“As I understand my function, it is to give some sense of what the greenhouse effect is, to try to say something about the greenhouse effect on other planets, to again underscore that this is a real phenomenon, and then perhaps I can take the liberty to say a few remarks about what to do about it.
“The power of human beings to affect, and control, and change the environment is growing as our technology grows, and, at the present time, we clearly have reached the stage where we are capable, both intentionally and inadvertently, to make significant changes in the global climate and in the global ecosystem; and we have probably been doing, on a smaller scale, things like that for a very long period of time. For example, slash and burn agriculture, which has been with us for tens of thousands of years, probably, changes the climate to some extent by changing the albedo, the reflectivity of the Earth. That massive changes have occurred is clear from the historical record: for example, Egypt was once the breadbasket of the Roman Empire, maybe the same role as the American Midwest plays today. That is certainly no longer the case; it is not a greenhouse-effect issue, may be an overgrazing issue, but is an example of how humans are perfectly capable of making these unexpected and inadvertent changes.
“Because the effects occupy more than a human generation, there is a tendency to say that they are not our problem; of course, then, they are nobody’s problem: not on my tour of duty, not in my term of office, and it’s something for the next century, let the next century worry about it. But the problem is that there are effects, and the greenhouse effect is one of them, which have long-time constants: if you don’t worry about it now, it’s too late later on, and so, in this issue, as in so many other issues, we are passing on extremely grave problems for our children when the time to solve the problems, if they can be solved at all, is now.
“If you ask what determines the Earth’s climate, clearly, the main thing that determines it is sunlight: sunlight is light that heats the Earth. Not all the light that arrives at the Earth from the sun goes to heating the Earth (some of it is reflected back; it’s just the part that is absorbed); and what happens is, there’s a certain rate at which sunlight is absorbed by the Earth’s surface, and there’s a certain rate at which the Earth’s surface radiates to space.
“What comes from the sun is in the ordinary visible part of the spectrum that our eyes are sensitive to; what the Earth radiates into space is in the infrared part of the spectrum: longer waves than red, that our eyes are not sensitive to; but it’s as legitimate a form of light as the kind that we’re used to.
“Now, if you calculate what the temperature of the Earth ought to be, from how much sunlight is being absorbed equalling how much infrared radiation would be radiated to space, you find that the Earth’s temperature by this simple calculation is too low: it’s about 30 centigrade degrees too low. And why is it too low? It’s too low because something was left out of the calculation. What was left out of the calculation? The greenhouse effect.
“The air between us is transparent (except in Los Angeles and places of that sort) in the ordinary visible part of the spectrum: we can see each other. But, if our eyes were sensitive at, say, 15 microns in the infrared, we could not see each other: the air would be black between us, and that’s because, in this case, of carbon dioxide. Carbon dioxide is very strongly absorbing at 15 microns and other wavelengths in the infrared. Likewise, there are parts of the infrared spectrum where water vapour absorbs, where we could not see each other if we were only as far apart as we are in this room.
“If you add these infrared absorbing gases to a planet, then, what happens is, the sunlight comes in as before but, when the surface tries to radiate to space in the infrared, it is blocked, it is impeded by the absorbing gases, and so the surface temperature has to rise so that there is an equilibrium between what comes in and what goes out. So, this is the greenhouse effect (it is a misnomer, for more reasons than one; it’s a misnomer in particular because that’s not how the florist’s greenhouse works, but that’s a very minor point).
“There are other gases which absorb in the infrared, all, or many, of which have been mentioned already: nitrous oxide, methane, the halocarbons; and these are products, partly, of agriculture, its fertilisers, refrigeration, aerosol spray cans, and so on, all products of our technology.
“We don’t generate much water into the atmosphere but we certainly do generate a great deal of carbon dioxide through the burning of wood and fossil fuels in apparently benign activity. Who could object to humans burning oil and coal, gas and wood?
“I’d like to stress that the greenhouse effect makes life on Earth possible: if there were not a greenhouse effect, the temperature would, as I say, be 30 centigrade degrees or so colder and that’s well below the freezing point of water everywhere on the planet. The oceans would be solid after a while; a little greenhouse effect is a good thing.
“But there is a delicate balance of these invisible gases, and too much or too little greenhouse effect can mean too high or too low a temperature. And, here we are, pouring enormous quantities of CO2 and these other gases into the atmosphere every year with hardly any concern about their long-term and global consequences.
“Now, certainly not all aspects of how increased CO2 and other gases into the atmosphere affect the climate are known: there are still many uncertainties, although the overall picture is, I think, quite clear and quite widely understood and accepted. But there are questions about aerosols, about clouds (you heat up the earth: how much increase or decrease in cloudiness is there? How does that change the albedo or reflectivity of the Earth?); there are questions about the ocean and its response time to an increase in CO2; there are feedback effects; and, therefore, it is certainly worthwhile to spend some additional money on further research on the subject.
“Another point is that the significant temperature changes on the Earth between ice ages and out-of-ice ages, glacial and interglacial time periods, seem to be connected with quite small changes in the amount of sunlight that reaches the Earth due to changes in the Earth’s orbital properties, and that is a suggestion that the Earth’s climate system may be very delicately dependent on the sorts of factors that we’re talking about here; and that’s why it makes sense to study past climatic change on the Earth as an attempt to obtain some calibration.
“Another source of calibration is the other planets. Every planet with an atmosphere has some degree of a greenhouse effect. The most spectacular case by far is the greenhouse effect of Venus: it’s the nearest planet, it’s a planet of about the same mass, radius, density as the Earth, but it is spectacularly different in several respects, one of which is that the surface temperature is about 470 degrees centigrade (900 Fahrenheit), and that enormous temperature is not due to its being closer to the sun. Because Venus is surrounded with bright clouds and, in fact, because it reflects so much light back to space, if that’s all that was happening, it would be cooler, not warmer, than the Earth.
“The reason for this absurdly high temperature on the surface of Venus (which is well understood; I mean, Soviet spacecraft have landed on Venus and in effect stuck out a thermometer: there is no doubt that that surface temperature is very high; and later US spacecraft have, as well), the reason is a massive greenhouse effect, in which carbon dioxide plays a major role.
“Now, the amount of CO2 in the Venus atmosphere is much larger than here. The atmosphere is almost entirely carbon dioxide and there is 90 times more of it there than here. But it is an indication of what can happen in an extreme case.
“You look at Mars or Jupiter or Titan, the big moon on Saturn, and you have additional examples of greenhouse effects: different gases, different amounts of sunlight reaching the surface, different planetary albedos and cloudiness, and, in all those cases, there is also a greenhouse effect.
“In addition, it has been possible to calculate those greenhouse effects fairly accurately, so that the kind of theoretical armamentarium which is used to calculate the greenhouse effect changes on the Earth is also used for other planets and therefore can be calibrated to some extent against those other planets. If we keep coming up with the right answer in all those different cases, then probably we understand fairly well how greenhouse effects work. It would, however, be worthwhile, and along the lines that Senator Gore was talking about, to have an increased programme through NASA to understand the greenhouse effects on other planets: this might be a very practical application of planetary exploration.
“As you’ve heard, the best estimates (they certainly have some uncertainties attached to them) are that, at the present rate of burning of fossil fuels, the present rate of increase of minor infrared absorbing gases in the Earth’s atmosphere, there will be a several-centigrade-degree temperature increase on the Earth, global average, by the middle to the end of the next century, and that has a variety of consequences, including redistribution of local climates, and, through the melting of glaciers, an increase in global sea level.
“There is concern on a somewhat longer time scale about the collapse of the West Antarctic ice sheet and a general rise of many, many metres in sea level.
“So, we have a kind of handwriting on the wall. Certainly there’s more research to be done but, as I say, there is a consensus: what can be done about it? The idea that we should immediately stop burning fossil fuel has such severe economic consequences that no one of course will take it seriously. But there are many other things that can be done.
“One has to do with the subsidies for fossil fuels: more efficient use could be encouraged by fewer government subsidies. Secondly, there are alternative energy sources, some of which are useful, at least locally: solar power is certainly one that might be of more general use; safe fission power plants, which are in principle possible; and, then, on a longer time scale, the prospect of fusion power: fission and fusion power plants in principle vent no infrared-active gases and therefore, whatever other problems they may provide, they do not provide a greenhouse problem.
“I’d like to close by just saying a few words on the kind of perspective that this problem, as related problems, poses to us. Here is a problem which transcends our particular generation: it is an intergenerational problem. If we don’t do the right thing now, there are very serious problems that our children and grandchildren will have to face. It is also a global problem: it is no good if just one or two major industrial nations take major steps to prevent a major increase, still further, in CO2 and other greenhouse gases. Because other nations may, through their industrial development, cause the problem by themselves; not to say that this is inevitable, but just to give an example: the largest coal reserves on the planet are the United States, the Soviet Union and China. China is undergoing a very major industrial development and the burning of coal is certainly something that must be very attractive for the Chinese looking into the future.
“I would say that there is no way to solve this problem even if the United States and the Soviet Union were to come to a perfectly good accord on this issue, without involving China, and many other nations that will be developing rapidly in the time period we’re talking about. So, here is a sense in which the nations, to deal with this problem, have to make a change from their traditional concern about themselves and not about the planet and the species: a change from the traditional short-term objectives to longer-term objectives; and we have to bear in mind that, in problems like this, in the initial stages of global temperature increase, one region of the planet might benefit while another region of the planet suffers, and there has to be a kind-of trading-off of benefits and suffering. And that requires a degree of international amity, which certainly doesn’t exist today.
“I think that what is essential for this problem is a global consciousness: a view that transcends our exclusive identifications with the generational and political groupings into which, by accident, we have been born. The solution to these problems requires a perspective that embraces the planet and the future, because we are all in this greenhouse together.”
Dr Carl Sagan, Cornell University, oral evidence to the Senate of the United States, 1985.1
Salient phrases in the foregoing include:
Humans are perfectly capable of making unexpected and inadvertent changes. The number two in ability to change the environment is the beaver. It can have devastating effects, but not these.
The power of human beings to affect, and control, and change the environment is growing as our technology grows. As is, now, our power to halt changes to the environment, because we have means and knowledge.
There is a tendency to say that [the effects of human activity] are not our problem; of course, then, they are nobody’s problem. If politics is now largely in the hands of big business, and big business needs to temper its activity to staunch climate degradation, there is a temptation to say two things: (i) how can we trust politics to persuade big business to do the right thing—are we not asking the lunatics to run the asylum? (ii) what can we as the little people do about something as big as climate change? If we the people cannot stop climate change, how do we make politics and big business stop climate change if they are instrumental in furthering it and reap financial rewards from doing so?
The time to solve the problems, if they can be solved at all, is now. “Now” was 1985. Much has been done. But much has been done to worsen the situation. Ice shelfs have melted and severe weather is much more the norm. A generation and a half has passed since Sagan gave his speech. Sagan died in 1996, at the early age of 62. It’s my age now. I could never achieve his level of expertise in any discipline of his, but perhaps I can do one thing with the years granted to me that weren’t granted to him: work to stop climate change.
If you add infrared absorbing gases to a planet, sunlight comes in but, when the surface tries to radiate to space in the infrared, it is blocked. This is not a greenhouse effect. It is an infrared oven effect: we are baking ourselves, as if we were pizzas. Dr Sagan talked of the inability of planet Earth to radiate (longwave) infrared light waves back into space when they’re blocked by greenhouse gases, and he cites the visibility offered by the human sight spectrum as a model: “We can see each other,” says he. No analogy is perfect, because, of course, the Senator had exactly the same eyesight capabilities as the Doctor, whereas the Sun can see the Earth in the shortwave spectrum, even if the Earth cannot see the Sun in the longwave. Like a trap: the light can enter through the greenhouse gases; but Earth cannot itself emit it in its longwave form. So we bake.
The idea that we should immediately stop burning fossil fuel has such severe economic consequences that no one of course will take it seriously. How severe does climate change have to become before severe economic consequences get cast aside? Or is that a question for the twenty-second century?
Whatever other problems [fission and fusion power plants] may provide, they do not provide a greenhouse problem. How bad does climate change need to get before fission and fusion would be embraced as saviours? As bad as burning all the coal, oil and gas makes it? Or must the threat of a military strike first be eliminated?
That requires a degree of international amity, which certainly doesn’t exist today (see my recent article here). Does it, today’s today? I think there’s less international amity in 2023 than there was in 1985, during the Cold War. What’s the carbon footprint of a war? Do we really need the Amazon jungle? Why do we recycle any plastic: can’t we just dump it all in the oceans? Are we trying to stop the tide from coming in, like King Canute did, or have we already enough proof of our powerlessness?
We are all in this greenhouse together. Elon and Jeff aren’t. Tons of people aren’t in this greenhouse, we have found. Many, many of us are busy building their airco systems. And some of us tell ourselves that that’s nonsense, because we’d like to be up there with them. The subliminal message that is being radiated is that the Earth is doomed, but those who work to annihilate it will be accorded a seat in the new comfort zone. This could be the reason for unabashed crookedness in politics, chumocracy, raping of the Amazon, gung-ho military actions, price gouging and rampant profiteering, denials of responsibility and greenwashing across the board. Here, Sagan may have been wrong: if it was true in 1985, we are not, at present, all in this greenhouse together.
You can watch Dr Sagan’s speech.
In 1985, it frightened me. In 2023, it has saddened me. In 1977, James Carter was passed a memo that first warned of these effects. He did too little. He never probably imagined that a problem of this magnitude for the entire world could be lobbied against, denied, denigrated, poo-pooed, manipulated and out-manoeuvred by oil and gas interests.
I’ll wager it was unthinkable to Mr Carter that moneyed interests would seek to prevail over the destruction of the third rock from the Sun. But he did too little to stop them. Mr R. W. Reagan, Mr G. H. W. Bush, Mr W. J. Clinton, Mr G. W. Bush, Mr B. H. Obama II, Mr D. J. Trump did too little. I’ve done too little. Because I’m little. The challenge before us is not to stop climate change. It’s far easier than that. All we need to do is stop oil & gas. Climate change will follow as a matter of course. As sunlight follows day.
If I had a wish for the world, it’d be this: let the unthinking wealthy awaken tomorrow speaking tongues and lavishing their ability, knowledge and means on mankind’s endeavour for a natural world.
Some music to meditate. You can take your bottom line and shove it.
Image: By credit NASA JPL - File:Planetary_society.jpg, Public Domain, https://commons.wikimedia.org/w/index.php?curid=24462106