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wsugaimd at 05:38 AM on 11 April 2012Shakun et al. Clarify the CO2-Temperature Lag
I have to be honest here. I am a skeptic. And heres why. I live on the slopes of Mauna Loa, not too far away, is the Mauna Loa Observatory (MLO) where the famous Keeling Curve was made. Its located at the 9000ft elevation(I've been there several times) and just below it, at the 4000 ft level is the most active volcano, Kilauea and its sister, Pu'u O'o vent which has been continuously erupting since 1983. Atmospheric inversions can bring up the C02 to the MLO and causes astronomical spikes in C02. Oceanic acidification data has come from the University of Hawaii Aloha research station located 100km N of Oahu...just at the edge of the great plastic debris field, which is being enhanced by 25 million tons of debris from the Japan earthquake. The biological activity in this area is logarithmically increased due to available surface area of this debris. And with the increased metabolism, there is significant release C02 and organic acids which decreases the pH. Also, the amount of sulfuric/sulfurous and hydrochloric acid from the volcano emissions blows over this area(estimated between 2000-10,000tons/day). With Kona winds, the vog plume blows over the Aloha Station, and currents regularly carry this acidified water to this area. Man also produces 27 billion tons of C02/yr but this is released into an atmosphere that already has 3,600 billion tons. Do the math and man puts out three fourths of 1% of all C02. Seems quite small.... These and other questions have always made me "skeptical".Moderator Response:[DB] The topic of this thread is "Shakun et al. Clarify the CO2-Temperature Lag". In the spirit of true skepticism, we do expect for you to follow up with any further questions on the more relevant threads already supplied to you by the helpful participants here. And when one "does the math" 30 gigatons of annual emissions heretofore sequestered from the carbon cycle that man is now injecting as a bolus slug back into that cycle quite scarcely "seems small".
[Sph] wsugaimd, Please continue to be skeptical! Pursue your questions to the end. Please engage all of your questions on the appropriate threads, because they truly are very simple questions to answer, and they can be answered unequivocally, beyond all doubt. The points you raise have solid, indisputable answers.
As such, if you pursue your skepticism, and then go beyond that to ask further questions and to properly understand the answers, you will begin to understand the problem we all face.
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danielc at 05:31 AM on 11 April 2012Shakun et al. Clarify the CO2-Temperature Lag
@Jim: absolutely correct... hence, the dry valleys in antarctica... colder = dryer, and dryer = less snow. I agree that it is a less important effect, but the cumulative impact of both hotter summers (increased melting) and colder/dryer winters (decreased accumulation) act effectively together to remove snow/ice rather rapidly. The current situation is "special" due to the fact that we are getting BOTH hotter summers and warmer winters - more melting AND more snow in winter... strange combination due to the overall net increase of CO2 (heat trapping)... -
dana1981 at 05:24 AM on 11 April 2012Monckton Misleads California Lawmakers - Now It's Personal (Part 2)
Lionel @20 - the reason Monckton's attribution is vague is undoubtedly because as usual he's misrepresenting his sources. Last time he claimed near unanimity regarding the cost effectiveness of his do-nothing path his reference was a paper by Tol. I looked at that paper, and it actually says the opposite - that a carbon tax is the proper response. Mockton thus far has been unable to point to a single peer-reviewed economics paper that supports his do-nothing approach, let alone a 'near unanimity'. As usual, he's full of crap. -
Jim Eager at 05:08 AM on 11 April 2012Shakun et al. Clarify the CO2-Temperature Lag
Re Daniel @ 35, while the corresponding decrease in high latitude winter insolation and consequent more extreme winter cold is less important, even this acts to inhibit ice sheet growth as reduced moisture leads to decreased snowfall accumulation and thus reduced ice formation. It's a two-prong attack on the ice sheet: less new ice formed during the colder, dryer winter, more old ice melted in the warmer, wetter summer. -
Lionel A at 05:06 AM on 11 April 2012Monckton Misleads California Lawmakers - Now It's Personal (Part 2)
John Russell @19 I posted a comment over at the foot of that second Concordensis article and Monckton of Brenchley has Gish Galloped in including this odd statement:'The economic argument against acting on CO2 is even stronger than the political argument. Even if one were to suppose, per impossibile, that the 3 Celsius degrees of warming predicted by the IPCC for this century as a result of our emissions of greenhouse gases were actually likely to occur, only 1.5 Celsius of this warming is attributable to the CO2 we add to the atmosphere this century...'
and'the peer-reviewed literature of climate economics is near-unanimous in concluding that it is more cost-effective to do nothing now and to pay the cost of focused adaptation to any adverse consequences of global warming that may in future occur than it is to spend any money now on climate mitigation.'
I was trying to discover how he can come to these conclusions but have been hamstrung by poor internet connectivity and sickness. I nearly have a response to some of that gallop but his attribution is always rather vague. -
Composer99 at 04:26 AM on 11 April 20122012 SkS Weekly Digest #14
Charlie A: I'm sure you've been constantly pushing that same stark choice over at websites such as WattsUpWithTthat and Bishop Hill when they engage in the same, right? Right? In any event, why you can't be bothered, in your criticism of this cartoon, to acknowledge the multitudes of other articles here on SkepticalScience which thoroughly discuss the scientific literature? I trust the false dichotomy you present is just an error. Right? -
danielc at 04:00 AM on 11 April 2012Shakun et al. Clarify the CO2-Temperature Lag
@Tom Curtis: I stated "Increased Northern and Southern Hemisphere summer insolation" - meaning more heat in Northern summer (June/July) and more heat in Southern summer (Dec/Jan). Your statement is more properly worded than mine, but they mean the same thing. Also, yes there was a decrease in insolation in the same places in their respective winter seasons... but the important thing is the summer, because a change from very cold to extremely cold is not as important or as impactful as a change from cool to hot.... -
Bob Lacatena at 03:12 AM on 11 April 20122012 SkS Weekly Digest #14
Alces, Please reference my napkin calculations here, where I conclude that:we would need to plant, today, redwood forests on at least 75% of all arable/agricultural land, and to allow them to grow for 100 years, before they successfully drew enough carbon (337 Gt) from the system to lower atmospheric CO2 levels back to the pre-industrial age... ...with only 25% of the agricultural land available after starting the "great carbon absorption" forests, we'll only be able to feed 25% of the 7 billion people currently alive.
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Tom Curtis at 02:10 AM on 11 April 2012Shakun et al. Clarify the CO2-Temperature Lag
danielc @32, with regard to your (1),the orbital change causes increased NH summer insolation and SH winter insolation. It also caused decreased NH winter insolation and SH summer insolation, as can be seen here:
Caption reads:
"Fig. 1. Comparison of insolation anomalies (16) over the past 150,000 years for 70'N (top), 50'N (middle), and 80°S (bottom). Insolation sufficient to begin major melting leading to the last interglaciation occurred only after ca. 135,000 years ago (line labeled ‘A’); an inference based on the observation that major melting over the more wel-constrained and re-cent deglaciation did not begin until the same level of insolation was reached at ca. 15,000 years ago (30) (line labeled ‘‘C’’). A much higher rate of Northern Hemisphere summertime insolation increase existed over the penultimate deglaciation (line labeled ‘‘B,’’ ca. 130,000 years ago) than over the most recent deglaciation (line labeled ‘D,’ ca. 12,000 years ago)."
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Lou Grinzo at 00:51 AM on 11 April 2012Shakun et al. Clarify the CO2-Temperature Lag
Great article. This is a paper, like the one by De Conto et al. about the permafrost/PETM linkage, that deserves considerable attention. Taking them together, I think it's fair to say that we continue to collect evidence that the Earth System is itself "wobbly" or "twitchy", thanks to the cascade of effects that can be unleashed by even a "minor" perturbation. We may be in the process of learning that the relative equilibrium that's held throughout human history was a much more precarious balance than we generally assumed, especially those of us who are not climate experts. The implications of this inherent nature of our environment, assuming our dawning realization is correct, are very grim. They tell us that not only does it take less of a shove to knock the Earth System out of its state of equilibrium, but that once that move to a new equilibrium state (or excursion through state-space in search of a new eq.) begins, it's extremely hard to reverse the process. You can go home again, but it's much harder than we thought. For those who like physical analogies, I always think of a ball resting in the bottom of a bowl. Poke it, and it rolls around a bit but returns to (virtually) the same position. This is how we prefer to think of the Earth System. But it's looking more and more like the ball is instead resting in a shallow depression on top of an inverted and very irregularly shaped bowl; nudge it very gently and it rolls around and comes to rest in its perch. But even a moderate poke sends it over the edge and going who knows where. And not to go all Jared Diamond about it, but I think there's a strong case to be made that the basic geography of the Northern Hemisphere loads the dice in favor of rapid warming events -- all that land at just the right distance to accumulate and then release carbon, surrounding open ocean that can quickly lose ice cover and kick off the albedo flip positive feedback. -
danielc at 00:12 AM on 11 April 2012Shakun et al. Clarify the CO2-Temperature Lag
@Michael: 1) Orbital change causes insolation increase in Northern and Southern Hemisphere summer. 2) Northern Hemisphere glacial ice caps melt rapidly enough to overwhelm thermohaline circulation. 3) Loss of consistent, global Thermohaline heat redistribution leads to loss of the ability to redistribute heat efficiently. 4) loss of heat redistribution is magnified in the Southern Hemisphere because of the relatively large percentage of earth's surface covered by ocean. The Southern Ocean warms up enough to release large volumes of CO2. 5) The rapid and large-volume increase in atmospheric CO2 feeds back to increase overall global temperature. Simply put: Orbital forcing leads to larger heat inputs at the poles relative to equator. The ensuing melting releases CO2 and fresh water. The fresh water disrupts thermohaline circulation, trapping heat in the oceans that would otherwise be redistributed. The CO2 released feeds back into the increasing temperature/heat greenhouse effect. If this happens fast enough, the CO2 and temperature/heat increases can rapidly overwhelm the negative feedbacks from weathering and organic sequestration.... -
2012 SkS Weekly Digest #14
Alces - "We have those plants. They are called trees. The output is wood. Why not grow more trees and sequester more carbon in wooden structures? When wooden structures reach the end of their lives, why not recycle the wood, perhaps as a biofuel?" Because when they get used as biofuel, or the trees otherwise decay, the carbon goes right back into the atmosphere. True sequestration will require keeping that carbon locked away (as coal, oil, and natural gas did) for tens of thousands of years while the carbon cycle and silicate weathering absorb the pulse of carbon we have released. That sequestration requires an increase of long term carbon mass kept from the atmosphere - at this point we simply don't have enough land area (even if, say, we stopped growing lower carbon density food) for high density forests sufficient to pull our current CO2 overburden out of the atmosphere. -
Tor B at 23:30 PM on 10 April 2012DeConto et al: Thawing permafrost drove the PETM extreme heat event
Great article and useful links. FYI, the Paleogene Period consists of the Paleocene, Eocene, and Oligocene Epochs.Moderator Response: (AS) Oops. I'll fix that, thank you. -
threadShredder at 23:30 PM on 10 April 2012Fred Singer Debunks and then Denies
@Moderator Response @16: I understand your policy and, of course, will abide by it. But it is a losing one. You clearly understand this is a war, and not a debate. The best way forward is to respond to deniers with the science and then you have to question their personal integrity when they refuse to respond rationally. -
Michael Whittemore at 21:22 PM on 10 April 2012Shakun et al. Clarify the CO2-Temperature Lag
I read the link, very informative, thanks. Just so I am clear, stopping of the (AMOC) forced the Southern Ocean to release CO2 which caused this feedback system. It was not the temperature rise in the southern ocean that caused it but the extra CO2. This CO2 had a g value of 0.8 leading to a 5 degree temperature increase? -
Tom Curtis at 19:59 PM on 10 April 2012Shakun et al. Clarify the CO2-Temperature Lag
Michael Whittemore @29, actually there is a much simpler explanation. Once the initial warming had commenced, it started a feedback cycle. The effect is that the first degree of warming causes feed backs which result in an additional g degrees warming. These in turn result in an further feed backs resulting in g^2 degrees warming, which in turn result in further feed backs, which cause an additional g^3 warming, and so on. So long as -1 < g < 1 degree C the consequence is a self damping cycle. That is because |g^x| < |g^y| where y > x whenever -1 < g < 1. As it happens, even the sum of an infinite series of such diminishing values will be finite. Consequently, the temperature increase from a given impetus will close in on some finite increase above the original and stabilize at that value, absent new forcings. For the glacial/interglacial transition, we are talking about slow feedbacks, for which the relevant value of g is about 0.8, leading to approximately a 5 degree increase in temperature after feedbacks from an initial one degree increase. So it is not necessary to find some mechanism which weakens the feedback cycle to bring the warming to an end. It will do so naturally so long as g < 1. This is all explained here. As a side note, some fake "skeptics" insist that any positive feedback must end in a runaway effect. They are making exactly the same logical fallacy as was made by Zeno in his famous paradoxes. -
Michael Whittemore at 18:42 PM on 10 April 2012Shakun et al. Clarify the CO2-Temperature Lag
So with the reduction of CO2 by Silicate weathering, this stopped the warming in the Southern Hemisphere, which in turn stopped the release of CO2 from the ocean. This would have allowed the planets global temperature to become in balance. So the Atlantic Meridional Overturning Circulation (AMOC) played no part in cooling the Southern Hemisphere, Right? -
Bernard J. at 18:29 PM on 10 April 2012Eocene Park: our experiment to recreate the atmosphere of an ancient hothouse climate
Adelady:...do we really know the physiological limits for bees and bats and the other small critters we rely on for crops?
For many we do, or we can easily infer from various distribution analysis methodologies. And your second point is right - our own physiological limits will be severely tested if we pass temperature limits affecting a pollinator species for a major food crop - or indeed that affect any specieas that performs any of the myriad ecological services to which most humans are completely oblivious. This is the basis of my second point at #16,and it is a part of the reason why I try to emphasis that humans are adapted to a certain specific mean global temperature range. Anyone who wants to suggest that we can easily adapt to higher temperature conditions needs to explain exactly how we drag along in that adaptation the rest of the biosphere on which we depend. Humans are not an ecological island, no matter how much a huge swathe of our species imagines otherwise, and omitting such facts from a fantasy future of easy adjustment favours nothing but the imaginations thus assuaged. -
adelady at 18:05 PM on 10 April 2012Eocene Park: our experiment to recreate the atmosphere of an ancient hothouse climate
"Direct physiological constraints are not the entirety of the story, but neither are they least amongst them." Maybe not for us. Leaving aside the issue of oil-based fertilisers, do we really know the physiological limits for bees and bats and the other small critters we rely on for crops? Our own physiological limits will be severely tested if we suddenly pass some temperature limit affecting a pollinator species for a major food crop. -
Bernard J. at 18:03 PM on 10 April 20122012 SkS Weekly Digest #14
Please, can Caerbannog's posts here be reposted as a separate and distinct thread? The elegance deserves it's own platform here. -
Doug Hutcheson at 16:36 PM on 10 April 20122012 SkS Weekly Digest #14
How optimistic are you that the human race will get its act together in time to stave off catastrophic climate change?
Nothing will be done until the momentum of public opinion is sufficient to overcome the inertia of vested interests, both political and commercial. The inherent difficulty in developing a velocity in public opinion through education (by definition, half the population has below average capability of understanding the problem) means that it will likely be a long time before the (velocity * mass) of public opinion reaches the critical momentum. The only hope for a swift change in public opinion lies in the occurrence of a crisis so great that everyone can see and interpret the evidence. Failing such a crisis, I have no expectation that opinion leaders will allow public perception to be led in a direction that would mandate prudent and timely action. Without such action, climate change is likely to adversely impact the ability of humanity to maintain its current level of societal sophistication. Whether this would be classed as a catastrophe is subjective. If a large fraction of our species was to die off and a large fraction of our current technology was to become unsupportable, I would class this as a catastrophe. YMMV. -
skywatcher at 16:31 PM on 10 April 20122012 SkS Weekly Digest #14
#18, you're trying to distract from the fact that your original comment and snide dig at SkS, IPCC and Joe Romm is incorrect. The cartoon does not mention losses, normalised or otherwise, it mentions "increased extreme weather". The best evidence we have, summarised by IPCC, also in numerous posts here, such as this one on Hansen et al 2011 is that actual extremes are increasing, both of temperature and precipitation. I don't suppose you'll be honourable enough to retract your snide comment at #12? Discussion of hurricanes and tornadoes here is an off-topic distraction, also these events are less important to the majority of world population that does not live in the path of these particular flavours of extreme weather - floods and droughts are much more globally relevant. -
Phil L at 16:05 PM on 10 April 20122012 SkS Weekly Digest #14
"If we had plants that created coal as an output, or in some other fashion sequestered the CO2 for the long term, that would be great..." We have those plants. They are called trees. The output is wood. Why not grow more trees and sequester more carbon in wooden structures? When wooden structures reach the end of their lives, why not recycle the wood, perhaps as a biofuel? -
Charlie A at 15:26 PM on 10 April 20122012 SkS Weekly Digest #14
@#15 Skywatcher -- I agree that there is indeed an upward trend in weather and climate related losses. This is to be expected as the population and economy expand. Normalization of the losses is an attempt to extract the underlying trend, if any, in climate. Of course looking directly at weather and climate statistics is a more reliable way to determine trends in climate. There is no trend in tornadoes (which is the extreme weather depicted in the cartoon), except for the increase in observed weaker tornadoes. This is to be expected as the observation network has changed dramatically with the installation of a doppler radar system across the USA. There is no trend in the stonger (EF3 and above) tornadoes, for which there is a more reliable record. Similarly, there is no trend in hurricanes, once the change in observation systems is taken into account (early records are land based and occasional ship reports. Then airplanes were used to observe known systems, and then finally satellite monitoring started.) A recent paper gives more details, with the conclusion of "Our analysis does not indicate significant long-period global or individual basin trends in the frequency or intensity of landfalling TCs of minor or major hurricane strength. This evidence provides strong support for the conclusion that increasing damage around the world during the past several decades can be explained entirely by increasing wealth in locations prone to TC landfalls, which adds confidence to the fidelity of economic normalization analyses." Historical global tropical cyclone landfalls, Journal of Climate. And yes, there has been observed trends in temperature extremes, although not nearly as strong as many claim, because daily temperature distributions are significantly non-normal. Trends in extreme precipitation events, are currently a subject of investigation and debate.Moderator Response: [JH} With all due respect, I believe that you are taking the cartoon way too literally. There is nothing to indicate that Tooles meant the cartoon to reflect today's conditions. When I looked at it for the first time, I projected the scene to be occurring in 2050. -
chriskoz at 15:16 PM on 10 April 2012Book review of Michael Mann's The Hockey Stick and the Climate Wars
I've finished the book over the Easter, and (only thereafter) deservedly so, put a five star review on amazon. Also, I've sent a short email of appreciation to MM himself (acknowledged with thanks), because I think MM deserves all friendly supports that he receives after the the amount of smear and bullying he was subjected to. Enduring the attacks of the denial machine was not easy task. The contrarian's focus on MBH98-99 was as silly as their arguments against AGW in general, so MM as the lead author was under big pressure defending not just himself but virtually the whole climate science. The account of the events is good, supported by numerous notes to follow up if required. The narrative is also good. -
caerbannog at 14:52 PM on 10 April 20122012 SkS Weekly Digest #14
Further, as an antipodean, I would appreciate maps of station sites that show the entire globe, and not just the North Atlantic and surrounding lands.
OK, I don't want anyone to accuse me of being a dogmatic Northern Hemisphericist.... ;) So for all the good folks down under, here ya go:
For what it's worth, feel free to pass the material that I've posted here around to friends/relatives/co-workers/etc... -- I hit one of my "fence sitting" relatives with it a couple of days ago, and it seemed to make a real impression on her. The fancy Google Earth "eye candy" does seem to help drive home the message.
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Bernard J. at 14:42 PM on 10 April 20122012 SkS Weekly Digest #14
How optimistic are you that the human race will get its act together in time to stave off catastrophic climate change?
Those readers who have followed my comments here and elsewhere for the last few years will know that I have been growing ever more pessimistic. Over the last few weeks I have reached the conclusion that humanity will not solve the carbon emissions problem, and that barring global pandemic and/or major global warfare, we will eventually burn as much of the fossil carbon accessible to us as we are able. Nuclear technology will not help, nor will other imagined technological fixes. The laws of thermodynamics preclude what is essentially a magical skipping over both the amount of energy that we have access to, and the pushing against entropy that would be required for high technologies to operate. Just go to the IPCC's worst case scenarios, and one will see what the most likely future is for the planet. Barring a political miracle, all the rest is arrant optimistic fluff. -
Bernard J. at 14:25 PM on 10 April 2012Eocene Park: our experiment to recreate the atmosphere of an ancient hothouse climate
And as an addendum, Andy S's observation about the rapidity of global warming is an important factor in how humans are - or are not - able to adapt as a species. Individuals will always be able to adapt to changes in temperature, but at the species level rapid temperature change is very undesirable. This leads to (or rather, stems from) discussions of the Holocene constancy that led to the development of agriculture and concurrently of human civilisations, but such has been described elsewhere and probably doesn't need to be repeated here. -
Bernard J. at 14:15 PM on 10 April 2012Eocene Park: our experiment to recreate the atmosphere of an ancient hothouse climate
dr2chase. It was genuinely not my intent to exacerbate your grumpiness. Perhaps you need to understand that as an ecologist I am looking at this in a slightly different context to the "next election cycle", or the "next house move" time frames that most Western people are inclined to employ. You mention individual people's abilities to adapt to local changes. I tipped a hat to this at the top of the post at #16. Certainly, no-one disputes that individually, and at local spacial scales and at certain temporal scales (days to years), humans have an amazing capacity for adaptation, temperature adaptation included. The problem for us as a species is greater than this, however. It might be worth re-reading my previous points and dwelling on them carefully, because they encompass some profound challenges to humans that render less impressive our current abilities to tolerate extremes of heat - and indeed of any weather type. Fact: oil will run out. Functionally, and globally, probably within half a century. Social/technological unpreparedness, and the resulting social/economic havoc that will ensue as shortages start to bite, might bring the effective functional end closer than around that ball-park estimate of half a century. Our industrial food production paradigm is implacably based on the production of nitrogen fertilisers derived from fossil fuels. Without oil the easiest feedstock with which to manufacture fertiliser disappears. Coal can be converted to other forms, including synth-oil, but a lot of (currently non-existent) infrastructure is required, and there is a thermodynamic cost to deriving the converted energy density. Thus the energy-return-on-energy-invested (ERoEI) from converting coal is lower than with oil-based feedstocks, and this in itself has profound technological and economic consequences. Frankly, humans have probably already left it too late to attempt a smooth transition to a non-oil based economy, whether one is considering food production, electrical power supply, fuel-based temperature regulation in buildings, or transport. Further, without full exploitation of coal there is little chance that our civilisation as we currently recognise it will continue into the future*. Where does this leave the younger amongst us, and our yet-to-be-born decendants? Basically, without the technologies that we currently use to manufacture textiles, to generate warmth (and coolth) and to keep everyone's neighbours from eyeing off any useful thing that they might have squirrelled away. In the near future a climate that is two or three degrees warmer might simply be a bit more of an inconvenience under a contracting economic regime, but it will grow ever more noticable as the extremes impact directly on our communities, and as the ecosystem services on which we rely (including a nacently non-fossil fueled agriculture) start to through curve balls at us. We might not as a species all die of heat exhaustion (in fact, few of us will), but many are still going to be directly and severely impacted by the increased heat extremes that the planet will experience. And by other indirect extremes, such as drought and flood, that come from heating the planet. And remember that this is going to happen with a loss of ability to manufacture industrial scales of food... Even then we won't plunge directly toward extinction. We might not lose even more than, say, around half of the peak human population before we accept a much-reduced standard of living, and decide to go hammer and tongs at the coal no matter that it's a Faustian bargain. And Faustian it would be. If humans do end up burning all of the coal on the planet (and current socio-political trends indicate that we will), then the final increase in mean global temperature will be in the range of 6 degrees celcius, or more. Even if we decide to forebear our current inclination to burning coal future, more desperate generations might not be so restrained, and may not recognise the lessons of Angkor, Easter Island and other such civilisations. In a climate that warm the extent of human-habitable regions will be much reduced, and certainly heat limits to human physiology will be a significant component of this fact. Add to this the requirement for ecosystem functions necessary for human survival, and that probably require similar climatic conditions to humans, and suddenly there's little room to squeeze in much of a niche for us as a species. In the end it's a whole suit of factors that combine to make any significant planetary warming undesirable for humans. Direct physiological constraints are not the entirety of the story, but neither are they least amongst them. [*Nuclear energy is not going to save us, but that's a topic for a different discussion.] -
R. Gates at 14:12 PM on 10 April 2012Shakun et al. Clarify the CO2-Temperature Lag
mdenison @ #8: The nonlinear response of the climate system would indicate that the rate of change of a variable, such as CO2 (and methane and N20) is just as important, if not more so in determining some final equilibrium state. The natural feedback mechanisms (biological & rock weathering) to maintain CO2 in a range can be overwhelmed, leading to an increasingly unstable system that will rapidly pass through a series of potential "tipping points" that are unpredictable by any model. The dramatic loss of sea ice in 2007 might be one such point, when at the time, it was seen as a "black swan" event, we see, only after the fact, that 2007 was no one-off black swan, but rather a new sharpening downward trend in Arctic Sea ice. Even in analyzing 2007's amazing summer low (which of course came close to being beaten in 2011) fingers were pointed an proximal causes, such as anomalous winds, currents, etc. When, from a wider perspective we now can see as part of a new normal in this rapidly evolving Anthropocene. The sharpening downward trend not predicted by any climate model as such tipping points can only be seen after the fact. An excellent article on this can be found at: http://www.pnas.org/content/105/6/1786.full.pdf+html Other such tipping points, only seen after the fact might well be events such as the Russian heat wave of 2010 and this March heat wave of 2012. Though the proximal causes might be found in unusual blocking events, we might find that the new norm of the Anthropocene is toward more frequent and intense blocking events. There is nothing in the last several million years remotely like what the Anthropocene is now evolving into, and no model will be able to forecast the nonlinear responses to the rapidly changing atmospheric composition of the planet(rapidly by all geological standards). Going to 560 ppm of CO2 in a few hundred years will have a different set of tipping points than going there in 10,000 years as the feedback response in each case is vastly different. -
skywatcher at 12:04 PM on 10 April 20122012 SkS Weekly Digest #14
#12 - interesting that in the same paragraph of the report we have:There is high confidence, based on high agreement and medium evidence, that economic losses from weather- and climate-related disasters have increased (Cutter and Emrich, 2005; Peduzzi et al., 2009, 2011; UNISDR, 2009; Mechler and Kundzewicz, 2010; Swiss Re 2010; Munich Re, 2011).
There is then a significant discussion of the confounding factors as well as increased exposure to losses which prevents a discernible climate signal in normalised losses. That you chose normalised losses is the problem here. You have selected the most challenging metric (for attainment of statistical significance) with which to criticise the cartoon, and as we'll see below, missed the mark anyway. The cartoon comment is about actual increased extreme weather and not normalised losses, so the cartoon is fairly accurate. Chapter 3 of the IPCC SREX report is the one you need to look at if you wish to criticise the cartoon. Here, we have:In many (but not all) regions with sufficient data there is medium confidence that the number of warm spells or heat waves has increased since the middle of the 20th century (Table 3-2).
and a more extensive quote from 3.3.1:The AR4 (Hegerl et al., 2007) concluded that surface temperature extremes have likely been affected by anthropogenic forcing. This assessment was based on multiple lines of evidence of temperature extremes at the global scale including the reported increase in the number of warm extremes and decrease in the number of cold extremes at that scale (Alexander et al., 2006). Hegerl et al. (2007) also state that anthropogenic forcing may have substantially increased the risk of extreme temperatures (Christidis et al., 2005) and of the 2003 European heat wave (Stott et al., 2004).
On precipitation (3.3.2):Based on evidence from new studies and those used in the AR4, there is medium confidence that anthropogenic influence has contributed to intensification of extreme precipitation at the global scale.
Readers are left to decide for themselves if they still think the IPCC should be inside or outside the bunker in the cartoon... -
Andy Skuce at 11:41 AM on 10 April 2012Eocene Park: our experiment to recreate the atmosphere of an ancient hothouse climate
dr2chase: I am sure that even in the most extreme scenarios, there will be places on the planet, at high latitudes or high altitudes, where humans will be able to live in some kind of self-sufficient manner with a modified form of our current agriculture. The question is whether these places will be large enough and connected enough to support the kind of specialized economies and trade that have raised standards of living and quality of life; at least for the most fortunate of us in developed countries. What particularly concerns me is the pace of the forced change, both for the physical environment and for our civilization. If this transition were taking place over tens of thousands of years, hundreds of human generations, I'd be fairly comfortable with it. Cities would have to be rebuilt several times over anyway, so sea level coming up fifty metres or so would be no big deal. Slow migrations and small changes in fertility could redistribute the population without major suffering. Advances in agriculture and technology would likely ease the transition. This change we are inflicting isn't a gentle wind gradually pushing the global supertanker off course, but, rather, an impact with a reef. It the suddenness and unpredictability of the coming changes that bothers me--the probably ugly consequences of forced adaptation over the next couple of centuries--not the unlikely prospect of the entire extiction of Homo sapiens in the longer term. -
JoeTheScientist at 11:37 AM on 10 April 2012Shakun et al. Clarify the CO2-Temperature Lag
Data seems to indicate more of a variation between roughly 80,000 and 120,000 year cycle length rather than the nominal "100,000" years, but it's rather irregular. Unfortunately there is no "cut and dry" level of insolation that is the exact trigger, no single simple trigger. On thing that seems to be a prerequisite for a full-blown interglacial/ termination is a very large accumulation of ice (probably both in terms of extent and thickness). Only a massive runaway ice melt seems to be able to dump enough fresh water fast enough into the arctic ocean to alter thermohaline circulation sufficiently to prod the deep southern ocean into disgorging its accumulated hoard of CO2, thus locking in the warming and the new interglacial. Melting the Greenland ice cap wouldn't be enough. It has to be HUGE! At one point in the last termination, the melting rate was fast enough to raise sea level 5 meters in a single century!!! Ice amok stops AMOC! A termination starts when NH summer insolation becomes intense enough to start net melting of the NH ice sheet. There are two runaway feedback effects involved. One occurs at the ice edges where the ice albedo begins decreasing as bare, newly exposed land absorbs more and more solar energy, shifting the energy balance even more than just the insolation change alone, leading to runaway melting at the edges. However there is also a less well known ice elevation feedback. As the ice sheet begins to melt at its elevated surface, it slowly decreases in elevation, but the more it does, the warmer the temperature at the ice surface and the faster it melts, leading to an almost irreversible runaway that rips through the ice not just at the edges but ultimately over much its surface. The thicker the NH ice sheet is and the greater its southern extent, the more dramatic its melting will be when the insolation balance shifts, and the more commandeering its effect on the thermohaline circulation which, if great enough, triggers the CO2 release from the deep southern ocean. Without this CO2 release, there isn't a full-blown termination, but just a pause in the ice age. -
Eric (skeptic) at 11:26 AM on 10 April 2012More Carbon Dioxide is not necessarily good for plants.
Thanks Tom. As usual you understand my question and the issues. I agree with most of what you say, but I am not sure if the forest loss will be significant enough to cause a temperature overshoot as postulated by R. Gates. My understanding from figure 1 in my second link in 232 is that the rapid rise in CO2 makes some trees more immune to subsequent temperature increases. The ultimate outcome will be dependent on the uniformity of the tree species and whether they are CO2-selected. In lands managed by the US Forest Service 2.5 million acres are replanted annually out of about 200 million and that can probably be increased significantly to meet new needs. -
mdenison at 10:21 AM on 10 April 2012Shakun et al. Clarify the CO2-Temperature Lag
Readers may also find the recently published paper Carbon Isotope Constraints on the Deglacial CO2 Rise from Ice Cores J Schmitt et al interesting. I was particularly intrigued by the timing they place on CO2 up-welling from the southern ocean. "Our new, high-resolution δ13Catm data constrain the period of this release of isotopically depleted carbon from the deep ocean to the atmosphere to between 17.4 kyr BP and 15 kyr BP" which appears to tie in very neatly with the Shakun et al period of low AMOC strength. -
Sceptical Wombat at 09:47 AM on 10 April 20122012 SkS Weekly Digest #14
"How optimistic are you that the human race will get its act together in time to stave off catastrophic climate change?" At some stage China is going to understand the importance of doing something serious about carbon emissions. When that happens it will use its economic and diplomatic clout to push its trading partners and neighbors to shoulder their fair share of the burden (or China's perception of their fair share). How far down the track we will be before that happens I don't know. -
mdenison at 09:26 AM on 10 April 2012Shakun et al. Clarify the CO2-Temperature Lag
There are some interesting questions raised near the end of an article by climate central regarding some of the uncertainties regarding details presented in this paper. They also report that Shakun and his collaborators are confident the main picture will not change significantly.The climate central article has been reposted at climate progress. -
Tom Curtis at 09:12 AM on 10 April 2012More Carbon Dioxide is not necessarily good for plants.
Eric (skeptic) @234, one aspect you are not taking into account is the succession of regrowth. If you clear an area of forest, the cleared area is quickly colonized by small rapidly growing plants. As years go by they are replaced, first by small woody shrubs and then rapidly growing soft wood trees, and then finally by slow growing hard wood trees. In a situation of rapid climate change, large sections of woodland will find themselves left behind by their climate zone and die back. With a pace of change of several degrees C per century, the rapidity of die back will be such that the successor plants will be the small rapidly growing plants, ie, grasses and weeds. These then may be supplanted by woody shrubs, but with sufficiently rapid climate change the climate will change to fast for the full succession (which takes centuries) to follow. The result will be the wide spread replacement of forests by open woodland or grassland. Such a replacement will result in a large loss in biomass, both because trees have more mass for a given deployment of leaf area than do shrubs and grasses, and because forests have a layered ecology with a canopy, potentially midlayers, and floor which enhances capture of available sunlight and (hence the lower albedo) and opens up more ecological niches which increases the efficiency of exploitation of available energy. This mechanism is medium term only. After a few centuries temperatures will stabilize if only because we will run out of fossil fuels. Once temperatures are stabilized, within a century the normal succession will reassert itself so that biomass will again increase. But the significant loss of forest land for grassland can certainly act as a short term positive feedback on CO2 warming. As an addendum I will note two further points. The first is that large scale species loss will result in a loss of specialization in ecologies, ie, a loss of efficiency in exploiting available energy. That will result in a long term loss of biomass, although much smaller than the effect described above. It is probably also a smaller effect than the gain in plant mass due to high CO2. However, (my second point) that gain in plant mass will also result in a loss of albedo in grasslands. -
funglestrumpet at 09:01 AM on 10 April 20122012 SkS Weekly Digest #14
"How optimistic are you that the human race will get its act together in time to stave off catastrophic climate change?" It is difficult to argue that the scientific case, apart from crossing a few ‘t’s and dotting a few ‘i’s, is as good as settled. That means that we as a species know that climate change is going to be a major issue for coming generations with the high probability that a great many are going to die from its effects. Yet even intelligent people with children and grandchildren who will likely suffer badly prefer the 'business as usual' scenario to facing the facts staring them in the face. The less intelligent will just agree what these opinion formers say and support such action or inaction they recommend. With the above in mind, I have absolutely no confidence whatsoever that we stand any chance of combating climate change, other than what will result from the efforts that will be made when it becomes impossible to ignore. Unfortunately by then positive feedbacks will have kicked in - if they have not done so already - and so it will be far too late. "Told you so!" will be very small compensation. I am also only too aware that if Nassim Nicholas Taleb’s Black Swan makes an appearance, it very likely will screw up things completely anyway. In truth, the only reason I keep on fighting is that I want to see all the people that have used (abused?) their positions of influence to put the human species, and with it my children and grandchildren, in this perilous circumstance face a court of law, preferably in The Hague, and be given long custodial sentences ('throwing away the key' length). While I probably may not live to see it, I sincerely hope that they do. -
Charlie A at 08:24 AM on 10 April 20122012 SkS Weekly Digest #14
SkS should be looking at the science, rather than doing science by cartoon. Re: the cartoon with the caption "Evidence is that increased extreme weather is due to climate change" --- it's a cute cartoon, but the message is incorrect. It's not clear who is supposed to be inside the "anti-science bunker". Perhaps it is Joe Romm or the IPCC since the latest IPCC SREX report says in section 4.5.3.3. Attribution of Impacts to Climate Change:Observations and Limitations, "There is medium evidence and high agreement that long-term trends in normalized losses have not been attributed to natural or nthropogenic climate change" And then goes on to say "The statement about the absence of trends in impacts attributable to natural or anthropogenic climate change holds for tropical and extratropical storms and tornados" and "The absence of an attributable climate change signal in losses also holds for flood losses" ------ There is a difference between peer reviewed studies of extreme weather and sensational newspaper reports. IPCC SREX looked at the actual scientific literature.Moderator Response: [JH] My God man, lighten up! -
dr2chase at 07:15 AM on 10 April 2012Eocene Park: our experiment to recreate the atmosphere of an ancient hothouse climate
@BernardJ, #16. I remain grumpy, and your points do little to make me ungrumpy. The people who live in the hottest (hottest+humidest) places on earth now often do not have air conditioning, and often engage in manual labor. They have heat waves, too. Disease vectors need more than just favorable climate. There was a malaria epidemic in Philadelphia in 1780. The town where I went to elementary school used to be called "Yellow Bluff", but yellow fever epidemics (in Florida) made "yellow" a bad word for attracting new residents. It's not just climate; public health is a big part of it, too. We also adapt in more ways than just deploying air conditioning. I grew up, and attended college and gradual school, in some pretty hot and humid places (Florida, Houston). Growing up, I often engaged in actual, outdoor, physical activity. Your body learns to sweat, you learn to drink more, you develop shade-seeking habits, etc. When I return to the ancestral home, it takes a few days for my body to figure out WTF to do, and then it copes. These places are nonetheless well cooler than true tropics. In addition, everything I read suggests that the greatest warming will occur away from the tropics, and recently I've read that jet stream changes around the poles may be the cause of our more extreme hot/cold/wet/dry weather in recent years. Looking at current maps of maximum wet-bulb temperatures, my guess is that if anywhere becomes uninhabitable, it will be places like Iraq (already hot and humid). Brazil's future weather might be like Iraq's weather now, and perhaps Houston will become more like Brazil today, and Washington DC more like Houston. There will be much whining, but Houston is already hot, already urban, already a heat island, and people live there now. An aggressive program of painting roofs and roads white would counter the heat island effect handily at little inconvenience to residents, in Houston and in every other city. I don't think the effort to slow climate change is helped by hyperbolic "we're all gonna die!!!!" pronouncements. There are some low-probability events that really would kill us all (oceans going anoxic). If sea level rise hits the high-end estimates (5cm/year for a century or so), millions of people will need to move to higher ground. But within the predicted range and distribution of future warming (at least in this century, maybe the next), no, the heat will not be a killer. (I'm aware of the killer-wet-bulb predictions. Those are for the case of a 12C rise in global mean temperature. IPCC BAU to 2100 is +4C, right?) -
MA Rodger at 06:50 AM on 10 April 2012Shakun et al. Clarify the CO2-Temperature Lag
John Russell @14 & boba10960 @16 Deary me! There's me calling for precision in terminology & then I call all aspects of the Milankovitch cycles "wobbles." However I think we're pretty much on the same hymn sheet. One thing mentioned but not explicitly is that the 100,000 year wobble (the variation in eccentricity) is by far the weakest yet is the one apparently triggering the recent ice age cycles. The same effect also has a 400,000 beat that is far stronger but I hear say that its effects aren't evident over the last 1 million years. And prior to that time, the more obvious 41,000 year wobble (angle of tilt) appears to have been triggering the ice age cycles back to when the 'modern' ice ages started 30 (?) million years ago. I will be a smart git & say that radial speed of orbit changes more with more elliptical orbit (in the extreme, think of comets) thus winter/summer for a particular hemisphere can vary in length. And there are two components to the precession 'wobble' (orientation of tilt & of eliptical direction) which combine to give a 21,000 year effect. My point here is that it all gets rather complex. That the 'trigger' occurs at the termination of an ice age is something I assume given the saw-tooth temperature profile of recent ice ages but I've yet to encounter authoritative discussion of it. (Perhaps I should emphasis use of the word "authoritative.") -
william5331 at 06:24 AM on 10 April 2012New Understanding of Past Global Warming Events
I'm a tad suspicious of the sudden appearance of land bridges without some sort of proof. However, in a fairly recent copy of New Scientist it was reported that under the sediment in an area between Iceland and Great Britain, sonar studies have discovered a reticulation of river beds. Apparently the hot spot that keeps Iceland above the surface of the earth sent a blob in this direction and there was for a time, land above the sea. Rivers developed and then as the magma cooled, this land sunk. They also point out other areas in the world where they think this is likely. Still not land bridges, though. -
Bob Loblaw at 05:40 AM on 10 April 2012Climate Scientists take on Richard Lindzen
Chris G @23: Are you sure that his 3/4 forcing and 1/3-1/6 observed warming numbers are actually correct?. Does he "show his work"? I wouldn't trust him to have provided accurate information... ...but I agree with your comment about reaching equilibrium. It's sort of like arguing that the bill of sale says the house cost $500k, but that can't be right because you've only paid $30k on the mortgage since you bought it last year. -
boba10960 at 05:08 AM on 10 April 2012Shakun et al. Clarify the CO2-Temperature Lag
@1 geologic “can anyone add detail to how the see-saw works?” Cooling of surface water in the high-latitude North Atlantic Ocean causes the density of water to increase so that it sinks toward the bottom (deepwater formation). The cold water that sinks flows southward, and it is replaced by northward flowing warm surface water. This large-scale process transports heat from the southern hemisphere to the northern hemisphere, making the southern hemisphere cooler than it would be in the absence of North Atlantic deepwater formation. When melting ice sheets add freshwater to the North Atlantic Ocean, the surface water is no longer dense enough to sink (freshwater is less dense than salty water), which stops the northward heat transport, leaving more heat in the southern hemisphere. Thus, according to the Shakun et al. paper, it is the initial melting of northern ice sheets that stopped the formation of deepwater in the North Atlantic, leaving more heat in the southern hemisphere, and causing the early signs of warming to appear in Antarctica. Related to this, one problem with the Shakun scenario is that they invoke an initial reduction in North Atlantic deepwater formation (AMOC - in the penultimate paragraph of their paper) about 19,000 years ago. They cite Pa/Th ratios in North Atlantic sediments as evidence to support this view (their reference 24). However, the actual data in reference 24, as well as sediment Pa/Th records presented in subsequent papers (e.g., J.-M. Gherardi et al., Earth and Planetary Science Letters 240 (2005) 710–723; Gherardi et al., PALEOCEANOGRAPHY, VOL. 24, PA2204, doi:10.1029/2008PA001696, 2009) all show the Pa/Th changing after 18,000 years, or nearly synchronous with the onset of rising CO2. This raises questions about the lags and ocean thermal inertia invoked by Shakun, and it suggests that other mechanisms with faster response times may have been involved. -
danielc at 05:03 AM on 10 April 2012Shakun et al. Clarify the CO2-Temperature Lag
@ Sapient Fridge... wow... sorry about that. Just a typo/brainfart of epic proportions. High Tilt = Warmer polar summer Low Tilt = Cooler polar summer My apologies for the confusion, and thanks for picking that up. -
John Russell at 04:45 AM on 10 April 2012Shakun et al. Clarify the CO2-Temperature Lag
@danielc As someone who spends a considerable amount of time fighting fake scepticism/denial -- call it what you will -- I very much agree with what you say. At my age (semi-retired) I accept I'll never get my head round everything to do with climate but I can clearly see how the jigsaw pieces fit together and the more I understand, the more I can do my bit to correct misinformation wherever it occurs. Like Hansen, I'm driven by concern for my grandchildren's future. -
r.pauli at 04:37 AM on 10 April 20122012 SkS Weekly Digest #14
Everything is a lesson. Lessons not learned will be repeated. -
Sapient Fridge at 04:31 AM on 10 April 2012Shakun et al. Clarify the CO2-Temperature Lag
danielc, I'm a bit confused. Near the top of your post you said "(High Tilt Angle = HTA) the polar regions receive a lot more sunlight in summer" and "(Low Tilt Angle = LTA) the summers are cooler" but further down you seem to have it the other way round:"High tilt = Cooler polar summers coupled with warmer polar winters = ice growth (assuming there are continents around to support glaciers). Low tilt = Warmer polar summers and cooler polar winters = ice shrinkage."
Lack of understanding on my part, or mistake in your post? -
mdenison at 04:14 AM on 10 April 2012Shakun et al. Clarify the CO2-Temperature Lag
#18 Nature link supplementary pdf
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