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Mark Lynas's "Six Degrees": A Summary Review

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Mark Lynas.

Mark Lynas.

Mark Lynas's Six Degrees* is first, a graceful yet massive synthesis of a very large selection of scientific research papers; second, an eloquent and honest plea for action on the 'slow-motion crisis' that is climate change; and third, a coherent account of how global warming would affect humans and their world, if allowed to proceed.

That makes it something of a modern classic--but not in the sense of being 'evergreen.' Given the rapid pace of climate research, any summary of the 'state of the art' is apt rapidly to become dated. Nor have sociopolitical developments been lacking since Six Degrees's publication in 2008. Accordingly, I'll try not only to evaluate and summarize the book, but also--to a limited degree at least--to update it, comparing its information with recent sources, such as the IPCC Fifth Assessment Report.

* Six Degrees: Our Future On A Hotter Planet, by Mark Lynas, National Geographic Society, 2008.


The central structuring metaphor of Six Degrees is that global warming is hell. Lynas doesn't quite put it so baldly, though a few of his adjective choices clearly imply it. But quotations from Dante's "Inferno" make the point quite clearly by serving as epigraphs for Chapter One, One Degree, and for the final chapter, Choosing Our Future.

Just as Dante's Hell was organized in increasingly dreadful circles, Lynas's account proceeds systematically from the "one-degree world" in which we live now--for global mean temperature is roughly .8 degrees Celsius above pre-Industrial levels--to the "nightmare" world of six degrees. For each level, Lynas sets forth the possible impacts and implications of that level of warming, as known at the time of writing. We’ll step through one chapter at a time. Each chapter also has a table summarizing the impacts. These tables are in separate articles, linked via sidebar capsules.

One Degree

In Dante’s vision of Hell, the outer circle was inhabited by 'virtuous Pagans' like Plato, whose only fault was not being Christian. Basically good, even great people, they were punished by nothing more severe than deprivation of contact with God. According to Lynas, the one-degree world, similarly, is 'not so bad.'

There is a laundry list of possible or observed impacts, from the return of the megadroughts western North America experienced during the Medieval Climate Anomaly, to the continuation of the already observed 'death spiral' of the Arctic sea ice, with its implications for Northern hemisphere weather and increased warming of the whole planet. Some, like the megadroughts, could be very serious indeed.

But at this level of warming there are climate 'winners,' too--for instance, the Sahel, the semi-arid transitional zone on the south flank of the Sahara, may become a little moister. For a table listing these impacts, see the article One Degree.

(Update: The boreal forest of Northern Canada may become moister as well, reducing wildfire risk there, even as that risk increases in places like Australia and the Eastern Mediterranean basin. Details in The One Degree World.)

It's just as well that it's not all bad, because the one-degree world is the one we all live in right now. As the current IPCC Assessment Report 5 makes clear, many long-projected impacts of warming are unfolding as expected. Indeed, some, such as Arctic sea ice loss or ice mass losses in Greenland's glaciers, have been proceeding faster than expected.

Greenland coastal island.  Image courtesy Turello, and Wikimedia Commons.

Greenland coastal island. Image courtesy Turello, and Wikimedia Commons.

Two Degrees

The two-degree world is less familiar, but not yet completely strange. Some aspects of the two-degree world--for instance, European heatwaves similar to the lethal 2003 event--are already emerging. Others, like ocean acidification, will become familiar news items to the children and grandchildren of present readers of this article.

While the use of computer climate models is the most familiar method of predicting future climate states, Lynas explains that ancient climates also give important insights into possible future change. For the two-degree world, the analog is the Eemian interglacial, which reached its warmest temperatures--roughly 2 degrees Celsius above 'pre-industrial' levels--around 125,000 years ago. If past patterns turn out to be true precedents for our future, northern China could get very thirsty, adding to the environmental woes already costing China so dearly.

(Update: Northern China is already suffering from severe water shortages. See Two Degrees for details.)

Water shortages could also be serious problems in Peru (as Andean glaciers disappear) and California (as snowpacks shrink.) Droughts due to declines in precipitation are expected in the Mediterranean basin, as already mentioned, and in parts of India, where increasing temperatures are also expected to challenge the heat tolerances of rice and wheat crops. Unsurprisingly, global food supplies are expected to be stressed as global populations peak this century.

Marine food sources will be severely stressed, too. Oceans will warm, bleaching coral and degrading reefs, diminishing their touristic value and, worse, their biological productivity. Increased stratification as the ocean surface warms will decrease the upwellings of nutrient-rich cold water, making oceans less productive.

At the same time, acidification will hurt species with calcium carbonate shells, including the plankton which form the entire basis for marine food webs. Already ocean acidity has increased by 30% due to carbon dioxide emissions. As Lynas puts it, "At least half the carbon dioxide released every time you or I jump on a plane or turn up the air conditioner ends up in the oceans... [It] dissolves in water to form carbonic acid, the same weak acid that gives you a fizzy kick every time you swallow a mouthful of carbonated water."

But that's just an overture; Lynas quotes Professor Ken Caldeira: "The current rate of carbon dioxide input is nearly 50 times higher than normal. In less than 100 years, the pH of the ocean could drop by as much as half a unit from its natural 8.2 to about 7.7." That would be a 500% increase.

Global pH trend map, pre-Industrial times to 1990s.  Image by plumbago, courtesy Wikipedia.

Global pH trend map, pre-Industrial times to 1990s. Image by plumbago, courtesy Wikipedia.

The precedent of the Eemian suggests that other changes to the ocean, too. The Arctic would likely be committed to a future without sea ice, with intensification of the consequences mentioned above. Ice loss would accelerate for Greenland's glaciers, too. That would mean increases in sea level rise. Currently seal level is rising at just over 3 millimeters a year--around a foot per century. That relatively modest rise has already contributed to the increased flood risks for events such as Superstorm Sandy.

But one modeling study put the threshold level for the eventual near-complete loss of Greenland's ice sheet at a local warming of just 2.7 C--which, due to Arctic amplification, means a global warming of only 1.2 C. Total melting of Greenland--luckily, something that would likely take centuries--would raise sea levels by 7 meters, submerging Miami and most of Manhattan, as well as large chunks of London, Shanghai, Bangkok and Mumbai. Nearly half of humanity could be affected.

So would numerous other species. Polar bears would be under serious threat due to loss of sea ice, as would other Arctic species; and the one-two punch of temperature rises and acidification would pose serious challenges to many marine species. But extinction threats in the two-degree world are not limited to the oceans. The principal investigator of a 2004 study, Chris Thomas, revealed that "Well over a million species could be threatened with extinction as a result of climate change."

The Golden Toad, extinct since 1989 due to climate change.  Photo by Charles H. Smith, of the U.S. Fish and Wildlife Service, courtesy of Wikimedia Commons.

The Golden Toad, extinct since 1989 due to climate change. Photo by Charles H. Smith, of the U.S. Fish and Wildlife Service, courtesy of Wikimedia Commons.

Three Degrees

In this chapter, climate regimes we might term 'sort of safe' are left behind. Partly that is because a political consensus of some standing has been that damage below this level might be in some sense acceptable, or at least reasonably survivable. But in part this fact is a reflection of non-linear nature of climate impacts, for above 2 C the risk of encountering what have become known as 'tipping points' rises--and rises unpredictably.

In Six Degrees the primary concern is for 'carbon cycle feedbacks.' In 2000 a paper called "Acceleration of Global Warming Due to Carbon Cycle Feedbacks in a Coupled Climate Model" was published--bibliographically known as Cox et al., (2000.)

Prior to Cox et al, most climate models had simulated the response of atmosphere and ocean to increasing greenhouse gases. But Cox et al was an early product of a new generation of "coupled" climate models. Coupled models added a new level of realism by considering the carbon cycle, in addition to atmosphere and ocean.

For carbon is an important ingredient for all life, and is ubiquitous in sea and sky. It is forever dancing from sky, to living tissues, to the sea--and the specifics depend, in part, upon temperature. For example, as temperatures warm, seawater absorbs less carbon dioxide, and as precipitation patterns change and plants grow (or die), they take up more (or less) carbon. Thus, carbon affects temperature, which affects life, which in turn affects carbon.

What Cox et al. found was startling, for those who spotted the implications. With 3 degrees of warming, "Instead of absorbing CO2, vegetation and soils start releasing it in massive quantities, as soil bacteria work work faster to break down organic matter in a hotter environment, and plant growth goes into reverse." The result, in the model, was the release of an additional 250 ppm of carbon dioxide by 2100, and an additional 1.5 degrees of warming. In other words, the 3 C world was not stable--hitting the 3 degree threshold meant hitting a 'tipping point' which led directly (though not immediately) to the 4 C world.

This effect was primarily due to a huge dieback of the Amazon rain forest. With warming and drying the rainforest collapsed almost completely. Later studies found globally similar effects, albeit in differing amounts. And recent study suggests that the likelihood of an Amazonian collapse may be lower than first thought--welcome news, to be sure.

Maps of the 2005 & 2010 Amazon droughts.  From  Lewis et. al, Science, Volume 331, p. 554.

Maps of the 2005 & 2010 Amazon droughts. From Lewis et. al, Science, Volume 331, p. 554.

But it can't be ruled out--nor can other carbon feedbacks. Lynas discusses the possibility of massive Indonesian peat fires, for example--in 1997-98, wildfires there released approximately "two billion tonnes of additional carbon into the atmosphere."

Another overarching fact gives one pause: three degrees of warming takes us beyond the Eemian interglacial as analogue. The Pliocene epoch, three million years before the present, was the last time global mean temperature was three degrees warmer than pre-Industrial. And during the Pliocene, atmospheric carbon dioxide was in the range of 360-400 ppm, according to studies of fossil leaves.

That's significant because modern carbon dioxide levels hit 400 ppm for the first time in 2013. In other words, our atmosphere already contains as much carbon dioxide as did the Pliocene version--and that was a world so different from ours that beech shrubs grew only 500 kilometers from the South Pole, in an area where the average temperature is -39 C today.

It is some consolation that such extensive changes could not occur overnight, and in fact might take centuries--if concentrations were to stabilize at 400 ppm, that is.

The list of potential climate impacts at 3 C is dispiritingly long. The recurring theme, though, is difficulties in conducting agriculture: drought in Central America, Pakistan, the western US or Australia, more monsoonal precipitation extremes in India, and strengthening cyclonic storms add up to a projected net global food deficit at 2.5 C. As Lynas puts it:

With structural famine gripping much of the subtropics, hundreds of millions of people will have only one choice left other than death for themselves and their families: They will have to pack up their belongings and leave... Conflicts will inevitably erupt as these numerous climate refugees spill into already densely populated areas... Uprooted, stateless, and without hope, these will be the first generation of a new type of people: climate nomads, constantly moving in search of food, their varied cultures forgotten, ancestral ties to ancient lands cut forever... As social collapse accelerates, new political philosophies may emerge, philosophies that seek to lay blame where it truly belongs--on the rich countries that lit the fire that has now begun to consume the world.

Note: Updated information on "The Three Degree World," drawn from the International Panel on Climate Change's Technical Summary to the Fifth Assessment Report, was posted 12/9/13, and can be found at the summary for that chapter. Follow the sidebar link above.

Borneo fires, October 2006.  Image by Jeff Schmaltz and NASA, provided courtesy of Wikimedia Commons.

Borneo fires, October 2006. Image by Jeff Schmaltz and NASA, provided courtesy of Wikimedia Commons.

Four Degrees

In a 4 degree world, food production continues to decline as the world is increasingly transformed. Ice loss becomes very extensive from the Alps to the Arctic; the latter region could eventually become essentially free of sea ice year-round. In the Antarctic, the loss of buttressing sea ice shelves could mean acceleration of glacial ice loss, particularly in the vulnerable Western Antarctic. The result would be further acceleration of sea level rise, putting even more extensive areas of the world's coasts under sentence of inundation: Alexandria, Egypt, Bangladesh's Meghna delta, much of Boston's central business district, and coastal New Jersey, to name just a few (in addition, presumably, to those places already mentioned in Two Degrees.)

Perhaps more ominously yet, the possibility exists that thawing Arctic permafrost--known to contain huge amounts of carbon--could release large amounts of methane and carbon dioxide into the atmosphere. Such a release could potentially create enough additional warming to make the 4 degree world unstable, just as the carbon cycle feedbacks discussed in the previous section might render the 3 degree world unstable.

Though the world 40 million years ago had less resemblance to today's Earth, making it less precise as an analogue than the Eemian, or even the Pliocene, that is how far back we must look in order to find a 4 degree world. What this analogue tells us is that a 4 degree world is largely ice-free, so we may expect that even the East Antarctic Ice Sheet could be committed to eventual melt with such an intense warming--though once again, that melt might take centuries to complete.

Other transformations would be taking place. Europe's Alps would be expected to more closely resemble the arid and forbidding Atlas Mountains of North Africa; European mean temperature might be as much as 9 C higher, and snowfall there might be reduced by 80%. At the same time, altered storm tracks would mean that western European coasts would see more westerly gales in conjunction with the rising sea levels--37% more such storms is the projection for England, for instance. Hydrological changes could disrupt ecologies (and even landscapes) in many places--as the fossil record shows happenes at Hall's Cave, Texas, during the end of the last glaciation.

Nor would all transformations necessarily be driven by climate change--though they would reinforce its negative effects. If current Chinese growth rates could continue linearly, by 2030 China would be consuming 30% more oil than the world currently produces, and eating fully two thirds of current global food production--obviously an unrealistic prospect. It may not be clear exactly where the limits to growth lie, but clearly they do exist.

The setting sun reaches the 'smog line' above Shanghai, February 9, 2008.  Photo by Suicup, courtesy Wikimedia Commons.

The setting sun reaches the 'smog line' above Shanghai, February 9, 2008. Photo by Suicup, courtesy Wikimedia Commons.

Five Degrees

Lynas description of the five degree world is as stark as it is brief: "largely unrecognizable."

Expansion of the atmospheric circulation pattern known as the "Hadley Cells"--by 2007, expansion by more than two degrees of latitude, or nearly two hundred miles had been observed--is projected to create "two globe-girdling belts of perennial drought." Elsewhere, more frequent extreme precipitation events make flooding the perennial risk.

Also, "Inland areas see temperatures 10 degrees or more higher than now." (It is frequently forgotten or overlooked in discussions of global mean temperature that temperatures over land rise much more than temperatures over ocean--and ocean, of course, occupies roughly 70% of the world's surface. This drags down the global average quite a bit in comparison with the continental mean.)

As to human impacts, "Humans are herded into shrinking 'zones of habitability'." (No doubt, as discussed in the previous chapter, the possession and governance of such zones would be hotly contested.) The Russian and Canadian north would become increasingly attractive real estate, bringing the boreal forest under great deforestation pressure, possibly invoking more carbon feedbacks and yet more warming.

While such a vision is deeply unsettling, the conditions described are not without precedent. The potential 5 C world has long been compared to a paleoclimate analogue 55 million years deep into the past: the "Paleocene-Eocene Thermal Maximum."

During the PETM, global temperatures were roughly 5 C warmer than pre-Industrial. But the most striking aspect was the Arctic amplification that apparently existed then. Alligator remains from that era have been found on Canada's Ellesmere Island in the high Arctic, and as Lynas puts it, "sea temperatures close to the North Pole rose as high as 23 C, warmer than much of the Mediterranean is today." With such elevated sea surface temperatures it is perhaps unsurprising that fossil evidence in ocean sediments indicates a mass extinction event during the PETM: the seas would have become thermally stratified, cutting off the oxygen supply to deep waters and killing everything reliant upon it. It's a grim scenario that recurs in Six Degrees under the bland label of 'ocean anoxia.'

The hammer's head marks the extinction boundary.  Uncredited photo.

The hammer's head marks the extinction boundary. Uncredited photo.

Lynas quotes Daniel Higgins and Jonathan Schrag as writing in 2006 that "The PETM represents one of the best natural analogues in the geologic record to the current rise in CO2 due to burning of fossil fuel." In large part that reflects the fact that the warming then--unlike the case for the Eemian interglacial, or for the Pliocene--was driven entirely by rapid releases of greenhouse gases.

But there are complications in interpreting this analogue. It seems that the greenhouse gas releases back then--either in the form of carbon dioxide from huge coal beds burnt by intruding magma, or of methane released from submarine deposits of 'clathrates' of the sort now being investigated for possible fuel use--were larger than those of the present day.

On the other hand, release rates are about 30 times faster today. Whereas the whole PETM transition took roughly 10,000 years, today we are considering changes taking place over decades, or at most a few centuries. Unfortunately, it is hard to know how these differences make things will play out from the standpoint of human survival.

Lynas has no doubt, however, that survival challenges would be very great. Food production would be severely affected, and some parts of the globe would likely reach occasional temperatures that would make unsheltered survival for more than a few hours impossible. To be caught without shelter would be to die.

The possible locations of climate 'refuges'--areas remaining relatively friendly to human survival--are considered. (See the summary table in the article "The Five Degree World" for locations.) So are the dual survival strategies of 'isolationist survivalism'--possible in, say, the mountains of Wyoming, but few today possess the necessary skills and knowledge to pursue it successfully--and 'stockpiling'--the main alternative in non-wilderness areas.

On balance, Lynas both strategies unlikely to succeed, except in infrequent instances.

Subsistence hunter butchering a caribou, 1949.  Photo by Harley, D. Nygren, courtesy Wikimedia Commons.

Subsistence hunter butchering a caribou, 1949. Photo by Harley, D. Nygren, courtesy Wikimedia Commons.

Six Degrees

For the 6 C world, little modeling work had been done as of the writing of Six Degrees. so paleoclimate analogues are the only relevant resource we have. Lynas discusses two such analogues, both much deeper in the past: the Cretaceous, and the end of the Permian.

The world of the Cretaceous period (144 to 65 million years ago) was very different from the present. The continents were far from their present positions--South America and Africa were still splitting apart from one another. There was massive and long-continued volcanic activity. Seas were about 200 meters higher, dividing present North America into three separate islands.

Even the sun was different--significantly fainter than today. But this cooling influence was offset by CO2 levels estimated to have been in the range of 1,200 to 1,800 ppm, enough to keep the planet very warm indeed. Evidence puts the temperatures in the tropical Atlantic--then about as wide as today's Mediterannean--at a startling 42 C (107.6 F.)

Life seems to have thrived--though present-day life would find Cretaceaous conditions not so much to its liking. Weather apparently was challenging: deposits of "tempestites"--rock formations created by massive storms--give mute testimony of intense storm activity. Rainfall rates in the (flooded) interior of North America seem to have reached 4,000 millimeters a year--roughly 13 feet!

Abundant life implies a carbon cycle active enough to match the enlivened hydrology. Plentiful organic remains meant that much carbon was sequestered, even as the intense vulcanism released massive quantities of carbon back into the atmosphere.

Ironically, we are now de-sequestering Cretaceous carbon in the form of coal and oil--in fact, at a rate a million times faster than that at which it was laid dow: one era of warming laying the foundation for another.

As in later eras, Cretaceous warmth led to ocean stratification and anoxia; evidence shows many warm 'spikes' accompanied by such anoxic episodes. One of the most marked in the whole fossil record actually occurred even earlier, however--183 million years ago, during the Jurassic era. Back then, a 1,000 ppm CO2 spike induced a 6 C rise in global mean temperature, creating "the most severe marine extinction event [in] 140 million years." The cause of the CO2 release is still being determined.

A reconstruction of the middle Jurassic Earth (170 million years ago.)  Map by Ron Blakey, courtesy Wikipedia.

A reconstruction of the middle Jurassic Earth (170 million years ago.) Map by Ron Blakey, courtesy Wikipedia.

But the most severe extinction event overall belongs, not to the Jurassic, but to the end of the Permian period, 251 million years ago. Fossil deposits from sites around the world show an abrupt extinction from this time, accompanied by abrupt drying and erosion. Carbon and oxygen isotope ratios both shift at the same boundary; the former shows disruption of the carbon cycle, while the latter shows an abrupt warming of about 6 degrees.

And the "Permian wipeout" was fast. From geological evidence found in Antarctica, the transition may have occurred over a mere 10,000 years--similar to the timescale of the PETM. In the Chinese rocks forming the "geological gold standard for the end-Permian," the transitional strata occupy just 12 millimeters.

The results of this spike were spectacularly horrible. The sequence of events is thought to have looked something like this: a geologic era with little or no mountain-building slowed CO2 sequestration, which depends on the weathering of rock. CO2 then accumulated to four times today's levels, creating long-lived warming and inducing feedbacks similar to those discussed in previous chapters: expanding deserts and stratifying oceans which reduced CO2 uptake further.

The anoxic oceans warmed ever faster--surface water, made salty and dense through intense evaporation, began increasingly to sink, carrying its heat to the depths. Hot seas fueled 'hypercanes'--tropical cyclones dwarfing today's hurricanes in ferocity and longevity--another challenge to an already stressed biosphere.

But this was just the prelude. A plume of magma erupted through the Earth's crust in Siberia, eventually piling up layers of volcanic basalt rock "many hundreds of feet thick, over an area larger than western Europe." Each eruption also brought forth "poisonous gases and CO2 in equal measure, sparking torrential storms of acid rain at the same time as boosting the greenhouse effect into an even more extreme state." With plant life decimated, atmospheric oxygen plummeted to 15%. (Today's value is about 21%.)

Explosive methane releases followed. A modern example of a similar process occurred August 12, 1986, at Lake Nyos in Cameroon, when carbon dioxide-saturated bottom waters, randomly disturbed, began to rise. As the water pressure decreased with depth, the carbon dioxide 'fizzed' out of solution, forming an ever-increasing cloud of bubbles which entrained rising lake water. The result was a eruptive 'fountain' erupting 120 meters above the lake surface. The resulting cloud of concentrated CO2, tragically, asphyxiated 1,700 people.

The same dynamics would have been at work in the methane-saturated waters of the end-Permian, though on a much larger scale. But while sufficiently concentrated carbon dioxide can asphyxiate, methane, concentrated enough, can explode. That is the principle of the modern "fuel-air explosive," or FAE.

The sinking of US target ship USS McNulty by FAE, November 16, 1972.  Image courtesy Wikimedia Commons.

The sinking of US target ship USS McNulty by FAE, November 16, 1972. Image courtesy Wikimedia Commons.

But those ancient methane clouds could have been much bigger than (for instance) the FAE deployed against the Taliban redoubt at Tora Bora. Chemical engineer Gregory Ryskin calculated that a major oceanic methane eruption "would liberate energy equivalent to 108 megatonnes of TNT, around 10,000 times greater than than the world's stockpile of nuclear weapons." (This is a clear typo; the world nuclear arsenal is about 5,000 megatonnes of TNT. Presumably 108 was intended, not '108.' That would at least yield the correct order of magnitude.)

But other possible 'kill mechanisms' may have been active. One possibility is that hydrogen sulfide gas may have been released in lethal concentrations. (As with the Lake Nyos CO2 eruption, there is a small-scale modern example of this: occasional hydrogen sufide 'belches' occur off the Namibian coast, though none so far has killed or even injured anyone.)

Ozone depletion may also have boosted damaging ultraviolet levels--by a factor of seven, according to one study.

Whichever combination of these 'kill mechanisms' was responsible, the fossil record shows that approximately 95% of all life was wiped out; the only large land vertebrate to survive was a pig-like dinosaur called 'Lystrosaurus.' It took about 50 million years for biodiversity to regenerate to previous levels. (For perspective, 50 million years ago the evolution of most modern placental mammals had just barely begun.)

Some aspects of the Permian wipeout can't be replicated at present, fortunately. But biodiversity is already under threat from non-climate anthropogenic factors. Another 'great dying' seems to be in progress. And carbon emission rates are far higher than anything seen in the past, suggesting greater rates of persistent climate change to follow. Methane hydrate and hydrogen sulfide release still seem to be real possibilities--even today there are periodic hydrogen sulfide 'belches' off the Namibean coast which hint at the possibility of wider releases in a warming climate.

Complete human extinction strikes Lynas as unlikely due to humanity's:

...unique combination of intelligence and a strong survival instinct. I myself have crawled down an Andean mountain in a state of delirious semiconsciousness when the easiest thing by far would have been to lie back and let go, but the survival instinct was too strong... Even given the most dramatic rates of warming imaginable, somewhere, surely, it will be still be possible to raise crops... And yet, somehow, that is scarce consolation given the torments that may lie in store.

Lynas ends the chapter with a statement of the ethical implications of the risks he lays out:

To me the moral path lies not in passively accepting our destructive role, but in actively resisting [ecocide.]

Protest following the Deepwater Horizon oil spill.  Photo by information, courtesy of Wikimedia Commons.

Protest following the Deepwater Horizon oil spill. Photo by information, courtesy of Wikimedia Commons.

Choosing Our Future

The final chapter changes tack. Having dealt with the range of disasters facing humanity, Lynas turns his sights on possible human responses to climate change. For this is no mere doom-and-gloom treatise. Despite the chapter's introductory list of things for which it was probably already too late in 2008--see the summary article, Choosing Our Future, for details--Lynas sees ample scope for action and for hope:

My conclusion in this book... is that we have less than a decade remaining to peak and begin cutting global emissions. This is an urgent timetable, but not an impossible one. It seems to me that the dire situation that we find ourselves in argues no for fatalism, but for radicalism.

After a consideration of uncertainties, the author sets forth the rationale for avoiding a warming of 2 C: basically, at this level we might set off a chain reaction of feedbacks. If 2 C were to lead to the massive Amazonian die-back discussed in Two Degrees, carbon feedbacks could lead to an additional 250 ppm of CO2 in the atmosphere, and an additional 1.5 C warming--we would then be in the 4C world. But that might invoke rapid permafrost melt which would take us to 5 C, and that could lead to methane hydrate releases good for another degree of warming. In summary, 2 C could perhaps lead inexorably to 6 C.

Lynas provides a table summarizing the sequence on page 279, reproduced here:


From this sobering table the author proceeds to strategy--in particular, the concept of 'contraction and convergence.' The idea is to provide a practical path to emissions reductions by resolving the issue of international inequality which has been a recurring stumbling block in climate negotiations. Developed countries--the biggest historical emitters--would 'contract' emissions the most, so that emissions would 'converge' on equitable shared per capita emissions. As Lynas puts it, "The poor would get equality, while all (including the rich) would get survival."

The difficulties in implementing carbon mitigation are then considered. First is the practical difficulty that fossil fuels provide great benefits, and are deeply entwined throughout our economies. Second is the penchant for denial, which the author sees as running very deep indeed: could argue that the whole economic system of modern Western society is founded on denial, in particular the denial of resource limitations. Schoolchildren are taught--and Nobel Prize-winning economics professors apparently still believe--that Earth-provided resources, from iron ore to fisheries, come into the category of "free goods," appearing as if by magic at the start of the economic process.

One forecast of peak oil.  Graph by ASPO and gralo, courtesy Wikimedia Commons.

One forecast of peak oil. Graph by ASPO and gralo, courtesy Wikimedia Commons.

After a brief digression on the subject of 'peak oil,' which "will not save us," an important and extended discussion of the concept of 'stabilization wedges' concludes the book. This idea, proposed by Princeton University scholars Robert Socolow and Scott Pacala, broke down proven mitigation strategies by the resources needed to reduce emissions by one billion tonnes of carbon by 2055. Each such billion tonnes counted for one wedge; eight wedges are needed to stabilize our carbon emissions. The scheme is explained fully at the CMI (Carbon Mitigation Initiative) website (see sidebar link, right.)

The discussion is useful in illuminating the problems of scale we face. For example, when Six Degrees was written:

...for wind power to achieve one wedge, two million one-megawatt turbines would be needed, a 50-fold increase... A wedge of solar photovoltaic electricity generation would need a 700-fold increase...

Lynas describes this as "daunting." However, it's much less daunting than it used to be. Wind power has risen 5-fold between 2008 and 2012, so that we now need to increase wind by a factor of ten; solar PV is up 7-fold, which reduces the factor required from 700 to 100.

(That's approximate. One confusion arises because in 2008, Lynas would not have had 2008 data on renewables available. It appears he was probably working with 2003 or 2004 data, which was likely the most recent available figures.

(In any case, global wind capacity at the end of 2013 was 283 GW, close to 1/7th of a wedge. 45 GW was added during 2012, so if annual additions continued at that level, we would reach one wedge of wind power in 38 years.

(As for solar PV, at the end of 2012 the world had 100 GW, having added 39 GW in that year. That would make the 'stabilization wedge' date 49 years in the future--though that number is still less realistic, as solar prices and growth rates have been accelerating still more rapidly than has been the case for wind. For example, a new study estimates that installation rates will rise to over 70 GW by 2020. Arithmetic says that if that is true, we would, in 2020, have nearly 300 GW installed PV, and would reach one stabilization wedge by about 2044 or so.)

Update, 7/10/14

A report by the commercial solar energy analytic firm NPD Solarbuzz projects global solar PV installation rates to reach 100 GW annually by 2018, and cumulative global capacity to reach 500 GW in the same year. That would bring one stabilization wedge of solar PV online by 2033.

On the other hand, Lynas points out, stabilization by 2055 is not enough--not if we wish to safely skirt the dangers of carbon feedbacks. To miss 2 C, we would need another 4 or 5 wedges. That brings up the contentious issue of lifestyle change in the wealthy world. It's a 'hard sell.'

Moreover, lifestyles have been changing in the developing world toward increased carbon intensity. Western diet and consumerism has become more and more normative around the world. As currently implemented, it is very carbon-intensive.

But the author points out that convenience does not equate with happiness:

All the evidence shows that people who do not drive, do not fly on planes, do shop locally, do grow their own food, and do get to know other members of their community have a much higher quality of life than their compatriots who remain addicted to high-fossil-fuel-consuming lifestyles.

Decision matrix--cooperate or escalate?  Image by Christopher X. Jon Jensen and Greg Riestenberg, courtesy of Wikimedia Commons.

Decision matrix--cooperate or escalate? Image by Christopher X. Jon Jensen and Greg Riestenberg, courtesy of Wikimedia Commons.

One hopes that the author's optimism is justified. But it is characteristic: Mr. Lynas is not peddling doom and gloom. 'Radicalism, not apathy,' is his watchword; and he envisions "...people happy to make changes in the knowledge that everyone else is doing likewise."

There is an old story about another visit to Hell: the latter-day Virgil privileged (if that is the word) to tour Inferno found a gigantic banquet table. Around it the damned sat starving, staring at food which they could not eat--their arms were all enclosed in splints, which made it impossible for them to bend their elbows and thus reach their mouths. A fiendish punishment, to which they reacted with all the anger and dejection one might expect.

But a tour of Heaven followed. Surprisingly, the same basics dominated: the blessed souls were seated around a banquet table, arms splinted. But in Heaven, hilarity and good fellowship reigned: everyone fed his or her neighbor.

So Lynas's vision of possible Earthly infernos ends with a vision of heaven on earth. Humans are often selfish, short-sighted and greedy, of course. But it's true, too, that our success so far on this Earth has been built upon ever-more intricate structures of cooperation. That potential, too, is part of our 'nature.' Mr. Lynas's book sets forth in great detail the future now being ushered in by short-sighted greed, so perhaps it is only fitting that at least a brief look at a future in which rational cooperation shapes events.

Which future will we choose?


Doc Snow (author) from Camden, South Carolina on December 01, 2013:

Excellent! I'm working on my fiction project, too, though it's slow. Must read yours...

P. Orin Zack on November 30, 2013:

I think I understand why you switch between music and climate. After delving that deeply into the horrific implications of the path we're on, a course of soothing music might be enough to keep you sane. Thanks for your hard work. (BTW, the series of short stories I'd told you that I started recently, which takes place in the climate effects at the end of the century, will soon have a third installment. I suspect that some more of what you wrote about here will end up in the fiction.)

i scribble on November 25, 2013:

Thanks for the link. I'll check it out.

Doc Snow (author) from Camden, South Carolina on November 25, 2013:

Thanks, Arlene! (I'm making a presumption based on your screen name here, I know.)

iscribble, thank you. That is extremely kind! Of course you are welcome to pass my stuff around if you feel it would be helpful in any way. It's a very flattering thought.

But don't be hard on Ric--when I posted to RealClimate that I had this Hub up, I specifically mentioned that I'd appreciate any editorial input readers there might provide. Can't complain that he took me at my word--and I'm really grateful to have those typos gone. That sort of thing really disfigures a Hub, in my opinion, so I'm truly grateful to him.

Speaking of Realclimate, it is a great resource for those who are up for a somewhat technical ongoing discussion of climate-related issues, with a heavy emphasis on the science:

It's moderated by some of the leading researchers in the area.

arlenerobles62 on November 24, 2013:

Thank you for the summary! Would surely follow your hub. Hope others do too!

i scribble on November 24, 2013:

Thanks for this! I'm clicking thru to buy the book on Amazon. May end up under a friend's or family member's Xmas tree after I read it-- my way of spreading the word. You are amazing in your ability to remain motivated in your writing/efforts despite so few comments. And one of them just wanted to point out typos! It's an absurd world we live in, isn't it?

Maybe I'll print out copies of some of your articles to hand out to my inner circle during the holidays. I assume you won't mind.

Doc Snow (author) from Camden, South Carolina on November 19, 2013:

Ric, thanks a bunch. I'll fix them asap.

Doc Snow (author) from Camden, South Carolina on November 19, 2013:

Thanks, Rock!

Yes, a lot of people approach global warming from the perspective of daily temperature variation: "So maybe it's 65 instead of 63. So what?"

Well of course 2 C would take 63 F to about 66.6 F, but more importantly there are 'non-linearities,' like the freezing point. Shift the monthly mean from 32 F to 35.6 F, and you have a very different regime for growing vegetables. Maybe better for string beans, say, but maybe not so good for proper dormancy for a number of tree crops.

Climate change, in the early stages, often has 'winners' and 'losers.'

At the other extreme, 98 F becomes 101.6 F and the risk of heat stroke and similar conditions goes way up.

But that's not the biggest factor, either: because temperature distributions tend to follow the famous 'bell curve,' a small warming in the mean temperature implies a big shift in the likelihood of extremely hot days. That concept is kind of elusive, I admit. But I have a diagram of it in the supplementary Hub, "The Two Degree World."

Ric Merritt on November 19, 2013:

Thank you for the summary. Typos you can search for: nothern China, acceptible, hability (should be habitability).

John Coviello from New Jersey on November 19, 2013:

Pretty incredible and scary rundown of the effects of global warming by degree. Thanks for writing this well written Hub Doc. People need to know what we are gambling with as we continue to dump carbon dioxide and methane into our atmosphere.