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wili at 04:54 AM on 30 May 20142014 SkS Weekly News Roundup #22A
Thanks for another week of well selected articles. Here's my nomination for the next "toon of the week": http://media.boingboing.net/wp-content/uploads/2014/05/1190cbCOMIC-climate-change-deniers.jpg
Moderator Response:[JH] Thaks for the positive feedback and the suggested cartoon.
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John Hartz at 03:39 AM on 30 May 2014The Wall Street Journal denies the 97% scientific consensus on human-caused global warming
SteveFunk:
The Oregon Petition also includes the names of people who have passed away. There's no way to ascertain whether someone who signed the petition a decade ago and subsequently died would hold the same opinion today given the amount of scientific evidence that has accumulated over the past decade.
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howardlee at 02:25 AM on 30 May 2014Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.
mancan18 @13 - Regarding the link between continental breakup, volcanic activity and these LIP & extinction episodes:
LIPs do seem, tentatively, to be concentrated at times when continents are breaking up. But they are caused by mantle plumes that extend from the core-mantle boundary, and not directly with the regular continental drift process.
It's important to emphasise that these LIP monsters totally dwarf any volcanic eruption ever witnessed by humans. In recent decades the total combined annual volcanic greenhouse gas emissions, including undersea volcanics and mid-ocean ridges, are equivalent to the annual emissions of a single state like Ohio or Michigan.
There is an association between long-term CO2 levels, climate, and the total length of subduction zones at any given point in geological time. But the climate is complex, and other factors (rock weathering rates related to mountain building, ocean currents related to continent configuration, life innovations, asteroid impacts...) all interact and play a role in global climate.
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howardlee at 02:02 AM on 30 May 2014Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.
Leland @24 from the Jourdan et al paper: "the Stage 4–5 transition is associated with a global sea-level rise and negative δ13C and positive δ34S excursions recorded in stratigraphic sections worldwide (e.g., Montañez et al., 2000; Hough et al., 2006)." [stage 4-5 is the same time as Kalkarindji.]
Yes we see a pattern of such events. Here's a list grabbed from a couple of papers - note that the dating of some of the events is better than others. The coincidence of LIP and Mass Extinction/Climate event is strongest where the latest high-precision dating has been applied (Permian, Triassic, Mid-Cambrian).
LIP event /extinction or climate event:
Columba River 17ma (Mid Miocene Climate Optimum)
Yemen/Afar 31ma (none?)
North Atlantic 62/56ma ?PETM/Hyperthermals?
Deccan Traps 66ma (Cretaceous extinction precursor)
Sierra Leone 70ma (?)
Caribbean 90ma (Cenomanian/Turonian Anoxic Event);
Madagascar 90Ma (ditto)
Hess Rise 100ma (?)
SE Africa/Maud/Georgia 100ma (?)
Kerguelen 120ma (?Aptian)
Ontong Java 122ma (Aptian Anoxic Event);
High Arctic LIP 130ma
Parana-Etendeka 132ma
Shatsky Rise 145ma
Karoo-Ferrar-Dronning Maud Land 183ma (Toarcian OAE)
Central Atlantic 201 (Triassic Mass Extinction)
Angayucham 210ma (?)
Siberian Traps 252ma (Permian Mass Extinction)
Emeishan traps 260ma (end Guadaloupian extinction)
Tarim 280ma (none?)
Skagerrak- Barguzin–Vitim - Carboniferous Rainforest Collapse (Moscovian and Kasimovian stages);
Viluy - End Tournasian;
Pripyat–Dniepr–Donets - End Famennian–end Frasnian;
Kola/Kontogero - End Frasnian;
Altay–Sayan - End Silurian (?);
Ogcheon S Korea - End Ordovician?;
Central Asian intraplate magmatism - End Late Cambrian;
Kalkarindji - End Early Cambrian;
Volyn - End Ediacaran;(From Kravchinsky 2012 & Bryan and Ferrari 2013) ma= million years ago.
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howardlee at 01:35 AM on 30 May 2014Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.
Billthefrog @16 wow, there's a lot in there! I'll do my best...
The Faint Young Sun Paradox is still just that - a paradox. We know from sediments at the time that there was liquid water and normal sedimentary processes, so the Earth was not frozen solid. The work of William Moore shows that very early Earth was essentially in Large Igneous Province mode all the time. There was a lot of CO2 in the atmosphere as plate tectonics handn't started yet (subduction started ~3.2 billion years ago) so the world was basically covered in volcanic islands, but lacked the large mountain ranges and surface area for weathering to draw down CO2 so fast. Yet experiments on fossil raindrops suggest the atmosphere was not so dense, so alternative atmospheric gas mixes have been inferred. We also know the oceans had about 26% more water in them, so the Earth's albedo was likely much lower. By the time of the ice ages @2.9, & 2.5Ga, subduction had started and continents had grown, and oceans had reduced somewhat, but until oxygen arrived the atmosphere was methane-rich. There's much more than I can fit here and it is still an area of ongoing research, and there has even been a suggestion that the sun back then might have been 5% larger (effectively negating the faint young sun paradox).
Regarding the slow decline of CO2 and temperatures since the Eocene hyperthermals, see this post. This decline has been correlated with a reduction in subduction zone length by Prof Zeebe and others. One critical event was the marooning of Antarctica by continental drift and the establishment of the Antarctic Circumpolar Current 33.5-30 million years ago, but increased weathering (Hymalayas, Andes) had a role. I reccomend THE book on the subject: "Earth's Climate Past and Future" by Bill Ruddiman. Hope this goes some way to answering your post.
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SteveFunk at 01:21 AM on 30 May 2014The Wall Street Journal denies the 97% scientific consensus on human-caused global warming
About 15 million people in the US have science or engineering degrees, excluding social science, according to this census source: http://www.census.gov/prod/2012pubs/acs-18.pdf And since the Oregon petition has been around since 1997, it surely includes a lot of people who were once skeptics but are not now, as well as fake names.
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Leland Palmer at 00:57 AM on 30 May 2014Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.
Many of these extinction events are associated with a Carbon Isotope Excursion (CIE)- a surge in C12 enriched carbon into the active carbon cycle. This C12 enriched (C13 depleted) surge of carbon is best explained by the dissociation of several trillion tons of methane hydrates, many scientists think.
The carbon isotope excursions, the oceanic anoxia, and the low level runaway climate change can all be tied together into a general theory of most mass extinction events, triggered by these flood basalt erruptions and subsequent release of methane from the hydrates.
So, now this middle Cambrian extinction joins this list, it appears. The paper is behind a pay wall, though. Does anyone know if there is a carbon isotope excursion associated with this extinction, and if so does anyone have a link to a paper claiming a coincident CIE associated with this extinction event?
A classic paper on the End Permian mass extinction and the probable role of methane release in that extinction is here:
How to kill (almost) all life - the end-Permian extinction event
" The extinction
model involves global warming by 6 degrees C and huge input
of light carbon into the ocean-atmosphere system
from the eruptions, but especially from gas hydrates,
leading to an ever-worsening positive-feedback loop,
the ‘runaway greenhouse’." -
howardlee at 00:54 AM on 30 May 2014Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.
Tom Curtis @ 15 - I concur. Thanks!
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howardlee at 00:52 AM on 30 May 2014Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.
Chriskoz @20 - That quote is direct from Jourdan et al's paper. The supplementary data can be found at ftp://rock.geosociety.org/pub/reposit/2014/2014190.pdf. see p 15 for randomness calculation.
They admit it is a "crude estimate" but go on to say: "Nevertheless, this series of
calculations suffice to demonstrate that the mass extinctions – LIP association cannot be due to chance with a probability of 6x10-9 % that the synchronicity between LIPs and mass extinctions is random." -
jgnfld at 23:13 PM on 29 May 2014The Wall Street Journal denies the 97% scientific consensus on human-caused global warming
austratsua @4:
It's always nice to be "lectured" on how science _really_ works!
1. Deniers deny. It's a simple, apt, descriptive adjective. And, it's far more apt than "alarmist" as the peer reviewed, scientific literature is remarkably free of alarmism. This can be contrasted to denier blogs stating "the economy will be destroyed" etc. if anything whatever besides business as normal is attempted. All the while ignoring that business as normal carries its own costs which may well "destroy" various parts of various economies, of course.2. Your explanation of how "science progresses by criticism" starts at the wrong place and comes to wrong conclusions. Heliocentrism did not change the course of the planets in the slightest. What heliocentrism did was allow more accurate, easier calculations. Evolution did not change how genes change over time. What evolution does is provide a nice framework for understanding these changes. There is simply NO _theory_ that is going to come along and suddenly make the Earth cool. What could make the Earth cool is various events and processes that are not presently occurring.
3. You don't "criticize" the fact that an apple falls when you drop it any more than you criticize the position of Mars in the sky. You criticize an explanation of why it drops or where the planet appears in celestial coordinates. And interestingly, physicists have really poor explanations--as opposed to very accurate descriptions--of exactly why that apple falls or planet moves.
4. I suggest people taking real science courses from a real scientific sources really do understand the scientific process and the role of criticism within it.
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Kernos at 22:49 PM on 29 May 2014The Wall Street Journal denies the 97% scientific consensus on human-caused global warming
Who are the 3% of climate scientists who deny AGW and what are their reasons?
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Jim Hunt at 22:31 PM on 29 May 2014The Wall Street Journal denies the 97% scientific consensus on human-caused global warming
For the latest news on the consensus amongst IPCC contributing climate scientists see:
"Transformational Climate Science"
Professor Peter Cox of Exeter University "provocatively" states that:Is it still possible to avoid 2 degrees using conventional mitigation? In fact it's likely to be blown out of the water!
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mancan18 at 20:25 PM on 29 May 2014Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.
Thanks Tom
Thanks scaddenp
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Tom Curtis at 19:19 PM on 29 May 2014The Wall Street Journal denies the 97% scientific consensus on human-caused global warming
austratsua @4:
"Are you seriously suggesting that the the earth's climate is as well understood as the heliocentric theory or evolution?"
No, they were not. They were denying that a sample of explicit endorsements as a percentage of the entire literature can quantify the level of agreement among scientists with a theory. Such a method applied to any scientific literature would fail, which is why it is necessary to quantify all endorsements (explicit and implicity) as a percentage of all endorsements plus rejections (explicit and implicit).
Your use of a puerile strawman to distract from the logic of the argument is noted.
'"if the 97% expert consensus is right, it means we’re in for several more degrees of global warming if we continue on a business-as-usual path." This is false. The consensus quoted in your paper said nothing about how much the world will warm in the next century.'
Having taken a stand for emperical science in your first determined attempt at distracting (see my prior post), you now forget that emperical study requires following the implications of a theory. An immediate implication of a low climate sensitivity is that it is not responsible for most of the warming over the last fifty years. The anthropogenic forcings are fairly well known, and coupled with a climate sensitivity would not have produced enough warming to account for 50% or more of the recent warming.
Conversely, with moderate or high climate sensitivities, the projectible changes in forcings with BAU will result in a large temperature response in the 21st century.
That you think otherwise merely shows that you do not follow through to the emperical implications of the theories that you support, or in this case reject.
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scaddenp at 19:07 PM on 29 May 2014The Wall Street Journal denies the 97% scientific consensus on human-caused global warming
I could ask, if coal is cheap, then why do US coal producers need subsidies and protection?
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Tom Curtis at 19:02 PM on 29 May 2014The Wall Street Journal denies the 97% scientific consensus on human-caused global warming
austratsua @4:
"Firsly, it is unseemly to attack people who disagree with you with terms like "denier"."
Firstly, despite your complaint, nobody was called a "denier" in either the original post, nor in the three comments that preceded yours. Rather, it was said that certain people deny certain propositions, ie, they claim that those propositions are false. You are so determined to control the terms of the debate that even use of simple verbs to describe the beliefs of others is now not OK with you.
So, here are two simple questions:
1) Do Bast and Spencer claim that there is not a 97% consensus of climate scientists who agree that >50% of recent global warming was caused by anthropogenic factors?
2) If Bast and Spencer do make that claim, why do you react so strongly against the simple description that they deny that claim?
Secondly, despite you concern about how unseemly the missing attack was, you seem unconcerned that Spenser should refer to climate scientists as "Global Warming Nazi's", unconcerned about Bast's use of billboards to draw a connection between AGW and the Unabomber, unconcerned about the frequent accusations that climate scientists are guilty of fraud (scientific, and less frequently) financial, an unconcerned about accusations that people seeking policy action against AGW are routinely accused of desiring genocide by your fellow pseudo-skeptics. Absent evidence the contrary, in the form of links to comments where you have protested such activity by your fellow pseudo-skeptics, I will conclude that your concern for civility is, like that of most of your fellow travellors, one sided and hypocritical.
The simple fact is that concern about the term "AGW denier" does not arise from genuine feelings of offense. They arise from the same desire to win the debate by persuasive definitions that led pseudo-skeptics to call themselves "skeptics". It is an attempt to controll the debate by controlling the language used in the debate. As with Orwell's "Big Brother", it shows a determination to controll the language to limit what can be thought.
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chriskoz at 18:57 PM on 29 May 2014Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.
Thanks Howard for another innteresting article about extinction.
I want to understand this sentence:
The authors note that the correlation between LIPs and severe extinctions is now so strong that there is a “negligible 6×10–9% probability that such correlation is due to chance alone,”
(my emphasis)
I'm not sure, if you refer to http://dx.doi.org/10.1016/j.palaeo.2012.06.029 as the source of that sentence because I don't have free access to it. So I want to confirm with you wheather this number is or is not a typo. How can we be so sure about the causes of events so deep in the paleo (60-500Ma)? What do you mean exactly by "due to chance alone" and how do you exclude an event so defined with such inbelievably high certainty?
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Doug Bostrom at 18:45 PM on 29 May 2014The Wall Street Journal denies the 97% scientific consensus on human-caused global warming
"cheap coal that could allow them access to clean water and clean air"
That's rather hysterically funny.
Here's what cheap, clean coal looks like in situ where "they" enjoy it :
With regard to risk aversion, we're all in this car together and (to stretch the metaphor) there are no seatbelts. I for one would rather have a cautious driver at the wheel, "inflicting" risk aversion on me, rather than a reckless fool doing the driving.
Doubtless folks wringing their hands about poverty in the 3rd World have already exhausted their own personal means of correcting that problem, for surely they would not be using such an emotional appeal as a cheap rhetorical expediency.
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scaddenp at 18:38 PM on 29 May 2014The Wall Street Journal denies the 97% scientific consensus on human-caused global warming
"Should wealthy risk-averse westerners be allowed to force poverty-stricken Indians and Chinese not to have access to cheap coal that could allow them access to clean water and clean air and a good life?"
Show me where this has been suggested. You could try discussing things seriously instead of jumping into cheap rhetoric. Or do actually believe this from reading misinformation somewhere? In fact the usual suggestion is to let non-Western countries increase FF use while alternatives are slowly brought in while the affluent West very sharply reduce their emissions. That would have been substance of all recent climate conferences.
It would be reasonable to hold alternative opinions to AGW if there was actually some data to support some other idea as opposed to, yes, denialism, and misinformation campaigns. If you really think that this exists by all means present the evidence on an appropriate thread.
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billthefrog at 18:05 PM on 29 May 2014Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.
@Tom & Glenn - Thank you
@ Graham RE: the RCP guide- Wow
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ranyl at 17:46 PM on 29 May 2014The Wall Street Journal denies the 97% scientific consensus on human-caused global warming
"Based on this quote the author is so sure that anthropogenic global warming is true that he thinks it's as obvious as the fact that the earth goes around the sun."
That CO2 is a Greenhouse Gas and warms the planet is as certain as the earth's goes round the sun. And this physical truth of global warming has gone through the progression from hypothesis, to theory, to accepted common knowledge, with all the trials and tribulations of peer review with several counter theories and arguments put against it over some 150years or so.
That this warming is amplified by the earth's internal systems (the climate sensitivity) has also gone through the same rigorous progression.
The uncertainty is how much the earth's internal system amplify the warming and consensus on an exact figure for this is hard to find, for 2 reasons, there are uncertainties in the measurements (like all measurements) and the system is complex and behaves chaotically, meaning that the climate sensitivity is dependent on the initial conditions of the system, in this the earth's continental arrangement, amount of sea ice present, amount of oceanic ice, amount of O2 etc, over geological time and thus is a moving target overall. Being in a time when there is large oceanic ice cover to melt away quickly is suggestive that this might be a time of higher CS than at others. As climate being dangerous, well as in the previous article this week, when CO2 and SO2 are released in large amounts into the atmosphere life can be dramatically reduced it appears, and although that is open to question, as the evidence mounts it is well into the established theory realm and thus most scientist would agree that global warming induced by burning coal can be quite dangerous I would suspect.
Maybe the authors should put out an scientist e-mail and ask several thousand that question sure they find that most would feel that climate change can be very dangerous to life per se never mind a complex civilization with ~50% of its population and more of its wealth near the ocean edge when sea levels are set to rise.
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austrartsua at 15:18 PM on 29 May 2014The Wall Street Journal denies the 97% scientific consensus on human-caused global warming
Wow, where to begin. Firsly, it is unseemly to attack people who disagree with you with terms like "denier". Criticism is central to scientific progress. You never know, you might actually improve your methodology if you listen rationally to criticism. Calling them "denier" and talking about irrelevent facts about their history and rupert murdoch is at best "post-modern" and at worst a cynical attempt to evade the criticism.
"By that standard, there’s less than a 1% expert consensus on evolution, germ theory, and heliocentric theory, because there are hardly any papers in those scientific fields that bother to say something so obvious as, for example, “the Earth revolves around the sun.” The same is true of human-caused global warming."
Are you seriously suggesting that the the earth's climate is as well understood as the heliocentric theory or evolution? Have you heard of scientific fallabalism? It goes like this. A new theory is always assumed to be wrong. This is the default position. Based on this quote the author is so sure that anthropogenic global warming is true that he thinks it's as obvious as the fact that the earth goes around the sun. If all scientists thought this way they would never be able to correct their mistakes and they would hold on to theories no matter what data comes in.
"if the 97% expert consensus is right, it means we’re in for several more degrees of global warming if we continue on a business-as-usual path." This is false. The consensus quoted in your paper said nothing about how much the world will warm in the next century. In fact the criteria did not require any quantification of the amount of warming in the future or in deed in the past 150 years. Accordingly, one could rightly claim to belong to your consensus and still predict relatively little warming over the next century. And then there is the issue of dangerousness. You are right to say that some people are more risk-averse than others. But does this mean that highly risk-averse people should be able to force those who are not so risk averse to pay more for energy? Should wealthy risk-averse westerners be allowed to force poverty-stricken Indians and Chinese not to have access to cheap coal that could allow them access to clean water and clean air and a good life? -
davidnewell at 13:48 PM on 29 May 2014It's too hard
davidnewell at 13:13 PM on 29 May, 2014
As more and more evidence accumulates in regard to the looming catastrophe, more serious consideration may be given to ways to counter at least the rate of increase, so that more time is available to employ other methods, and educate "the masses".Somewhere here someone took some "shots" at the technique found at
WWW.EarthThrive.Net,
mumbling a dismissive comment relating to the amount of CO2 dissolved in the Gulf Stream, or something.. Totally non-bearing on the proposal.
===============
I propose to defend the matter, thru simplicity.l. Many here may find "fault",
but it's hard to argue against this..
=========================
I propose a "new measurement" of alkalinity.
Maybe it's NOT new, but it's new to me, and facile for raising my point.Total Alkalinity, volume, (vs. CO2) = volume of pure CO2 adsorbed / volume of solid substrate
Abbreviated TA(sub)v or TAv, it can be in any dimensional system,
as long as they are "in common". ( of course)My laboratory measurements were in CC.
Ranges of TAv for surface alkali soils ranged between about 2 1/2 to over 3.
(there are speculative reasons to think that lower levels will be more reactive..)
I presently cannot find this (following) calculation, so anyone of interest can do so.
Given the elongated inverted pyramid approximation of (say) the Black Lake Desert,
which is about 25 miles long by 10 miles wide..
Assume that it is a rectangular box 1 mile deep.
Given a conservative TAv of 2.5, what is the weight of CO2 in tonnes possible if all the material was reacted.???????
After that is derived, then we can see if further consideration of the other objections may be warranted.
==============
Lets see: 22.4 liters^ of CO2 = 1 mole wt of CO2, in grams, at STP.
formula wt = 44.grams/ mole
======================
According to my trusty HP-55, which is still running after all these years,
under consideration is 25X10X1, which is 250 cu miles of "dirt",
which can ultimately sequester (with a TAv of 2.5), 625 cu miles of CO2.
1 cubic mile =4.16818183 × 10^15 cubic centimeters
625 " = 2.605113641 x 10 ^18 "
or 2.605113641 x 10 ^15 liters.or (changing decimal pt) 26.05113641 x 10 ^17 liters,
which, when divided by 22.4 liters, = 1.2 X 10^17 moles of CO2,
or, multiplying by the mole weight of CO2, 44,
equals ~5 X 10 ^ 18 grams ,
or 5 X 10^12 tonnes.Anyone who used an HP55 in college is old as the hills,
OVER the hill,
and probably missing a screw, as well..Please point out my errors, other than those which are simple approximations.
=======================
All that is needed, urgently, is to employ a technique
which reduces the rate of increase in circulating CO2,
while "other measures" take effect. If we can take 5 billion tonnes
OUT of the air, per year, we "MIGHT" have a chance.Pumping costs be damned!
AT the very LEAST civilization is "under threat" by our combined ignorance.
(This "rant" is more "refined" at www.EarthThrive.net, so I'l discontinue it,
here..)For far less than Gov Moonbeam's favorite projects of continuing stupidity,
ie the "twin tunnels" under the Delta, and/or the "Train to Nowhere",
we could implement this plan,
AND
(side issue)
produce a hell of a lot of clouds going dowwind.It may be noted that many of the playas (the above is just an example, although one of the larger playas, to be sure..) are "saline" in nature, and are "wet" at some depth under the surface. Maintaining conditions for bicarbonate stability (dampness) is not difficult.
Thank you for your time.David Newell
=================
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scaddenp at 13:15 PM on 29 May 2014The Wall Street Journal denies the 97% scientific consensus on human-caused global warming
Moderation
Moderator Response:OnePlanetForever, please take note and abide by the comments policy, noting especially the section on politics. There are plenty of other sites for political rants. Please stick to the science.
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Glenn Tamblyn at 10:56 AM on 29 May 2014Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.
Billthefrog
Another important event around 30-35 million years ago was the separation of Sth America and Antarctica, allowing the formation of the Antarctic circum-polar current, tending to isolate Antarctica and allowing it to colmore
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scaddenp at 09:44 AM on 29 May 2014Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.
mancan18 - you might also like to have quick look at this guide to the RCPs. Economics would prevent burning everything but working out atmospheric concentrations also require taking into account how the natural systems draw-down (or otherwise) excess CO2. A typical pseudo-skeptic will argue that environment will continue to draw down 50% of emissions, ignoring that as temperatures rise, the oceans eventually emit CO2, rather than absorb it.
You can play with really extreme scenarios but the RCPs are a far better guide to what is realistic (and frightning enough at that).
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billthefrog at 09:41 AM on 29 May 2014Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.
Thanks Howard,
What you say pretty well reinforces what I understood from the Climate Change MOOC I recently did at Exeter University.
The reason I put a question mark on the Palaeoproterozoic snowball/slushball event having primacy was simply cause I don't know enough about the earlier Archean Eon. Could the Faint Young Sun of those far off days have been instrumental in an even earlier snow/slush ball? Do we have enough preserved crust from that long ago to tell? I know that some zircon crystals have been radio-dated at around ~4.3 billion years, but whether there is sufficient preserved crustal material - I just don't know.
Moving to more recent times and the Pleistocene glaciation. If my understanding is correct (cue a huge guffaw from the wife at this point), temperature wise we've been on a downward slope since the heady days of the Eocene. The Indian Plate went sailing full tilt into the Eurasian Plate starting about 65 MYA and causing (initially) a major carbon release into the atmosphere. (Chicxulub, the Deccan Traps and the start of the Himalayan orogeny - a lot of stuff going on about then.)
About 50 MYA, the Himalayas and the Tibetan Plateau had popped up, exposing lots of nice fresh silicate surfaces just ripe for weathering - with the concommitant CO2 drawdown. (I don't really know how much credence is given to the postulated Azolla Event and its resulting major carbon sequestration which is, by some, thought to have happened at about the same time - to within a million years or so.)
Obviously, the continents were still dancing around, getting their rocks off, so to speak. (Stealing a line from the great Terry Pratchet.) However, I understood that it was the sealing off of the Panama Ithmus that was the final piece of the jigsaw that allowed the reformation of massive polar ice sheets.
Have I got that just about right?
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Tom Curtis at 09:34 AM on 29 May 2014Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.
billthefrog @6, while rate of change is the main driver of extinction, the Earth can, and has in the past, reached temperatures where the absolute temperature value drives extinction. The obvious examples are the two slushball Earth episodes discussed by howardlee @12. Equivalent episodes today would extinguish all, or nearly all complex multicellular life on Earth, regardless of the rate of onset.
Of more concern are episodes like the end Permian mass extinction where tropical temperatures rose sufficiently to be seasonally uninhabitable. Global temperatures of about 10 C above the preindustrial will make large sections of the tropics uninhabitable to large warm blooded vertebrates based on absolute values of wet bulb temperature. There is evidence that the absolute limits are to be found for most complex multicellular life at temperatures about that level.
Humans would have to be terminally foolish to raise temperatures so much that absolute limits on temperature become a major factor in extinctions. Currently, however, terminally foolish best describes global policies on geen house gases.
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Tom Curtis at 09:23 AM on 29 May 2014Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.
mancan @18, a worst case emissions scenario would not just consume proven reserves (on which your figure is based) but a substantial proportion of the total resource base (TRB). That is, it will access coal not currently commercially viable either due to increased energy prices, or due to improved technology (such as coal seam gassification). Unsurprisingly, estimates of the TRB are less certain than those for proven reserves. At the outside, determined exploitation of the fossil fuel TRB would lift atmospheric CO2 levels above 5000 ppmv (based on the IEA 2011 estimate). At the low end, determined exploitation of the TRB will lift atmospheric CO2 levels to about 1500 ppmv (based on WEC 2010 figures). The former will raise temperatures to levels at which multicellular life may be impossible - and certainly impossible for large, warm blooded vertebrates such as humans. The later will lift temperatures to levels at which periodic tropical heat waves will result in 100% mortality for large, warm blooded vertebrates. That may be devestating, even apocolyptic for the economy, but should not represent an extinction threat for humans (many of whom live outside the tropics). Intermediate estimates will reproduce conditions very similar to those during the end Permian extinction, making the tropics seasonally uninhabitable for large, warm-blooded invertebrates.
For practical purposes, I do not think these scenarios are relevant in that they would require sustained, high tech exploitation of fossil fuel resources well into the next century - something that may be made economically impossible by global warming, and certainly socially impossible. I think the upper end of realistic scenarios is well represented by the IPCC's RCP 8.5 scenario out to 2100:
Beyond 2100, we will need to reduce CO2 emissons to zero to avoid the very dangerous tail of the RCP 8.5 scenario.
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Tom Curtis at 08:50 AM on 29 May 2014John Oliver's viral video: the best climate debate you'll ever see
BojanD @8, if you are rating abstracts, your task is to assign each abstract to one of seven bins (categories). In doing so, each abstract can only be assigned to one bin; and no assignment can be arbitrary. These two requirements, together with the guidelines on rating abstracts and the descriptions of the rating levels themselves provide an operational definition of "endorses AGW" and "rejects AGW" for Cook et al.
Now, suppose you have an abstract that says in part "40 to 45% of the recent (late 20th century) temperature rise is attributable to anthropogenic factors, with natural factors being responsible for 55-60% of that rise". If we compare the abstract to rating category 7 (rejects with quantification), then we must place this abstract in that bin for it explicitly states, and quantifies, that natural factors are responsible for more than 50% of recent warming.
According to you, however, we must also place the abstract in bin 2 (explicitly endorses without quantification), for (according to you) "endorsing AGW" means anthropogenic factors are "means [are] a cause and not necessarily the main one", and if they are are the cause of 40-45% of the recent warming, they are certainly a cause but not the main one.
That means by your definition, either we must place that abstract in two bins, or the bin we place it in is arbitrary, depending on which bin we compare it to first rather than any particular features of the abstract. As placing an abstract in two bins is prohibitted, and as rating must be non-arbitrary, it follows that your definition is wrong. Indeed, the only definition that does not fall foul of the requirement of exclusiveness of rating (only one rating permitted) and non-arbitrariness is a definition that defines "endorses AGW" as endorsing recent warming to be at least 50% caused by anthropogenic factors.
In one respect, this more precise definition does not make much difference in that we gain the greater precission of definition only at the cost of a potentially greater error rate in classification. That is, with the more precise definition, it is more probable that an abstract that should have been rated 4 was rated 3. However, even if we suppose 50% of all endorsing abstract ratings reported in the paper are in error, and should have been rated 4, that still leave a 96.2% endorsement rate among papers not rated as neutral (compared to 98% reported in Cook et al). Such a 50% error rate is absurdly high, so whatever the actual error rate, the substantial result of Cook et al stands even with the accurate, precise defenition of "endorses AGW".
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mancan18 at 08:24 AM on 29 May 2014Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.
I like following the Skeptical Science discussions but I'm only a lay person with regard to climate science. I was wondering whether there were any studies that related continental drift and the break up of the supercontinents and shifting of the continental plates around the planet to the excessive volcanic activity that led to these mass extinctions.
I know that the IPCC do have a climate prediction outcome for business as usual, but has anyone done a maximum emissions outcome if all the known reserves of fossil fuels are consumed. Also, it seems to me that the only analyses regarding emissions is based on current consumption, where great comfort is taken by deniers that there will be 100 to 200 years of coal left to burn. But, this assumes that the developing nations will remain low emitters per capita. What would happen if everyone in the world were emitting per capita the same as the high emitter per capita countries like Australia or the US? Unlike the CO2 doubling debate, perhaps there also needs to be a worst case maximum emission scenario debate, because this would get to the heart of the equity debate. My simplistic analysis of such a scenario indicates that there would only be about 40/50 years of coal left if we consumed at a maximum emissions rate and we would put the CO2 levels back to the time of the dinosaurs in a very short time. I wonder what the predictions regarding the climate and mass extinctions would be in such a scenario.
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howardlee at 07:49 AM on 29 May 2014Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.
Joel and Bill - There have actually been 2 "snowball" episodes, and a number of major ice ages on the planet, long before the most recent Pleistocene ice age.
About 2.9 billion years ago there was an ice age when microbes evolved methanogenesis, which reduced the CO2 levels in the atmosphere. This was early in Earth's life a time when the sun was less bright than now.
The first snowball Earth (actually more of a slushball because some areas were not frozen) coincided with the rise of atmospheric oxygen around 2.5 billion years ago. The Earth froze because there had been a lot of methane in the atmosphere, which oxidized on contact with the newly-minted oxygen, removing a greenhouse gas blanket and plunging the planet into a deep freeze in 3 separate ice ages spread over 200 million years.
The second snowball Earth (the famous one - but even this was more of a slushball) occurred around 700 million years ago. This was in response to the first greening of land surfaces, which boosted oxygen levels that had been declining since the Great Oxidation Event 2.5 billion years ago. Boosting oxygen once again removed methane that had recovered somewhat as oxygen declined, but more importantly it boosted rock weathering rates which drew down CO2 from the atmosphere. The episode involved at least 3 separate global ice ages, 720-700 million years ago, 650-630 million years ago, and briefly 580 million years ago.
There was another brief ice age around 517 million years ago known as the MICE event in response to the Cambrian Explosion proliferation of life (and probably enhanced biological pump).
There was another major ice age in the Ordovician in response to the rise of vascular plants and the enhanced weathering and carbon drawdown they triggered.
The ice ages in the Carboniferous-Permian were probably a combination of so much carbon being locked away as coal (CO2 levels down to about 220ppm) and the coincidence of high continental areas at the South Pole. There's some suggestion that an asteroid impact may have tipped the balance to ice age at one point also.
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billthefrog at 07:22 AM on 29 May 2014Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.
@ Joel
Oops! I discovered the Snowball Earth site a few years back, but hadn't noticed that it had gone inactive. Mea culpa
NOAA has an interesting palaeoclimatology portal that you might find useful.
Examples of teaching resources covering this material can be found here and here.
A far more detailed description of the first (?) of these events way back in the Palaeoproterozoic Era, the Huronian glaciation, was given in the Proceedings of the National Academy of Sciences.
Hope that helps.
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Chris Snow at 07:14 AM on 29 May 2014The Wall Street Journal denies the 97% scientific consensus on human-caused global warming
Anything that references the Oregon Petition, which claims that 31,000 scientists deny AGW can safely be dismissed as a load of old tosh. As you say, anyone with a college degree can sign the petition. Still, 31,000 sounds a lot until you realise that around a quarter of the US adult population have college degrees. Taking a fairly conservative estimate of 40 million potential signatories since 1998, we get 31,000 / 40,000,000 = 0.0775%. So the 31,000 scientists deny AGW claim is more accurately stated as fewer than 0.0775% of US college graduates since 1998 can be bothered to sign a petition denying AGW, which doesn't sound quite so impressive.
Regarding the 97% consensus, I reckon that here in the UK it's closer to 100%. I can't actually think of a British climate scientist who is a sceptic. Which is why we often end up with someone like Nigel Lawson in the media arguing the sceptic case.
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Alpinist at 06:59 AM on 29 May 2014The Wall Street Journal denies the 97% scientific consensus on human-caused global warming
Another stupid WSJ editorial about climate change. What a surprise. Here's something I posted at RC a couple years ago:
"Sigh, another day, another stupid WSJ editorial…it’s almost as predictable as high temperature records. You might think that the WSJ would be interested in a fact based reality. You would be wrong."
Some things just never go out of style.
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BojanD at 06:11 AM on 29 May 2014John Oliver's viral video: the best climate debate you'll ever see
Not sure I'm following you. I've read the guidelines on rating abstracts and they don't align well with what you're saying here. Just consider that a lot of papers are from the 90s and if the paper from that period explicitly endorses IPCC view (see 3.6), than they endorse the view of the FAR and SAR report and the SAR found discernable influence, not main one. Of course I'm aware that was the state of the climatology of that period, but we're not discussing the evidence here, but the consensus.
I've rated some abstracts myself and there were a lot from the third category implicit endorsement that I've rated as fourth (no position) when the main cause was the issue. If I read "one of the sources of CO(2) and other greenhouse gases (GHG) that influence global climate change", I can't possibly know if this influence is the main one. So Cook et al correctly worded the main findings, but Bedford and Cook didn't, which is surprising, but not that terribly important. -
Joel_Huberman at 02:44 AM on 29 May 2014Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.
@billthefrog - Thanks for letting us know about the interesting Snowball Earth web site. So far as I can tell, though, the last news postings at that site were in 2006. Is there a reason why the site hasn't been kept up? Are there any other sites dealing with the Snowball Earth hypothesis that might provide more current information?
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howardlee at 00:13 AM on 29 May 2014Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.
billthefrog - I think most workers in the field accept the end cretaceous was a "double whammy" - LIP-generated global warming triggering a significant extinction, with the impact dealing a final blow. It's interesting to note that the pendulum is definitely swinging back to emphasize the role of the Deccan Traps LIP as originally highlighted by Gerta Keller.
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howardlee at 00:06 AM on 29 May 2014Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.
Climatelurker - It''s clear that some LIP events have been associated with severe extinctions and others have had more mild extinctions. The Emeishan LIP that occurred just before the Siberian Traps generated global warming and an extinction event much less severe than the Siberian Traps did.
That some LIPs have more severe effects on life than others is a puzzle. It probably relates to eruption rate, presence/absence of organics in the sediments at the LIP location, and other random things. As the authors of one paper noted: "...larger eruptions of flood basalts which clearly had no effect on global ecosystems (e.g. Tarim). The reason why some LIPs are contemporaneous with mass extinctions could be related to random conditions which cannot easily be predicted such as: parental magma composition, geographic location, composition of country rock, or vulnerability of species."
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howardlee at 23:49 PM on 28 May 2014Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.
Villabolo - you are correct for the Kalkarindji LIP - the authors mention oil specifically. In the Permian Siberian Traps LIP it looks like it was mainly coal. In this generalized figure I used "fossil fuels" as a collective noun and to make clear the parallels between the past and today's climate change. In all cases the heat from the magma baked the organic-rich sediments converting them to methane and CO2 (with a host of other nasties mixed in).
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billthefrog at 22:28 PM on 28 May 2014Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.
@ climatelurker
As scaddenp rightly states, rate of change is absolutely critical in terms of extinction potential. In the case of both bolides and mega-volcanism, there is a double whammy. The initial spectacular aerosol cooling is likely to be pretty short-lived, as these particles will not have a long atmospheric residence time. On the otherhand, so-called greenhouse gases have this habit of lingering on, and on, and on...
One of the fingerprints of massive CO2 build up is the presence of cap carbonate deposits, as discussed in this piece from the Snowball Earth site.
Also, the following from the BBC describing some of the dramatic events on the planet's timeline might be of more than passing interest. Scroll down to the bottom of that screen and there are links to various extinction theories (incl climate change) as well as the varying habitats that would have been extant at different times.
Incidentally, I've just noticed that one of the scientists appearing in the BBC video clips (Paul Hoffman, from the Earth and Planetary Sciences Dept at Harvard) is also involved with the Snowball Earth project.
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BC at 13:54 PM on 28 May 20142014 SkS Weekly Digest #21
I couldn't access the first link under El Nino Watch
Moderator Response:[PS] I notice that it is not actually a link. Till author fixes it, try this:
"How El Niño Might Alter the Political Climate"
[JH] The link has been inserted into the OP. Thank you for bringing this glitch to my attention.
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DSL at 13:28 PM on 28 May 2014Antarctica is gaining ice
Anthony, check out the sea level rise explorers here and here to see what a few meters or a few dozen meters of SLR mean for agricultural and infrastructural destruction, and population displacement.
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Daniel Bailey at 13:00 PM on 28 May 2014Antarctica is gaining ice
http://pubs.usgs.gov/fs/fs2-00/
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michael sweet at 12:10 PM on 28 May 2014Antarctica is gaining ice
Anthony,
This SkS thread says tht if Geenland melted it would raise sea level 6 meters. You would expect at least the same amount from Antarctica. Here in Florida a 12 meter sea level rise would inundate 3/4 of the state, home to about 15 million people. Bangladesh would be long gone. That seems like a lot to me. How much is a lot to you?
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Charliec65 at 07:43 AM on 28 May 2014Looking for connections
I agree with placing the growth of the human population into the essay. We're living in a "life bubble" much like our recent financial bubble. We unfortunately don't have a central bank to come to the rescue. The correction will likely be as hard as the beneficial rise as we've experienced over the past 300 years.
Broadly living processes have little capability to control their growth rates. There isn't one life form that fails to over-exploit its environment. We have been shaped by evolution to reproduce, expand into environments, and wage war from verbal to physical when necessary or possible to sustain our groups. Humans like to think of themselves as separated from nature by nurture, but that's a tenuous connection in the best of times.
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scaddenp at 07:29 AM on 28 May 2014Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.
climatelurker - what is important is the rate of change. A rapid change over 3C may have more effect than a very slow change over say 6C. The initial cooling by aerosols and then rapid warming by GHG are probably both important. I think the most useful numbers would be rate of change in forcing (W/m2/century) which is much more informative than % concentration. However, for paleoevents, it is very difficult to get high precision both dating and forcing. CO2 is only indirectly measured by change in a proxy for pH which in itself must have a large time-constant for ocean mixing. Estimating the forcing from aerosols on a volcanic eruption that has never been observed is even more complex. We struggle to measure aerosols even today.
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villabolo at 06:09 AM on 28 May 2014Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.
On the volcanic diagram, in the white box at the lower left, it says "fossil fuels". Shouldn't that read fossil oil instead? It became a fuel from our modern persapective.
Moderator Response:[JH] Nope. Natural gas is a fossil fuel. It is not fossil oil.
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climatelurker at 05:33 AM on 28 May 2014Rapid climate changes more deadly than asteroid impacts in Earth’s past – study shows.
I'm curious what the differential is between pre and post extinction events, if there's a threshold beyond which massive die-off's are (or appear to be) set in motion. Maybe as a percentage of current atmospheric levels, or an absolute change? I've seen there are links to how fast the changes occur, but how much isn't clear (at least not to me). Would love to see an article about CO2 levels at different times, and what they were before and after these events. I imagine such a discussion would have to take into account feedbacks and absorption saturations, et cetera... I can hear the deniers already, "CO2 is already almost saturated! Adding more won't do anything!"
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Anthony10658 at 05:24 AM on 28 May 2014Antarctica is gaining ice
The Vice news program on HBO had an interesting story of how the Glacial land ice is melting in Greenland at a rapid rate. If Greenland becomes green, and all the land ice melts, can we really expect the sea level to rise by that much?
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