Santa's Bathing Suit: Global Warming, Then and Now
***********POSTSCRIPT A ADDED 4/12/06*************
Part 1: A Wake-Up Call from Long Ago
At eighty degrees' north latitude, less than a thousand miles from the North Pole, lies the arctic tundra of Ellesmere Island in northern Canada. Winter lasts nine months of the year, and temperatures can approach -70°F.The nearest tree of any sort is a thousand miles to the south. Yet hidden in the permanently frozen soil are the remains of a forest. Analysis shows the trees to be Metasequoia glyptostrobiodes, today a popular landscape tree which is killed by temperatures below -10°F. The tree remains are 55 million years old.
Deep-sea sediment cores from the bottom of the Arctic Ocean have found microscopic fossils of tiny organisms called foraminifera. The species found indicate that sea surface temperatures 55 million years ago approached 65°F at the North Pole. Santa Claus could have worn bathing trunks.
Indeed, the earth was warmer yet at other times in the more distant past, such as the late Cretaceous, around 90 million years ago, and temperatures were to edge close to this level once more about 3.5 million years later. What makes the episode 55 million years ago different is its suddenness--in the hills and valleys of climate change over time, as measured by oxygen-isotope ratios in sediments, it stands out as a weird, needle-like spike. The earth was very much cooler both just before and just after this event occurred. Paleoclimatologists have named it the Paleocene-Eocene Thermal Maximum, or PETM for short. Its story is the story of a long-ago ecological and climatological catastrophe. The oceans became stratified, and shallow water no longer mixed with deep water. Oxygen disappeared from the deep water, along with much of deep-sea life. The oceans became acidic, and could not absorb carbon dioxide as well as usual. Ocean animals had difficulty forming shells. Carbon dioxide levels in the atmosphere soared, helping to heat the planet. On land, the mid-latitudes became subtropical deserts. Mass extinctions happened just as they had with the Chicxulub asteroid impact nine million years earlier (though not quite on that scale). It took hundreds of thousands of years for the
weather to return to the way it previously was. The face of life on earth was changed forever.
Figure1: Plot of foraminiferan carbon and oxygen isotope ratios against time. Note that the oxygen isotope ratios are correlated with temperature. (Image credit:http://www-odp.tamu.edu/publications/208_IR/chap_01/images/01_f07.gif)
The geological record is not good at recording phenomena that occur on time scales shorter than about 10,000 years. In other words, a process that took 10,000 years to complete would leave the same signature in the rocks as the same process if it took only a day. The record tells us that the PETM arrived too swiftly to measure,in 10,000 years at the most. There are reasons to suspect it may have happened much more quickly than that, perhaps only in a decade or two. A clue to why it happened may be found in the carbon isotope plot. Living things absorb carbon-12 more readily than carbon-13. Also, if the ratio of these isotopes in the environment changes, living things will record this change in such body parts as shells or bones, and this ratio can be graphed over time. Figure 1 shows that a lot of "light" carbon (which had presumably originated in living things or their remains) was dumped into the environment extremely rapidly at the PETM. This could have been in the form of carbon dioxide, but most researchers believe that the carbon was released in the form of methane, a short-lived but much more potent greenhouse gas. The PETM was apparently what climatologists call a methane catastrophe.
To understand how this might be possible requires explaining a curious fact about the physics of methane and water. At low enough temperatures and high enough pressures, water molecules array themselves into a cage-like structure around methane molecules,forming an ice-like solid known as methane hydrate (click here for a more complete explanation). As much as two quintillion cubic feet of methane may be stored in the muck just under the surface of the world's continental shelves today in this form, representing more reserves than all other fossil fuels combined. When pressure is reduced or temperature is increased, methane hydrate fizzes like Alka-Seltzer and decomposes back into methane gas and water. You can light the escaping gas, making possible a sort of "burning ice" parlor trick (Figure 2).
Figure 2: Methane hydrate decomposing at atmospheric pressure. Liquid water is seen dripping away at the bottom. (image credit: http://www.usssp-iodp.org/Images/flaming_hydrate.jpg)
A methane catastrophe starts when some process affects part of the methane hydrate beds so that they become unstable. In the case of the PETM, the trigger may have been the intrusion of hot magma under some part of the hydrate beds. It could have been geological uplift of a bed to the point that the overlying pressure was insufficient to maintain the hydrate stably. Or it might simply have been warming of the deep oceans to the point where the pressure/temperature line of instability crept down into the beds from above. The climate was, after all, slowly warming just before the PETM. Whatever the trigger, a substantial quantity of methane is released into the atmosphere. This causes the planet to heat up, which pushes the instability line deeper into the hydrate beds, releasing more methane, and so on in a sort of chain reaction which only ends when most of the hydrate beds are exhausted and huge quantities of methane have been dumped into the atmosphere, resulting in a spectacular warmup. The methane oxidizes in about ten years to carbon dioxide, which is only about 5% as strong a greenhouse gas; but by then the damage is done, and even that much carbon dioxide is a formidable force for maintaining abnormal warmth. The acidic ocean and chaos in terrestrial plant ecosystems further impair recovery, and only after several hundred thousand years can the climatic effects of the catastrophe finally dissipate. There have been other methane catastrophes in the earth's past, most notably at the Permian-Triassic boundary (251 MYa), the Pliensbachian-Toarcian (183 MYa) and the early-Aptian (117 MYa). Each was associated with sudden, traumatic climate changes.
Why am I telling you this story? It is a cautionary tale from across the immensity of time. It just might be important.
Part 2: Global Warming Today--Yes, It's Real
I am surprised that, even today, many persons speak as if the idea of global warming were only an unsubstantiated assertion, a bogeyman conjured up by (presumably suspect) leftist groups to further their political and environmental agendas. Part of this misunderstanding, I think, revolves around the word 'theory'. To many laymen, this connotes a statement of doubtful veracity, something not supported by evidence. Not so to the scientist. In scientific parlance,
such an assertion would be termed a conjecture.
If it be supported by some body of evidence, it is an hypothesis. Only if it has successfully predicted the result of an observation or experiment whose outcome was not previously known can it earn the highest honorific of theory. A scientist always bears in mind that any theory, in principle, may be found inadequate in the light of future observations. All too often, this professional caution and humility is mistaken by the layman for a
confession of ignorance or lack of confidence in a belief. Think of how the public debate about evolution has been warped by a similar confusion. For global warming, you will see shortly that there is evidence. Let us cut to the chase, then, and present some information about recent history:
Figure 3: ground station (middle plot) and satellite (top and bottom plots) graphs of global temperature change,
1982-1998. (Image credit:
There is no doubt that the temperature was rising steadily from 1982 to 1998. Ground measurements have sometimes been criticized as potentially limited by the sampling bias caused by where measurements can be taken. No such caveat applies to the satellite measurements, which involve
remote sensing of the entire globe from space. The ground and corrected space measurements are actually in very good agreement over the long run, anyway.
As the air temperature warms, we would expect the average sea surface temperature to be increasing also, and this is indeed what we find:
Figure 4: Global Sea Surface Temperature
Change, 1955-2000 (Image credit: http://climate.virginia.edu/
On the whole water expands as it is heated, which (along with melting glaciers) would be expected to make sea levels rise. Guess what:
Figure 5: Global Sea Level Change, 1993-2000 (Image credit: http://www.csr.utexas.edu/gmsl/output/output_plot_noIB_GSLrise.jpg)
However, we need more than just recent history to put these observations into perspective. What has the climate been like in the last several centuries? Just what constitutes "normal" climatic variation? How warm are we now, compared to the Medieval Maximum (an event of likely solar origin) when Vikings farmed southern Greenland? From the more distant past, we do not have direct temperature measurements. As in the case of the PETM, temperature is tracked by means of proxies, which are quantities which
are known to vary in a predictable way when the temperature changes, such as oxygen isotope ratios, tree ring spacings, and the like. Michael Mann of the University of Virginia and his coworkers recently compiled this reconstruction of the recent history of global temperature, dubbed the "hockey stick" plot because of its shape (Figure 6). Based on this plot, Mann asserted that the earth (or at least the northern hemisphere) is the warmest it has been in 650,000 years.
Figure 6: Northern Hemisphere temperatures 1000-1999, as reconstructed by Mann, et. al. (black and blue lines) The broad hump at the left of the graph is the Medieval Maximum. (Image credit:
Foul! cried the critics. It is still too cold to farm in Greenland, so how can this be? Indeed, there seem to be legitimate issues with how Mann et al. calibrated modern instrumental data (composing, primarily, the blade of the hockey stick) with historical proxy data
(making up the shaft). Two other researchers, McIntyre and McKitrick, reanalyzed the data and published this corrected version (at least for the data since 1400):
Figure 7: Corrected Northern Hemisphere temperatures 1400-1999 (red line) as computed by McIntyre and McKitrick
(image credit: http://www.envirotruth.org/images/graphs/
So maybe it was as warm as today as recently as when Columbus sailed, at the tail end of the Medieval Maximum,
which looks much more robust an event in this view, and probably at its height encompassed much milder weather even than today's (explaining the Viking farms in Greenland better). The two curves still look about the same after 1550, though. There is another curve, compiled by Hans von Storch, and using a different mathematical methodology and a different data set. It shows the peak of the Medieval
Maximum just about even with today's temperatures.
Figure 8: Hans von Storch's climate reconstruction, 900-1999 (blue line) (Image credit: http://www.worldclimatereport.com/wp-images/RIP2.GIF)
Whichever graph you find most credible, one thing is clear: the climate has been relentlessly warming since 1900 (or a bit before), and is now warmer than it has been in quite a while; if the present trend has not yet rivalled the Medieval Maximum in extent, it may not be long before it does. Data from tropical glaciologists also adds support to this view: high-altitude icefields which until recently had yielded undisturbed cores dating back to the last ice age have suddenly had their records obliterated by meltwater--in the last twenty years. Globally, every successive year since the Pinatubo hiatus has been one of the five warmest years ever recorded, and most are in the top two or three (2005 is the new #1).
Part 3: Why is it happening, and what does it portend for the future?
That global warming is happening is easy to establish. Why it is happening is a slightly more complex story. The temperature of the earth may be controlled either by external (astrophysical) factors or by internal (atmospheric and surface) factors. One astrophysical factor that has certainly shaped climatic history over the last million years is the evolution of the orbital and rotational mechanics of the earth. This is a fascinating subject in itself (see here), but as the shortest cycle of importance is 22,000 years, and as the current predicted trend according to these factors alone is cooling, we cannot look here for any explanation of the (humanly) recent past.
The other astrophysical factor is, of course, the output of the sun itself. Our sun is not considered by astronomers to qualify as a variable star (and be thankful for that!), but its output is not absolutely constant, either. It is instructive to look at what the sun has been doing over the past few centuries:
Figure 9: Variations in solar irradiance in three
wavelength bands, 1600-2000, as calculated from sunspot number. The small serrations correspond to the familiar
11-year sunspot cycle. The period of low irradiance from 1642-1716 is the Maunder Minimum, when sunspots were completely absent. The feature at about 1810 is the
Dalton Minimum. (Image credit: http://www.john-daly.com/hockey/
The variations depicted (<1%) seem quite small, given that solar irradiance varies 9% over the course of a year, due to the eccentricity of the earth's orbit; but the climate is exquisitely sensitive to these small changes. The Maunder Minimum is remembered in Europe as a time of infamously harsh winters and crop failures. The Dalton Minimum brought yearly freeze-overs to the Thames River in London, played a role in Napoleon's calamitous winter retreat from Russia in 1812, and, incidentally, gave our culture the stereotype of a white Christmas. When combined with the 1815 eruption of Tambora (VEI 7), it brought snow flurries to Pittsburgh in July.
Meanwhile, the run-up from 1880 to 1960 corresponds suspiciously to the sudden rise in temperature on the climate graphs. Could this be the whole story? There are those who think so, but I do not agree. Consider the following graph:
Figure 10: Estimated solar irradiance and surface temperatures, 1860-1995 (image credit: http://www.brighton73.freeserve.co.uk/gw/solar/temp_vs_spot_irradiance.gif)
For most of the period, the curves more or less track each other, the agreement getting better with time as measurements improve. Then, around 1980, something funny happens: even as solar output has more or less levelled out, surface temperature starts climbing once again, and has continued to climb to this day. Whatever is making the temperature rise today must be something happening here on earth.
Most of us have either seen a graph like the following, or have heard assertions based upon it:
Figure 11: Average global temperature anomaly and carbon dioxide concentration in the atmosphere, 1860-2000 (Image credit: http://img.villagephotos.com/p/2004-12/910679/dtCO2.jpg)
The implication is clear, as the standard story goes: humans dumping carbon dioxide into the atmosphere through the burning of fossil fuels have caused the temperature rise we have observed since then. Though there is a big kernel of truth in this, it is misleading if so baldly stated. The climate responds swiftly to changes in the output of
the sun, just as a small dinghy can start, stop, and maneuver quickly. Changes in carbon dioxide are another matter: the gas is chemically buffered by the ocean and chemically stored in and released from numerous other biological and geological sinks, connected by a web of
feedback loops. Increased carbon dioxide levels both cause warming and are caused by it. This introduces all manner of time delays between cause and effect, such that the climate is more like the Titanic than a dinghy when it comes to responding to carbon dioxide and other greenhouse gases--slow to start and slow to stop. Most, if not all, of
the warming prior to 1980 can probably be ascribed to solar variation; but the greenhouse-gas changes have finally worked their way through the system and the effects are starting to show. The discrepancy isn't large yet, but it probably will be in another quarter century; and even if mankind instantly ceased all carbon-dioxide-emitting activities, carbon dioxide levels and temperatures would still continue to rise for a long time before peaking.
Figure 12: Various scenarios for projected carbon dioxide emission (left) and atmospheric concentration (right), 1990-2100 as computed by the Intergovernmental Panel on Climate Change. Notice the time lag. The "best case", i.e. unreasonably optimistic, scenario is in green. (Image credit: http://www.ghgonline.org/images/ipcc5b.gif)
But this, of course, is not what is happening: there are six billion humans in the world (soon to be 12+ billion), most as yet poorer than we are, and they all want to live as we do, with oil and coal presumably being the fuels that will be chosen to help make that economic dream a reality.
And then, of course, there is the matter of methane, the other major greenhouse gas, currently accounting for about a fifth of the total atmospheric greenhouse load but increasing in relative importance. 60% of methane release into the atmosphere today is due to a miscellany of human activity as shown in Figure 13.
Figure 13: Breakdown of total human-caused (left, 60%) and natural (right, 40%) sources of methane entering the atmosphere, according to EPA and IPCC, respectively. (Image credits: http://www.epa.gov/methane/images/globalanthro.gif, http://www.epa.gov/methane/images/methane_naturalchart2.gif)
Notice that a large share of the human contribution has to do with agriculture and cattle. There is even an hypothesis (see
this article) that humans and their livestock already caused some warming of the climate, even before the Industrial Revolution, by means of increasing methane emissions. Are we close to triggering a methane catastrophe like that which defined the PETM?
Figure 14: Atmospheric methane concentration, 1984-2003, after Dlugokencky, et al. (Image credit:
What we see in Figures 13 and 14 suggests that this is not so, just yet. Methane levels, though they were climbing until 1999, seem to have levelled off. There is no sign of the rapidly accelerating upward curve one would expect if a methane catastrophe were actually underway, and only a fiftieth of present emissions are thought to come from hydrate beds, mostly shallow on-land deposits. Since temperature levels in the Middle Ages were apparently in excess of today's without triggering any such event directly, there is little reason to believe that today's climate could do so. However, there is still the carbon dioxide issue to reckon with. The climate may not yet be as warm, historically speaking, as it was in the Middle Ages, but a certain amount of future warming is already beyond our control, and we will get there, and beyond, soon. Beyond that, we are sailing in uncharted waters. Temperature measurements indicate that the deeper ocean is warming, and the line of instability is creeping down toward the depths where the larger hydrate beds lie. It would be hard to know when the point of no return has happened--a methane catastrophe may quietly become inevitable many decades before it actually happens, unless some intervention as yet unknown to us can be brought to bear (Stephen Baxter plays with this idea in his novel Transcendent.)
Even if the threshold temperature as such is not reached, higher temperatures would make it easier for some secondary trigger (such as magmatic intrusion) to set a chain reaction off.
What would it be like if a methane catastrophe were to happen in the near future? I do not wish to engage in idle fear-mongering, and we cannot say exactly how probable such a scenario really is, beyond noting that it has happened before, 55 million years ago; but the scenario is not so wildly improbable that it can be omitted here. The event would first be apparent on the instruments that measure methane concentration. Perhaps within a few months to a year, the first tangible effects would be felt: even before global temperatures rise noticeably, jet stream and storm tracks will start to shift radically, rearranging the world's weather patterns. It seems likely that much of the world's cropland that is not presently irrigated will quickly become arid and unusable. True, other land farther north and south may become more favorable, but it would take a lot of time to bring all of it on line as farmland--and there won't be time. A corn farmer from Iowa can't just pull up stakes overnight and move his farm to Siberia or the Canadian Arctic; there are all sorts of political, cultural, and national issues that would make this impractical. The upshot would be that a substantial portion of mankind's food supply would suddenly be interrupted, and there would no longer be enough food on earth to keep everyone alive (reserves typically amount to only 60-90 days' worth). Desperation would ensue; there would almost certainly be widespread, brutal wars fought over what food sources remained. To add insult to injury, when temperatures began to spike in earnest, parts of the Greenland and West Antarctic ice sheets might break up, permanently inundating all the world's coastal cities. I do not think that humanity would go extinct, but I have some doubt as to whether anything resembling civilization as we know it could survive such an event--and most civilized people are not very good at coping and surviving if their civilization disappears out from underneath them.
The situation on the natural front would be even more bleak. The world of 55 million years ago was an unbroken carpet of virgin wilderness. If conditions changed, flora and fauna could, to some extent, survive by moving north or south as conditions demanded. Today, by contrast, much of our biological heritage lies in a scattered archipelago of remnant tracts we call parks or preserves, often chosen more for scenic beauty than biological merit, and isolated from one another by vast expanses of sterile zones (farms, cities, etc.) If it gets warmer or colder or wetter or drier, most of the life in these parcels has nowhere to go but extinction. Most likely the mass extinctions this time around would be considerably greater. None of today's deep-ocean islands existed 55 million years ago, but perhaps somewhere on the Emperor Seamount Chain in the northwest Pacific, hidden beneath the waves, lies a record of what happened to life on isolated islands during the PETM. This would be the most telling evidence of what we might expect. Or consider a more recent anecdote about two species in isolated, confined habitats: in the late 1980s, a particularly robust El Niño almost wiped out the Galápagos penguin, and may have killed off the Monte Verde golden toad. Today's wildlife is clearly vulnerable even to global warming of the ordinary kind. I leave it to the imagination how such species would fare in a methane catastrophe.
It is an ugly scenario, with consequences comparable to what a significant asteroid impact or global nuclear war might wreak. Like asteroid impact, it is a planetary-defense issue, but our society is much more adept at tracking asteroids than at predicting methane catastrophes. Like an asteroid impact, a methane catastrophe becomes progressively more difficult to avert the nearer it draws. Unlike an asteroid, it is invisible until it happens, if it happens.
Part 4: What is an appropriate attitude to take toward this?
There are many possible answers to this question. I will enumerate some of the better-known ones. Some of you may hear yourselves speaking in one of them. I do not intend to hide my biases as I discuss them, but I hope that this may provide fuel for reasoned debate.
The Confidently Skeptical Answer: "All
this is just supposition and speculation. Thirty years ago scientists were warning of a possible new ice age, and now this. In another thirty years, it will be something else again. This probably has no implications for what mankind has done or will do."
Critique: This is premised upon a popular distortion of the recent history of climatology. The new ice age hypothesis was never taken seriously by most mainstream climatologists, but was something of a fringe idea which got more than its share of play in the popular media of its day. We know immeasurably more about the topic than we did thirty years ago, due both to more sophisticated measurement and to far more powerful computer models. Almost no one takes the new ice age idea seriously any more, at least in the present context. Scientific ideas are not mere arbitrary fashions or fads like necktie width--they gain or lose credence as they are examined in the light of an ever-increasing store of information, and they do eventually tend to converge on the truth.
Given the information you have seen presented here and knowing what could be at stake if this view were wrong, would you regard this as a prudent or responsible stance on which to base public policy?
The Deus ex Machina answer:
"Sure, things don't look so wonderful just now, but it will all work out. Either the scientists will all turn out to be wrong, or the sun will go into another quiescent period and cool the earth off again, or someone will invent some miracle fix to save the day, or space aliens or ______ (fill in the blank) will appear just in the nick of time to save the world, but somehow that cavalry is going to come riding over the hill right on cue. Nothing to worry about."
Critique: Indeed? And what if what comes riding over the hill is a hostile war band instead of the cavalry? What if the sun increases its output? What if the scientists aren't wrong? Would you have the confidence to bet the farm on this one?
The Don't Blame Us answer: "Climate has changed before, and it will change again. It is nature's way, and we are foolish to think we can stop it or interfere with it. It actually has little to do with human activities."
Critique:This position is often espoused by those who believe that contemporary climate change is due only to solar output variations. Look again at Figure 10, and the discussion thereunder. Do you still believe this? Does it matter? This illustrates a point: debate over to what extent current global warming is human-caused or not can erupt into a distracting sideshow. We know from the PETM that methane catastrophes can happen even without human assistance, given the right circumstances. Does this mean that such an outcome is not worth averting, just because it is possibly natural? Let us go back to the asteroid analogy. Suppose we were informed by astronomers that a 10-mile-wide asteroid had a 90% chance of colliding with Earth in 30 years. Surely no one could blame this on humanity--but do you think most of us would therefore be content merely to sit on our collective keister, doing nothing except hope for the lucky 10% chance of a miss? Of course not. Surely, mankind would at least try to devise a means of deflecting the rock before it hit, whether successful or not. Why not use what power we have to do good? Nature, in the final analysis, does not care whose fault it is.
The Silver Lining answer: "We should not assume that global warming is a bad thing--we will get warmer weather, longer growing seasons, and maybe no more winter (and who wants winter, anyway? Most people would be more than content with a seasonless, perpetual-summer climate.) Wouldn't it be neat to have palm trees in Minneapolis?"
Critique: This naive view ignores the changes in rainfall pattern which might well make the longer growing season a moot point. It ignores the possible peril of triggering a methane catastrophe either directly or by inducing a flip-flop somewhere in ocean currents bringing warm water closer to hydrate beds. It ignores widespread starvation that might engulf the tropics as formerly arable land desertifies. It ignores what might happen to the earth's oxygen supply if most of the remaining rain forests ceased to be forests due to diminished rainfall. It assumes that the inevitable ecological holocaust will be without consequence for humanity. The new-found tropical paradise will come at a cost we cannot even gauge yet. Most probably, when Santa slips on his bathing suit, we all get ashes in our stockings.
The Fatalist's answer: "There is no way to avoid catastrophe. Mankind is fated to destroy the world, and there is really nothing anyone can do to change that. We may as well eat, drink, be merry, and not worry about it, for aprez nous le chaleur."
Critique: This goes to the other extreme from the other answers we have examined, but arrives at the same conclusion. If we actually knew beyond reasonable doubt that the premise of this answer were true, e.g. if the signs of a methane catastrophe beginning were already evident, then this answer might make a perverse sort of sense--but we know no such thing. Why throw away whatever chance we might have to make things better, as long as we do not know we have no such chance?
The Orthodox Green answer: "We need to abandon our gluttonous, materialistic way of life, turn our back on modern civilization and its wasteful and polluting technological appurtenances, and go back to the simple, rural way of life. Furthermore, we should not attempt to meddle actively with the climate in any manner, even if we believe our efforts to be well-intended; for such efforts are a delusion and a folly which will inevitably do more harm than good."
This view is heir to an honorable American tradition, harking back to such writers as Henry David Thoreau and Edward Abbey. If only reality were so simple! Living this vision is a fine gesture, even a noble one; but it is a hard road to travel. If you have chosen this way, you are certainly not to be condemned for it; but do not deceive yourself that all your fellow humans suddenly will rush after you to abandon the only way of life they have ever known, and for reasons most of them will never even comprehend, unless you wield deeper magic than the Pied Piper. This is not how people act; most likely, your fellow humans will look upon you as a crank or crackpot. If you have chosen this way, you may assuage your individual conscience that you are no longer part of the problem, and in addition you have made a powerful symbolic gesture; but it is only symbolic, for not enough others are likely to follow suit to have any significant effect on the course of history. If you propose to save the world this way, you are blowing smoke. As to the question of whether we should intervene in the affairs of nature, we are already doing so, for better or worse. Why not learn to do it responsibly?
The Bully Pulpit answer: "We should devote massive resources and effort to exhort the public to drive less, drive smaller cars, use mass transit, buy sustainably produced goods, set the thermostat higher, live closer to work, live in smaller houses or apartments, etc., etc."
Critique: Again, not an ignoble idea. The problem is that it has already been done. Those who will take such counsel, already have. Those who have not, will not, even though you repeat yourself a thousand times. By now, you are preaching either to the choir or to the deaf.
The Muddle Earth answer: "We could continue more or less as we are, making incremental adaptations as crises demand, slowly improving efficiency and developing cleaner technology here and there, and we will more or less muddle through and in a few centuries we will gradually turn the corner on this issue. There will be vast damage to the planet's biodiversity, alas; but in another fifty thousand generations the biosphere will recover and diversity will be back."
Critique: Maybe. This may in fact be the most probable scenario, given past history. But is it really the best we can do? Fifty thousand generations is many times more than have ever lived. It is a long time. Maybe this could happen, if global warming is limited to that of the ordinary kind. If any substantial methane catastrophe occurs, there will be no muddling through that.
The Pragmatic answer: "We should aggressively pursue two aims. The first is to develop ways to allow our way of life to continue in a way that will be recognizable to us, but without that way of life being dependent on the burning of carbon-containing fuels. The second is to develop aggressive biological and physical interventions either to remove carbon dioxide from the environment (sequestration), to stabilize methane hydrate beds, and to control and reduce the amount of sunlight reaching the earth's surface to the extent necessary to compensate for increased greenhouse-gas presence."
Critique: To me, this sounds like the most hopeful and constructive approach. Having said this, one must acknowledge frankly the several challenges facing anyone hoping to make this vision a reality. As to finding ways to remove carbon dioxide from the atmosphere, all the ideas proposed so far have been infeasible either for technical reasons (e.g. fertilizing the ocean with iron), for geographic/demographic reasons (planting more forests), for financial reasons on the scale that would be necessary (mechanically filtering it from the air and injecting it down wells), or downright loony (surrounding the earth with quadrillions of polar-orbiting foil sheets to reduce solar irradiance). When it comes to finding ways to devise a new, sustainable basis for our civilization, we are hardly doing any better. Government leaders are still mired in a 1970s mindset, seeing the current situation merely as an energy crisis. Hydropower, solar power, wind power, and tidal power are still only marginal contributors to the nation's electricity budget. Nuclear fission, for political reasons, has been written off as an option, and research into how it might have been made safer or better pretty much ceased thirty years ago. Nuclear fusion seems to be a will-o'-the-wisp that was fifty years in the future in the 1970s--and still seems to be fifty years off, at least. Power satellites might help in theory, but there isn't the cash on earth to pay for even one of them. Governments' answer to the energy situation seems largely to be "Find more oil! Dig more coal!" The sole significant exception, corn-derived ethanol, is itself a carbon dioxide emitter when burned--and ultimately, in its production cycle, consumes more petroleum than it replaces, making it a complete mockery.
Even more woeful is the transportation
sector, almost totally dependent on petroleum-based fuels for
everything from automobiles to trucks to trains to airplanes. The first automobiles in the 1880s were propelled by gasoline-powered piston engines. Today's cars still are. The much-touted hybrid vehicles are unquestionably more efficient than their predecessors, but they still cannot run without gasoline. Although battery-powered vehicles have been around in one form or another for almost a century, General Motors abandoned its EV-1 program a few years ago, and today the most substantial battery-powered production vehicle you can drive is a golf cart. General Motors developed a hydrogen fuel-cell electric sedan prototype a few years ago. It looked promising, having performance comparable to that of a gasoline-powered car. They have no plans to market any such vehicle in the foreseeable future; though the project may actually have produced something worthwhile, it seems to have been regarded by company management as purely a propaganda gesture,something to boost the company's progressive image and its sales of (gasoline-powered) vehicles. What a shame. Today, you cannot buy a production car or truck in North America that runs on anything but gasoline, diesel fuel, or natural gas. For those parts of their track systems that have not been electrified, railroads still have only one option: diesel. This situation completely stymies and frustrates those who might be early adopters, who might otherwise help lead society forward, who might help justify the development of infrastructure to support new technologies. As long as it is taken as a given that therecan be no transportation without fossil fuels, we are at an impasse,for transportation accounts for a large portion of our carbon dioxide emissions.
In short, to be serious about this, society needs better ideas and needs to be more open-minded about exploring those ideas. Some examples: volcanoes have
shown us that injecting sulfate aerosols into the upper atmosphere can lower temperatures worldwide by a degree or two. Mankind also produces sulfate aerosols, primarily by burning "dirty" coal. This is considered pollution, a curse. But is there a way this curse might be transformed into a blessing? Or perhaps some way might be found to refine the ocean-fertilization idea so it will work after all. Perhaps new fuel and power technologies would be better accepted at first in another context--the technology to build a 150-hp electric outboard,for example, already exists, and it could be powered either by a battery or HFC rig. (It would be very quiet, too.) If this technology became accepted in marine applications, perhaps that would grease the way for highway use. On the other hand, perhaps someone could find ways to make paying for environmental interventions possible, if they are deemed appropriate; or perhaps laws could be changed to make it easier for individual power generators to sell excess power back to the grid everywhere. Whether or not any of these particular ideas have merit is beside the point; I cite them merely as examples of the kind of outside-the-box thinking that needs to be encouraged and supported on as broad a scale as possible. Even if some of the ideas which are put forth seem absurd, one should not be too harsh on their authors; they, after all, are trying, and that is something worth honoring and nurturing. Many of the "first drafts" of important ideas in human history probably seemed ridiculous at the time; it often takes a lot of refinement and tinkering to make something work.
Moreover, if our society's coping with these issues is to transcend mere muddling, it must have focus--and leadership. This need not originate with politicians (and most likely won't); it could come from political activists, from engineers and inventors, from think tanks, from corporate or university research laboratories, from influential persons in the blogosphere, or even from certain stubborn ordinary persons with the grit and flair to champion a cause.
So much of the literature on this subject is fraught with despair, anger, anxiety, and finger-pointing. I would like to conclude this posting on a more hopeful note. The answers are out there, if we know how and where to look. They might even be right under our noses. And when we find them, we can stop worrying about ashes in our stockings.
Postscript A: Rapid Climate Change and Extinction Rates
Extinction and loss of biodiversity are much in the news these days, and many of you out there ccare very much about this problem. Could rapid global warming, in and of itself, tend in general lead to enhanced extinction of species? What has the distant past to teach us about the connection? Let us start by examining the climate over the past several hundred million years:
Figure A1: Global temperature reconstruction of the past 542 million years, as reconstructed by oxygen isotope ratios (image credit: http://content.answers.com/main/content/wp/en/9/9c/Phanerozoic_Climate_Change.png)
For decades, we were fed the stereotype of the Mesozoic era as a tranquil, unchanging paradise lasting 150 million years, a sort of Tahiti writ large, a tropical idyll in which the odd T. rex was the worst thing to be worried about, as giant dinosaurs lazed about in warm ponds while nibbling tasty tidbits. NOT! The climate of the Mesozoic was indeed, on the average, much warmer than today's, but there were precipitous up-and-down fluctuations, many on a larger scale than anything that has happened in the last few million years. Figure A1 if anything understates the case; it does not resolve many short-term features, such as the results of the methane catastrophes 183, 117, and 55 MYa, which would show, if depicted, narrow upward spikes to yet-higher levels. A warmer climate seems to be if anything more treacherous and unstable than the cooler one which we are used to, and more prone to extreme events such as methane catastrophes and periods of anoxia and euxinia in the oceans (today, only the Black Sea is still euxinic.) But what about extinction rates? Bambach and coworkers compiled the following plot in 2004, which is about the best one I can find:
Figure A2: Extinction rates, by genus, over time (Image credit: http://www.palaeos.com/Paleozoic/Ordovician/Images/Bambach.gif). The spike at 65 MYa corresponds to the presumed Chicxulub impact (non-climatic).
Again, the low temporal resolution of the data proves somewhat frustrating. The Permian-Triassic extinction is well-depicted; beyond this, there are indeed bumps in the plot around 183 and 117 MYa, but they are no larger than some other excursions around them. Beyond the P-T event, it is difficult from these plots to tie a specific spike in the extinction graph to a specific rise or fall in temperature. What does come through, though, is the general rate of extinctions in the Mesozoic-much higher than anything found in pre-industrial modern times. Today's cooler climate, long regarded as "harsher" than the distant past, may, by its relative stability, provided a sheltering milieu for humans and human civilization to develop.
There is anecdotal evidence of extensive extinctions occurring around the times of several rapid warming events, even if these plots fail to resolve these occurrences. The PETM is one example. Another example is drawn from about 12,000 years ago, at the end of the last glacial period. A large portion of North America's large mammals went extinct in a short time. For decades, this phenomenon was assumed to be the result of humans' entering the continent, when it was assumed that no humans were in North America before the "Clovis horizon" of 11,500 years ago. As it has become apparent that humans have been in the New World substantially longer than this, the Clovis dogma has crumbled among anthropologists, and the ancient human-extinction link must be regarded with new skepticism. In 1991, Dewey McLean argued for a much different interpretation: the rapid warming induced maternal heat stress among female mammals of cold-adapted species, especially the most vulnerable large ones, resulting in a catastrophic collapse of fertility and subsequent extinction. I cannot tell you with certainty if this is true, but McLean marshals some interesting arguments.
The last few thousand years have given us a climate which has been extraordinarily stable, even by the standards of the past million years. Civilization has risen and flourished in part because of this--it is what has made agriculture feasible on anything above subsistence level. Though few of us are farmers any more, we are still dependent on agriculture for our basic food needs, and agriculture's existence is dependent on the fact that climate is stable enough that what can be grown where does not rapidly change in most places. The present population has grown far beyond what mere subsistence agriculture could support--that bridge is burned. Now, apparently, due to our actions, we are pushing the system back toward the big roller coaster of the past--except that, by habitat fragmentation and destruction, we have removed all the seat belts this time. But if our society sheds its attitude of denial and sets about solving this problem, it doesn't have to be this way.