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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 -
mdenison at 04:10 AM on 10 April 2012Shakun et al. Clarify the CO2-Temperature Lag
... In the same post, Willis Eschenbach criticized the paper saying "My rule of thumb about these kinds of things is, no error bars … no science." ... Not only do such comments ring hollow on reading the paper but a look at the supplementary material shows page after page after page (37 pages) of reasoned discussion, analysis and quantification of the uncertainties in the paper. For those who want a look the supplementary pdf is not behind a paywall. It's hard work reading through it and you may not come away much the wiser but I think you certainly come away with a clear idea of the care climate scientists put into their work. -
danielc at 04:04 AM on 10 April 2012Shakun et al. Clarify the CO2-Temperature Lag
@John, being skeptical is not a problem... it's a requirement to do good science. It's when one hides one's complete unwillingness to admit the reality of solid facts, data, and basic math and physics behind a rhetorical mask of supposed skepticism that problems begin to arise and civility begins to decay. Honest questions deserve honest answers. False skepticism that masks accusations of fraud, dishonesty, lies, and alarmism for political advantage (e.g. Lindzen, Monckton, and the rest) deserves nothing but contempt. -
boba10960 at 04:03 AM on 10 April 2012Shakun et al. Clarify the CO2-Temperature Lag
@9 and @13 I wrote the following before seeing the post @14 by danielc, but I will post it anyway. Three features of Earth’s orbit change in regular patterns: 1) The shape of the ellipse (more elliptical vs. more circular) varies on a 100,000 year cycle, 2) The tilt of Earth’s axis varies on a 41,000 year time scale (the greater the tilt the more sunshine reaches polar regions to melt ice sheets), and 3) Earth’s axis wobbles on time scales of 19,000 and 23,000 years. All three cycles combine to regulate the amount of sunshine reaching high latitude regions in summer, the primary variable regulating the growth and melting of ice sheets according to the Milankovitch hypothesis. Of particular importance is the combination of (1) and (3), whereby maximum melting of northern hemisphere ice sheets occurs when the phase of the wobble causes the northern hemisphere summer to coincide with Earth’s closest approach to the sun during a particularly elliptical orbit. As far as I know, each of the last several ice age termination occurred under these conditions. -
John Russell at 03:57 AM on 10 April 2012Shakun et al. Clarify the CO2-Temperature Lag
@danielc #14 Thanks very much for the very clear explanation. I got it. Apologies if I took it back to basic levels! I really don't understand why so many 'sceptics' claim they've been 'abused' when asking questions on SkS. Ask a straightforward question and you get a straightforward answer. Thanks. -
John Russell at 03:46 AM on 10 April 2012More Carbon Dioxide is not necessarily good for plants.
@Eric #232 You say, "My argument is not that this is good (likely not), but that the net biosphere response will not be 'overwhelmed' as R. Gates puts it, rather the opposite. " It's worth pointing out that R.Gates actually said, "Not only can short-term feedbacks be overwhelmed, long-term biosphere feedbacks might as well" (my bold). It's clear that R.Gates was not suggesting -- nor did I assume -- that a rapid increase in CO2 would lead, necessarily, to a die-back of the biosphere. In the worse case though I'm sure you would agree that it could certainly lead to a die-back of life as we know it. To my mind that's bad enough. We're playing with fire. -
danielc at 03:32 AM on 10 April 2012Shakun et al. Clarify the CO2-Temperature Lag
@John Russell: The tilt and the change of tilt with time actually has a huge impact in several ways. 1) with the rotation axis tilted strongly toward the sun (High Tilt Angle = HTA) the polar regions receive a lot more sunlight in summer, and that sunlight in summer is more direct (more watts/m2). The result of HTA is extreme temp. differences between short hot polar summer and long cold polar winter. The result is ... no ice age - the hotter summer makes more of a difference than a winter that is just a bit cooler. 2) With the rotation axis weakly tilted toward the sun (Low Tilt Angle = LTA) the summers are cooler and the winters relatively warmer, however the short, cool polar summer encourages retention of winter ice and snow, and season upon season, the snowpack grows, compresses and forms glacier ice... LTA appears to correspond well with glacier/ice cap growth. 3) Couple Tilt changes from HTA to LTA with longer and shorter term periodicities in the orbital shape (eccentricity) and precession of the seasons (where in the eccentric orbit the tilted earth faces the sun) and you can map out high-latitude insolation reasonably well. 4) Couple that with the position of continents (Low heat capacity rock at high latitude vs high heat capacity water... as well as a stable platform needed to grow ice caps in the first place) and you start to see strong correspondences between orbital forcing and ice growth or shrinkage. So it is NOT that there is a global heat increase triggered by orbital mechanics!! Given the minor and short term cycling of solar output, the fact is that over long time scales, the total global heat budget is approximately constant. It is that the distribution of heat - the timing of when certain areas get hot, and how hot they get - changes. 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. Juice that system a bit with eccentricity and precession to magnify or dampen the tilt signal... Now, here's the funny thing: currently the earth is head from a high-ish tilt scenario into a lower-tilt scenario... and the polar summers are getting warmer. Either the theory is wrong... or something else is happening! What else could be happening? Well, perhaps the total heat budget being relative stable is no longer operative!!! Adding more heat-retentive materials to the atmosphere, losing heat reflective materials from the polar regions = keep more heat. The heat budget is now in a state of IMBALANCE. Homeostasis (invoked by Lindzen and Monckton) has been disrupted. The current trend of observed year on year and decade on decade temperature and heat changes in particular regions runs counter to what the geological record and orbital mechanics tell us should be happening. -
John Russell at 02:58 AM on 10 April 2012Shakun et al. Clarify the CO2-Temperature Lag
@MA Rodger #9 Apologies for my 'woolliness' -- the result of trying to use simple language! Yes, I was meaning that the sun's output remains constant but, as a result of the orbital cycles, the distance between the sun and Earth (and thus the energy arriving) varies. However there seems to be more to these orbital cycles than you mention. As I understand it our position relative to the sun varies in at least three ways. 1) The shape of the ellipse varies -- sometimes being closer to circular and sometimes being flattened. 2) The position of the sun within the ellipse varies (or more accurately it's the position of the Earth's orbit that's varying), sometimes being nearer the centre and sometimes slightly off to one side. And 3) the Earth wobbles on its axis as you describe, favouring one pole or the other in terms of arriving warmth. I'll stand corrected but I don't think this last variation, 3), is going to be a trigger for a global heat rise, as it's just redistributing the sun's energy from one one half of the globe to the other. So the main cause of an ice age is both 1) and 2) conspiring against us. Is this correct? Sorry if this is a bit simple for some, and perhaps veering a little off-topic. But certainly for me, and probably many other non-scientists, it's useful for basic understanding. -
danielc at 02:50 AM on 10 April 2012Shakun et al. Clarify the CO2-Temperature Lag
http://www.pnas.org/content/105/44/16855.full.pdf+html?with-ds=yes is a good reference for talking about the weathering aspect... Basically, weathering of glacially derived sediments (in moraines) takes ~12 to 25 kyears to run to completion... so weathering and CO2 stripping lags well behind CO2 and T increases... but it does catch up in the end ... as long as no extra CO2 is released. Ooops. -
Eric (skeptic) at 02:30 AM on 10 April 2012More Carbon Dioxide is not necessarily good for plants.
michael sweet, I realize now that thrive is not the right word. The vegetative biosphere will grow net and fill in with plants that can grow in more varying and/or stressed conditions. A lot of those plants will be weeds. OTOH will a little part time effort I can make 5 acres thrive. Full time with equipment I could do 4-5 times that. That will be repeated worldwide on various scales. I also realize there are millions of acres that won't come back to a productive and diverse state, not just because of climate change as you mention but because of CO2 selectivitity. All the papers I referenced back up the reduction in diversity. They also mostly back up the net growth. -
dana1981 at 02:18 AM on 10 April 2012Shakun et al. Clarify the CO2-Temperature Lag
CBD @6 - what I mean is that ~7% of the net warming occurs between the orbital 'trigger' and the CO2 rise. The remaining ~93% of the warming lags behind the CO2 rise (as illustrated in Figure 1). -
michael sweet at 01:56 AM on 10 April 2012More Carbon Dioxide is not necessarily good for plants.
Eric, It is good that you are referencing peer reviewed papers. Your first reference shows that some ecosystems have evolved to survive very hot temperatures. How does this limited example show "clearly that the biosphere will thrive"? Your second reference states "demonstrating the reality of multiple-factor influences, and reminding us that surprises can be expected. I read more "surprises can be expected" not the biosphere will thrive. There is also the strong posibility that what thrives will be jellyfish and the tuna will die out. While lots of jellyfish means the biosphere is "thriving" it is not very useful to those who are looking for something to eat. When you cut down rainforest, jungle grows back. It takes decades, or more, for the rainforest to repair itself. If climate continues to change, the rainforest will never come back. If farmers cannot count on an orchard yielding fruit for 30 years they will not plant the trees in the first place. Few people expect all life on the planet to die off. It is possible that much of the useful life will die off and all that is left is weeds. Can 8 billion people be fed and housed on weeds? -
danielc at 00:58 AM on 10 April 2012Shakun et al. Clarify the CO2-Temperature Lag
@ #4: Silicate weathering. Increased CO2 and temperature cause (among many other things) 1) a decrease of ice cover, exposing fresh rock that was once covered, and 2) enhanced production of carbonic acid (acid rain) in the atmosphere (higher partial pressure of CO2 and warmer temperatures to help drive the reaction H2O + CO2 --> H2CO3 (l). The net result of acid rain falling on fresh rock with small grain sizes is enhanced silicate weathering and net reduction of CO2(atm). This cycle is one of the stronger negative feedbacks that drives the system back toward equilibrium, but it works on a much slower time scale than the initial dumping of CO2, so it takes a while to kick in... -
Eric (skeptic) at 00:15 AM on 10 April 2012More Carbon Dioxide is not necessarily good for plants.
John Russell, thanks for the reply. Other than my work, I spend the largest amount of my time combatting weeds: mulching, pulling, cutting, planting non-weeds, spraying, and burning (in order of preference). The bottom line is clearly that the biosphere will thrive, see http://tbi.montana.edu/topics/inthenews/pdfsdocs/Science_Stout.pdf for one example and figure 1 here http://research.eeescience.utoledo.edu/lees/papers_PDF/Norby_2004b_NewPhyt.pdf for another. But it won't be pretty. Evolution is slow like you say, but infilling with invasives will happen in a few years in an area where native plants are wiped out by climate change effects. My argument is not that this is good (likely not), but that the net biosphere response will not be "overwhelmed" as R. Gates puts it, rather the opposite. -
John Hartz at 00:08 AM on 10 April 2012More Carbon Dioxide is not necessarily good for plants.
Suggested reading: “Which plants will survive droughts, climate change?,” UCLA Newsroom, April 5, 2012 To access this news release, click here -
John Hartz at 00:06 AM on 10 April 20122012 SkS Weekly Digest #14
Speaking of plants… “Which plants will survive droughts, climate change?,” UCLA Newsroom, April 5, 2012 To access this news release, click here
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