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Lone Star State of Drought

Posted on 18 November 2011 by Rob Honeycutt

For fans of Climate Denial Crock of the Week Peter has a new video up addressing the extreme drought conditions seen this past year in Texas.  The video includes clips from climate scientists, Jerry Meehl of UCAR, John Nielsen-Gammon from Texas A&M and the Texas State Climatologist, Ben Santer of Lawrence Livermore, and Noah Diffenbaugh of Stanford University.

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Comments 1 to 35:

  1. So the Texas drought is, as the video identified, strongly correlated with La Nina:

    But La Nina is also correlated with lower ( than normal years or El Nino years ) global temperatures.
    This ( now double dip ) La Nina event is quite independent of the very real warming due to ghgs.
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    Moderator Response: [Albatross] Fixed image width
  2. CW @1,

    Sigh, you are missing the point. I do not think that anyone in the know is entirely blaming the development of the drought and heat wave over the southern great plains on global warming. They are saying that the underlying warming trend made a bad situation worse (i.e., that the event was likely stronger than it would otherwise have been). Dr. Nielsen-Gammon has some interesting posts up on this. It is more than a little disconcerting that we are already seeing a discernible anthropogenic signal so early in the anthropocene.

    That chart you showed above is the teleconnection for the winter months, the drought peaked during the summer. This is a more appropriate image, for precipitation:



    [Source]

    Note that for JJA there is not a very strong La Nina signal at all for temperature:



    So just as it is wrong to entirely attribute the development and intensity of this drought and heat wave to AGW, it is just as wrong to claim that the intensity of the heat wave and drought were solely the result of La Nina.

    Hansen has showed using observations, that globally, the area affecting by marked warm events is on the increase.



    Likewise Dai et al. (2004), again using observations, have shown that the areas under the impact of drought or pluvial have increased:

    "The global very dry areas, defined as PDSI <-3.0, have more than doubled since the 1970s, with a large jump in the early 1980s due to an ENSO-induced precipitation decrease and a subsequent expansion primarily due to surface warming, while global very wet areas (PDSI >+3.0) declined slightly during the 1980s. Together, the global land areas in either very dry or very wet conditions have increased from ~20% to 38% since 1972, with surface warming as the primary cause after the mid-1980s. These results provide observational evidence for the increasing risk of droughts as anthropogenic global warming progresses and produces both increased temperatures and increased drying."

    It is very difficult to argue with such compelling observational evidence. In closing a comment by Dr. Nielsen-Gammon:

    "It is plain that heat records should and are increasing, and hot episodes should and are becoming more extreme, as the climate warms. In the specific case of the Texas 2011 heat, natural factors appear to have been so strong that it would have set a record even in the absence of climate warming, but it would almost certainly not have been so intense as to be four sigmas above the long-term average without the contribution of climate warming."
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  3. There's some interesting research on these southwestern US droughts at Lamont Doherty. This figure reveals a very conspicuous decrease in drought area over the long term that has reversed during the 20th century.


    --source

    In the detail (lower panel), the red curve shows this increase. Please note this figure dates from 2004, so the current drought is not included in the assessment that 'the current drought is not historically exceptional.'

    Rather than focus on individual droughts, which may well be driven by oscillations, this research looks at the long term.

    The dynamical causes of imminent subtropical drying appear distinct from the causes of historical North American droughts such as occurred in the 1950s and during the 1930s Dust Bowl. ... In contrast to historical droughts, future drying is not linked to any particular pattern of change in sea surface temperature but seems to be the result of an overall surface warming driven by rising greenhouse gases. Evidence for this is that subtropical drying occurs in atmosphere models alone when they are subjected to uniform increases in surface temperature.

    Their short term projections do not look good:


    -- full scale

    GFDL's Isaac Held had a hand in this report, offering a great catch phrase:

    Warming of the global climate is expected to be accompanied by a reduction in rainfall in the subtropics and an increase in precipitation in subpolar latitudes and some equatorial regions. This pattern can be described in broad terms as the wet getting wetter and the dry getting drier -- emphasis added

    Note: here is the original source (Cook et al 2004) for the two-panel figure above.

    If the Z-C modeling results hold up, it is plausible that continued warming over the tropical Pacific, whether natural or anthropogenically forced, will promote the development of persistent drought-inducing La Nina–like conditions. Should this situation occur, especially in tandem with midcontinental drying over North America, the epoch of unprecedented aridity revealed in the DAI reconstruction might truly be a harbinger of things to come in the West.
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  4. Albatross, muoncounter, thanks for those two comments, very informative.
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  5. O.K.

    But I prefer these revised ( in discussion) position Dr. Nielsen-Gammon. In this post - especially the following set of conclusions:

    „So it appears that global warming, if it has affected mean precipitation, has had a minor impact compared to other influences, and even the sign of its effect on precipitation is unknown. Until we learn more, it is appropriate to assume that the direct impact of global warming on Texas precipitation has been negligible, and that the future precipitation trend with or without global warming is unknown.”

    ”... global warming on Texas had a net beneficial effect in the 20th century ...”

    “Texas would probably have broken the all-time record for summer temperatures this year even without global warming.”

    North America - the last ice age - a period of 21-17 thousand. years ago: “At the most extreme stage of the last glaciation, most of Canada and much of the northern USA were covered by an ice sheet thousands of metres in thickness. Colder and often drier than present conditions predominated across most of the USA.”

    12 thousand years ago: “On the eastern part of the Beringian land bridge, insect communities suggest that present-day temperatureshad been reached (Elias et al. 1996).” “Through much of the southern and central Cordilleran area of the USA, conditions may have been slightly moister than at present (although generally semi-arid), with greater woodland and scrub cover than at present. The same appears to have been the case for the lowland American and Mexican deserts to the south (Thompson et al. 1993, Benson et al. 1997).”

    Conclusion: Aside from the ENSO and PDO, the increasing frequency of extreme heat and drought in Texas is - before - the effect - in the scale of decades to centuries - decrease in temperature, no temperature increase. But now we have a secular trend rising temperatures. Warming ... so it's good news for most areas of Texas and the United States.
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    Response:

    [DB] "Warming ... so it's good news for most areas of Texas and the United States."

    You continue to prosecute an agenda of quote-mining to support predetermined conclusions, like the unsupported hand-waving one you close with.  You have been posting similarly here at SkS for 3 years now; I can no longer excuse a lack of familiarity with the language for your behavior here.

    Please note that posting comments here at SkS is a privilege, not a right.  This privilege can and will be rescinded if the posting individual continues to treat adherence to the Comments Policy as optional, rather than the mandatory condition of participating in this online forum.

    Moderating this site is a tiresome chore, particularly when commentators repeatedly submit offensive, quote-mining or off-topic posts, intentionally misleading comments and graphics or simply make things up. We really appreciate people's cooperation in abiding by the Comments Policy, which is largely responsible for the quality of this site.
     
    Finally, please understand that moderation policies are not open for discussion.  If you find yourself incapable of abiding by these common set of rules that everyone else observes, then a change of venues is in the offing.

    Please take the time to review the policy and ensure future comments are in full compliance with it.  Thanks for your understanding and compliance in this matter, as no further warnings shall be given.

  6. OK

    I understand.

    If our "common intention ", it is important not to ignore the findings of science.
    - should not be a problem: “a lack of familiarity with the language for your behavior here.”
    The more so that the most I put quotes. Often from - quoted by me - papers a meta-analysis type - a very rich references.
    It is not my intention being always a skeptic - to AGW, “the policy” is foreign to me ...
    My intention is a higher level of discussion on this website - just Science. I simple like Science, not skeptics. Skipping significant findings is not science, however .
    This blog has an excellent technical construction. This should be - in full - use ...
    I don’t want anything - contrary to the facts - prove. I wants “to get” to the scientific truth (I'm “heavy” working on this for many hours a day), but do not a shortcut.

    Therefore, the comment I consider my duty. The decision to remove my comments is your sovereign decision and depends only on the objectives that you want to achieve. I will respect your decision each.

    Sincerely,
    A. Semczyszak
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  7. Returning to the drought in Texas. Do not have here (however) a more simple answer?

    It is worth noting that the last mega - drought -'Great Drought' of years AD 1276-1299 - in North America; it’s the beginning LIA. Cooling of the oceans.

    Springer et al., 2008.: “Moisture transport across North America may have lessened during droughts because of weakened north-south temperature and pressure gradients caused by cooling of the tropical Pacific and Atlantic Oceans.
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  8. I am curious what sort of attribution can be made for some impact on this drought due to the poleward expansion of the Hadley Cells due to climate change.

    From Observed poleward expansion of the Hadley circulation since 1979 – Hu & Fu (2007):
    The subsidence regions of the Hadley circulation, because of the dryness of the troposphere and lack of high clouds, can be identified as the region with high OLR. For the OLR records the locations of the poleward edges of the Hadley circulation are roughly defined as the most poleward latitude at which the zonal mean OLR is equal to 250 W m−2. Figure 4 shows the zonally averaged temporal evolution of the OLR from the HIRS Pathfinder for four seasons in NH. The poleward ex- tension of the northern Hadley-circulation branch based on the 250 W m−2 OLR is about 2.14◦, 2.75◦, 2.56◦ and 2.67◦ in latitude for the four seasons, respectively, as shown in Fig. 6a. One can alternatively use other OLR contours to measure the poleward expansion. But results do not change very much. For example, the poleward expansion of contour 240 W m−2 is about 2.05◦, 3.11◦, 3.07◦ and 3.04◦ in latitude for the four seasons. The consistent poleward expansion of different OLR contours can be clearly seen in Fig. 4.
    Figure 4 is here:



    Examining this figure, note that Texas resides roughly between 30˚N and 36˚N (look at that latitude specifically, in the figure, and how it evolves over time), and very near the edge of the Hadley cell and so in an area likely to be affected by resulting changes in precipitation.

    A change in latitude of just 2.5˚ of the edge of the cell would shift it over half of the "height" of Texas, and so have a sizable contribution to precipitation changes.

    Is anyone familiar with this? Can anyone shed any light on defensible inferences from this?
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  9. Arkadiusz @6&7,

    "OK. I understand."

    Actually, you do not seem to understand at all. You are clearly smart and intelligent, but unfortunately that means that you are just all the more equipped to enforce your bias.

    "My intention is a higher level of discussion on this website - just Science. I simple like Science, not skeptics. Skipping significant findings is not science, however . "

    Odd then that you do not recognize that you are doing exactly what you are accusing others of. You are also butting heads with great scientists like Nielsen-Gammon, Hansen, Dai, Trenberth, not to mention many years of research. They are the ones who have the knowledge, insight and qualifications to speak to this.

    You are entitled to your own opinions, but not your own facts. Quote mining to seek out text that appears to support your prejudices is not science. For example, Nielsen-Gammon, who you quote mined to infer that warming was good for TX in the 20th century is irrelevant, because it is now the 21st century and what is of concern is the future. As Dr. Nielsen-Gammon says:

    "It is plain that heat records should and are increasing, and hot episodes should and are becoming more extreme, as the climate warms."

    You also left out this text that immediately followed your mined quote:

    "However, none of the viable cooling mechanisms are sustainable, so warmer temperatures in Texas are extremely likely in the future, and based on temperatures in the first eleven years of the 21st century, those days are already here."

    Only those in deep denial are still pushing this myth that certain extremes are not on the increase and that the odds of extremes will not continue to increase as the climate system becomes more energetic.

    "It is worth noting that the last mega - drought -'Great Drought' of years AD 1276-1299 - in North America; it’s the beginning LIA. Cooling of the oceans."

    First, note that Springer et al. say "may". Regardless this is a red herring and logical fallacy to boot, because we know that the N. Atlantic and Gulf of Mexico are warming and will very likely continue to warm-- those are the primary sources of moisture over the southern great plains.

    Now please stop fabricating debate. It should be blindningly clear to anyone following this what your agenda is (and no, it certainly does not appear to be seeking the "truth") and that you are clearly biased.
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  10. Re #7, the Springer et al. paper is titled "Solar forcing of Holocene droughts in a stalagmite record from West Virginia in east-central North America."

    That is one of the reasons I said it is a red herring. It is also not relevant because we are talking about warming oceans and land temperatures, not cooling.
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  11. Sphaerica @8,

    That is a plausible hypothesis. There has been paleo research that has shown poleward shifts in the ITCZ in response to warming in the past has been associated with dramatic shifts in precipitation. Check out this work by Sachs and Myhrvold (2011):

    "Multiyear drought conditions in the southwestern U.S. could persist as that area becomes more like the semiarid region of northern Mexico."
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  12. 11, Albatross,

    I have that issue of Sci Am, but don't remember reading the article. I just dug it out and will read it over lunch, then try to track down a copy of the Sachs paper.

    I've always pointed out (with deniers/skeptics who want to argue that higher temps must mean more precipitation) that the shifting Hadley cells may well carry one of the greatest dangers of climate change, because the effect is both predicted and recognized in observations, and it specifically carries huge and continuous precipitation changes -- and Texas and the whole southernmost US, as well as current Mediterranean countries like Greece, Italy and Spain, may well be very, very dramatically and adversely affected. The deserts of the world will grow as the Hadley cells grow. Anyone who lives north of a desert needs to worry a lot.

    I'm just wondering now are those effects already being felt, or is that still not really in the equation yet (i.e. any climate change impact on this drought is limited to increased evaporation due to increased temperatures impacts on more dynamic precipitation patterns, potentially due to more dramatic La Nina effects exacerbated by climate change -- but not yet to Hadley cell poleward expansion).
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    Moderator Response:

    [DB] Try here:

    http://faculty.washington.edu/jsachs/lab/www/Sachs-Myhrvold_A_Shifting_Band_of_Rain-SciAm11.pdf

    [Sph]

    For the record, DB's link is to an online copy of the article. This link here is to a copy of the 2009 paper by Sachs, Southward movement of the Pacific intertropical convergence zone AD 1400–1850

    Is it poor form to "moderate" one's own comments?

  13. Sphaerica #8: "poleward expansion of the Hadley Cells due to climate change."

    More from the Lamont websites on this subject:

    As the planet warms, the Hadley Cell, which links together rising air near the Equator and descending air in the subtropics, expands poleward. Descending air suppresses precipitation by drying the lower atmosphere so this process expands the subtropical dry zones. At the same time, and related to this, the rain-bearing mid-latitude storm tracks also shift poleward. Both changes in atmospheric circulation, which are not fully understood, cause the poleward flanks of the subtropics to dry.


    full scale

    Or as quoted previously, dry areas drier and wet areas wetter. That is not an ENSO-driven effect.
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  14. Arkadiusz @6&7, re the response by Albatross at 9,

    Let me say that I am deeply offended that you engaged in such quote mining. I am not at all surprised, but it really gets tiresome when deniers go through papers and make what is obviously a clear effort to misrepresent the content of the paper and refashion it to say the exact opposite of what it really says.

    This to me is reprehensible and indefensible behavior on your part.

    I for one will hesitate to accept anything you say without studying it in great detail, and all other readers are strongly advised to do likewise -- your credibility in all discussions is now severely in question and you will have a very hard time regaining anyone's trust.

    And please don't insult us all with obviously questionable statements like this:
    It is not my intention being always a skeptic - to AGW, “the policy” is foreign to me ...
    My intention is a higher level of discussion on this website - just Science.
    Demonstrate this through your actions and actual statements, not through loud protests of innocence and nobility.
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  15. Oh, BTW, I didn't intend to be entirely Northern-Hemisphere-centric -- obviously the expansion of the Hadley cells will have similar dire consequences to those near arid regions in the Southern Hemisphere... meaning some in South America (the Amazon), central Africa, and Australia.

    In fact, it's hard to find an area of the globe that is not heavily populated and civilized and in serious danger of major and insurmountable precipitation changes due to this particular side-effect of global warming.

    And we're only somewhere around 0.6˚C right now. Imagine what this will mean if we actually hit 2˚C, or even just the 1.4˚C to which current CO2 levels appear to have us committed.
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  16. Looking carefully at the projection in the figure here, there is a narrow zone between tan and light blue where the change is forecast to be close to 0.

    Our resident 'skeptics' will no doubt take comfort in pointing to those areas and saying 'nothing different here.'
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  17. 13, muoncounter,

    Yes. That's exactly what I'm talking about, but in the context of this particular drought, I'm questioning whether or not these effects are already being felt and working (which could be the case), or if this is only the tip of the melted-ice-berg and "you ain't seen noth'n yet."

    For a global context, I think this other image from the Lamont websites is good to see:


    Click for full scale image.
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  18. 16, muoncounter,

    Except that the yellow/brown below that narrow band looks to make all of the Southwestern US (a region of recent population explosion) a rather inhospitable place to live.

    Bad times ahead.
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  19. Hi,
    I've been to a few presentations by experts in climate modelling, and where I live around Lake Ontario the image shown twice in this thread by Lamont-Doherty has my area depicted as "light blue" - or to receive more rainfall.
    This coincides well with other analyses I have seen.

    What surprised me is the claims I have heard that despite greater rainfall, our local soil moisture content is to DECREASE over the next 100 years because of increased evaporation and rain coming not in a drizzle-form but more in storm spurts - icreasing run-off.

    This is worrying if it is hoped that the growing drought areas will be supplied with crops by the areas that may receive more rainfall; only to find out the "wetter" areas will actually have diminished crop yeilds - potentially - because of the surprising decrease in soil moisture content.
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  20. Sphaerica @18, I find brown band over the Iberian peninsular, France, Italy and the Balkans more concerning, if only because of the much higher population density of those regions. Also concerning is the drying over much of southern Africa, where the inhabitants do not have the economic resources for effective adaption.
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  21. Manwichstick @19, that is a genuine concern. The east coast of Australia, for example shows little change in Precipitation - Evaporation, but that is because increased flooding during La Nina events is expected to compensate for more frequent, and more intense drought during El Nino events. The compensation, of course, is entirely in the long term average, not in the farmer's paddock where there is a loss of productivity under both conditions.
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  22. Manwich#19: "our local soil moisture content is to DECREASE over the next 100 years"

    Can you reference any of those presentations, or at least the presenters so readers here can look them up?

    The relatively new concept of 'flash drought' seems relevant here.

    Drought is usually thought of as a slow-onset disaster, but much like flash floods, drought can develop very quickly. During summer, if evapotranspirtation (ET) – loss of water from the soil and plants to the atmosphere – is high, soil moisture can be depleted rapidly producing drought conditions even when precipitation departures are not all that extreme. In addition to soil moisture status, ET is affected by temperature, relative humidity, solar radiation (sunlight) and wind. Any one of these can contribute to higher-than-normal ET rates, but when several combine the results can be disastrous.

    These conditions existed in Oklahoma in 2000 and of course Texas/New Mexico 2011. The Oklahoma Climatological Survey makes a key point:

    It is interesting to note that for the year as a whole, the summer months (June - August), and the fall months (September - November), the seasonal statistics do not necessarily indicate that the state experienced a severe drought because heavy rains preceded and followed this dry spell.

    In the US Drought Monitor archives, one can see how quickly the 2000 Oklahoma flash drought came up.
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  23. Our resident 'skeptics' will no doubt take comfort in pointing to those areas and saying 'nothing different here.'

    I would point out that light blue is ok too.
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  24. 23, Eric,

    Sorry, I didn't get the point of your comment. Could you be more clear?
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  25. Sorry, that comment was mainly for muoncounter. He said skeptics would take comfort in (only) the "no change" zones in his image shown in #13 (similar to yours in #17). I countered that light blue is ok. I should probably have elaborated: "light blue is relatively ok due to slight precipitation excesses being a lot less problematic than major precipitation deficiencies".
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  26. 25, Eric,

    I got that much. I just wasn't sure if you were honestly or sarcastically suggesting that a small or even large region of increased rainfall somehow offset vast areas of precipitation deficit.
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  27. Eric @25,
    I'm very sceptical about your elaboration that "light blue is OK". If that precipitation, in order to to make up for a previous long drought, falls as 100mm/h downpour for a few weeks causing widespread floods and soil erosion (as it did in QLD in January), then the total can look like your light blue. But it's definitely not "OK".

    IMO all of those graphs are hardly relevant to real problems: we don't know the changes in precipitation rate. It would be nice to have such "average rate-anomaly" if somebody ever tried to predict it. If such anomally was minus-zero it would not be bad even for slightly brown regions but I gues it'd be all plus-zero along with temps.
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  28. chriskoz, I agree we need the distribution of rainfall to decide. It is pretty clear from current events that the distribution will change by season and be heavily affected by natural patterns particularly meridional versus zonal flow here in the USA. In the case of Texas the deciding factors are the strength of the Aleutian low and the upper troughs that drop down the west coast and move east. As they weaken, Texas gets less rain chances.
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  29. Tom Curtis:

    The east coast of Australia, for example shows little change in Precipitation - Evaporation...


    In my corner of Australia it's a rather more grim picture, with a rather dark shade of black plastered over the map.

    Given the tinderbox conditions that we already experience here in summer, the future is a worrying one indeed. Only today I was surveying the lower acres of my land, contemplating the changes I'll need to make in preparation for the inevitable conflagration that will come.

    There's already a peculiar interaction between (current lack of) summer humidity and poor soil moisture retention here, that can result in drought-equivalent conditions within days after a whole season of flooding rains. In recent years, the hot nor'westers have ensured that even the usually wet creeklines have been withering in a way that some old orchardists here say is particularly ususual.

    I suspect that given a full allotment of three score and ten, I will live to see my deep forested valley completely razed - something that even the 67 fires did not totally manage. After the fires in Melbourne two and a half years ago, most locals here say that they are simply going to run when the time comes, although I fret that the topography might be unforgiving should an arsonist torch the bush in just the wrong place.

    Whatever the future brings, my kids will definitely live in a different landscape to the one that was here when I was a lad.
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  30. Bernard J. @29, I take it your part of Australia is Victoria?
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  31. Bernard J,

    Not that I would push anyone into the lion's den, but I wish you'd express such clear and vivid fears to Jo Nova on her site. She seems to feel that she is a lone, valiant, heroic defender of truth, freedom and The Australian Way, and that in her golden heart of hearts and courageous will to speak out against (in her mind) climate change fraud she has the best interests of all of Australia as her goal, but primarily those of the poor, downtrodden farmer under the thumb of the greedy, irresponsible politicians.

    It would be interesting to see how she responds to her imagined defense of the poor Australian farmer when she learns that at least some of you recognize that her attitudes are hurting, not helping, your futures.
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  32. Sphaerica#17: "I'm questioning whether or not these effects are already being felt and working"

    Kysely 2010 is very revealing on that question:

    Analysis of the long-term temperature series at Prague-Klementinum reveals that the July 2006 heat wave, covering 33 consecutive days, was the longest and most severe individual heat wave since 1775. ... Owing to an increase in mean summer temperatures, probabilities of very long heat waves have already risen by an order of magnitude over the recent 25 years, and are likely to increase by another order of magnitude by around 2040 under the summer warming rate assumed by the mid-scenario. Even the lower bound scenario yields a considerable decline of return periods associated with intense heat waves. Nevertheless, the most severe recent heat waves appear to be typical rather of a late 21st century than a mid-21st century climate. -- emphasis added

    The future is upon us.
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  33. 32, muon,

    Thanks for the reference, but in this case I'm actually looking specifically for attribution of precipitation changes to changes in Hadley cell poleward expansion, not climate change in general.

    I don't expect to find any, because the changes are so small and hard to detect (heavily influenced by short term weather variations), and attribution is so difficult, even though a mere 2.5˚ change in latitude could, in fact, be greatly affecting conditions in Texas because of it's location so near to the edge of the Hadley cell and the associated arid area.

    I think in about 5-15 years we may well see just such a study, demonstrating that this drought and future precipitation changes in Texas are among the first directly detectable impacts of the expansion of the Hadley cell as a result of climate change.

    But for now... I think finding actual scientific detection and attribution of the proposed effect is probably not possible.
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  34. Bernard J,

    Here is Figure 5 from Hu and Fu, the changes in OLR for the Southern Hemisphere. Note Australia's precarious position between about 15˚S and 35˚S, and the Hadley cell's large role in creating and maintaining the vast deserts in Australia's interior... and hence the serious implications for Australia of an expansion of the Hadley cell.

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  35. Sphaerica If you're looking for precipitation changes as evidence of expansion of Hadley cells, I'd take a long hard look at Perth.

    Perth is north of Sydney (just barely), on the other side of the continent. The only reports I remember are those from BOM showing the dramatic, and apparently permanent, loss of inflows to Perth's water catchments in the 70s. I've always regarded that fact as the canary in the coalmine of global warming. Not just for Australia, but for the world.

    The change is particularly devastating, mainly because Perth's evaporation rate is also the highest for any Australian capital city. I don't recall anything showing that the rate has increased, but I'd not be surprised if it had.
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