’t like MOND, so we’re only willing to consider it when all other options have failed.

I hope it is obvious from the above that this attitude is not a healthy one in science. In cosmology, it is doubly bad. Just when, exactly, do we reach the last resort?

We’ve already accepted that the universe is full of dark matter, some invisible form of mass that interacts gravitationally but not otherwise, has no place in the ridiculously well tested Standard Model of particle physics, and has yet to leave a single shred of credible evidence in dozens of super-sensitive laboratory experiments. On top of that, we’ve accepted that there is also a distinct dark energy that acts like antigravity to drive the apparent acceleration of the expansion rate of the universe, conserving energy by the magic trick of a sign error in the equation of state that any earlier generation of physicists would have immediately rejected as obviously unphysical. In accepting these dark denizens of cosmology we have granted ourselves essentially infinite freedom to fine-tune any solution that strikes our fancy. Just what could possibly constitute the last resort of that?

hammerandnails
When you have a supercomputer, every problem looks like a simulation in need of more parameters.

Being a brilliant scientist never precludes one from being wrong. At best, it lengthens the odds. All too often, it leads to a dangerous hubris: we’re so convinced by, and enamored of, our elaborate and beautiful theories that we see only the successes and turn a blind eye to the failures, or in true partisan fashion, try to paint them as successes. We can’t have a sensible discussion about what might be right until we’re willing to admit – seriously, deep-down-in-our-souls admit – that maybe ΛCDM is wrong.

I fear the field has gone beyond that, and is fissioning into multiple, distinct branches of science that use the same words to mean different things. Already “dark matter” means something different to particle physicists and astronomers, though they don’t usually realize it. Soon our languages may become unrecognizable dialects to one another; already communication across disciplinary boundaries is strained. I think Kuhn noted something about different scientists not recognizing what other scientists were doing as science, nor regarding the same evidence in the same way. Certainly we’ve got that far already, as successful predictions of the “other” theory are dismissed as so much fake news in a world unhinged from reality.