Saturday, March 9, 2013

A graph and a chart


     I have a hard time remembering facts.  Dates, numbers that sort of thing.   So I have looked around for something that would help me remember what's going on.    here's a couple of handy items.   I am thinking of printing them off and carrying them around with me.  Perhaps I could put them in my wallet, next to my VISA card, so I could be reminded , when I fill up my car with gas.  Or perhaps I could hang them off the car mirror - They are colorful, and quite visually attractive.  Don't you think?

     The first is the chart from the World Bank/Potsdam Institute report  Why a four degree future must be avoided      It shows some computer run results of temperature.  As you can see, there is some variety, although they all head in the same direction.  You can pick a year and see some of the options for temperature.  For instance, when will we hit 4 degrees?  It depends on your assumptions.  Using current assumptions, we have about a 10% chance of hitting  4 degrees as early as 2050, but more likely it'll only be 3 degrees!  .     

Inline image 2

 The second is a nice chart from Grist -  which has all kinds of cool info.  Including the number of tons of carbon left in our diet  (500); years before we use it up (13); and lot's us fun facts about what things will look afterwards. 

How many gigatons of carbon ...?

Now, we can put these together and see what the near future looks like..  So how does 150 look?   A little bit hotter.  But so what?  

One thing to look at is agriculture.  According to the chart we see yields of corn and wheat reduced by 30-40%,  Could be a problem

Here is a nice summary of some of the basic implications
from  Dan Allen    

Perhaps the most valuable contribution of the discipline of history is the reduction of both the quantity and magnitude of surprises a civilization may encounter as the future unfolds before them. For more forward-looking civilizations, these lessons of history allow both (1) a changing of course to head-off foreseeable and avoidable problems, and (2) prudent preparations to gird themselves for the inevitable consequences of unsolvable predicaments.
And these benefits of history are as relevant for natural and climatic history as any other aspect of history – economic, political, social, military, etc. So for those willing to search beyond the vacuous and outright-deceptive mainstream press (see useful references above), there are many relevant climatic history lessons to be learned – especially in regards to the crucial topic of human agriculture.
In this essay, I’ll present four of these climate-history lessons with relevance for agriculture. Each lesson will be illustrated it with a single, catchy, climate-history graph, and the graph’s implications for both our possible future climate and agriculture will be discussed.
Now, in case you just want to cut to the chase (or if my flowery prose affendeth), I’ll also just summarize these four lessons below. Each lesson, I think, addresses profound concerns for humanity that are ignored -- and, in fact ARE being ignored -- at our extreme peril. So here they are:
LESSON ONE: STABILITY REQUIRED. Civilization-scale human agriculture requires a certain degree of climatic stability and is thus an artifact of the abnormally-stable Holocene period during the past 10,000 years. We almost certainly need to maintain this stability for agriculture to function on anything close to its present scale.
LESSON TWO: VIOLENCE KILLS. Due to various positive feedback loops that amplify even small warming or cooling trends, Earth’s climate system is prone to huge, violent shifts once tipping points are passed. Human agriculture would almost certainly fail catastrophically if such a shift were initiated now. Unfortunately, the latest scientific studies suggest that we appear to be flirting with just such a shift.
LESSON THREE: RESILIENCY, RESILIENCY, RESILIENCY. Even the relatively-muted climatic shifts of the Holocene have presented serious challenges to agriculture. Civilizations that lacked agricultural resiliency have perished in such shifts. As the coming climatic shifts threaten to be much larger than any experienced during the Holocene, building as much resiliency as possible into our post-carbon agriculture is of the utmost importance.
LESSON FOUR: STOP DIGGING THE HOLE. The Earth has experienced climatic regimes unimaginable to our human species, much less human agriculture. It is not inconceivable that our industrial climatic depredations could force a shift on such a scale. It is obviously best that we avoid this. Ending the industrial experiment as quickly as possible may be absolutely necessary in this regard.
And one more note: Although this essay is quite long, I think you’ll find it well-organized along the lines of these four lessons and then some practical steps we can undertake to help confront the coming agricultural challenges. I’m also of the opinion that the material in this essay covers some of the most crucial issues facing our species -- and thus a bit of time spent thinking about them is indeed time well spent.
LESSON ONE: STABILITY REQUIRED -- Civilization-scale human agriculture requires a certain degree of climatic stability and is thus an artifact of the abnormally-stable Holocene period during the past 10,000 years. We almost certainly need to maintain this stability for agriculture to function on anything close to its present scale.
Figure 1: The Past 20,000 Years. Temperature from Greenland ice cores over past 20,000 years. Average global temperatures follow a similar trend over the same period. Note the unsettled ice-age glacial climate from 20,000 to 12,000 years ago, followed by a rapid transition to the relatively-stable, warmer interglacial period. Agriculture began ~10,000 years ago at the start of this climatically-stable period we call the Holocene. (Graph from
Take a look at Figure 1 above – specifically the red temperature line. By proxy of ice cores from Greenland, it’s essentially a plot of Earth’s temperature over the past 20,000 years -- as we transitioned from the end of the last colder glacial ‘ice age’ to the present warmer interglacial. Notice how the last glacial ice age climate (from 20,000 to 12,000 years ago), while never exceptionally stable, becomes violently unstable around 15,000 years ago, until it finally rises dramatically and stabilizes at the current warmer interglacial period around 10,000 years ago.
A key feature of this graph is the striking consistency of the most recent 10,000-year interglacial period – named the Holocene -- relative to the prior 10,000 years. It was, in fact this unusual degree of climate stability during the Holocene which allowed the development of human agriculture and its eventual large-scale implementation. And it was this growth of agriculture, with its resulting food-energy surpluses it provided, that allowed the growth of towns and cities – and crucially, the establishment of a human population size far above what was possible for hunter-gatherer societies.
The implications of this climatic stability/agricultural relationship for post-carbon agriculture are clear: We almost certainly need to maintain some Holocene-like degree of climatic stability for agriculture to function on its present scale.
As anyone who has ever gardened or farmed knows, there are multiple crops and livestock to fill just about any climatic niche. BUT…there are very few crops and livestock that can thrive in the multiple climatic niches we would experience intermittently in a destabilized climate. Based on their genetic makeup, different food species can heroically tolerate SOME pretty severe environmental stresses – heat, cold, drought, wetness, pests -- but never ALL stresses. Just like people, they can’t be good at everything.
So while some level of climatic variation can be accommodated by skillful agricultural practices (e.g., crop diversity, water management, temperature moderation), at some degree of variation beyond the ‘normal’ muted variations of the Holocene, the biological limits of these food species are breached. The large-scale agricultural model would then fail catastrophically. Yields would bottom-out. Civilizations would fall. Human population would plummet.
Of course, short-term climate-related agricultural failures already do occur periodically on a localized scale – the Dust Bowl drought, for a recent example. But should the climatic destabilization occur more widely and persist longer, we would be in very serious trouble indeed.
So the main lesson of the 20,000-year graph is that agriculture – both ancient and modern – utterly requires an unusual degree of climatic stability. And since all populous civilizations – from the ancient Sumerians to the modern Industrialists– are based ultimately on agriculture, human civilization thus utterly requires this same unusual degree of climatic stability.
In other words, an unusually stable Holocene-like climate is not just a nice thing for a populous civilization to have, it’s a damn necessity. And as we’ll see in the next section, prospects for maintaining this climatic stability under the onslaught of our industrial depredations are not looking good.
LESSON TWO: VIOLENCE KILLS -- Due to various positive feedback loops that amplify even small warming or cooling trends, Earth’s climate system is prone to huge, violent shifts once tipping points are passed. Human agriculture would almost certainly fail catastrophically if such a shift were initiated now. Unfortunately, the latest scientific studies suggest that we appear to be flirting with just such a shift.
Figure 2: The Past 600,000 years. Cyclical temperature trends (black line) over the past 600,000 years from Antarctic ice sheet cores – which mirror global trends. Note violent climatic swings due to initiation of positive feedbacks once apparent tipping points are passed. Today’s elevated greenhouse gas concentrations (also shown on graph) are likely pushing the climate system towards several tipping points – possibly within the near future. (Graph:
Take a look at the 600,000-year temperature graph in Figure 2 above – specifically the black temperature line. The main feature of the graph is a passably-regular 100,000-year cycle between warmer interglacial (like now) and colder glacial (ice age) climates.
Note that we saw the most recent glacial-to-interglacial transition in the previous graph (figure 1). Glacial ice age climates (like the one from 20,000 years ago) are characterized by colder global temperatures and permanent ice sheets extending down to even temperate regions (like New York). The interglacial climates (like right now) are characterized by warmer temperatures and permanent ice sheets existing only near the poles or in high mountains.
The Earth’s climate system for the past almost-million years has flipped back and forth between these extremes in a more-or-less regular manner. This regularity is caused -- initially at least -- by regular changes in the shape and orientation of Earth’s orbit around the Sun. (Look up the Milankovich cycles for more details.)
But aside from this interesting ‘cycling’ feature of Earth’s climate, another startling piece of information leaps from the graph: the climatic changes between glacial and interglacial climates are not smooth. In fact, they are jumpy as heck – violent shifts that often cover a majority of the glacial-interglacial variation on the order of centuries or even decades perhaps.
Look for a moment again at Figure 1 (the 20,000-year graph) to see more detail on this astounding non-linear feature of the Earth’s climate system – especially the shocking leap at around 11,500 years ago. It is thought that this monumental shift occurred possibly in as little as ONE SEASON! What the? And comparably violent shifts are peppered throughout the 600,000 year ice core record (which has by now expanded to 800,000 years). And each violent shift is associated with a host of species extinctions as whole biomes rather suddenly just disappear.
But the secrets of these violent and deadly shifts are generally known: positive feedback loops. For while gradual, mild solar radiation changes from the Earth’s orbital variations initiate the warming or cooling trends, it is the ‘tipping-point’ initiation of these feedback loops that cause the rapid runaway amplification.
For example, an increase in solar radiation prompts reflective ice caps to begin melting, opening up darker, more sunlight-absorbing water – which then heats up even faster to melt even more ice, which then absorbs even more heat energy…etc. Now, I won’t go into more details here, but this positive-feedback amplification can actually arise from a host of sources at the same time: polar ice sheets, carbon stored in the ocean, carbon stored on land, ocean currents, and perhaps even interactions with the stratosphere.
And, again, once these positive feedbacks are initiated by the solar radiation changes, they accelerate rapidly until a host of negative feedbacks can eventually check them.
But the graph in Figure 2 is frightening beyond just establishing the violently jumpy nature of the climate system. Carbon dioxide level from industrial fossil-fuel burning have risen to their highest level in 15 million years (!) and serve to exert a warming pressure on the climate system even greater than the regular warming from the orbital cycles. This, in turn, threatens to shove the climate system past one or more of the dreaded positive-feedback tipping points within the next decade or two – if they haven’t, in fact, done so already.
It’s important to note here that these positive feedbacks can sneak up on us quickly. Their non-linear nature causes the warming effects to appear relatively slow and tame at the start– but then pick up speed and accelerate violently as their run progresses. This is simply the nature of the mathematical exponential function. See Chris Martenson’s excellent ‘Crash Course’ video for an instructive lesson on this type of exponential change.
So we have much to fear if these positive feedbacks are initiated – for even if the initial changes appear slow, the detection of their occurrence AT ALL should be very alarming. In light of this, recent reports of accelerated melting of polar ice sheets and elevating methane emissions from boreal and polar regions are not encouraging. See James Hansen’s (NASA, Columbia University) constantly-updated climate diagnostic graphs (e.g., temperature, sea level, ice sheet volume, and sea ice extent) to track these accelerating changes: Joe Romm at also does a good job with regular updates of scientific climate studies (although there are a lot of political posts along with the science-related ones).
The main concern here is this: Atmospheric levels of the greenhouse gases CO2 and CH4 (as released from ocean or land sources) often seem, historically, to be part of the positive feedback loops that RESPOND to and exaggerate slow, subtle changes in solar radiation – as evidenced by the close correlation of atmospheric levels of these gases with temperature in Figure 2. But industrial humans are now also unintentionally using these gases – especially fossil-fuel-derived CO2 -- as actual INITIATORS of these accelerating, carbon/ice, positive-feedback loops. That’s what I call innovation!
So beyond the point made in ‘lesson one’ – that human agriculture almost certainly cannot withstand such huge, sudden climatic shifts and instability as have occurred outside the relatively-stable Holocene – we can garner a second climatic-agricultural lesson from this graph: Such violent destabilized shifts occur suddenly and rapidly once the tipping points that initiate these accelerating feedback loops are exceeded. And while the boundaries of these tipping points are still somewhat murky, we seem to be awfully close to passing them due to elevated CO2 concentrations.
And it is furthermore a near certainty that we cannot initiate these runaway positive feedback loops and hope to maintain something that resembles human agriculture.
Or any civilization like our present one.
Or a human population even remotely close to our present one.
LESSON THREE: RESILIENCY, RESILIENCY, RESILIENCY -- Even the relatively-muted climatic shifts of the Holocene have presented serious challenges to agriculture. Civilizations that lacked agricultural resiliency have perished in such shifts. As the coming climatic shifts threaten to be much larger than any experienced during the Holocene, building as much resiliency as possible into our post-carbon agriculture is of the utmost importance.
Figure 3: The Past 2000 years. This graph shows northern hemisphere temperatures over the past 2000 years (as reconstructed from a number of studies) plotted relative to temperatures in the mid- 20th century. Note the significant decade-scale climatic variation even within this relatively stable Holocene period. Also note the larger century-scale warming/cooling trends -- and how the most recent 1000-year cooling trend has been rapidly reversed under the influence of CO2 from fossil-fuel burning. (Graph from:; but see also and also
So now take a look at Figure 3. This one shows the temperature over just the past 2000 years – taken from a number of published studies that use various proxies (e.g., tree rings, lake and sediment cores, etc) to reconstruct the temperature of the northern hemisphere.
The striking feature from this graph – which, again, encompasses only the last 2000 years of the current 10,000-year Holocene period -- is that even the relatively-stable Holocene did, in fact, contain a significant amount of climatic variability. Note both the numerous decade-scale fluctuations, as well as the larger multi-century-scale warming and cooling trends. It’s important to note that – although they are not shown in the graph -- these temperature fluctuations were also accompanied by significant fluctuations in seasonal patterns and overall amounts rainfall. In other words, each shift in the graph above is accompanied by some crushing drought or period of extended cold, wet weather in some part of the world.
Also note that, unlike the extended 600,000-year graph (Figure 2) with it’s orbital-driven, feedback-exaggerated, glacial-interglacial temperature cycles, the decade-scale variations above in Figure 3 are mostly due to variations in solar output and periodic changes in pathways of heat flow around the globe via ocean currents and wind patterns.
So what does this climate graph have to say about agriculture? Well, a lot actually. Even though these relatively-muted climate shifts of the past 2000 years pale in comparison to the violent glacial-interglacial jumps shown in Figures 1 and 2, they posed very significant challenges for agricultural civilizations at the time. Unlike hunter-gatherers who can move away from unsuitable climatic trends, agricultural civilizations are more-or-less stuck where their fields are, and are thus, much more vulnerable to even small climatic fluctuations.
Brian Fagan, in the three excellent books referenced at the start of this essay, details the extreme challenges faced by a number of agricultural civilizations around the world to these seemingly-mild climatic shifts within the Holocene. For example, while the Europeans basked in a favorable climate during the medieval warm period, Central and North America was subject to a series of crushing droughts that contributed significantly to the collapse of the Mayan Empire. Monsoon failures, droughts, and excessively cold-wet summers contributed at various times to unspeakable famines in India, China, and Europe at other times during these past 2000 years. Historical examples abound of these climate-agricultural connections.
The main lesson to be gained from these histories is that agricultural resiliency – an ability to roll with the climatic punches, so to speak -- was the key to whether a civilization persisted or perished during one of these inevitable climatic hiccups of the Holocene. For the civilizations that did persist, their agricultural resilience was accomplished by a combination of crop diversity, clever hydrological engineering, extensive food storage infrastructure, and the ability to expand or migrate to more suitable neighboring lands.
For the civilizations that perished – who, for whatever reason, were unable or unwilling to incorporate the resiliency measures above -- their fate consisted of a combination of famine, extreme societal simplification (i.e. collapse), and dispersion outward to be enveloped within other still-existing civilizations. It was not the end of the world necessarily, but still, they became but a shadow of the civilization they once had been.
A mere glance at the very recent violent upward surge in temperature and atmospheric greenhouse gases at the very edges of Figures 2 and 3 -- coupled with some basic understanding of the non-linear climatic and ecological workings of the Earth – is enough to suggest that the coming ‘hiccups’ in the years ahead will be significantly more challenging than anything experienced so far in the Holocene. In fact, the Holocene – this relatively stable 10,000-year period, this cradle of human agriculture -- has effectively already ended. We have already entered the ‘Anthropocene’, a climate dominated by the warming effects of human-derived CO2 and all the other climatic changes and feedbacks this CO2 will initiate. And despite our considerable climate knowledge, we have indeed entered the great unknown.
How will our agricultural civilization handle the undoubtedly-serious climatic challenges to come – the temperature extremes, the droughts, the more intense storms, the sea-level rise, the ocean acidification, and all the other changes? How can we build the necessary agricultural resiliency to confront the coming challenges? I’ll address these questions shortly. But first let’s pan-out a bit and take a look at just one more climate-history graph – this time for the looooooooooong view of climatic history and its implications for our species in general.
LESSON FOUR: STOP DIGGING THE HOLE -- The Earth has experienced climatic regimes unimaginable to our human species, much less to human agriculture. It is not inconceivable that our industrial climatic depredations could force a shift on such a scale. It is obviously best that we avoid this. Ending the industrial experiment as quickly as possible may be absolutely necessary in this regard.
Figure 4: The Past 500-million years. This graph shows approximate global temperature trends (as reconstructed from geologic samples) over the past 500-million years. Note the appearance of a semi-regular cycling between a ‘hothouse’ Earth (tropical to poles) and a ‘great ice age’ Earth (ice present – like now), with a period of around 150-million years. While the origin of these ancient temperature estimates are less certain than the orbital-driven, 100,000-year, glacial-interglacial cycles from Figure 2, they are thought to occur due to slow geologic cycling of carbon between rocks and the atmosphere. Note that our species has developed evolutionarily during only the most recent 2-million ‘great ice age’ years of this 500-million year graph. (Graph from But see also Archer’s ‘The Long Thaw’ and Nature, 408, 698-701, 2000)
A look at the deep-time, ultra-long-scale climate history (Figure 4) also has some significant lessons to teach us. This big ol’ Earth is about 4500 million years old, so this very long-term graph above still encompasses only about 10% of the Earth’s history – but it covers just about the entire history of multi-cellular organisms, of which we are proudly one.
The key feature of Figure 4 is that the Earth seems to oscillate between hot and cold temperature extremes with a very long period of around 150 million years. And to illustrate the unimaginable time span encompassed by this graph, note that the 100,000-year glacial-interglacial cycles of the past almost-million years (Figure 2) -- like the 2-million year evolutionary development of our human species itself -- fit in just the thinnest sliver at the left of Figure 4.
The ‘hot’ phase shown on Figure 4 (ex: 80, 250, 375, and 500 million years ago) corresponds to an ice-free Earth, where tropical conditions can extend to the poles. Think of those paintings of dinosaurs frolicking among tropical ferns in the ancient humid Arctic swamps of Greenland.
The ‘cold’ phase in Figure 4 (ex: RIGHT NOW, 130, 300, and 440 million years ago) corresponds to an Earth WITH ice. So don’t feel left out just because we’re no longer in the northern hemisphere’s Holocene ‘little ice age’ of a few hundred years ago (Figure 3), or even the glacial ‘Ice Age’ of 20,000 years ago (Figure 1) – because we’re deep into one of the Earth’s ‘GREAT ICE AGES’, and we have been now for millions of years! Woo hoo!
Another way to think of all these climate cycles is that, while we’re at the top of a warm phase on the 100,000-year cycles, we’re near the bottom of a cold phase on the 150-million year cycles. And while the origin of the 100,000-year cycles is confidently attributed to wobbles in the Earth’s orbit (with amplification from positive feedbacks), the origin of the 150-million-year cycles is less certain.
It is thought that these cycles arise from a sort of slow geologic thermostat: (1) plate-tectonic subduction of carbon-rich ocean crusts periodically release CO2 to warm the Earth, and then (2) the super-charged hydrological cycle of a hot Earth accelerates erosion and weathering that pulls CO2 back into the rocks – which cools the Earth.
In any case, the hot-cold cycles of Figure 4 do have some lessons for us today – although they’re lessons more for our species in general rather than agriculture per se.
The lessons are these: The Earth is capable of climatic regimes FAR different from the few glacial-interglacial cycles in which our 200,000-year-old species has existed – and even from the 2-million years during which we have evolved. In other words, much of the Earth can exist in temperature regimes far outside the biological tolerances of our bodies. And while it is uncertain whether our current fossil-CO2 climatic forcings, with all their attendant feedbacks, will be enough to cause a climatic shift outside of these human tolerances, such a shift is scientifically conceivable.
In fact, eminent climate scientist James Hansen (NASA, Columbia University) has suggested that unless we reduce atmospheric CO2 from its present 390 ppm down to 350 ppm (note: the typical interglacial CO2 maximum has been around 280-300 ppm), we can likely expect catastrophic climatic changes. Hansen suggests that, due to the amplifying effects of numerous positive feedbacks, such a shift could well hurl the climate into a new, decidedly-human-unfriendly (or even biologically-unfriendly) stable state. See his new book (referenced above), as well as his paper, ‘Target Atmospheric CO2: Where Should Humanity Aim?’, at
What this scientifically-plausible risk thus implies is that industrial civilization is quite possibly on a trajectory straight to hell. Literally hell. Anything hotter than the far-left point on Figure 4 is literally hell to our 200,000-year-old human species. It’s biophysically incompatible. We just can’t go there. And we’re still doing everything humanly possible in order TO go there – burning fossil fuels as fast as we can mine them, pumping out more and more CO2, forcing the climate system ever closer to the deadly positive-feedback tipping points.
The obvious implication, of course, is that we need to stop. We need to stop right now. Because we don’t KNOW exactly where the tipping points lie. Heck, maybe we already passed some key ones. Or maybe we’ll pass them soon if we continue industrial business-as-usual for 10 more years, or 5 more years, or one more year. We just don’t know -- but the consequences of continuing the homicidal industrial experiment one day longer than we need to is utter lunacy when confronted with the hard climatic realities we face.
We simply need to acknowledge the unyielding nature of the physical laws that govern our planet and behave accordingly. And that ‘simply’ means ending the industrial experiment as soon as possible. Of course, apparently we’re NOT going to end it – at least until it implodes upon itself. But if that takes another 5 years, or ten years, or whatever, it may well be too late to save not just agriculture, not just our species, but Life itself. In light of these very real risks and our uncertainties as to where the tipping points lie, it’s utterly unconscionable for any thinking, feeling person NOT to want an end to this fossil-fuel-saturated industrial madness immediately.
Once enlightened as such, Life on Earth quickly turns from ‘temporarily beleaguered’ to ‘mortally endangered.’ Civilization turns from ‘bumbling blight’ to ‘deadly pathogen.’ Derrick Jensen turns from lunatic to sage. Wendell Berry turns from ‘mad farmer’ to prophet.
For more on the logic connections required here, check out high-school teacher Greg Craven’s clever little video entitled “What’s the worst that could happen?” at
Taking another tack, you could say that the lessons here are closely related to The First Rule of Holes, which is this: STOP DIGGING. In other words, we undoubtedly are in a hole – it is apparent to all but the most willfully ignorant that we are initiating some very potentially-dangerous alterations to the Earth’s climate system. If we wish to get out of the hole we need to first stop digging – i.e. stop forcing the climate with ever more CO2.  


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