Arguments
Recent Comments
Prev 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 Next
Comments 82251 to 82300:
-
jerryd at 01:39 AM on 20 June 2011CO2 Currently Rising Faster Than The PETM Extinction Event
KR - To be honest, this has been very illuminating for me also. I had never heard of "Skeptical Science" before a few days ago when I accidentally clicked Rob's article when searching for something else. I discuss and argue these things with my friends and colleagues all the time, but didn't really think anyone outside our small circle was terribly interested. It's not like the topic will show up on Letterman, although Lee has an article coming out in Scientific American shortly, so who knows ... I think you can access my initial submission (and all the comments, including the imagine harder quote from Lee) as follows: 1. http://www.clim-past-discuss.net/papers_in_open_discussion.html 2. click "most commented papers" 3. third one down I've also sent a copy to John (per previous post) and maybe we can set this into some sort of tutorial for everyone to comment on. Jerry -
KR at 01:09 AM on 20 June 2011CO2 Currently Rising Faster Than The PETM Extinction Event
jerryd - "It's from a paper that should come out in the next month or so in Climates of the Past. Maybe there is a way I can send the figure and paper to this site?" Anything you can point us to, such as a link to the paper, would be great, Jerry. Speaking just for myself, I've found this discussion extremely illuminating! It's always great to hear from someone working with primary data. I had been thinking about the "Antarctica peat" idea, but I suspect you're quite right about the mass balance not supporting that as a major contributor. -
Chris Colose at 01:07 AM on 20 June 2011The Planetary Greenhouse Engine Revisited
guinganbresil, Your post #16 is really just full of assertions rather than any physics that can be usefully implemented in radiative transfer modeling. To treat even an Earth-like atmosphere radiatively can involve treating it as a stack of many near isothermal layers, with the temperature and absorber distribution as well as scattering. The upper atmosphere matters, but you can't just insert a cloud deck and watch the temperature soar to 735 K. Actually, in simplistic layer models with one blackbody absorbing layer, the surface temperature is constrained to be no more than the emission temperature multiplied by 2^0.25. This is especially the case where those clouds also make the albedo very large, and to first-order, offset their greenhouse effect. In post 17, there's no reason parcels of air will become bouyant, since the atmosphere will relax into a temperature required to eliminate convection. Also note that the equation for adiabatic lapse rate is not a function of the IR absorption Of course not, because in deriving that formula you turn off radiation. -
dana1981 at 00:44 AM on 20 June 2011The Climate Show 14: volcanoes, black carbon and Christy crocks
Thanks for giving me credit too, John. First time ever I've been called a "bloke"! -
Bob Lacatena at 00:42 AM on 20 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
178, jatufin, In the misquoted words of Darth Vader, as he tried to line up young Luke Skywalker in his sights and save the Death Star from total destruction:The Dunning-Kruger is strong in this one!
And then he blew poor Skywalker's x-wing fighter to little bits, and the Empire ruled the galaxy for the next 1,000 years. -
Bob Lacatena at 00:35 AM on 20 June 2011CO2 Currently Rising Faster Than The PETM Extinction Event
48, jerryd,With Lee, a classic exchange: "Lee, this is really hard to imagine; Jerry, you need to imagine harder."
This is a fabulous quote, and maybe should be put on a poster for all scientists, as well as anyone interested in climate science -- since both sentiments are keys to solving scientific problems and riddling our way towards the truths, and at the same time doing so in a congenial spirit of adversarial-cooperation. Interestingly, the climate debate is replete with this exact scenario and pair of opposing behaviors, with each component present in due proportion (understand the boundaries, and find the occasional, unexpected ways around them). -
Rob Painting at 23:11 PM on 19 June 2011Linking Extreme Weather and Global Warming
Generally, La Nina (now finished I guess) gives NZ wetter and warmer weather, and El Nino; dry and cool. Last winter was slightly above average, temperature wise. You can find the data at NIWA, but they don't compare the months to the long-term records, which is a bit useless. -
jerryd at 22:39 PM on 19 June 2011CO2 Currently Rising Faster Than The PETM Extinction Event
Rob, Laughing ... one of my favorite movies. The coal argument is an interesting one, but I think very much a "red herring" considering mass balance. The total amount of coal in strata of all ages is <20,000 Gt (Höök et al., Fuel, 89, 3546-3558, 2010). So, I find it difficult to suggest (without a long path through the chocolate factory) that the little bit of coal preserved in late Paleocene rocks, while greater than during some time intervals, is somehow meaningful. Received the email from John Cook and will pass along the paper and figure as it was originally posted on the EGU "open access" journal web site. I don't think there are any copyright issues this way (the final paper is slightly different, because of some corrections). Will be fun to see what people think. Jerry -
Bern at 22:25 PM on 19 June 2011The Climate Show 14: volcanoes, black carbon and Christy crocks
Speaking of long-term trends, has anyone charted the length of The Climate Show per episode? There certainly seems to be a strong recent upward trend, but whether it's statistically significant... :-P Another good show. 'Watched' it while doing some noise modelling work (gotta love dual-screen setups...) -
Rob Painting at 21:58 PM on 19 June 2011CO2 Currently Rising Faster Than The PETM Extinction Event
Jerryd - "I think the press releases for the forthcoming paper by Cui et al. (Nature Geoscience, 2011) initiated this thread." Yup, but I have read the paper. Cui 2011 "imagine" that the Late Paleocene was a 'coal giant'. Maybe you need some of this Jerry? The attraction of the paper was that it was the latest attempt to constrain the rates of carbon release during the PETM. I kinda preferred the organic carbon scenario (warts n'all) because it implied our current emissions weren't quite so bad. And yes, we'd be very interested in your latest paper. John Cook has sent you an e-mail I believe. -
jerryd at 21:28 PM on 19 June 2011CO2 Currently Rising Faster Than The PETM Extinction Event
scaddenp -- jerry - what about multiple event scenario? Elevated carbon in atmosphere, then volcanism in sedimentary basin releasing a spike big enough to trigger hydrate release at poles. With low pole - to equator gradient, the feedbacks release hydrate world wide. On longer term, the elevated temperatures speeded up methane production from sedimentary reservoirs (which are huge by comparison to surface carbon reserves). (This latter is what colleague is pursuing). This is, I think, close to the correct answer. I have made a figure showing how I think things work in the Early Paleogene. It's from a paper that should come out in the next month or so in Climates of the Past. Maybe there is a way I can send the figure and paper to this site? (I am traveling through Europe right now so cannot post on my home site easily). Then, you all can have fun finding the holes and problems in my logic. Jerry -
jatufin at 21:04 PM on 19 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
I have one quite close person, who is intelligent and in many ways open minded. And despise of his lack in education his understanding of scientific matters is well beyond layman. Still he insists, he can trisect an angle with a compass and a straightedge. He is in complete denial about mathematics, which show you can't do it. Neither can he produce any viable proof of the process for scrutiny. It's all about "the conspiracy of the high educated". -
jerryd at 19:47 PM on 19 June 2011CO2 Currently Rising Faster Than The PETM Extinction Event
Tom -- it all comes down to mass balance. There is no way to change the isotopic composition of the huge mass of carbon in the ocean by adding something of similar composition. This gets back to the pool and paint analogy. You have a large swimming pool of very light pink colour (d13C of ~1 per mil). You can add pretty much as much white or light pink as you want (d13C of 0-2 per mil), and the pool gets more full, but the colour does not change very much. You need to add something very red (d13C of -25 to -80 per mil), and still quite a bit, to get the pool to change colour. Following the previous post, Kurtz et al. (Paleoceanography, 2003) did the carbon mass balance exercise for the early Paleogene. They tried to drive the late Paleocene carbon isotope high and the early Eocene low as well as the PETM through formation and burning of peat. It's a very cool idea ... except there is a problem when one looks carefully at the masses involved. The +1 d13C excursion necessitates the storage of about 60,000 Gigatonnes of carbon in peat during the late Paleocene. (Note, this would be storage in a transient surface reservoir -- think of this as a hot tub on the side of the pool. It would not be burial, because the carbon needs to return to the exogenic carbon cycle in the early Eocene to drive PETM, other hyperthermals, and the long-term drop in d13C). The problem concerns the mass. The entire terrestrial biosphere, including soil, humus, peat, plants (and newts) at present-day is on the order of 2000-3000 Gt C. So, if this is the explanation, then one needs to imagine a terrestrial carbon reservoir radically different than present-day (more specifically, at least 5-10 times larger). I think the press releases for the forthcoming paper by Cui et al. (Nature Geoscience, 2011) initiated this thread. If you read the paper, you will see that they touch on this problem toward the end. More specifically, the authors suggest an input of 12,000 Gt C from land to cause the d13C excursion across the PETM; they then note that this is tremendously large compared to terrestrial pools at present-day. I have hassled Lee Kump and Rob DeConto about this mass balance problem (both are friends). With Lee, a classic exchange: "Lee, this is really hard to imagine; Jerry, you need to imagine harder." -
JMurphy at 19:35 PM on 19 June 2011Linking Extreme Weather and Global Warming
Thanks for the info, Rob. Seems to be isolated areas, rather than whole regions or countries, so far ? Any idea what it was like this time last year, or the previous one - if this is not too much off-topic. -
Paul D at 19:31 PM on 19 June 2011The Climate Show 14: volcanoes, black carbon and Christy crocks
Thanks for the applause and compliments :-) -
Rob Painting at 19:18 PM on 19 June 2011Linking Extreme Weather and Global Warming
JMurphy -"I haven't noticed anything to do with abnormally cold temperatures in the Southern Hemisphere"
Brisbane, Australia has been cold by all accounts. Just ask John Cook! In contrast, just across the ditch here in northern New Zealand it was 21 °C yesterday and nudging 20°C today. In the thick of winter! Looks like they're getting the "normal" cold further south in NZ though. -
jatufin at 19:02 PM on 19 June 2011Phil Jones - Warming Since 1995 is now Statistically Significant
165 I would call a man with PhD in his field some frantic hobbyist :) Einstein might has been outsider of the scientific community, but he was very aware of the works of others. He himself stressed intuition, logics and 'inner view'. But the real ground breaking thing, General Relativity (1916) is based on some very serious (and tedious) mathematics. It is also a work of some strange and ultimately genius person, with extraordinary inner view... Maybe one could do great things as hobbyist. But at least you should learn the language professionals use, so you work could be criticized. If your day job is in McDonalds' is rather irrelevant. -
JMurphy at 18:51 PM on 19 June 2011Linking Extreme Weather and Global Warming
With regard to cold Winters, I haven't noticed anything to do with abnormally cold temperatures in the Southern Hemisphere so far his year. I remember that the last couple of years had various local or regional unusual cold periods down there (especially in South America) which were highlighted by some posters as an indication of a coming 'ice-age' but I am more interested in whether there is some sort of link between cold spells in the Northern and Southern Hemispheres, because the UK had two cold spells over the last two Winters too. If there is a link, I look forward to a nice mild Winter again. Or, at least (because it was only really December that was cold here), a milder run-up to Christmas. If there is no link, who knows what the Winter will be like ! -
jerryd at 18:33 PM on 19 June 2011CO2 Currently Rising Faster Than The PETM Extinction Event
The long-term benthic foraminifera carbon isotope record for the Cenozoic is published in Zachos et al. (Science, 2001). An updated benthic foraminifera oxygen isotope record was published in Zachos et al. (Nature, 2008) but without the paired carbon isotope record; however, Jim has put the data on his web site (go to http://es.ucsc.edu/~jzachos/Publications.html, and then to 2008 publications). Interestingly, The first really nice long-term carbon isotope record for the Early Cenozoic was published by Shackleton and Hall (DSDP, 84, 1984). It can be downloaded at: http://www.deepseadrilling.org/74/dsdp_toc.htm The age axis is bit off in the above works, but not by too much. In any case, you will see that, from about 62 to 58 Ma, the d13C of the ocean (~exogenic carbon cycle) increased by ~1 per mil. Then, from about 57 to 52 Ma, the d13C of the ocean decreased by about 2 per mil. The peak in long-term temperature (the EECO) occurs at the end of the drop. Superimposed on the fall in d13C are the carbon injections related to the hyperthermals (i.e., the PETM occurred about half way along the drop). Assuming that the long-term and short-term d13C excursions are related, there is really only one way to explain things. Massive amounts of organic carbon were stored somewhere in the Late Paleocene (this preferentially removes 12C, increasing the d13C of the ocean); this carbon returned to the ocean, sometimes sporadically, during the latest Paleocene-early Eocene. The ideas in both Rob's and Andy's abstracts are appealing in this respect. Store a bunch of peat or gas hydrate, and then return it. However, I think the peat idea has some serious mass balance problems. -
Gwinnevere at 17:42 PM on 19 June 2011The greenhouse effect is real: here's why
Hello (no41) MoreCarbonOK; Yes. It is definitely man-made. The reason that any one of us — capable of performing basic calculations in mathematical physics (apart from reading the many convincing linked/argued documentations in Skeptical Science on the many details from many research groups) — can know why we certainly are on the right path in addressing Global Warming to Anthropogenic causes, is this one — please, MoreCarbonOK, and do tell your friends about it too: With a general human evolution of technology (illustrating image as below, details in AGW, the energy curve basic function as y=a[1–1/(1+[x/b]^n)], n=2, its derivative gives the effect [power] transient [ocean heat absorption, value 0,878 W/M² period 2000-2010, fairly in accord with other sources (Hansen group 2005), also in line with a more simple evaluation from Stefan-Boltzmann-radiation law, provided a correct interpretation], its integral gives the carbon-dioxide concentration [yielding a 98% match with measured values up to 2009, and further], both latter as long as t is added by fossil-carbon)
Fossil-Carbon curve (black) from WIKIMEDIA COMMONS and RENEWABLE ENERGY — Critical Evaluation of the U.S. Renewable Energy Policy, 2009, respectively
http://commons.wikimedia.org/wiki/File:Global_Carbon_Emission_by_Type_to_Y2004.png
http://www.renewableenergy.typepad.com/
it is IMPOSSIBLE to omit an additional temperature component (t) from a general fossil-carbon combustion temperature (T) from an emitted (combusted) amount (m) of the fossil carbon into the local atmospheric mass locale (M), account taken upon a general emissivity or absorption coefficient (a), simply expressed as
t/T=a(m/M) giving t = Ta(m/M)
[Temperature and Energy are proportional — as in the familiar General Gas Law: pV=kT=E giving T=E/k].
With account taken for thermal resistance
(R=t/P, P the irradiating power from the Sun: t catalyzes a thermal resistive increase from the already given irradiating Solar power)
the expression enhances to yield for a double
t := 2Ta(m/M)
[Of course, as long as a T exists (for fossils roughly around 2000-2200 °C), also a t inevitably will follow. But with no T (or a very low negligible value of it), also no t will be added: zero AGW].
With the given industrial fossil-carbon curve and its adopted mass-scale to fit the general energy-curve (E), m/t can be calculated [adopted value from 2005 as (average yearly scale base) 10.17094 T12 KG/°C, T for 10^+, with the reported yearly ca m=7 T12 KG fossil carbon to the measured total GW of ca t=+0.7°C], and (with a general Earth-based a=0.7, meaning ca 0.3 albedo) also M can be calculated [value 3.52138 T16 KG to be compared to the total atmospheric EarthM=5.3 T18 KG].
With simple figures [density at STP (Standard Temperature and Pressure) everywhere the same] M holds only at most h=60 meters above the solid Earth-surface to account for the measured t(AGW)-curve
— which (hence) excludes any AGW-debate on higher lying atmospheric layers (type Christy’s arguments, but also Lindzen’s »climate sensitivity»): these may (and do) contribute, but have no significance in the AGW-basics.
With a 50 pixel graphical square unit to draw from, and taking a more or less »simple» ocean (two-complex) period of type (cosx)+(cos3x) [coefficients must be added to get a scaling match to the other given curves] together with the basic t|E-smoothed fossil-carbon component, in all
y = 6[1-1/(1+[x/10]^4)] + 0.222(0.9[(2cos (pi x/1.48)) + 0.5(cos (3pi[x-0.1]/1.48))]),
or the corresponding now-year-based connection as
t(NASA)
= –0.4
+ (1.765)[1–1/(1+[(YEAR–1815)/212.7]^4)]
+ 0.0653(0.9[(2cos pi (YEAR–1880)/31.48)+0.5(cos 3pi[YEAR–1880-0.1]/31.48)])
we have the dotted (5) from the already known and well recognized sources (as) in
http://www.universumshistoria.se/AAAPictures/AGW1.htm
[The NASA-curve is reduced to 65% horizontally to match the time scale of Fossil-Carbon; The Fossil-Carbon vertical scale is then reduced to 33% to match (a closest possible approximation to) the (t|E)+(SeaPeriod) = NASA-curve vertical scale].
And as we clearly can see, the predictive power is unmistakable — however no account taken upon additive (radiative forcing) components (making the figure even worse); There is, obviously, only one known agent to account for the measured Global Warming:
industry. Safely. Exactly. Precisely.
While humanity is bound to the E-part of the t|E-function, it is necessarily not so to the t-part if, and only if, a solution is found in reducing the fossil energy source. (Meaning: we cannot stop human evolution, but possibly we can find another energy source than fossils to feed our [unstoppable] technological evolution, thereby removing a further t-increase).
Christy and Lindzen give wrong arguments (causing public chaos) because they do not account for the (unnoticed but simple) math-base (t/T-form) making up (an unmistakable equivalent to) the measured NASA-curve: the industrial fossil-carbon driving the whole (land-marine max height=60 meter) measure.
Radiative Forcing high above the Earth surface is explicitly not within the basic AGW-proof (the t/T-form giving a max h=60M), and therefore makes no contribution to the clarification of the AGW-quest itself. (Debates on the subject, not distinguishing the different aspects, make dead-end discussions).
AGW is no natural variation.
Hence, AGW cannot be explained by the general math referred to as Arrhenius’ expressions (often termed »radiative forcing» and associated with the higher atmospheric layers).
To explain (mathematically) for AGW, hence, a strict isolated mathematical-physical complex must be found (»no Arrhenius math»), including all the seven (7) known ingredients to the observed (A)GW-complex [and too, it must include »Arrhenius curves» as a special case if given specific offsets — so is also the case, indeed]. That is what the simple t/T-connection does — with a seemingly fine alignment to already presented figures.
wkg/Gwinnevere
-
guinganbresil at 17:10 PM on 19 June 2011The Planetary Greenhouse Engine Revisited
"An adiabatic lapse rate only needs to develop by convection where air parcels at the surface become buoyant with respect to the air above it. In an infrared transparent atmosphere with no sources and sinks of energy, convection would eventually give out and the tropopause would migrate to the surface, developing a deep isothermal region." This is a very one-dimensional view... A planetary atmosphere is on a sphere illuminated by a sun - resulting in heat sources and sinks from differences in insolation from day to night and season to season. The natural state of a non-trivial planetary atmosphere has a lapse rate in the troposphere. In this imagined isothermal atmosphere, any vertical movement of parcels of 'air' would necessarily result in a change in internal energy, and heat transfer to or from the parcel - moving the temperature distribution toward the expected temperature lapse rate. In other words, this isothermal atmosphere can only me maintained if there is no vertical exchange in the atmosphere. Also note that the equation for adiabatic lapse rate is not a function of the IR absorption - monotonic gases like Argon still have a significant adiabatic lapse rate. -
trunkmonkey at 16:58 PM on 19 June 2011CO2 Currently Rising Faster Than The PETM Extinction Event
scaddenp Doesn't explain dC13. Not a really great idea. Pretty much untestable even if it were. Just threw it out in the spirit with several other folks thinking outside the box. -
Rob Painting at 16:56 PM on 19 June 2011Linking Extreme Weather and Global Warming
Tom Curtis @ 52 - I'm going to cover a couple of those papers in the next chapter on Amazon drought. The key point, as you mention, is that ENSO variability depends on the mean state of the tropical Pacific. When the tropical Pacific is cool (as in the MWP) the frequency/intensity of ENSO declines (although there still can be some pretty wild swings). When the tropical Pacific is warm then ENSO ramps up. That's what the proxies indicate. -
Tom Curtis at 16:01 PM on 19 June 2011Linking Extreme Weather and Global Warming
Eric (skeptic) @53, looking at Gergis and Fowler, and regardless of when the anthropogenic signal was strongest, the entire twentieth century has been unusually warm relative the the preceding 375 years, and the period since 1940 has been unprecedented in the last 485 years for the tropical Pacific, which was quite cool during the MWP. Consequently the fact is that 43% of extreme events occur in the warmest 21% of the time reconstructed, and that 30% of extreme events occurred in the very warmest 12.8% of the time. Not only that, but the coldest period, also experienced unusually low numbers of extreme events, particularly El Nino's relative to other periods:"Our results are consistent with the conclusions of D’Arrigo et al. (2005) concerning solar/temperature related modification of ENSO behaviour. Periods of inactivity were identified throughout the record; most notably, during the 1600s ENSO appears to have weakened, coincident with the height of the commonly defined Little Ice Age (∼A.D. 1550–1850) and Maunder Minimum (∼A.D. 1645–1715) epochs. Hendy et al.’s (2002) coral Sr/Ca SST reconstruction shows northern Australian SSTs 0.2◦ to 0.3◦C cooler than the long-term average between 1565 and 1700. This corresponds to enhanced La Niña activity in our reconstruction (1520s to 1660s) and a period of relative El Niño quiescence from the 1600s to 1780s."
Consequently it is grossly misleading to suggest that this evidence is based on a correlation over just 30 years; and while, as is true of all empirical evidence, it could be just the result of an accidental correlation, it is likely (>66%) that the correlation between increased tropical SST and increased ENSO activity and intensity is not coincidental. In fact, where it not for the fact that we clearly do not fully understand the mechanisms involved, I would say it is very likely (>90%). If you wish to claim that is not a fair range on our certainty, you need to present some substantial evidence. -
scaddenp at 14:59 PM on 19 June 2011CO2 Currently Rising Faster Than The PETM Extinction Event
truckmonkey, and that explains the dC13 how? Also to create significant amount of C14 would suggest radiating the earth in a way that would be somewhat deadly for all land fauna. -
dhogaza at 14:25 PM on 19 June 2011Linking Extreme Weather and Global Warming
Does anyone have any data showing an increase in snowfall with an increase in winter temperatures?
You're looking too narrowly. The big nor'easters that hit New England are sorta hurricane wannabees that start in the Atlantic off the SE US coast or further south. They then roar north and dump snow when they hit arctic air sitting over NE (or further south). It doesn't matter if winter temps increase, as long as they're low enough for snow to fall. -
Eric (skeptic) at 13:36 PM on 19 June 2011Linking Extreme Weather and Global Warming
Tom (#53), that might be suggestive as the authors state, but post 1970's when AGW was a clearer factor the El Nino & La Nina sample size is very small (can't rule out coincidence). -
Eric the Red at 12:50 PM on 19 June 2011Linking Extreme Weather and Global Warming
Sphaerica, More data showing the relationship between winter temperature and snowfall. This is mainly due to more days above freezing. http://www.cleanair-coolplanet.org/information/pdf/winterindicators_09.pdf Does anyone have any data showing an increase in snowfall with an increase in winter temperatures? -
trunkmonkey at 12:32 PM on 19 June 2011CO2 Currently Rising Faster Than The PETM Extinction Event
jerryd Wouldn't pelagic carbonate(shallow photosynthesizing silicic slab carbonates)be your red and benthic clay carbonates (marls)be your white? It seems photosynthesis is the isotopic filter. Getting way out there even for me, cosmic rays turn nitrogen into carbon 14, which becomes co2 for a half life of 5700 years. After a burst ceases it all decays innocently back to nitrogen (who me?)with paleoclimatologists none the wiser. -
Tom Curtis at 12:18 PM on 19 June 2011Linking Extreme Weather and Global Warming
Further to my 52, here is a bar chart from Gergis and Fowler showing the number and intensities of El Nino and La Nina events for each century over the indicated period. The lack of weak events in the 1500's is probably a function of reduced proxy number and quality in that period, but through out the rest of the record, weak events vary in approximate proportion with strong events, and strong events increase in frequency in the 20th century, the opposite of what we would expect if the change in frequency was an artifact of the proxy record. What the data shows is that with warmer conditions, both El Nino conditions and La Nina conditions become more frequent, and that the stronger events become more frequent relative to the weaker events. Also, the increase of frequency of El Nino events is slightly greater than that for La Nina events.
-
Mike Palin at 12:00 PM on 19 June 2011Who's your expert? The difference between peer review and rhetoric
A measure of the impact of a research article is the number of citations it receives in the peer-reviewed scientific literature. These are imperfect because of the difficulty of separating positive and negative citations (self-citation can be more easily filtered), but such numbers are routinely used to estimate quality of ones work in making a case for promotion or other research assessment exercises. Citations are also used as a measure of the "impact factor" of various scientific journals. -
Tom Curtis at 11:59 AM on 19 June 2011Linking Extreme Weather and Global Warming
Badgersouth @51, a search on google scholar for the terms ENSO & ("global warming" v "climate change") 2009 or later produces the following articles of interest: Models: Latif and Keenlyside, "El Niño/Southern Oscillation response to global warming", PNAS 2008 Collins et al "The impact of global warming on the tropical Pacific Ocean and El Niño" Nature Geoscience 2011 Both indicate that models disagree about the effects of global warming on the ENSO. Historical: Gergis and Fowler "A history of ENSO events since A.D. 1525: implications for future climate change" Climatic Change 2008 Gergis and Fowler indicate a significant anthropogenic effect on El Nino intensities:"Although extreme ENSO events are seen throughout the 478-year ENSO reconstruction, approximately 43% of extreme and 28% of all protracted ENSO events (i.e. both El Niño and La Niña phase) occur in the 20th century. The post-1940 period alone accounts for 30% of extreme ENSO years observed since A.D. 1525. These results suggest that ENSO may operate differently under natural (pre-industrial) and anthropogenic background states."
Doran et al "Analyzing ENSO Period Changes in a Proxy Record Spanning the Last Millennium" Geophysical Research Letters 2009 Doran et al indicate a change in the frequency of ENSO shifts:"The time series model analysis of the Palmyra corals shows ENSO period changes that are similar to the broad patterns observed in the wavelet analysis (Figure 2). ENSO periods are generally higher during the pre-1850 interval (μ = 6.4 years, σ = 1.9 years, N = 9), while periods post-1850 are lower (μ= 4.0 years, σ = 0.60 years, N = 4). This 2.4- year decrease in ENSO period from pre-1850 to post-1850 is statistically significant (p < 0.1). In particular, three of the four estimated ENSO periods in the post-1850 interval are at or below the lower limit of periods observed pre-1850. Additionally, there is a shift in ENSO period at 1700 that is more pronounced than the shift observed at 1850. This earlier shift may reflect changes in forcing, such as increased volcanic activity..."
Li et al "Interdecadal modulation of El Niño amplitude during the past millennium" Nature Climate Change 2011 Li et al conclude that warmer conditions are correlated with enhanced ENSO variability, a finding in agreement with Doran et al. I am making no claim to expertise, so I can't say that these studies are representative, and for most of them I have read only the abstract so I can't comment on their validity. They are, however, consistent with the evidence as I have seen it summarized. -
guinganbresil at 11:59 AM on 19 June 2011The Planetary Greenhouse Engine Revisited
The "Greenhouse Effect" is an imprecise term. The effect of an atmosphere on the planet's surface temperature is affected by multiple atmospheric constituents. Greenhouse gases are the most obvious and most discussed, but suspended particles including liquid droplets, ice crystals, aerosols and dust also contribute. In the case of Venus, the top of the clouds are obviously opaque in the spectral region shown in figure 1 above. The regions in which CO2 is transparent show an emission brightness temperature corresponding to the temperature of the cloud tops. The contributions of different greenhouse constitutents are not additive. The CO2 in Venus' atmosphere only contributes to the planetary emission spectrum above the cloud tops - all the CO2 below the clouds does not affect the outgoing planetary spectrum. If one were to keep all else constant and replace all of Venus' CO2 below the 1 atmosphere altitude with dirt, the new equilibrium surface temperature would be a little less than Earth's, and the emission spectrum would be essentially the same. (Yes, I am ignoring the effect of the blocking of the very long wave emissions seen from Venus through the clouds - that is not the point...) The point is that the high surface temperature on Venus is clearly a result of the thick dense atmosphere through the lapse rate, and the IR absorption of CO2 is not a significant factor. -
John Hartz at 10:56 AM on 19 June 2011Linking Extreme Weather and Global Warming
What are the latest findings on how the ENSO is being impacted by climate change? What's the most recent SkS article on this issue? -
Tom Curtis at 09:35 AM on 19 June 2011CO2 Currently Rising Faster Than The PETM Extinction Event
jerryd @38, I do not follow your reasoning. First, you state that the d13C of Cabonate is from 0 to 2. It is not possible that carbonate on the floor of the Tethys was closer to 0 per mil and hence depleted in C13. It seems that given the range of d13C concentrations you give for Carbonate, you cannot run the argument that you run against Kent and Muttoni. Second, given that the floor of the Tethys was carbon rich because it was a shallow, life rich sea, does this not suggest that Tethys carbonate is likely to have been C13 depleted relative to other carbonates? -
chris at 09:34 AM on 19 June 2011CO2 Currently Rising Faster Than The PETM Extinction Event
Sphaerica at 23:51 PM on 18 June, 2011 "Is it possible that carbon existed in some form prior to the PETM which we no longer see in noticeable quantities today? That is, could there have been some sort of release mechanism which entirely escapes our imagination, exactly because it all "let loose" during the PETM?" There is a possible answer that was reported at the American Geophysical Union in December which fits your question. Quoting from a write-up in Science by Richard Kerr (see page 142) reporting on a couple of talks on the PETM:"In the next talk, paleoceanographer Robert DeConto of the University of Massachusetts, Amherst, and his colleagues claimed that a larger source of carbon dioxide in Eocene times would have been the permanently frozen ground of polar regions. No ice sheets covered polar ground in Eocene times, and the land area of Antarctica was far larger than it is today, DeConto said. That would have made for widespread permafrost, storing organic matter that—if thawed and decomposed—would yield large amounts of carbon dioxide. In their model, extremes of orbital variations caused permafrost to melt in summer and release its carbon dioxide. Enough would have come out fast enough to drive the observed warming, DeConto said."
That would fit your scenario...except perhaps the bit about "entirely escap(ing) our imagination"! Another group (A. Ridgewell et al) also suggest a role for Milankovitch cycles (earth orbital varibility) in the PETM:"Ridgwell and his colleagues included orbital variations in a computer model of early Eocene climate, when the world was slowly warming under a strengthening greenhouse. When the orbital variations in the model combined to make an extreme contrast between summer and winter temperatures, the model's ocean circulation would slow and stagnate. That allowed the deep ocean to warm, warming the sea floor. And that's where natural methane hydrates reside—the “ice that burns.” Warm them and they decompose into water and methane. That methane can escape the sea floor, oxidize to carbon dioxide, and warm the world."
The role of orbital cycles as a factor in the PETM is quite appealing since the timescales (few thousands of years) are appropriate. -
JMurphy at 09:31 AM on 19 June 2011Linking Extreme Weather and Global Warming
adrian smits wrote : "All I said was it appears cooler temps seem to create more violent weather events than a supposedly warming climate!" Rather than relying on appearances, can you provide any backing for any hypotheses you may have, especially if you believe that the global climate isn't warming ? -
scaddenp at 08:50 AM on 19 June 2011CO2 Currently Rising Faster Than The PETM Extinction Event
Further thought - Kent and Muttoni are assuming carbon from carbonate, but could also be subducting a pile of carbon-rich sediment, pushing them rapidly through the oil/gas window. -
chris at 08:41 AM on 19 June 2011CO2 Currently Rising Faster Than The PETM Extinction Event
jerryd at 07:49 AM on 19 June, 2011 O.K. that's very interesting jerryd. I haven't looked at the d13C data associated with the entire Paleocene/Eocene period with consistently raised [CO2] (rising to a maximum at the EECO). Do you have a paper/link where the long term d13C data are compiled? I guess the implication is that at least a good chunk of the increased [CO2] during this period was biogenic. And a couple of questions arise. Why were [CO2] levels maintained so high (2500-3000 ppm apparently) during this period? Was weathering particularly inefficient for some reason? And does the low values for d13C apply to the full period (from around 65 MYA to 50 MYA) or does it drop particularly during the apparent rise of [CO2] during the period ~ 55-50 MYA? There's no question that the d13C data are a fantastic bonus with which to supplement proxy data for absolute [CO2]. I have to say the Kent and Muttoni hypothesis is rather appealing since it does seem to provide a coherent explanation for post-Cretaceous [CO2] data, but if it's not consistent with the d13C data then that's not too good for the theory. Sounds like a promising area for further thought! -
scaddenp at 08:37 AM on 19 June 2011CO2 Currently Rising Faster Than The PETM Extinction Event
jerry - what about multiple event scenario? Elevated carbon in atmosphere, then volcanism in sedimentary basin releasing a spike big enough to trigger hydrate release at poles. With low pole - to equator gradient, the feedbacks release hydrate world wide. On longer term, the elevated temperatures speeded up methane production from sedimentary reservoirs (which are huge by comparison to surface carbon reserves). (This latter is what colleague is pursuing). -
Tom Curtis at 08:36 AM on 19 June 2011Linking Extreme Weather and Global Warming
Norman @42, I'm glad you posted that quote as it tells my your source is rubbish. This is not because it assumes that because a certain type of event has had a natural cause in the past, that therefore it cannot have an anthropogenic cause in the the present or future. That fallacy is equivalent to a doctor assuming that because a cough can be caused by the common cold, that therefore your cough could not be caused by tuberculosis and ignoring all other symptoms. Rather it is because your source does not know that the Southern Oscillation and the El Nino effect are just two sides of the same coin, ie, the atmospheric pressure effect and the thermal effect of the El Nino Southern Oscillation. A source that cannot get that right is sure to miss such subtleties as that historical and some model evidence suggest that increased global temperatures are associated with an increased frequency of El Nino conditions. They are also likely to miss, as you have, that El Nino's are associated with East coast, not SW coast droughts in Australia, and the the drought in SWWA has persisted in through this very strong La Nina year. In fact the persistent reduction in rainfall in SWWA is most probably a result of a southerly shift in the prevailing westerlies due to the Hadley cell getting larger - almost certainly a consequence of, and historically associated with rising global temperatures. -
Bob Lacatena at 08:12 AM on 19 June 2011Linking Extreme Weather and Global Warming
[Previous comment was a response to 46, Eric the Red] -
Bob Lacatena at 08:12 AM on 19 June 2011Linking Extreme Weather and Global Warming
From Bednorz, the first paper you linked (emphasis mine):Precipitation is also an important factor in the ‘non-active’ regions. Only at the beginning and at the end of winter is air temperature the dominant parameter of snow-cover formation in northwestern Europe. In the middle of winter, when the temperature is well below zero, the increases in snow-cover depth are mainly controlled by precipitation (Clark et al., 1999).
It's also important to note that that is a study of past climate, in a relatively steady, stable regime (1960-1993), in a very localized area (E. Europe). There is little that can be better than simplistically inferred from it about the impacts of serious climate change on global snowfall (or snowfall in other regions of the globe). The same applies to your second paper, which studies the period from 1901-1994, and only in Switzerland. While temperatures did rise in that period (at most, 0.5˚C), I believe the extension of what is viewed there to the globe, under a dramatically changing climate regime and greater temperature increases (and accordingly greater precipitation pattern changes) is unwarranted. In general, I believe your logic that overall snowfall will be diminished by the factor of the later onset of winter (cooler temperatures) and the early onset of spring (warmer temperatures) is valid, but the assumption that this factor will completely override any accompanying increases in precipitation during the winter months (due to other factors, such as specific humidity, and circulation patterns such as the Hadley Cell changes) is unwarranted. -
jerryd at 07:49 AM on 19 June 2011CO2 Currently Rising Faster Than The PETM Extinction Event
I just read the Kent and Muttoni paper (PNAS, 2008) ... It's interesting. However, I think the hypothesis is demonstrably wrong. Here's why: 1/ The long-term maximum in Earth surface temperature over the last 80 million years or so occurred at about 50-52 Ma. For better or worse, we call this the Early Eocene Climatic Optimum (EECO). 2/ I entirely agree with the paper that this peak in warming was associated with high amounts of carbon in the exogenic carbon cycle. There are several good arguments to support this notion. 3/ However, the d13C of carbonate is around 0 to +2 per mil (depending on age). (For those that I have lost here, see below). 4/ This means that, if the temperature rise was driven by CO2 from carbonate, there should be no significant change in the d13C of the exogenic carbon cycle. (The ocean having a d13C composition of nominally +1 per mil). 5/ In fact, the d13C of the exogenic carbon cycle reaches a prominent low at 50-51 Ma. This implies that the source of carbon was very depleted in 13C; that is, most likely related to organic carbon. Basically, there is no way to add massive amounts of carbon to the exogenic carbon cycle from carbonate and have a prominent long-term d13C excursion. **** After numerous scribblings on wet napkins, and trying to explain carbon isotopes and the carbon cycle, here's my best effort. Carbon has two stable isotopes, 12C and 13C. The ratio of these two isotopes is typically expressed in terms of d13C, with carbonate close to zero. Various reservoirs (ocean, biosphere, atmosphere) have different d13C. For whatever reason, it seems much easier for most people to think of things where carbon reservoirs are pools, and carbon isotopes are white (12C) and red (13C) paint. Consider the ocean as very light pink. Carbonate is white; organic carbon is red. The Kent and Muttoni paper suggests that massive amounts of white are added to a very light pink reservoir. It implies that the pool should become lighter. The geological record shows that, instead, the pool becomes a deep crimson. -
Eric the Red at 07:47 AM on 19 June 2011How would a Solar Grand Minimum affect global warming?
yes, Since the last half of the 20th century was a time of high sunspot activity, a period of low activity would help set the bounds of the relationship (if any) between the sunspot cycle and global temperatures. -
Eric the Red at 07:22 AM on 19 June 2011Linking Extreme Weather and Global Warming
There are several reference to the relationship between temperature and snowfall. Those areas which are belwo freezing for most of the year will likely see an increase in snowfall as temperatures approach freezing. Thesse areas are few. The rest will experience more days above freezing, and hence more rainfall amd less snowfall. http://onlinelibrary.wiley.com/doi/10.1002/joc.1014/pdf http://www.springerlink.com/content/k631170346751481/ -
Eric (skeptic) at 07:02 AM on 19 June 2011Linking Extreme Weather and Global Warming
A proxy for poleward migration of the subtropical jet (i.e. expansion of the Hadley cells) is lower stratospheric cooling at 30 degrees latitude, see http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-11-00027.1 The TLS plot showing latitude cross section does show some slight cooling at 30 degrees:
ignoring the two volcanoes. But that cooling seems to have leveled off.
-
adrian smits at 06:54 AM on 19 June 2011Linking Extreme Weather and Global Warming
When you're talking about the current temperature it should have a bigger impact on the weather than the 5 year average temps. All I said was it appears cooler temps seem to create more violent weather events than a supposedly warming climate! -
Norman at 06:36 AM on 19 June 2011Linking Extreme Weather and Global Warming
Sphaerica @41 Here is an interesting article on Hadley cells. Info on Hadley Cells. -
Norman at 06:31 AM on 19 June 2011Linking Extreme Weather and Global Warming
Tom Curtis @ 37 Here is some information you may find useful. History of Australia's droughts and causes. You may want to look at page 3 and below to see if global warming is causing an increase in severity of Australian droughts. Here is a quote from that page: "Many scientists believe that human activities associated with the generation of ‘greenhouse gases’ are causing climate change. (See STUDIES 2/2000.) This, however, does not cause drought as it has been experienced in Australia over thousands of years. Natural climate change in Australia is caused by two major elements – the changes in the pressure of air in the atmosphere circulating between Tahiti and Darwin (measured by the Southern Oscillation Index – SOI); and the temperature of currents moving across the equator from South America to the area to the north of Australia (known as the El Niño effect)."
Prev 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 Next
