The University of Texas at Austin
  • Climate myths: Jackson School sets the record straight

    By Marc Airhart
    Marc Airhart
    Published: Nov. 8, 2010
    Climate

    Climate change is one of the most important and contentious issues facing society. The question of how (or whether) we respond to climate change is ultimately political, but it is a political question intertwined with science. To inform the scientific aspects of the debate, climate scientists at the Jackson School of Geosciences agreed to address eight common myths about climate change. Know will cover these myths in separate installments published over eight days.

    Myth No. 1: What global warming? Earth has actually been cooling since 1998.
    Some people skeptical of global warming claim that Earth’s global surface temperatures have been falling or have leveled off since 1998. They point to data now several years out of date from U.K. researchers that put 1998 as the warmest year on record. They also point to an unusually cool summer in North America in 2009 followed by an abnormally cold winter across all of the northern hemisphere. People who had to shovel record snows from their driveways or live without power during ferocious snowstorms in the northeastern United States began to doubt decades of scientific evidence on global warming.
    Continue reading this myth …

    Myth No. 2: Increased carbon dioxide (CO2) can’t contribute to global warming: It’s already maxed out as a factor and besides, water vapor is more consequential.
    Some climate skeptics claim that the carbon dioxide (CO2) currently in the atmosphere is already “saturated” in its ability to absorb longwave radiation from Earth and therefore additional CO2 in the air won’t make a difference — won’t, that is, absorb more heat. They also argue that water vapor is a more potent greenhouse gas and therefore increases in CO2 shouldn’t be a concern. These claims have been made in recent years by Hungarian physicist Ferenc Miskoczi and other scientists. They were repeated in the Skeptic Handbook, published in 2009 by science writer Joanne Nova. Yet the seed of the argument actually goes back more than a century.
    Continue reading this myth …

    Myth No. 3: You can’t trust climate models because they do a lousy job representing clouds and aerosols.
    Climate modelers have traditionally had a hard time incorporating clouds because clouds are very complex. On the one hand, by reflecting sunlight, they tend to cool Earth. On the other, they tend to hold in heat from the surface, which is why cloudy nights tend to be warmer than clear nights. The models also divide the atmosphere up into blocks much larger than clouds, so it’s difficult to create realistically sized clouds.
    Continue reading this myth …

    Myth No. 4: There have been big climate changes in the past, such as the Little Ice Age and the Medieval Warm Period, so why can’t recent climate changes just be explained by natural variability?
    People who dispute evidence of recent global warming sometimes point to two episodes in the past 1,000 years called the Little Ice Age and the Medieval Warm Period — times when northern hemisphere temperatures were higher or lower than average for decades or even centuries — as examples of internal variability, a kind of natural randomness in the climate system that can’t be explained by any specific forcing. If true, perhaps internal variability could explain the current rapid global warming, skeptics argue. In other words, maybe our current warming is just an unlucky roll of the dice, a blip rather than a long term trend.
    Continue reading this myth …

    Myth No. 5: Natural forces such as solar variability, cosmic rays or volcanic eruptions can explain the observed warming.
    Nearly all of the heat at the surface of Earth comes from radiation from the sun. Perhaps, as one hypothesis goes, that radiation has become more intense in recent decades and is making the planet warmer. A second, more complicated hypothesis involving the sun proposes that higher solar activity tends to suppress the levels of cosmic rays, high energy particles from space, hitting our atmosphere. Cosmic rays help form water droplets and clouds. Clouds are thought to have an overall cooling effect on the planet. Still with us? So in this view, if the sun is more active, then there are fewer cosmic rays, less cloud cover, and a warmer Earth.
    Continue reading this myth …

    Myth 6. The urban heat island effect or other land use changes can explain the observed warming.
    The urban heat island effect is a well documented phenomenon caused by roads and buildings absorbing more heat than undeveloped land and vegetation. It causes cities to be warmer than surrounding countryside and can even influence rainfall patterns. Perhaps, the argument goes, ground based weather stations have been systematically measuring a rise in temperature not from a global effect but from local land use changes.
    Continue reading this myth …

    Myth 7. Natural ocean variability can explain the observed warming.
    The oceans are the largest single reservoir of heat in the climate system. And they do have internal cycles of variability, such as the Pacific Decadal Oscillation (PDO) and the Atlantic Multi-decadal Oscillation (AMO). These cycles have impacts on the sea surface temperature in specific regions that vary from year to year and even from decade to decade. So perhaps, the argument goes, we just happen to be in a warm period that will last a few decades and the oceans will eventually switch back to a cool period.
    Continue reading this myth …

    Myth No. 8: In the past, global temperatures rose first and then carbon dioxide levels rose later. Therefore, rising temperatures cause higher CO2 levels, not the other way around.
    Ice cores from Dome C in Antarctica record surface temperatures and atmospheric concentrations of CO2 going back over 800,000 years. During that time, several ice ages came and went. After each ice age ended, temperatures rose first and then several centuries later, CO2 concentrations rose. This lag, some skeptics conclude, proves that CO2 increases are caused by global warming, not the other way around.
    Continue reading this myth …

    You are invited to post comments and follow-up questions on this site. You can also e-mail climate scientists questions. The scientists cannot respond to all questions individually but will address recurring themes with new entries.

    • Quote 2
      Rob Weathers said on March 1, 2012 at 5:49 p.m.
      There is little doubt among scholars that climate variation exists and has existed for, as evolutionists would argue, millions of years. To take a 100 year climate snapshot through our myopic weather eye and proclaim that the current variation is based on human development would be equivalent to observing sunlight for a blink of an eye and insisting that nightfall ceases to exist. Where is the intellectual honesty?
    • Quote 2
      Spartacusisfree said on Oct. 12, 2011 at 7:23 a.m.
      Oh Dear! In 2007, modeller Jeff Kiehl summarised nine climate models and concluded that in time the CO2-AGW signal would rise out of 'aerosol noise'. Yup: there's absolutely no experimental proof of any net CO2-AGW. As any professional engineer or physicist will confirm, 'back radiation' is really 'Prevost exchange energy' and can do no thermodynamic work. And the 'cloud albedo effect' cooling supposed to hide CO2-AGW is imaginary too, a mistake by Carl Sagan. Correct it and the sign reverses for thicker clouds. In 2004 after NASA knew there was no experimental proof of the level of this cooling needed to prove 'high feedback' it claimed clouds with small droplets reflect more sunlight. There's no such physics. Look at any rain cloud and they're dark underneath because the droplets are large! Two other errors; the amplification of TSI increase at the end of ice ages starts >2000 years before any CO2 rise and the cloud albedo heating effect, the real GW/AGW, is what triggers that process; we presently have c. 9K greenhouse warming, the IPCC's 33K is a deception because it includes lapse rate. This 'science' is probably the biggest scientific fraud in History.
    • Quote 2
      matt said on Oct. 12, 2011 at 6:11 a.m.
      We have already added 40% more CO2 and have seen a 0.6 degree C warming. If ALL that warming is due to CO2, ie, ALL natural forces stopped 100 years ago, then that warming is inline with lab experiments that show that doubling CO2 will lead to a 1 degree C increase (non linear effect). Thus positive feedbacks are not in evidnce and the current warming and CO2 levels will only be beneficial to the planet.
    • Quote 2
      UT Geologist said on Aug. 30, 2011 at 12:50 p.m.
      Dr. Wegman's report wasn't peer reviewed because it wasn't intended for publication, it was prepared for a committee of congress. And in spite of your assertion, mainstream climate scientists have indeed agreed with the statistical criticisms, INCLUDING Hans Von Storch, whom you mention (and I will discuss below), but first a comment: Your use of "mainstream climate scientists" is just another way of stating the old "consensus" argument. In 1998, Dr Arthur Robinson, Director of the Oregon Institute for Science and Medicine, posted his first global warming sceptics petition on the Institute’s website (www.oism.org). It eventually attracted the signatures of more than 17,000 Americans with science degrees. Widely known as the Oregon Petition, it became a counterweight for the “all scientists agree” mantra of the man-made climate change crowd. Now his list includes around 31,500 man-made warming sceptics with science qualifications. More than 9,000 hold scientific PhDs. Almost 31,500 sceptics happens to be more than 12 times as many scientists as the 2,500 scientific reviewers claimed by the IPCC to form a scientific consensus. You bring up principal component analysis (PCA)that was used in the Mann hockey stick reconstruction. Canadian scientists Stephen McIntyre and Ross McKitrick uncovered a fundamental mathematical flaw in the computer program that was used to produce the hockey stick. In his original publications of the stick, Mann purported to use a standard method known as principal component analysis, or PCA, to find the dominant features in a set of more than 70 different climate records. McIntyre and McKitrick obtained part of the program that Mann used, and they found serious problems. Not only does the program not do conventional PCA, but it handles data normalization improperly. In a conventional PC calculation, the mean of each series is subtracted from each column prior to the rest of the algorithm. Instead of doing this, Mann’s Fortran program had only subtracted the 1902-1980 mean from each column. This is a highly unusual procedure. The effect is that tree ring series with a hockey stick shape no longer have a mean of zero and end up dominating the first principal component (PC1). In effect, Mann’s program mines for series with a hockey stick shape. In the critical PC1 of the North American network, the top-weighted Sheep Mountain series, with a hockey stick shape gets over 390 times the weight of the least weighted series, which does not have a hockey stick shape. Dr. Mia Hubert of the Katholieke Universiteit Leuven in Belgium, who specializes in robust statistics, checked to see if Mann’s unusual standardization influenced the climate reconstruction. She confirmed:“Tree rings with a hockeystick shape dominate the PCA with this method.” Therefore this improper normalization procedure tends to emphasize any data that do have the hockey stick shape, and to suppress all data that do not. To demonstrate this effect, McIntyre and McKitrick created some meaningless test data that had, on average, no trends. This method of generating random data is called Monte Carlo analysis, and it is widely used in statistical analysis to test procedures. When McIntyre and McKitrick fed these random data into the Mann procedure, out popped a hockey stick shape! McIntyre:“In each simulation, there are some red noise series that happen to go up in the 20th century, some that go down and basically everything in between. If we used Mann’s method on red noise, we consistently obtained hockey sticks with an inflection at the start of the 20th century. We have repeated the simulation thousands of times and in 99% of the cases, the result of the PCA was a hockey stick.” You mentioned Dr. Hans von Storch, a specialist in climate statistics. After reviewing McIntyre and McKitrick's criticisms on the hockey stick, he agreed that “simulations with red noise do lead to hockey sticks. McIntyre and McKitrick’s criticism on the hockey stick from 1998 is entirely valid on this particular point.”
    • Quote 2
      UT Geologist said on Aug. 30, 2011 at 12:10 p.m.
      Dr. Wegman's report wasn't peer reviewed because it wasn't intended for publication, it was prepared for a committee of congress. And in spite of your assertion, mainstream climate scientists have indeed agreed with the statistical criticisms, INCLUDING Hans Von Storch, whom you mention (and I will discuss below), but first a comment: Your use of "mainstream climate scientists" is just another way of stating the old "consensus" argument. In 1998, Dr Arthur Robinson, Director of the Oregon Institute for Science and Medicine, posted his first global warming sceptics petition on the Institute’s website (www.oism.org). It eventually attracted the signatures of more than 17,000 Americans with science degrees. Widely known as the Oregon Petition, it became a counterweight for the “all scientists agree” mantra of the man-made climate change crowd. Now his list includes around 31,500 man-made warming sceptics with science qualifications. More than 9,000 hold scientific PhDs. Almost 31,500 sceptics happens to be more than 12 times as many scientists as the 2,500 scientific reviewers claimed by the IPCC to form a scientific consensus. You bring up principal component analysis (PCA)that was used in the Mann hockey stick reconstruction. Canadian scientists Stephen McIntyre and Ross McKitrick uncovered a fundamental mathematical flaw in the computer program that was used to produce the hockey stick. In his original publications of the stick, Mann purported to use a standard method known as principal component analysis, or PCA, to find the dominant features in a set of more than 70 different climate records. McIntyre and McKitrick obtained part of the program that Mann used, and they found serious problems. Not only does the program not do conventional PCA, but it handles data normalization improperly. In a conventional PC calculation, the mean of each series is subtracted from each column prior to the rest of the algorithm. Instead of doing this, Mann’s Fortran program had only subtracted the 1902-1980 mean from each column. This is a highly unusual procedure. The effect is that tree ring series with a hockey stick shape no longer have a mean of zero and end up dominating the first principal component (PC1). In effect, Mann’s program mines for series with a hockey stick shape. In the critical PC1 of the North American network, the top-weighted Sheep Mountain series, with a hockey stick shape gets over 390 times the weight of the least weighted series, which does not have a hockey stick shape. Dr. Mia Hubert of the Katholieke Universiteit Leuven in Belgium, who specializes in robust statistics, checked to see if Mann’s unusual standardization influenced the climate reconstruction. She confirmed:“Tree rings with a hockeystick shape dominate the PCA with this method.” Therefore this improper normalization procedure tends to emphasize any data that do have the hockey stick shape, and to suppress all data that do not. To demonstrate this effect, McIntyre and McKitrick created some meaningless test data that had, on average, no trends. This method of generating random data is called Monte Carlo analysis, and it is widely used in statistical analysis to test procedures. When McIntyre and McKitrick fed these random data into the Mann procedure, out popped a hockey stick shape! Said McIntyre:“In each simulation, there are some red noise series that happen to go up in the 20th century, some that go down and basically everything in between. If we used Mann’s method on red noise, we consistently obtained hockey sticks with an inflection at the start of the 20th century. We have repeated the simulation thousands of times and in 99% of the cases, the result of the PCA was a hockey stick.” You mentioned Dr. Hans von Storch, a specialist in climate statistics. After reviewing McIntyre and McKitrick's criticisms on the hockey stick, he agreed that “simulations with red noise do lead to hockey sticks. McIntyre and McKitrick’s criticism on the hockey stick from 1998 is entirely valid on this particular point.”
    • Quote 2
      UT Geologist said on July 29, 2011 at 11:57 a.m.
      Oh for heavens sake Marc! Dr Wegman's report wasn't peer reviewed because it was a report to congress and not intended for publication. The reason "mainstream" climate scientists don't share his conclusions is because most "mainstream" climate scientists are not PhD statisticians. Further, his conclusions disagree with their pre-concluded and well-funded "climate research". Several stories appeared lately in the news on AGW. Dr. Roy Spencer, a principal research scientist at the University of Alabama in Huntsville and U.S. Science Team Leader for the Advanced Microwave Scanning Radiometer flying on NASA’s Aqua satellite, reports that real-world data from NASA’s Terra satellite contradict multiple assumptions fed into alarmist computer models. NASA satellite data from the years 2000 through 2011 show the Earth’s atmosphere is allowing far more heat to be released into space than alarmist computer models have predicted, reports a new study in the peer-reviewed science journal Remote Sensing. The study indicates far less future global warming will occur than United Nations computer models have predicted, and supports prior studies indicating increases in atmospheric carbon dioxidetrap far less heat than alarmists have claimed. And in other news: A federal wildlife biologist whose observation in 2004 of presumably drowned polar bears in the Arctic helped to galvanize the global warming movement has been placed on administrative leave and is being investigated for scientific misconduct, possibly over the veracity of that article. And in other news: CERN's research in Geneva has determined that cosmic rays affect cloud formation. The CLOUD experiment builds on and confirms earlier experiments by Danish physicist Henrik Svensmark, who demonstrated that cosmic rays provide a seed for clouds. Tiny changes in the earth's cloud cover can account for variations in temperature of several degrees. The quantity of cosmic rays therefore has an influence on climate, but this isn't factored into the IPCC's "consensus" science at all. And in a stunning development, CERN Director General Rolf-Dieter Heuer ordered that the scientists refrain from drawing conclusions from the latest experiment, because, Heuer says, "That would go immediately into the highly political arena of the climate change debate." And this captures the problem with the AGW debate entirely - that scientific research is being manipulated by politics. The politicians direct funding for the sort of research they want to see and the scientists are all to happy to oblige, knowing to not bite the hand that feeds them.
    • Quote 2
      UT Geologist said on July 29, 2011 at 10:25 a.m.
      "Climate models get energy balance wrong, make too hot forecasts of global warming" HUNTSVILLE, Ala. (July 26, 2011) — Data from NASA’s Terra satellite shows that when the climate warms, Earth’s atmosphere is apparently more efficient at releasing energy to space than models used to forecast climate change have been programmed to “believe.” The result is climate forecasts that are warming substantially faster than the atmosphere, says Dr. Roy Spencer, a principal research scientist in the Earth System Science Center at The University of Alabama in Huntsville. The previously unexplained differences between model-based forecasts of rapid global warming and meteorological data showing a slower rate of warming have been the source of often contentious debate and controversy for more than two decades. In research published this week in the journal “Remote Sensing” http://www.mdpi.com/2072-4292/3/8/1603/pdf, Spencer and UA Huntsville’s Dr. Danny Braswell compared what a half dozen climate models say the atmosphere should do to satellite data showing what the atmosphere actually did during the 18 months before and after warming events between 2000 and 2011. “The satellite observations suggest there is much more energy lost to space during and after warming than the climate models show,” Spencer said. “There is a huge discrepancy between the data and the forecasts that is especially big over the oceans.” Not only does the atmosphere release more energy than previously thought, it starts releasing it earlier in a warming cycle. The models forecast that the climate should continue to absorb solar energy until a warming event peaks. Instead, the satellite data shows the climate system starting to shed energy more than three months before the typical warming event reaches its peak. “At the peak, satellites show energy being lost while climate models show energy still being gained,” Spencer said. This is the first time scientists have looked at radiative balances during the months before and after these transient temperature peaks. Applied to long-term climate change, the research might indicate that the climate is less sensitive to warming due to increased carbon dioxide concentrations in the atmosphere than climate modelers have theorized. A major underpinning of global warming theory is that the slight warming caused by enhanced greenhouse gases should change cloud cover in ways that cause additional warming, which would be a positive feedback cycle. Instead, the natural ebb and flow of clouds, solar radiation, heat rising from the oceans and a myriad of other factors added to the different time lags in which they impact the atmosphere might make it impossible to isolate or accurately identify which piece of Earth’s changing climate is feedback from manmade greenhouse gases. “There are simply too many variables to reliably gauge the right number for that,” Spencer said. “The main finding from this research is that there is no solution to the problem of measuring atmospheric feedback, due mostly to our inability to distinguish between radiative forcing and radiative feedback in our observations.” For this experiment, the UA Huntsville team used surface temperature data gathered by the Hadley Climate Research Unit in Great Britain. The radiant energy data was collected by the Clouds and Earth’s Radiant Energy System (CERES) instruments aboard NASA’s Terra satellite. The six climate models were chosen from those used by the U.N.’s Intergovernmental Panel on Climate Change. The UA Huntsville team used the three models programmed using the greatest sensitivity to radiative forcing and the three that programmed in the least sensitivity.
    • Quote 2
      Marc Airhart said on June 10, 2011 at 1:19 p.m.
      UT Geologist, thanks for writing. Wegman's non-peer reviewed conclusion isn't shared by mainstream climate scientists. In response to his report, Gerald North testified before Congress that "none of the statistical criticisms that have been raised by various authors unduly influence the shape of the final reconstruction. This is attested to by the fact that reconstructions performed without using principal components yield similar results." At the same hearings, Hans van Storch testified that the tendency to produce hockey-stick shapes from random data would only apply if there were no other significant signals, and "in very many practical situations it would not show up."
    • Quote 2
      UT Geologist said on April 11, 2011 at 2:56 p.m.
      I never said Wahl & Amman used Yamal series, I said that Briffa did. Briffa's self-exculpatory statement is hardly compelling. Wahl & Amman used Mann, Bradley, Hughes (MBH) 1998, 1999. MBH used weather station data from 1902 to 1995 as a basis for "calibrating" proxy data. They adjusted the proxy data to match the instrument data. They assumed that the instrument data were accurate, but as I've pointed out before, the instrument data is not reliable. There are serious questions with the surface monitoring network, such as the loss of arctic stations and urban heating effects. Surfacestations.org has audited most of the stations in the USHCN network and found that almost 70% are improperly located near urban heating sources to produce greater than +2degree C error. By altering the tree proxy data to match the temperature, they essentially used temperature increases to show temperature increases. In 2006 a team of statisticians led by Edward Wegman, chair of the National Academy of Sciences’ Committee on Applied and Theoretical Statistics prepared a report for the House Committee on Energy and Commerce. The Wegman Report found that MBH method creates a hockey-stick shape even when supplied with random input data. "It is not clear that Dr. Mann and his associates even realized that their methodology was faulty at the time of writing the MBH paper. The net effect of the decentering is to preferentially choose the so-called hockey stick shapes." Further, it is not disputed that CO2 concentrations are increasing, and that CO2 causes plantlife to grow. The key problem with using tree ring proxys for temperature is that temperature is not the only thing that affects tree growth. CO2 and precipitation also affect tree growth.
    • Quote 2
      Marc Airhart said on April 4, 2011 at 4:57 p.m.
      UT geologist, regarding your earlier claim, Keith Briffa did not "cherry pick" data to arrive at a temperature reconstruction. He explains: http://www.cru.uea.ac.uk/cru/people/briffa/yamal2000/ And furthermore, the very temperature reconstruction you were initial criticizing (Wahl & Ammann) doesn't include any of the Yamal tree ring data. It does however show a sharp uptick in temperatures in the past century consistent with other reconstructions.
    • Quote 2
      Marc Airhart said on April 4, 2011 at 4:34 p.m.
      Thanks for writing, UT geologist. This goes back to your earlier claim that "most of the last 11,400 years ... have been warmer – and often considerably warmer – than the present." Koch & Clague's paper seems at odds with that when they write: "Our study also indicates that Medieval time is not a good analogue for current warming. Glaciers in western Canada and Alaska are presently retreating rapidly and are significantly smaller than they were during Medieval time."
    • Quote 2
      UT geologist said on April 4, 2011 at 10:59 a.m.
      EPA Whistleblower Criticizes Global Warming Science and Policy in New Peer-Reviewed Study published in International Journal of Environmental Research and Public Health http://www.icecap.us/ Washington, D.C., April 1, 2011 - The scientific hypotheses underlying global warming alarmism are overwhelmingly contradicted by real-world data, and for that reason economic studies on the alleged benefits of controlling greenhouse gas emissions are baseless. That's the finding of a new peer-reviewed report by a former EPA whistleblower. Dr. Alan Carlin, now retired, was a career environmental economist at EPA when CEI broke the story of his negative report on the agency's proposal to regulate greenhouse gases in June, 2009. Dr. Carlin’s supervisor had ordered him to keep quiet about the report and to stop working on global warming issues. EPA’s attempt to silence Dr. Carlin became a highly-publicized embarrassment to the agency, given Administrator Lisa Jackson’s supposed commitment to transparency. Dr. Carlin’s new study, A Multidisciplinary, Science-Based Approach to the Economics of Climate Change, is published in the International Journal of Environmental Research and Public Health. It finds that fossil fuel use has little impact on atmospheric CO2 levels. Moreover, the claim that atmospheric CO2 has a strong positive feedback effect on temperature is contradicted on several grounds, ranging from low atmospheric sensitivity to volcanic eruptions, to the lack of ocean heating and the absence of a predicted tropical “hot spot.” However, most economic analyses of greenhouse gas emission controls, such as those being imposed by EPA, have been conducted with no consideration of the questionable nature of the underlying science. For that reason, according to Dr. Carlin, the actual “economic benefits of reducing CO2 emissions may be about two orders of magnitude less” than what is claimed in those reports. Sam Kazman, CEI General Counsel, stated, “One of the major criticisms of Dr. Carlin’s EPA report was that it was not peer-reviewed, even though peer-review was neither customary for internal agency assessments, nor was it possible due to the time constraints imposed on Dr. Carlin by the agency. For that reason, we are glad to see this expanded version of Dr. Carlin’s report now appear as a peer-reviewed study.”
    • Quote 2
      UT geologist said on March 29, 2011 at 2:27 p.m.
      You're completely missing my critizism of these earlier studies. The data available in these earlier studies was purposefully chosen to produce a pre-determined result. Rather than allowing the data to lead the conclusion, the conclusion was pre-determined and the data chosen and massaged to fit it. Data and emails released from the CRU shows exactly what they were doing. When the updated Polar Ural dataset no longer produced the desired result, that dataset was discarded and replaced with the Yamal series, then the Yamal series was parsed. The full data sets should have shown a MWP, but an MWP was contrary to the narrative they were trying to promote, so the data was either replaced, massaged, or reduced until it did fit the narrative. You cannot honor the scientific method unless you honor the data you are working with. Presenting new studies that support the narrative using different data does not excuse the prior violation of the scientific method. Has "False but Accurate" become the new standard in science? Now, getting to your recent research: Koch & Clague are not arguing that there was no MWP, they’re arguing that glaciers were able to advance during the MWP because warm areas were interrupted by periods of cooling, interspersed with variable patterns of precipitation. They very clearly assert that the advance of these glaciers were the result of increased winter precipitation due to prolonged La Niña-like conditions. In otherwords, there were a few cold winters with lots of snow during the MWP, but that doesn't disprove the MWP. Koch and Clague acknowledge the importance of increased precipitation and show that glaciers without a consistent accumulation zone (where the glacier "packs on weight") will not survive. There are many glaciers, such as those in the Himalayas where the temperature very seldom gets above freezing, so the only variable that affects their growth is precipitation.
    • Quote 2
      Marc Airhart said on March 14, 2011 at 11:07 a.m.
      Hello again, UT geologist. New research continues to bear out the notion that the Medieval Warm Period was not uniformly warmer across the planet for an extended amount of time. Take for example, a paper published last month in the journal Climate Change. Johannes Koch and John J. Clague conclude that several glaciers in western North America and elsewhere advanced during that time. Not only does it suggest that the MWP was not uniformly warmer around the world, it also suggests weather was more anomalous than today. For example, precipitation patterns and ocean/climate cycles like El Nino may have been different.
    • Quote 2
      UT geologist said on Feb. 21, 2011 at 1:25 p.m.
      Your assertion that the Medival Warm Period was a regional effect does not appear to be supported by the research. Studies in Australia and New Zealand contradict your assertion about tropical pacific. Data published by 932 individual scientists from 544 research institutions in 43 different countries indicate that the MWP was real and global. http://www.co2science.org/data/mwp/mwpp.php I continue to be astounded by your reliance on old (and discredited) papers. The National Academy of Sciences report on Climate Reconstructions is from 2006. The proxy data that this report is based upon was found in 2009 to have been cherry-picked to produce a "hockey-stick". CRU Researcher Keith Briffa selected increasingly smaller data subsets from the Yamal Tree Ring Chronology to produce the CRU proxy record used widely by other researchers including the NAS in 2006. In Briffa's work, by 1988 there were only 12 cores used, by 1990 the count was only ten, dropping still further to just five in 1995. When Briffa's data were finally released in 2009, researcher Steven McIntyre replaced the abbrevieated Yamal series with the nearby larger (34 sample) Khadyta River series. "The revised chronology was simply staggering. The sharp uptick in the series at the end of the twentieth century had vanished, leaving a twentieth century apparently without a significant trend. The blade of the Yamal hockey stick, used in so many of those temperature reconstructions that the IPCC said validated Michael Mann's work, was gone." A summary of this finding, and the many problems that researchers have encountered in obtaining the raw data from CRU and Briffa is nicely summarized here: http://bishophill.squarespace.com/blog/2009/9/29/the-yamal-implosion.html or if you prefer McIntyre's summary, here: http://climateaudit.org/2009/09/27/yamal-a-divergence-problem/
    • Quote 2
      Marc Airhart said on Jan. 31, 2011 at 4:57 p.m.
      UT geologist, thanks for writing. I'd like to see a reference for your claim that "most of the last 11,400 years ... have been warmer – and often considerably warmer – than the present." I'm frankly skeptical. With regards to the Medieval Warm Period, there were regions of the planet that were hotter than today, but other areas such as the tropical Pacific were much cooler. When it is all averaged, global temperatures are significantly warmer today. According to a National Academy of Sciences Report on Climate Reconstructions in 2006, "Presently available proxy evidence indicates that temperatures at many, but not all, individual locations were higher during the past 25 years than during any period of comparable length since A.D. 900." http://books.nap.edu/openbook.php?record_id=11676&page=3
    • Quote 2
      UT geologist said on Jan. 5, 2011 at 12:53 p.m.
      Marc, you correctly point out that the Wahl & Ammann graph only goes back to 1400. My apologies. However, that raises another interesting point. Focusing on more recent reconstructions diverts attention from the fact, well established in the scientific literature, that most of the last 11,400 years, since the end of the last Ice Age, have been warmer – and often considerably warmer – than the present. The Bronze Age, the Roman era, and the medieval warm period were all warmer than the present. Also, each of the past four interglacial warm periods was up to 6 C° (11 F°) warmer than the present. The current Holocene interglacial has persisted since the end of the Pleistocene, about 11,400 years ago. May I remind you that glaciers once extended as far south as Kansas, and that NY City was once covered by a mile of ice. I think I prefer it warm, we have much more to fear from the cold. The attempt in these abbreviated reconstructions is to ensure that no one looks any further back in the historical record, for anyone who has done so realizes that today’s temperatures, far from being exceptional, are in fact very well within the natural variability of the climate. One more point on Wahl & Ammann: the focal point of the Wahl Ammann graph is the most recent data showing temperature spikes upward. It should be noted that where the spike begins is when proxy data are substituted for instrument data (especially since the proxy data started showing declining temps, and so we have researchers trying to "hide the decline" by switching to instrument data). The researchers carefully chose to use only northern-hemisphere temperature data. In this way, they were able to overstate the 0.6 C° (1.1 F°) warming of the 20th century by an impressive but less than honest 100%, making it look more like 1.2 C° (2.2 F°). Why is Northern Hemisphere important? Proir to the 1990's there were over 12,000 global surface measuring stations. Then between 1989 and 1992, the Soviet Union collapsed, and they shut down most of their surface measuring stations, and most of these were located in very cold regions (the most expensive ones to maintain). By 1995 there were approximately 6,000 surface stations left, about half as many. You don't need much imagination to realize how removing that much cold data from the dataset affects the global average. Look at this figure http://www.ncdc.noaa.gov/sotc/service/global/map-blended-mntp/201010.gif its from the NOAA folks that are saying that 2010 is going to be the hottest on record. Look at where so many of the large positive temperature anomalies are: Far Northern Canada, Greenland, Siberia. The places where the temperature is supposedly increasing the most also happens to be where its usually coldest, and where weather stations have been removed. You can't have good science without complete confidence in the data, knowing its sources, the multiple variables that affect it, etc... and that data has to be avaiable to all to prove or disprove the theory. The ClimateGate emails clearly show a conspiracy to hide data and methods. I suggest you all read "ClimateGate: Caught Green-Handed" by Lord Christopher Monckton of Brenchley- former advisor to Margaret Thacher and a leading intellectual on this topic. http://scienceandpublicpolicy.org/images/stories/papers/originals/Monckton-Caught%20Green-Handed%20Climategate%20Scandal.pdf
    • Quote 2
      Marc Airhart said on Jan. 3, 2011 at 12:41 p.m.
      Dick, here’s part 4: Ginny Catania, assistant professor and research associate at UT Austin, received her PhD in geophysics from the University of Washington. Catania’s research focuses on ice sheet and glacier dynamics, combining remote sensing observations with ground-based field work in Greenland and Antarctica. Among several other major grant-sponsored studies, Catania is currently the principal investigator for a National Science Foundation funded project studying the ice flow history of Thwaites Glacier in West Antarctica.
    • Quote 2
      Marc Airhart said on Jan. 3, 2011 at 12:40 p.m.
      Dick, here’s part 3: Charles Jackson, research scientist at UT Austin, received his PhD from the University of Chicago. He uses computer models of the climate system to interpret modern and paleoclimate observations in terms of the physics of the atmosphere, ocean, cryosphere, and their coupling. In particular, Jackson is working to find and root out sources of uncertainty in the models. From 2001 to 2004, he was an associate editor for the journal Geophysical Research Letters and is currently an associate editor for the journal Reviews of Geophysics. In 2006, he was selected as a National Academy of Sciences Kavli Frontiers of Science Fellow.
    • Quote 2
      Marc Airhart said on Jan. 3, 2011 at 12:40 p.m.
      Dick, here’s part 2: Rong Fu, geoscience professor at UT Austin, received her PhD in atmospheric sciences from Columbia University. Her research focuses on the interaction between the water cycle and surface climate. Recent work has centered on the Amazon rainforest and on the Tibetan Plateau. Before coming to UT Austin, she was an associate professor at the Georgia Institute of Technology. In 1995, she received the National Science Foundation’s CAREER Award. In 2004, Fu received the Outstanding Overseas-Chinese Scientist Award from the Chinese National Science Foundation.
    • Quote 2
      Marc Airhart said on Jan. 3, 2011 at 12:40 p.m.
      Dick, thank you for asking about the credentials of our four featured climate scientists. For readability, I’ll post this in four installments. Here’s part 1: Kerry Cook, geoscience professor at UT Austin, received her PhD in atmospheric sciences from North Carolina State University in Raleigh. Her research focuses on how Earth’s surface structures affect atmospheric circulation and precipitation and how those impacts in turn affect surface structures. She spent six years as a researcher at the Geophysical Fluid Dynamics Laboratory at Princeton University. For 18 years before coming to UT Austin, she was a professor of Earth and Atmospheric Sciences at Cornell University. Cook serves on the Board of Trustees for the University Corporation for Atmospheric Research (UCAR), a nonprofit consortium that manages one of the world’s leading climate research institutions, the National Center for Atmospheric Research (NCAR).
    • Quote 2
      Dick Standaert said on Dec. 31, 2010 at 4:40 p.m.
      The Climate Myths article claims to be about science, not politics but as the UN's IPCC Summary for Policymakers, Climategate, the Hockey Stick illusion and many other cases have shown politics and policy are trumping science. It is nearly impossible to judge what is called science. To publish an article about climate myths without first establishing your credentials seems out of order. To challenge the so called myths by citing other authors interpretions without an examination of the collected unprocessed climate data seems out of place. When scientist present graphs titled "resonstructed temperature" or use terms like "corrected" or "smoothed" to describe their data I question their interpretation. My suggestion---- start for scratch, establish your scientific credentials before presenting conclusions.
    • Quote 2
      Marc Airhart said on Dec. 20, 2010 at 1:30 p.m.
      Thanks for writing, UT geologist. You mention that the Medieval Warm Period (MWP) isn’t included in the Wahl Ammann graph, implying it must be flawed. Please check the dates on that again. The graph starts in 1400 AD, after the end of the MWP. The graph does cover the time period of the Little Ice Age and decreased temperatures are clearly visible in the graph at that time. A host of proxy temperature records (including ice cores, corals, lake sediments, boreholes, stalagmites, and glaciers) indicate that the past century was the warmest in at least the last 500-1,000 years (depending on how far back each record can be traced). That’s leaving out tree rings altogether. Hardly sounds like cherry picking to me.
    • Quote 2
      UT geologist said on Dec. 17, 2010 at 5:49 p.m.
      Amazing that this article still makes use of discredited work. The red graph on the first page in front of the earth photo is the Wahl and Ammann reiteration of the highly discredited (the statistical bias and the influence of the bristlecone pines is well known) Mann et al "Hockey Stick" . The Mann graph and this Wahl & Ammann graph both conveniently eliminate the Medival Optimum warm period and the Little Ice Age to create a flat graph that spikes upward only in the most recent time, to give the misleading impression that it has never been warmer in recorded time. The elimination of the Medival Optimum was facilitated by the use of tree ring proxy data by Keith Briffa who cherry picked data in order to claim that coldest year of the millennium was AD 1032, a statement that, if true, would have completely overturned the idea of the Medieval Warm Period. Researcher Steven McIntyre: "We show that the Polar Urals data set in Briffa et al [1992] fails to meet a variety of quality control standards,both in replication and crossdating. The conclusion of Briffa et al. [1995] that 1032 was the "coldest year" of the millennium proves to be based on inadequate replication of only 3 tree ring cores, of which at least 2 are almost certainly incorrectly crossdated." In private emails released in the Climategate scandal, Briffa admits "...the magnitude of the extreme years in the early Urals reconstruction were not adjusted to account for inflated variance related to low chronology replication - so they are sort of right that the emphasis on 1032 is probably overdone." In the response to Myth 4, the Medival Warm Period and the Little Ice Age are acknowleged. If so, then why prominently display a graph that deceptively eliminates them?
    • Quote 2
      Marc Airhart said on Nov. 17, 2010 at 10:58 a.m.
      Phil, thanks for writing. All you've said is that CO2 makes up a small percentage of the atmosphere. That's hardly an argument against its greenhouse potential. The pre-industrial levels of CO2 in the atmosphere (also an extremely small proportion of the atmosphere) was enough to make Earth about 30 degrees C warmer than without it. It would require stepping outside of physics to think that doubling the CO2 concentration would NOT affect climate.
    • Quote 2
      Phil Holbrook said on Nov. 16, 2010 at 5:36 p.m.
      Absolute truths are an unshakable premise in any logical-factual argument. Carbon Dioxide is a clear, colorless and odorless gas at earthly atmospheric temperatures and pressures. Carbon Dioxide is an ideal gas http://en.wikipedia.org/wiki/Gas_laws. The comprehensive partial form of the universal gas law is Dalton's law. Ptotal = Pgas + PH20 Where PTotal is the total pressure of the atmosphere, Pgas is the pressure of the dry gas mixture in the atmosphere, and PH2O is the water pressure at that temperature. In this formula, Pgas = 78%Nitrogen (N2), 21%Oxygen (O2), 0.93%Argon (A), and less than 0.04%Carbon Dioxide (CO2). PH2O = 0 to 4% depending on net relative humidity. http://www.physicalgeography.net/fundamentals/7a.html The advocates of anthropogenic “greenhouse” gas have stepped outside long accepted laws of physics to grasp at a straw of an explanation. To accept these speculations is to deny the governing laws of physics that were described above. If an anthropogenic “greenhouse” gas advocate has anything other than laws of physics the as his explanation it is his duty to explain it. There are many other versions climate myths available from google. There is little overlap and no obvious contradiction with the rigorous description of physics that is described above. Anyone is welcomed to join this debate.
    • Quote 2
      nobody special said on Nov. 15, 2010 at 6:19 p.m.
      Sure, we can have a "two sided discussion" or a "balanced debate". I, for one, believe that evolution through natural selection is true due to vast amounts of overwhelming evidence, but in order to be "fair" we need to entertain the possibility that all of modern biology is a lie perpetuated by scientists and politicians. Surely we must listen to every dissenting opinion, regardless of whether that opinion was presented in the peer-reviewed scientific literature, in an op-ed in the WSJ, or in a blog post. It just wouldn't be *fair* otherwise. When do you folks want to have this debate?
    • Quote 2
      W M said on Nov. 15, 2010 at 3:48 p.m.
      HS, it's not a two-sided debate, the evidence is pretty clear and the only politics involved are on the part of those who ignore the vast majority of evidence to pick and choose pieces that fit their worldview.
    • Quote 2
      HS said on Nov. 14, 2010 at 6:21 p.m.
      Two-sided debate please. It's no different from partisan politics of White House under Mr. Obama who is the biggest gainer and propagator of climate change propaganda.
    • Quote 2
      Guillermo Aldana said on Nov. 12, 2010 at 7:45 p.m.
      Just keep in mind, that back in the 1920's science developed "eugenics" - and we got away from it because of dissent, not consensus. Science does not progress by consensus; and Scientist should publish results which are un-biased by their convictions or funding organizations. The funding organization has the right to the data; and may request that not be published; after all they did paid for a service; but the scientist have a right to the rest of the world to bring to light the realities of their studies. This can be done, without divulging any "proprietary" information.
    • Quote 2
      Geo1 said on Nov. 12, 2010 at 5:02 p.m.
      Climate change has been the norm during earth's history. The past 150 years have represented a time of unusual climate stability during which earth's population has increased several fold. So, we are due. That said you don't pump billions of tons of CO2 into the atmosphere without some consequence. That is something all the models agree on. Rather than assuming it is all us Al, what is needed is serious non-bias research to determine how much and how fast we can moderate global warming and also identify what is beyond our control . Then we can develop a strategic plan rather than scatter shooting with some serious economic consequences for all. But that would require a national strategic energy policy. Anyone seen one yet?
    • Quote 2
      Andrew said on Nov. 12, 2010 at 9:48 a.m.
      John St. Lawrence: Just a few people who don't believe in global warming: Richard Lindzen, professor of atmospheric sciences at MIT. John Coleman, founder of the Weather Channel Joseph D'Aleo, chairman at the American Meteorological Society John Christy, lead author on the IPCC Paul Reiter, IPCC and Pasteur Institute
    • Quote 2
      Guillermo Aldana said on Nov. 11, 2010 at 10:25 p.m.
      I propose a two sided discussion
    • Quote 2
      grigs said on Nov. 11, 2010 at 8:00 p.m.
      There's what ... 2% or 3% of climate scientists who are "skeptics." How many of them work for Cato Inst? American Enterprise Inst? Heartland? Heritage? Write them to find the "other" side of the pseudo-argument. It's the best scientific opinion that petro-dollars can buy.
    • Quote 2
      John St.Lawrence said on Nov. 11, 2010 at 5:01 p.m.
      Kim: can you name any actual climate scientists on the other "side" of this issue? If it seems one-sided to you, it's probably because the "debate" has been over for some time now.
    • Quote 2
      Kim Edge said on Nov. 11, 2010 at 2:49 p.m.
      Will scientists from both sides of the debate be there, or will this be another one-sided discussion?
    • Quote 2
      Guillermo Aldana said on Nov. 11, 2010 at 7:51 a.m.
      Farmer makes a very good point. May I suggest to the people in charge of publishing this website that they request trends from "Jackson" - we have one of the top geo-physics program in the country; and I doubt they would write something that strong, if they did not have equally strong data to support their claim. What I am finding out is that Scientist have gotten into this bad trend of having their data speak their conviction; if the data says it, then say it; but don't color it. If there is other data that may speak to the contrary, but it has not been collected by your study - then say that also. Data please!!!
    • Quote 2
      G. Thomas Farmer said on Nov. 10, 2010 at 12:06 p.m.
      The 1998 myth is an example of how to lie with statistics. 1998 was not the warmest year on record and has been shown to be the result of a prolonged El Nino. We are currently headed for the warmest year on record, 2010. One or two years don't really mean much, however, when the planet has been warming rapidly since the 1970s.
    • Quote 2
      John Gahan said on Nov. 10, 2010 at 11:05 a.m.
      Over-simplification and correlation is not scientifically viable. Concentrating on CO2 with its low heat resonance within a narrow waveband(14.77u)as opposed to other atmospheric gases with differing concentrations and (in some cases)much broader wavelengths(H2O)leads me to believe this university is making a case against something (CO2) rather than focusing on the effects and influences of all atmospheric gases.
    • Quote 2
      Gary said on Nov. 10, 2010 at 9:19 a.m.
      Is there a comprehensive list of where exactly the temperature stations are located that climatologists use for their study? Also, is there a record of when a station was set up and began being used?
    • Quote 2
      Tweets that mention Climate myths: Jackson School sets the record straight « Know -- Topsy.com said on Nov. 10, 2010 at 8:16 a.m.
      [...] This post was mentioned on Twitter by Kasey Collins, Brendan. Brendan said: @adamsbaldwin Interesting...the Jackson School (UT Geology) is debunking climate change myths. Thoughts? http://tinyurl.com/28unzo4 [...]
    Share:
    • Digg
    • del.icio.us
    • StumbleUpon
    • Facebook
    • Google Bookmarks
    • LinkedIn
    • Twitter
    • Print
    • email

    Related Topics

    , , ,