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My oh Miocene!

Guest commentary by Sarah Feakins

Our recent study in Nature Geoscience reconstructed conditions at the Antarctic coast during a warm period of Earth’s history. Today the Ross Sea has an ice shelf and the continent is ice covered; but we found the Antarctic coast was covered with tundra vegetation for some periods between 20 million and 15.5 million years ago. These findings are based on the isotopic composition of plant leaf waxes in marine sediments.

That temperatures were warm at that time was not a huge surprise; surprising, was how much warmer things were – up to 11ºC (20ºF) warmer at the Antarctic coast! We expected to see polar amplification, i.e. greater changes towards the poles as the planet warms. This study found those coastal temperatures to be as warm as 7ºC or 45ºF during the summer months. This is a surprise because conventional wisdom has tended to think of Antarctica being getting progressively colder since ice sheets first appeared on Antarctica 34 million years ago (but see Ruddiman (2010) for a good discussion of some of the puzzles).

Where did this record come from?

The ANDRILL program is a multinational collaboration involving scientists from Germany, Italy, New Zealand and the United States to drill through ocean sediments around Antarctica. The drilling effort in the austral summer of 2007 involved a rig perched upon the Ross Ice Shelf, drilling down through the ice, 400m of water below that and then grinding down 1km into the sediments. The sediments are bagged and then transported back to the storage facility in Florida from where they are parcelled out to analysis laboratories across the world.

It can take years to process all this sediment and perform all the compositional, elemental and isotopic analyses that need to be done. Numerous scientists work on getting the most information possible out of the core. One of the early findings was the unexpected discovery of abundant pollen in the Miocene part of the core by Sophie Warny (Warny et al, 2009). The pollen came from types of tundra vegetation and indicated summer temperatures above freezing, which was also inferred from the presence of freshwater algae.

After Sophie found the pollen, I began to search for molecular fossils of those same plants. The waxy coating of plant leaves is remarkable for its resilience in sediments. In addition those leaf wax molecules capture an isotopic record of past rainfall. It is these isotopic signatures that allow quantitative insights into temperature and rainfall.

To extract the leaf waxes we don’t look for visual fossils, instead we use organic solvents to dissolve and extract the leaf waxes out from the sediments. Those organic molecules are then purified by passing through a series of filtering steps in the lab. Ultimately we wind up with a pure concentration of the leaf waxes which can be analyzed by mass spectrometry (see photo).

How are the results interpreted?

The leaf wax hydrogen isotope evidence was interpreted in comparison to model experiments. Jung-Eun Lee (JPL) conducted experiments, after adding water isotopes into a model dubbed GRAM (Frierson et al, 2006) because it requires a gram of computational effort rather than a ton in a full general circulation model. With the aid of the isotope-enabled model version, iGRAM, we can simulate the movement of water around the planet and track the water isotopic signatures. The goal was to see if modern relationships between different points in space that have different isotopes in precipitation and temperature are valid when we instead consider changes at the same point over time. Model experiments suggested a small upwards tweak in the temperature reconstructions for the Miocene from 2ºC to 7ºC. These experiments also reveal the dynamics behind the isotopic values: more evaporation from the warmer high latitude oceans and increased rainfall at high latitudes. (Ed. In similar experiments for Greenland (Werner et al, 2000), the changes in the seasonal cycle were important in understanding the isotope paleo-thermometer).

The iGRAM model is however an idealised aquaplanet, (i.e. no continents at all) so it isn’t useful for the interior of Antarctica, but deep sea records suggest that glacial ice volume was about 50% of modern volume at that time. It is however difficult to do full general circulation model experiments for this period because of the difficulty of constraining boundary conditions in the Miocene – what the land surface looked like, what greenhouse gas levels were, etc. An aquaplanet is perhaps good enough for these tests as conditions at the coast are really set by the oceans.

In terms of figuring out how the climate system operates, temperature is one of the simpler variables to reconstruct (not that any of this is really simple). Figuring out how precipitation changes is harder, largely because models can’t capture the scale of clouds let alone raindrops. What the leaf waxes provide is an archive of the isotopic composition of precipitation – much as the ice cores do for the past million years. Of course an ice core is not as simple as a rain gauge, and a plant has biology that an ice core doesn’t, but crucially if plants are growing, leaf waxes are probably preserved in sediments allowing us to push these isotopic records back beyond the ice core records to address questions about what climate was like further back in time.

How robust are these results?

What is reassuring here is that all the lines of evidence presented, from various microfossils, molecular fossils, isotopes and model experiments, all point to temperatures at the coast of Antarctica reaching above freezing point in summer months, probably around 7ºC (45ºF).


Downcore results through the Miocene section show at least two periods of exceptional warmth.

It is in those warm, periods further back in time, that might help us understand a little more about how warmer climate systems operate, and that information might just be important as we contemplate our future.


References

  1. S.J. Feakins, S. Warny, and J. Lee, "Hydrologic cycling over Antarctica during the middle Miocene warming", Nature Geosci, vol. 5, pp. 557-560, 2012. http://dx.doi.org/10.1038/NGEO1498
  2. W.F. Ruddiman, "A Paleoclimatic Enigma?", Science, vol. 328, pp. 838-839, 2010. http://dx.doi.org/10.1126/science.1188292
  3. S. Warny, R.A. Askin, M.J. Hannah, B.A. Mohr, J.I. Raine, D.M. Harwood, and F. Florindo, "Palynomorphs from a sediment core reveal a sudden remarkably warm Antarctica during the middle Miocene", Geology, vol. 37, pp. 955-958, 2009. http://dx.doi.org/10.1130/G30139A.1
  4. D.M.W. Frierson, I.M. Held, and P. Zurita-Gotor, "A Gray-Radiation Aquaplanet Moist GCM. Part I: Static Stability and Eddy Scale", Journal of the Atmospheric Sciences, vol. 63, pp. 2548-2566, 2006. http://dx.doi.org/10.1175/JAS3753.1
  5. M. Werner, U. Mikolajewicz, M. Heimann, and G. Hoffmann, "Borehole versus isotope temperatures on Greenland: Seasonality does matter", Geophysical Research Letters, vol. 27, pp. 723-726, 2000. http://dx.doi.org/10.1029/1999GL006075

193 Responses to “My oh Miocene!”

  1. 101
    Ian says:

    Ray Ladbury (#98) comments that Dr Christy cherry picked the 1930s as being an anomalous decade. Well not really for if the current or previous decade is showing the same pattern it clearly won’t be anomalous. Will it? In any event whether or not the weather events in the 1930s are anomalous, it shows that extreme weather events have occurred in times not currently thought associated with climate change caused by human actions. Obviously if a pattern of events similar to the events in the 1930s occurs now, why would this be anymore influenced by human actions than in the 1930s? Why shouldn’t the events now be due to the same causes as in the 1930s? Obviously thaty possibility couldn’t be ruled out. Could it? I’m sorry but I don’t understand why selecting the 1930s is cherry picking

  2. 102
    Jack Maloney says:

    Update for #91 and #92 from WUWT:

    An issue has been identified in the processing of the data used in Watts et al. 2012 that was placed online for review. The authors are performing detailed reanalysis of the data for the Watts et al. 2012 paper and will submit a revised paper to a journal as soon as possible, and barring any new issues discovered, that will likely happen before the end of September.

  3. 103
    Hank Roberts says:

    > if the current or previous decade is showing the same pattern
    > it clearly won’t be anomalous. Will it?

    Depends. What has changed since the 1930s?
    Assume for now the 1930s was wholly natural variation, ignoring the CO2 increase to that point.

    Assume for now the current variation is wholly natural, ignoring the CO2 increase to this point.

    Does that make sense to you?

    Now, assume the current variation includes the expected effect of increased CO2, on top of natural variation. How much of today’s conditions would you attribute to the change in CO2? How much of today’s conditions would you attribute to natural variation?

    Now, what if you take the assumed natural variation from the 1930s,
    and add to that the variation expected from the increase in CO2 since then.

    What conditions would you expect today, adding both together?

  4. 104
    SecularAnimist says:

    Ian wrote: “Why shouldn’t the events now be due to the same causes as in the 1930s? Obviously that possibility couldn’t be ruled out. Could it?”

    What you are saying is that we can’t rule out the possibility that the gigatons of carbon that human activities have added to the Earth’s atmosphere over the last century has NOT had the effect that basic physics tells us it MUST have.

    It’s up to you to explain how that could be possible.

  5. 105
    Unsettled Scientist says:

    Ian says>it shows that extreme weather events have occurred in times not currently thought associated with climate change caused by human actions

    Congrats, this is well known by the climate science community. Find me any climate scientist who has said extreme weather events have *not* occured in the past, uninfluenced by human driven climate change. You won’t find one. It is not logical to X event occurred in the past without human influence therefore humans cannot do it.

    High speed hadrons collide all the time without humans having done it in the past. We do it with super colliders now. Mountains fell under natural processes in the past, we use dynamite now. Are these events just part of the natural pattern? That something in past occurred due to different causes does not rule out the current scientific consensus of the cause. These aren’t new questions you are posing, they have been dealt with decades ago.

    You fell on your face once when just walking and tripping over your own feet. Today I stick my leg in front of yours and you fall on your face. Obviously I had nothing to do with, it was just a natural event because in the past you have fallen on your face without me intervening.

    Need more examples of this logical fallacy?

  6. 106
    t_p_hamilton says:

    Ian said:”He clearly showed that these extreme events had occurred at least as frequently in previous years notably the 1930s. The data he presented were very persuasive.”

    Actually, Christy did not show any such thing. Many US stations started taking data around 1900, a few following decades were very cold because of extensive volcanic activity. It is no surprise that the 1930’s which had little volcanic activity, poor land use leading to dust storms, and a short number of years to “beat”, had record temperatures.

    See the realclimate article http://www.realclimate.org/index.php/archives/2011/11/on-record-breaking-extremes/

  7. 107
    Unsettled Scientist says:

    Oooooh, I just thought of a good example for the logical fallacy that because events (such as warming or extreme weather) have occurred in the past due to natural causes means that humanity cannot cause them. Earthquakes! I like it because it is a phenomenon that covers a huge area. The Earthquake happens in DC/Virginia and people in New York feel the shaking. It was SciFi to think of the military creating an space-based earthquake gun (Under Siege 2). But we do it now with fracking. Pump a ton of water and other junk down into the Earth, boom, earthquake!

    Now I can already predict some saying that fracking doesn’t cause earthquakes. That too is an analogy to the climate debate. On mainstream news television you’ll see people claiming it’s not true that fracking causes earthquakes (or that AGW isn’t real). Neither of these are the interesting scientific questions anymore. It’s been studied and a consensus built. The interesting scientific problem now is predicting the magnitude of the earthquakes.

    Method predicts size of fracking earthquakes

    In news media you’ll see debates about whether fracking can cause them, whether AGW exists. This does not reflect the scientific discussion.

  8. 108
    Ray Ladbury says:

    Ian, it is not just the decade that is cherrypicked. Whenever a denialist focuses on the 1930s as the worst ever, they also focus on the continental US. The 1930s were indeed extreme…in the US. And it was extreme for cold as well as warm. But the US is not the world, and when you have records being not just broken, but shattered on a yearly basis, and when high temperature records are outnumbering low records 20:1, then a curious mind…one not blinded by ideology…might wonder what is going on.

  9. 109
    John E. Pearson says:

    101 Ian says: ” In any event whether or not the weather events in the 1930s are anomalous, it shows that extreme weather events have occurred in times not currently thought associated with climate change caused by human actions. Obviously if a pattern of events similar to the events in the 1930s occurs now, why would this be anymore influenced by human actions than in the 1930s?”

    Ummm. What gave you the idea that the dust bowl wasn’t influenced by human actions?

  10. 110
    Jim Larsen says:

    107 Unsettled said, “I can already predict some saying that fracking doesn’t cause earthquakes.”

    Well, your phrasing is misleading. The total quantity of earthquakes is set by continental drift. So, one can have a HUGE earthquake which kills thousands and destroys much property, OR one can have a hundred small earthquakes which do nobody any harm. I’d say that causing hundreds of earthquakes is a GOOD thing. Wouldn’t you?

  11. 111
    Patrick 027 says:

    Re my 85″There’s of course the cooling of the underlying lithosphere after it forms, too.” – not to give the impression that lithospheric mantle is simply rock formed from magma deeper under the surface – my understanding is that it is the leftover rock from partial melting that produced the magma to form crust; it is to at least a large extent that which didn’t melt in the first place (I think) and is just cooling because it’s been brought closer to the surface in the process of mantle convection. Anyway, back to extreme weather etc…

  12. 112
    Ian says:

    On second thoughts perhaps I will be given the chance to answer some of the critics. Comment 109 asks “Ummm. What gave you the idea that the dust bowl wasn’t influenced by human actions?” If this poster had read what I wrote this comment would, perhaps, not have been made. What I actually said was “..extreme weather events have occurred in times not currently thought associated with climate change caused by human actions”. Comment 108 implies I have “a mind blinded by ideology”. I could say that any one who cannot see that previously there have been extreme weather events not due to human production of CO2 but still seems to believe that current events can only be due to human CO2 production, also has a mind blinded by ideology. Christy clearly shows that since the 1930s extreme high temperatures have been and still are declining. The increasing ratio of high to low temperatures in the recent decade could well be due to human factors such as land clearing not human CO2 production. Comment 104 is more an article of faith than a reasoned scientifically based assessment. Comment 106 cheerfully ignores the Stromboli eruption of 1930 which, according to the author, should have lead to colder following decades. However several of these decades were still warmer than currently is the case. Why is that? Comment 107 clearly shows the author is responding to something i didn’t say. He states the logical fallacy that previous events cannot have been caused by hunan action. I actually said “not currently thought associated with climate change caused by human actions”. I guess that’s enough but I hope that this post isn’t deleted because it argues a case that isn’t compatible with the preconceptions of those that usually post to and possibly those that moderate, this site.

  13. 113
    Hank Roberts says:

    > a HUGE earthquake … OR one can have a
    > hundred small earthquakes

    Citation needed. You’re claiming:
    large quakes can be prevented by fracking
    equating the energy released by a hundred small harmless quakes to that from a single damaging quake.

    That’s incredible.

  14. 114
    Unsettled Scientist says:

    Ian, please explain the substantive difference between “In any event whether or not the weather events in the 1930s are anomalous, it shows that extreme weather events have occurred in times not currently thought associated with climate change caused by human actions. Obviously if a pattern of events similar to the events in the 1930s occurs now, why would this be anymore influenced by human actions than in the 1930s? Why shouldn’t the events now be due to the same causes as in the 1930s? Obviously thaty possibility couldn’t be ruled out. Could it?” and the implication that humans are not the cause. What are you trying to imply here?

    An honest reading is that you are saying since it happened in the past due to natural causes, we cannot rule out human causes. Modern climate science has specifically done just that, ruled out the natural causes of climate variation. Are you just looking to get a basic understanding of climate science in general? Some causes of change are natural, some are human causes. It sounds like you started off with Christy “frying” modern climate science, but now are saying you don’t know the first thing and are looking for what could cause climate to change at all? I have a feeling you’re just playing a semantical game and aren’t really interested in learning how we are causing the climate to change right now.

  15. 115
    Hank Roberts says:

    OK, Ian, you managed not to dismiss my question to you in 103; the others ask basically the same thing — do you understand that the change in CO2 changes the temperature, and that’s added to natural variation?

    If you don’t believe CO2 changes the temperature, then yes, you can believe what’s happening is the same thing both in the 1930s and the 2010s.

    Add the change from increased CO2 to the natural variation.

  16. 116
    t_p_hamilton says:

    Ian claims:”Comment 106 cheerfully ignores the Stromboli eruption of 1930 which, according to the author, should have lead to colder following decades. However several of these decades were still warmer than currently is the case. Why is that?”

    Stomboli has been continuously erupting, and with very low explosive index. There are even categories of VEI which are called Strombolian. Google image search with “20th century volcanic forcing” shows clearly volcanic forcing (which is negative) around 1900 is larger than at mid 19-th century.

    Ian cheerfully ignores what else I said, one of which is that number of record is not equal to number of extreme events. To keep it simple imagine how many records are set in the first year of a station? Answer: 365 high records and 365 lows (unless it is a leap year)!

  17. 117
    t_p_hamilton says:

    oops, mid-19th century should be mid 20th century.

  18. 118
    Hank Roberts says:

    Oh, I see Ian has blown off the science about CO2 and temperature with “Comment 104 is more an article of faith than a reasoned scientifically based assessment. ”

    Ian, you should read Spencer Weart — first link in the right sidebar under Science — which explains the science and how it has developed.

    Whoever’s telling you the science is ‘faith’ hasn’t read it.

  19. 119
    Unsettled Scientist says:

    Indeed Hank! Citation very much needed. Jim Larson @110 has mirrored the “it’s good for you” argument of the AGW denialati. Since I preemptively stopped the “fracking doesn’t cause quakes” argument, we skipped right to “it’s good for you.”

    Jim, please prove me wrong. I love learning about the natural world, so if there is peer reviewed science out there saying fracking reduces the frequency of “HUGE” earthquakes, I would love to learn about it. If this is true, wouldn’t it be smart to pump water into the California ground to cause a lot of small earthquakes?

  20. 120
    Ron R. says:

    Ian: To say I was surprised to see my comment (#89) had been published would be an understatement so thank you for that.

    Ian: I hope that this post isn’t deleted because it argues a case that isn’t compatible with the preconceptions of those that usually post to and possibly those that moderate, this site.

    Ian apparently has been given a load of bull about RC.

    Anonymous Coward: I’ve had comments suppressed on RC. It’s not because I’m a denier (I’m not).

    Same here. Numerous times. Does it bother me? Not in the least. I don’t know how many posts don’t make it through. I suspect most everyone has had posts not published.

    One has to keep in mind that this is a blog with a moderator and he/she is within his/her rights not to publish comments that are not contributing to the discussion at hand, otherwise it would be chaos.

    That said, my feeling is that RC usually bends over backwards to try not to censor, thus we see OT comments and poorly thought out arguments fairly often. One senses though that the moderator(s) are allowing them with a certain gritting of the teeth. Perhaps censorship prevents people from making a public fool of themselves.

    Helpful hint: Relax, unclench that anus and don’t take yourself, your wisdom or your supposed importance to the world tooo seriously and you will be fine.

  21. 121
    Steve Fish says:

    Earthquake facts and fiction from the USGS for Jim Larsen.
    http://earthquake.usgs.gov/learn/topics/megaqk_facts_fantasy.php

  22. 122
    Hank Roberts says:

    So which “Jim Larsen” are you? Several people by that name have rather responsible positions related to climate or public policy and blog quite a bit, but there’s no way for us to tell who’s who from the name alone. Your background would help understand where you might be getting the estimates you’re quoting, if you care to tell us what source you’re relying on and if it’s someone else’s policy paper.

  23. 123
    Jim Larsen says:

    ” If this is true, wouldn’t it be smart to pump water into the California ground to cause a lot of small earthquakes?”

    Yes, I’ve read exactly that, though it was long enough ago. Basically, every small earthquake could be said to have prevented/reduced a larger earthquake at a later date. I’ll wander the web and see what is available, but essentially I’m starting at zero. I’ll let you know what I find, if anything.

  24. 124
    John e Pearson says:

    112 Ian prebvaricated “On second thoughts perhaps I will be given the chance to answer some of the critics. Comment 109 asks “Ummm. What gave you the idea that the dust bowl wasn’t influenced by human actions?” If this poster had read what I wrote this comment would, perhaps, not have been made”

    I read and quoted precisely what you wrote. “In any event whether or not the weather events in the 1930s are anomalous, it shows that extreme weather events have occurred in times not currently thought associated with climate change caused by human actions. Obviously if a pattern of events similar to the events in the 1930s occurs now, why would this be anymore influenced by human actions than in the 1930s?””

    Are you claiming or not claiming that the dust bowl was not influenced by human actions. My reading is that you are making the implicit claim that the dust bowl was not influenced by human actions. If you are not claiming that the dust bowl was not influenced by human actions then I have no idea what you are talking about.

  25. 125
    flxible says:

    “Basically, every small earthquake could be said to have prevented/reduced a larger earthquake at a later date”
    Pure baloney, and you’ll not find any support for that idea at any earth science site. Take the time to read the link Steve Fish gave at 121.

  26. 126
    Unsettled Scientist says:

    >Jim Larsen says: I’ve read exactly that. But I’m essentially starting at zero.

    I guess you missed both requests for a citation. Here’s a third request for some peer reviewed science saying exactly that. Not sure what you mean by starting at zero, does that mean you didn’t read exactly that ? Either way we await any actual evidence from the literature.

  27. 127
    Patrick 027 says:

    Re Ian – “I could say that any one who cannot see that previously there have been extreme weather events not due to human production of CO2 but still seems to believe that current events can only be due to human CO2 production, also has a mind blinded by ideology.

    Few if any people believe that the only reason the Earth continues to rotate and the moon still raises tides and water still boils at ~100 deg C at sea level, is that humans are propping it all up with CO2 emissions. More to the point, of course some extreme events would be happening now without anthropogenic CO2 or anthropogenic anything for that matter. But humans have pumped CO2 into the atmosphere (and other things) and this has effects. You can see the ‘bite’ CO2 takes out of OLR in spectra from satellites, and this is as can be predicted, and given the shape of that bite, and the shape of the absorption spectrum which produces it, a doubling of CO2 will under present Earthly conditions (be careful about applying this to Venus, etc.) block some 3.7 +/- 0.5 W/m2 of OLR, global average (going from memory here)(this is something that can be calculated – although great accuracy requires a lot of number crunching, the underlying physics and math is simple – thermodynamics via Kirchoff’s law (of thermal radiation), conservation of energy via Schwarzchild’s equation) (after stratospheric adjustment) – meaning that if nothing else changes, Earth’s climate system (below the tropopause) heats up at that rate. Well if you gain heat, either the temperature goes up or you melt something, or both, etc. Temperature increase increases OLR and that’s how equilibrium is restored, although the amount of change required can be amplified or reduced by other feedbacks; models with known physics, paleoclimatic evidence, and historical observations all suggest a net positive feedback (after the Planck response) and they converge toward the same range.

    With temperature increasing, the saturation vapor pressure of H2O increases – not that the atmosphere tends toward 100 % RH everywhere – some parts are actually very dry, but that’s understandable given the way air circulates and given precipitation – but generally the atmosphere will gain H2O and water vapor provides concentrated heating mid-air in updrafts; the water vapor abundance changes the convective energy flux differently than it changes the energy available in the air and so this affects the circulation. surface albedo feedback and effects on when and where sea ice occurs affect horizontal temperature variation, and this affects the circulation. Circulation affects where precipitation occurs. There’s more than just temperature change that happens; but if you raise the temperature and hold variability constant (not that variability can’t change), you get fewer extreme cold spells and more frequent and more intense heat waves.

    Starting with the basics, you could expect short-term variability in the midlatitudes to be reduced with GHG, H2O feedback, and aerosol cooling effects on DTR, and also a reduced overall temperature variation pole-to-equator, reducing the temperature variation associated with air masses and fronts, etc. – however that last part isn’t quite so simple (seasonal, not even over latitude, not the same Northern vs Southern hemisphere – see wind-driven upwelling, etc., there’s probably other stuff) – but changes in precipitation location and timing can cause drying in places – is expected to – and if that regionally reduces H2O vapor and cloud cover, you can get larger DTR and without evaporative cooling, extreme heat waves can amplify. Also warmer winters can lead to more snowfall, up to a cutoff point. Greater available latent heat may fuel more intense extratropical and tropical cyclones. From some physics of atmospheric circulation, a given SST anomaly should tend to cause greater impact in atmospheric circulation (ENSO-style) when it is on top of a higher average temperature. This isn’t quite as simple as the basic ‘more GH effect = higher temp’ and there’s a lot I’m not sure about offhand, but there are people who study it.

    Christy clearly shows that since the 1930s extreme high temperatures have been and still are declining.” – Does he? Globally? Christy isn’t exactly a go-to source for me – please explain how he does this.

    The increasing ratio of high to low temperatures in the recent decade could well be due to human factors such as land clearing not human CO2 production.” – fine if you have no data to go on; why ignore the body of knowledge already gained. Was there a recent boom in land clearing in the U.S.? What effect would that have?

    Not on the point of extremes but more generally, it should be pointed out that there are differences in the spatial-temporal effects expected of different forcings, and this is used in attribution studies.

    Comment 104 is more an article of faith than a reasoned scientifically based assessment.” – See Hank Roberts @ 118 and my first paragraph – it deserves emphasis.

    He states the logical fallacy that previous events cannot have been caused by hunan action.” – Do you mean (according to someone else) that human action couldn’t have been a factor 80 years ago? Or 200 years ago? 5000 years ago? No, of course it was a factor in some things, though of different kinds and sizes (for climate, global average anthropogenic forcing has increased a lot since 1930). Much of the last 800,000 years, not as much. Hundreds of millions of years ago? Well I don’t think Emmitt Brown ever took the Delorean there.

    The logical fallacy being addressed was that just because something that happened was not caused by humans in the past doesn’t mean humans can’t cause it now (in fact it helps us understand what effects we may have – CO2 changed naturally in the past – although usually much more slowly). A related point is that even if natural variability is still occuring, it doesn’t mean there isn’t a human effect (see above)(and there are attribution studies – people don’t just assume this stuff – although if we had no such work to go on, it would still be the safer bet (and we have to make the bet, we’re in this world and living requires decisions) that anthropenic forcings are having effects similar to what is expected based on known physics) – perhaps this may be more directly related to your statements.

    the preconceptions of those that usually post to and possibly those that moderate, this site.” – assumes opinions were arrived at without much care – your preconception, apparently.

  28. 128
    Patrick 027 says:

    Re Ian specifically on the Dust Bowl – well, yes there were human effects aside from global average climate forcing. I don’t know all the details of that. However I thought natural variability did play a role too (in that it was hotter than otherwise – and globally there was a bit of a peak relative to the forced trajectory sometime around then, although … ?) – but anyway, it was quite hot in the U.S. in particular. So with it being hot now, this time in association with greater global average temperatures, there may be differences in what to expect but also perhaps similarities to what happened then. However similar it may be, a big difference is that it won’t simply end it 10 years and not come back for another 70. I think it may be here to ~stay, except for a few anomalously cool years sometime in the near term (because variability isn’t gone), and barring a refreshing supereruption.

  29. 129
    Hank Roberts says:

    for John and Ian both — the dust part of the dust bowl was certainly worse due to the transformation of the buffalo prairie first by market hunting, then by pure stupidity, burning and grazing.

    After that came the “sodbusters” — who were misled, to their misfortune, into destroying the roots after the earlier colonists had destroyed the above-ground part of that ecosystem.

    Google the phrase “rain follows the plow” for that.

    The temperature swing at the time was what it was — Ruddiman’s work suggests anthropogenic warming started well before the 1930s, but it was a small addition to the natural variation at the time; now, it’s bigger.

  30. 130
    Jim Larsen says:

    Hank, I’m nobody in particular and have zip zero nada qualifications. Everything I say here is mere opinion, and often is just thoughts meant to provoke a discussion.

    I looked around a bit about earthquakes, and the concept of inducing earthquakes via water injection or even just dropping a heavy weight appears valid, BUT….

    first, the magnitudes of devastating quakes are so large that it would take a thousand or a million small quakes to “compensate” for one immense one.

    Next, damage caused by the immense one is an “act of God”, which means it’s blameless, while the damage caused by the induced quakes is actionable. Thus, it is “better” to have thousands of folks killed and a city destroyed than to have 1 person slightly injured in an induced quake. This pretty much precludes significant research on the subject.

  31. 131
    Jim Larsen says:

    126 Unsettled says, “I guess you missed both requests for a citation. Here’s a third request for some peer reviewed science saying exactly that. Not sure what you mean by starting at zero, does that mean you didn’t read exactly that ? Either way we await any actual evidence from the literature.”

    You didn’t read my post very well. I said I read about earthquake mitigation techniques long ago (and merely reading something doesn’t make that something right) and I’d look at what the current ideas are. I did exactly that, and feel I added to the discussion.

    I’m awaiting your citation showing that small earthquakes don’t reduce the stress on faults. Since common sense says that such ought to be the case, I’d say you need to provide citations. If you think my point is wrong, then provide something which substantiates your stance. Otherwise, you’re just wasting bandwidth.

    NEVER NEVER NEVER ask for citations without providing YOUR OWN. (yes, this is one of my pet peeves. I refuse to provide citations to someone who doesn’t provide them herself.)

  32. 132
    Aaron Lewis says:

    Hank, Re 129
    The buffalo prairie also contained a large number of very shallow, perched aquifers resulting from old buffalo wallows. A settler would see a wetland and think there was water. A ten foot deep, hand dug well would yield a bit of water in the wet years, but a drilled well would puncture the bottom of the aquifer, and drain it.

  33. 133
    Patrick 027 says:

    re my – “Starting with the basics, you could expect short-term variability in the midlatitudes to be reduced with GHG, H2O feedback, and aerosol cooling effects on DTR, and also a reduced overall temperature variation pole-to-equator“… It was that last part which pertains particularly to the extratropics, or at least it could in this very basic approach – but note the complexities/caveats…

  34. 134
    Unsettled Scientist says:

    @Jim Larsen, I *did* provide a citation for my claims! I said that fracking causes earthquakes and the interesting scientific question now is not whether that is true, but how to predict their magnitude. See the link to the paper in Nature? Sorry about your pet peeve, but you’re wrong about me not providing a citation for my claim.

    You are the one claiming that fracking has an effect on the total number of HUGE earthquakes. I made no statement about that at all, so what am I supposed to cite? Where is your citation, for the FOURTH TIME? As I said, I love learning about the natural world so if there is any evidence I would love read it.

    Don’t make us ask 5 times. Either drop it and realize you don’t have the science to back up what you said, or provide a citation. I don’t need to provide a citation to disprove your claim, I provided a citation to prove my claim (fracking causes earthquakes and the cutting edge of science is trying to predict their magnitudes), provide one to prove yours.

  35. 135
    Hank Roberts says:

    > The total quantity of earthquakes is set by continental drift.

    > mere opinion, and often is just thoughts meant to provoke …

    Decline to be provoked. There are lots of blogs where that’s valued. Not so much here where people are trying to learn about the science.

  36. 136
    Unsettled Scientist says:

    BTW, Jim, common sense is terrible when it comes to science. I think it was Feynman who famously said something to the effect that the purpose of science is to stop you from fooling yourself and you’re the easiest person to fool.

    Did you look at the link provided by Steve Fish @121? I did.

    “It would take 32 magnitude 5’s, 1000 magnitude 4’s, and 32,000 magnitude 3’s to equal the energy of one magnitude 6 event. So, even though we always record many more small events than large ones, there are far too few to eliminate the need for the occasional large earthquake. As for “lubricating” faults with water or some other substance, if anything, this would have the opposite effect. Injecting high- pressure fluids deep into the ground is known to be able to trigger earthquakes—to cause them to occur sooner than would have been the case without the injection. This would be a dangerous pursuit in any populated area, as one might trigger a damaging earthquake.”

    Don’t forget, the Richter scale is logarithmic. All those fracking earthquakes have little to no impact on releasing the energy that is involved in HUGE earthquakes. So there you go, there is one source for you stating the opposite of your claim.

  37. 137
    Susan Anderson says:

    Thanks to Hank Roberts and Aaron Lewis for providing some facts about human manipulation and the dust bowl, which need to be front and center in teh stupid about dust bowl comparisons. Another massive human engineering fail.

    I do wish the fascinating on-topic discussions (Patrick and Ron) that challenge and inform would continue, instead of this guff about Watts appalling but megaphonic anti-science and his public access to the Congressional moneybag hoarders who ignore reality and truth – science’s focus, unlike theirs, is on finding out and learning more.

    Inhofe, the enabler of money before truth, appears not to believe in the position he espouses, but to be willing to fry all our futures for the sake of his campaign coffers:
    http://www.youtube.com/watch?v=TdaZ5zIWB-M
    http://thinkprogress.org/climate/2012/03/16/446008/inhofe-maddow-global-warming/

  38. 138
    Dan H. says:

    How much human changes attributed to the dust bowl can not be firmly established. The lack of rain and record temperatures were definitely natural. We just aided natural in achieving the worst agricultural crisis in American history.

    [Response: your first two sentences are contradictory. – gavin]

  39. 139
    Patrick 027 says:

    Re 137 Susan Anderson – I’ve been educating myself about obliquity and precession, with the intent to post it (though in unforced variations); but then I decided to start with something related: Chandler wobble – it’s not really climate-related, although that in itself may be a good point because someone out there thinks otherwise – but it is related to ‘true polar wander’ which is another hypothesis related to Snowball Earth… it is also related to the fact (so far as I understand) that precession approximately carries the Earth’s body with it – that is (under certain conditions which the Earth seems to meet present time I guess), you could stick an axle through the symmetry axis of the Earth (the principle axis of maximum principle moment of inertia) and it would approximately follow along with the angular momentum and instantaneous angular velocity vectors – setting aside continental drift, etc (this is something I took for granted until … I think it was a few years ago, somebody brought up the point and it occured to me that I didn’t really know).

    Maybe I should post it here after all? (PS might take a few more days)

  40. 140
    Unsettled Scientist says:

    Here’s hoping we wise up, change our ways, and don’t aid nature in achieving the worst agricultural crisis in Human history.

  41. 141
    Dan H. says:

    Gavin,
    Please explain why you feel these are contradictory. Rereading my post, I find no contradiction.

  42. 142
  43. 143
    Steve Fish says:

    Re- Comment by Dan H. — 4 Aug 2012 @ 8:34 PM:

    Relative to Gavin’s comment, I am embarrassed to have to tell you this, but if you ask “How much human changes attributed to the dust bowl can not be firmly established” then you also can’t assert that the lack of rain and temperature changes are completely natural. Why don’t you check this out so you can talk intelligently? While you are at it, do you know whether or not this period in the Midwestern US was just local weather or indicative of global climate? Otherwise, why do you think that this is an important data point on a climate forum. Steve

  44. 144
    JCH says:

    I do not know its impact, but farming practices of the times left the South Dakota landscape covered in black dust. Droughts now do not look like this. This picture was taken a few miles from my father’s 1960s ranch near Gann Valley, where a record high was set that still stands.

  45. 145
    flxible says:

    DanH simplified: We can’t establish an attribution, but it was definitely natural.
    Of course DanH wouldn’t see any contradiction in that statement.

  46. 146
    Unsettled Scientist says:

    Dan H, the contradiction is that first you say that how much human contribution can attributed is not possible, then you make a statement of certainty about the human contribution not being there. Thise are mutually exclusive. Honestly, not sure why Gavin didn’t just dump that one to the bore hole or demand you actually provide references because you always get it wrong. Rather than reply to this with more word play, how about you link to whatever it is you’re trying to say, it will be much clearer that way.

  47. 147
    Jim Larsen says:

    DanH may be incorrect about the Dust Bowl rainfall and temperatures being entirely natural since land use affects both, as does CO2 concentrations, but his two statements are completely consistent. Attributing one pair of factors to natural variability in no way determines the attribution of other factors. Dan’s just trying to limit the scope of possible attribution. The basis for his statements might be the common misperception that since actual NET temperature increases didn’t break through natural variability until recently, CO2 had NO affect until recently.

    Is that correct, Dan? Do you believe that increased CO2 concentrations in the 30s had no affect on temperature and rainfall since natural variability somehow precluded it? Assuming “No”, perhaps if you modify your stance to “largely natural” from “definitely natural” and provided a smidgen of logic or evidence, then you would gain more traction.

  48. 148
    Unsettled Scientist says:

    >Attributing one pair of factors to natural variability in no way determines the attribution of other factors. Dan’s just trying to limit the scope of possible attribution.

    He’s limiting it without any evidence or sound reasoning. If you can’t establish how much human activity contributes, then you cannot rule out human activity and say it was definitely natural. CO2 emissions are not the only thing humans to do change climate, so reading CO2 into “human” is also incorrect. CO2 and temperature are not the sole drivers of climate change, especially regional (not global) climate change.

    He’s doing this just to argue, just to spread confusion, without anything to back up his assertions. Sound familiar? It’s like saying fracking reduces the frequency of huge earthquakes without any scientific references.

  49. 149
    Susan Anderson says:

    guys, please, the facts about the dustbowl era are pretty clear. If you must, just stick to them and let Dan H. stew since he doesn’t realize massive fails have consequences. The rest of us seem to realize there are similarities in our conviction we can engineer earth to feed our exploitative needs forever.

    That was also a time of great oil well boomishness. How things cycle around, innit?

    Patrick027, your stuff is above my head, but that’s the way I like it. Learning is fun and not a waste of time, not now, not ever. When I chose art for my career, one of the reasons is that it will never be fully and completely resolved.

  50. 150

    “…but his two statements are completely consistent.”

    Logically, yes, but in context, no. That is, in the real world precip, temperature, evapo-transpiration and albedo (to name a few) are not so easily disentangled as that. If human activity can’t have its consequences ‘attributed’ (if that’s not too gross a misuse of the term), then one can’t rule out potential consequences for rainfall and temperature.

    But Susan’s right, though I couldn’t resist chiming in, anyway–obsessing about this particular nit is probably not the best idea ever proposed.


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