Climate change or climate forcing?

kw: book reviews, nonfiction, astronomy, astrobiology, exoplanets, climatology, climate change, global warming

Do we need to save the planet? It doesn't need it. Do we need to save the biosphere? We don't yet have the power to end it. Do we need to save civilization? Probably. This last is the question taken up by Adam Frank in Light of the Stars: Alien Worlds and the Fate of the Earth. He takes a new approach, you could say a Galactic approach, even a Universal approach, to setting parameters around the future of human civilization.

Dr. Frank uses a quieter tone than the noisy polemicists in the toils of public debate. He is nonetheless speaking as a prophet, warning us all of the consequences of the greatest of human endeavors, "the project of civilization." I found it notable that he never mentions the IPCC Reports. This is not to say that he doesn't give them any credence, but he is preaching to the unconverted: I learned long ago, in Christian evangelism, it does no good to quote Bible verses to someone who doesn't believe the Bible. Similarly, the content and methods behind the IPCC's work are challenged at every point by "climate deniers", so it is no use appealing to those reports.

In this book the author begins with Carl Sagan's metaphor of Western civilization as a teenager, grown up in body but not in judgement. Here in the US at least, we give 15- or 16-year-olds licenses, and the keys, to drive automobiles, knowing full well that their minds won't mature, and they will have very poor impulse control, for at least ten more years. So, at the very least, we in the First World are like a teenager with the keys to the energy sources of Planet Earth, and we have shown an utterly insatiable appetite for more and more energy use. This chart is instructive:

This shows energy use per person (credit: Our Finite World). The technology to mine and use coal jump-started the nascent Industrial Revolution in about 1850. Petroleum and Natural Gas triggered a further jump beginning right after World War I, which was stalled by the Depression, and then re-invigorated by World War II. The "flat spot" from about 1970-2000 is the effect of the Arab Oil Embargo. I suspect the development of Fracking to rejuvenate oil production in non-Arab nations is responsible for the jump after 2000.

So now we use four times as much energy per person as someone in 1820. That is a global average. Per-person use in the First World is in the 250-300 GJ/yr range, or 3-4 times the global average. So that is our "car". It has a lot of horsepower.

The question Sagan asked, based on figures from the 1960's, is, "Can the Earth provide the needs of human civilization, forever?" To abolish poverty worldwide, we'd need to roughly triple global resource use, particularly energy use. But we are seeing "cracks in the wall" already. Someone once said, to raise the entire population to the American level would require four more Earths.

What is Adam Frank's line of analysis? He continues with the Drake Equation, formulated in 1961,
that uses several factors to estimate the number of alien civilizations we might find using efforts such as SETI, the Search for Extra-Terrestrial Intelligence, which uses radio frequency reception, in hopes of overhearing the alien version of "I Love Lucy". He dissects this for us and then presents the uses of a method developed by Svante Arrhenius, 122 years ago, to determine how much the earth will warm based on how much extra carbon dioxide gets into the atmosphere. "Climate science" is not new stuff, folks!

The Arrhenius method doesn't just work on Earth. It was used to understand what happened to Venus, to raise its temperature to 600°F, and why Mars is a bit warmer than it would be without any atmosphere, though daytime highs in its "Tropics" range around -10°F. Mars and Venus both have an atmosphere containing 95% carbon dioxide. Venus has a very, very heavy atmosphere while the air on Mars is very thin, about 1% of Earth-normal. But our air contains, at present, 400 ppm CO₂, or 0.04%. Martian air with enough nitrogen added to have the density of Earthly air would still have 0.95% CO₂, nearly 24 times as much! So the temperature range on, for example, airless Phobos, compared to that on Mars, validates the Arrhenius analysis for a CO₂-induced greenhouse effect (yes, Phobos is colder).

After presenting the history of exoplanet discoveries—a few thousand are now known—the author turns the Drake Equation on its head, to determine the "Pessimism Line". That is his term for how pessimistic you need to be to say we are surely alone in the Universe: Knowing that the stars in all the galaxies range in age up to 10+ billion years, and that there are about 100 billion stars in each of 100 billion galaxies (or perhaps even more) in the visible Universe, how pessimistic do you have to be to strongly aver that our Human civilization is the first and (so far) only civilization to have arisen in the Universe?

In 1961 the only factor of 7 in the Drake Equation that was known was the rate of star formation in the Milky Way Galaxy, about one per year. All the other terms were speculative, and all possible values of, for example, the chance that a planet will be at a "just right" distance from its star (in the habitable zone), were strongly supported by various people. You could find someone who'd argue that the probability was close to zero; someone else who'd argue that any star that had planets probably had at least one in the habitable zone. Now, with a few thousand known exoplanets, we know that nearly every star has multiple planets, and about 40% of those have at least one planet in the habitable zone. So the unknown terms are:

• Can life form easily, or not?
• Once formed, can life develop "intelligent" species easily, or is it very hard?
• Is the likelihood that an intelligent species will form a global civilization large, or small? and 
• Once formed, how long will such a civilization continue?

By turning all this around backwards, the combination of these "biological" and "sociological" terms needed to make it very unlikely that more than one civilization has ever been formed, was found to be 10^-22. That is one in ten billion trillion. This is a quantitative estimate of how hostile the Universe must be to civilization, for us to be alone in all space and time (to date). Effectively, this analysis presents you with a pile of sand, a trillion tons of it, containing ten billion trillion grains, and asks, "Knowing that at least one sand grain represents a civilization in the Universe, how likely is it that no other grain of sand represents a planet with a civilization? Not one single one?"

For most of us, the thought that civilization arose only once in ten billion trillion attempts is rather ludicrous. Even Peter Ward with his Rare Earth analysis, is probably not that pessimistic!

Dr. Frank then goes further, asking, "What does it take for a civilization to be sustainable, very long-term?" Numerous isolated and semi-isolated civilizations on Earth have risen and fallen. It seems even Earth, so hospitable to life of many kinds, can he hostile to civilizations…or, at least, unforgiving of egregious errors. Further, civilizations that fell, did so quickly. The environmental disasters, caused by the Easter Islanders and the Mayans all doing what people do to have a thriving society, reduced populations to about one tenth of what had once been in just one or two generations. Even today, there are fewer Mayans than there were in 1200 AD. These are two examples of civilizations that fell not because of conquest by someone else, but at their own hand. Two cases of a teenager driving right off a cliff.

The book closes with an appeal to wake up and grow up. It would be well to heed it. To my understanding, no civilization yet produced on Earth has figured out the trick to sustaining itself without perpetual growth. In the US, a growing GDP is required for a "robust" economy. The US government recently announced a 4.1% annual growth rate (that really means 0.335% growth for that particular month). It is good in a way. But if it keeps up, we can project it into the future: In just 17 years, GDP would double, and it would keep doubling again every 17 years. By 2100 AD the US GDB would be 27 times what it is today. What chance is there of that happening? Hmmm??

Suppose we finally get the analysis right, and find out that, for human civilization on Earth to be sustainable for 100, or 1,000, or 10,000 years, we would have to reduce our population to at most two billion, and the general lifestyle and level of energy expenditure (both personal and corporate) would need to match that of Peru (about ¼ of what us Americans are used to)? Then what? I'll tell you what: whatever the actual level of lifestyle really is, in time the biosphere will enforce it.

We are not divorced from Earth. We cannot act as though we were not part of nature. Nature can get along without us. We cannot get along without nature. Civilization is an experiment. It may be one that eventually fails. The Pessimism Line only tells us how unlikely it is that we are on the only planet to develop civilizations. It doesn't tell us how long they last. That part of the Drake Equation is still entirely unknown.

I would put it this way: If there is any chance for a global civilization to develop and thrive, and properly care for all its members, without constant growth in both population and standard of living, we need to figure that out right away. Or we, too, will crash, just a bigger version of the Mayans or Easter Island.