![Should you be a Global Warming skeptic? What an intelligent non-scientist needs to know about Anthropogenic Global Warming (AGW)* Borepatch [at] gmail [dot] com * AGW is the theory that mankind is causing the planet's temperature to increase, due to our burning of carbon-based fuels.](https://image.slidesharecdn.com/shouldyoubeaagwskeptic-091218163453-phpapp01/85/should-you-be-a-global-warming-skeptic-1-320.jpg)
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Should You Be A Global Warming Skeptic
- 1. Should you be a Global Warming skeptic? What an intelligent non-scientist needs to know about Anthropogenic Global Warming (AGW)* Borepatch [at] gmail [dot] com * AGW is the theory that mankind is causing the planet's temperature to increase, due to our burning of carbon-based fuels.
- 4. 1066 and all that Image credit: Wikimedia. Public Domain picture.
- 7. Harvests were good Enough food surplus to build Cathedrals Image credit: Linda Howser Image credit: Wikimedia. Public Domain picture.
- 9. The Little Ice Age Greenland Vikings starved to death Image credit: Frederik Carl Peter Rüttel via Wikimedia. Public Domain picture. Every Man, woman, and child. They even ate their dogs. But they starved to death anyway. Jared Diamond tells their story.
- 13. Reason #1 to be (scientifically) skeptical about AGW We know that climate changes. We know that it's been warm in the past – as warm or warmer than today. We know that it got cold in the not so distant past – much colder than today. We know that it's been getting warmer for at least 300 years, probably longer. It's not clear how burning fossil fuels starting in 1850 explains this.
- 16. Reason #2 to be (scientificaly) skeptical about AGW Any time you see a long-term climate record chart (like the one I used earlier), you should ask yourself: " How many different data types did they use, and how accurately were the data sets spliced together? " It's easy to mess this up.
- 20. Reason #3 to be (scientificaly) skeptical about AGW The ”Hockey Stick” is a big problem for AGW proponents. Mann's 1998 article that was used to justify the UN IPCC report is no good. AGW proponents have been scrambling for several years to find a replacement Hockey Stick that holds up. So far, they haven't.
- 23. The Very Model of a Modern Major Hockey Stick Source: IPCC, Fourth Assessment Report You are here Medieval Warm Period Little Ice Age
- 24. What if you don't splice? What if you only used proxy data? We removed the Thermometer Data. This is all data from tree rings. You're comparing Apples to Apples. Medieval Warm Period Little Ice Age What happened to my hockey stick?
- 25. Reason #4 to be (scientificaly) skeptical about AGW Any time you see a sudden and dramatic change at exactly the place that two different data sets were spliced together, you should wonder if the change is due to the splice.
- 34. Reason #5 to be (scientificaly) skeptical about AGW The raw temperature data has been ”adjusted”. The adjustments make up most or all of the reported warming. Sometimes the raw data show cooling, but adjustments create a large reported warming. How the adjustments are done is poorly explained.
- 39. Reason #6 to be (scientificaly) skeptical about AGW Many formerly rural weather stations have now been surrounded by growing cities. Much or all of the reported temperature increase is likely due to the city Urban Heat Island effect, not global climate change. The Surfacestations.org group is documenting as many of the 1200+ US weather station locations.
- 44. Reason #7 to be (scientificaly) skeptical about AGW AGW needs postive forcing of CO 2 to work. We don't see it. Quite frankly, this isn't surprising – you don't see positive forcing just about anywhere in the Universe.
- 48. In Summary: It's been warm – and cool – in the past. It's been warming up for 300 years. It's not clear how burning fossil fuels since 1850 explains this. When you see long-term climate reconstructions, ask how many data sets were used and how they were spliced together. The ”Hockey Stick” graph has been shown to be wrong. AGW proponents haven't found a replacement that holds up. The raw temperature data has been adjusted aggressively. It looks like it's changed the results. Nobody has explained why. Many weather stations that used to be rural are now in the middle of rapidly growing cities. This makes them read high. ” Positive Forcing” hasn't been shown to fit nature, for CO 2 or for pretty much anything else.
Notes de l'éditeur
- If you want to be scientific, the answer is "yes". Science relies on skeptical reception of new theories; like the Legal system, it is an adversarial arena where the strong theories survive and the weak theories are passed over. More than anything, Science relies on data. The most elegant theory is empty, if the data contradict it. The old saying is true: The Scientist proposes and Nature disposes. This presentation outlines serious problems in the data behind the theory of Anthropogenic Global Warming (AGW). But before we start, let's take a short look at the climate history of the last millennium.
- We know from the historical record that it was warm in the Middle Ages. Maybe warmer than today. Maybe a lot warmer. For example, William The Conqueror's Domesday Book showed that there were many vineyards in England in 1086 AD. For example, Vikings colonized Greenland in the 10 th Century. For example, agriculture was productive enough to provide a surplus sufficient to allow construction of Cathedrals all over Europe.
- This picture is from the Bayeaux Tapestry, showing ships in William the Conqueror's invasion fleet sailing from Narmandy to England. In 1066, William defeated and killed the Anglo-Saxon king, Harold, and became king of England.
- The Domesday book was a census of taxable assets, done late in King William I's reign.
- The Vikings aggressively explored, conquered, and settled all over Europe in the 10 th and 11 th Centuries, from Normandy in France, to England (the Danelaw) to Russia to Constantinople. They also spread westward, to Iceland and Greenland. Ultimately, Leif Ericson reached what is now Canada.
- Agricultural production was high during the Medieval Warm Period. Not only was there enough of a surplus to pay for stone masons to build the Cathedrals, there was enough time left over after tilling the fields that Joe Everyman could help the building as well. These were communal efforts.
- Around 1300AD the temperature began to fall dramatically; in the space of just a couple generations all of the warming from the MWP was erased. This period is called the "Little Ice Age" (LIA), and it was absolutely catastrophic for the populations of the time. A population weakened by repeated crop failures was decimated by the Black Plague. The age of Cathedral building came to a sudden end.
- Jared Diamond's book devotes a chapter to the disappearance of the Greenland Norse. It was horrific: The animal bones in those topmost layers tell a grim story. They include: foot bones of small wild birds and rabbits, which would normally have been considered too small to be worth hunting and usable only as last-ditch famine food; bones of a newborn calf and lamb, which would have been born in the late spring; the toe bones of a number of cows approximately equal to the number of spaces in that farm's cow barn, suggesting that all cows had been slaughtered and were eaten down to the hoofs; and partial skeletons of big hunting dogs with knife marks on the bones. Dog bones are otherwise virtually absent in Norse houses, because the Norse were no more willing to eat their dogs then we are today. By killing the dogs on which they depended to hunt caribou in the autumn, and by killing the newborn livestock needed to rebuild their herds, the last inhabitants were in effect saying that they were too desperately hungry to care about the future. See http://borepatch.blogspot.com/2009/06/failure-of-imagination.html
- We have lots of stories from the 17 th through 19 th centuries telling of times colder than today. There used to be a winter festival in London, held on the Frozen Thames river.
- When the rebel American army captured Ft. Ticonderoga from teh British Crown in 1775, the cannon were desperately needed by the rebels in Boston. Colonel Henry Knox reached the headquarters of the Continental Army in Cambridge. The young Boston bookseller had pulled off a daring plan. He had led a small group of men on a 300-mile journey from Boston to Fort Ticonderoga in New York State. Once there, the party disassembled cannon taken when the British surrendered the fort and retreated to Canada in May 1775. In less than two months time, Knox and his men moved 60 tons of artillery across lakes and rivers, through ice and snow to Boston. On March 7th, 2,000 Continental soldiers maneuvered the guns to a hill overlooking the city. The British had no choice but to evacuate Boston. http://massmoments.org/moment.cfm?mid=29
- The Little Ice Age continued into historical times. Not only do we have written records describing what are clearly much colder conditions, but we have thermometer readings from around 1650AD and later that confirm that temperatures have been increasing - at least up to 1940 or so. We'll come back to that later - there are disturbing questions about the thermometer record.
- Scientists use "proxies" as a temperature substitute. Proxies are things that react to temperature, and which are measurable. Trees will tend to grow faster when it's warmer, and slower when it's colder, so examining the tree ring width will tell you that some years were probably warmer, and some were probably colder. There are other proxies, notably ice cores drilled from glaciers, which also provide visible annual layers. Colder years will typically have more snow and less melting, and so the layer will be thicker; warmer years have less snow and more melting, and layers will tend to be thinner.
- Proxies are not thermometers. There are other things that effect tree ring width than temperature: drought, shade from older trees that are nearby, etc. There is a maximum biological limit to how much a tree can grow in any year, no matter how hot it is. See http://borepatch.blogspot.com/2009/10/yad061.html This means that joining ("splicing") historical temperature data from two or more different data sets - say, tree rings for 1000AD to 1750AD, and thermometer readings from 1750AD to the present - is tricky and error prone. Certainly the annual temperature variation will be different; other things like rate of change may very well be off as well. See http://borepatch.blogspot.com/2009/08/climate-change-data-suspect.html
- You don't hear much about the "Hockey Stick" in the press anymore, although it was all over the news back in 1999. The Intergovernmental Panel on Climate Change (IPCC) relied heavily on it, and the Kyoto Accords were based on its analysis. Countries signing the treaty agreed to cut their Carbon Dioxide output levels (unsurprisingly, none have). George W. Bush took a lot of heat (so to speak) from progressives when he (like Bill Clinton before him) refused to submit the treaty to the US Senate for ratification.
- This is the famous Hockey Stick graph from the 2001 IPCC report. Notice that there are two different colored lines, showing that two different types of data have been spliced: RED is measured thermometer temperature. BLUE is from a mix of different proxies, including tree rings, ice cores, and other proxies (like sea coral).
- The Hockey Stick appeared prominently in Gore's film, An Inconvenient Truth in 2006, even though the Hockey Stick itself was the subject of a considerable scientific controversy, and was soon shown to be not just incorrect, but likely knowingly falsified. Two amateur researchers, Steve McIntyre and Ross McKitrick demonstrated conclusively that one of the data sets used by the stick's creator, Michael Mann, was inappropriate for showing temperature. Further, one of the data sets was labeled "Censored" (suggesting that Mann knew or should have known not to use them), and his computer model contained a bug that caused even random data input to produce a Hockey Stick shaped curve. The best introduction to this controversy is "Caspar and the Jesus Paper", although Orson Scott Card has an excellent - if pungent - introduction, too. You can find both of them at http://borepatch.blogspot.com/2008/08/scientific-fraud.html
- AGW proponents thought they found a replacement for Mann98, with Keith Biffra's 2003 study of tree rings from the Yamal penninsula in Siberia. Unfortunately, that study collapsed too, mostly because of the extremely small number of trees in Biffra's data set (only 12 trees). See http://borepatch.blogspot.com/2009/10/yad061.html
- Let's dissect this graph.
- First, take a look at the splice. There is a major discontinuity in the graph at exactly the point where the two data sets are spliced together. This doesn't mean that the graph is wrong, but your radar should be going off when you see this. Basically, you should wonder whether the swhape of the graph is the result of how the data was joined together, rather than the result of what is ostensibly being measured. Actually, this graph is terribly hard to read, because at least 4 data sets have been merged into the blue ”proxy” line. Let's take a look at a later IPCC chart that shows the different data sets explicitly.
- This is from the IPCC 4 th Assessment Report (AR4). It's a hockey stick. The solid black line starting around 1825 is the thermometer record; the other lines are different studies of proxy temperature. You can clearly see the Medieval Warm Period, and the long Little Ice Age. Remember, the curve spikes skyward where they've joined the thermometer record to the proxy record. You can explicitly see that here.
- So what if you remove the spliced data? After all, we have over a thousand years of tree ring data. What if we just look at that? ” When one gets an inflection point right at the place where two data sources are spliced, as is the case here, one should be suspicious that maybe the inflection is an artifact of mismatches in the data sources, and not representative of a natural phenomenon. And, in fact, when one removes the black line from measured temperatures and looks at only proxies, the hockey stick shape goes away ...” http://www.climate-skeptic.com/2007/11/the-splice.html Stop and look at that for a minute. You can clearly see the Medieval Warm Period around 1000AD, you can see the Little Ice Age bottom out around 1700AD, and you can see that we're a little less warm now than we were in the MWP. The data here are purely tree rings, so we're comparing the same thing. The moral is that sometimes when you try to turn an apple into an orange, you get a lemon. Notice that this does not say that things are not warming - in fact, it confirms the warming trend. What it suggests is that historically this is not unusual. Neither is it sudden, or a Hockey Stick.
- We're told that temperatures have been rising for 100 years, and that 1998 was the ”warmest year in 1000 years”. Remember, we don't have thermometer records from that far back, so when you hear than, you know that someone spliced proxy data to thermometer data. But we have decent thermometer records dating from the late 19 th century, and some that's older. But you need to know how the sausage is made. There is meat (raw data), and filler (”adjustments”). This doesn't mean that the data is necessarilly wrong, or that sousage isn't tasty. But it's not filet.
- There are two parts to the data: the raw temperature readings, and adjustments to the readings. The raw numbers are easy - they're just the instrument reported temperature for the weather station. Look outside your house at your thermometer - that's the raw data. Adjustments are modifications to the readings, to "remove inhomogeneities" in the raw data. You (like me) may look at that and say Whiskey Tango Foxtrot are inhomogeneities? CRU helpfully provides an answer: ” Most long-term climate stations have undergone changes that make a time series of their observations inhomogeneous. There are many causes for the discontinuities, including changes in instruments, shelters, the environment around the shelter, the location of the station, the time of observation, and the method used to calculate mean temperature. Often several of these occur at the same time, as is often the case with the introduction of automatic weather stations that is occurring in many parts of the world. Before one can reliably use such climate data for analysis of longterm climate change, adjustments are needed to compensate for the nonclimatic discontinuities.” OK, we don't want a jump in the historical record if you move a station or replace a thermometer with a better one. But. All the Climatologists in the world will look at this data. How much do the adjustments change the results? See http://borepatch.blogspot.com/2009/12/how-to-create-scientific-consensus-on.html
- How much do the adjustments change the results? We don't know, but people are starting to look. They're starting to find that adjustments change the data a lot. They change the data so much that they show that the earth is warming when the raw data may show that it's cooling. Let me say that again: Thermometers may be showing that the Earth is cooling, but adjustments to this data show a rapid temperature rise. The most interesting analysis of Global Warming science is occuring right here, on this topic. Lots of people from all over the world are looking at the difference between raw and adjusted data, to see if the adjustments make sense. Mostly, they don't.
- The blue line is the raw data from the five weather stations in Darwin. It shows a 0.7°C cooling over the 20th Century. The Black lines are the adjustments to this data, showing a big jump in 1940 and a substantial increase since then. They turn the raw data decline into a 1.2°C increase over the course of the 20th Century. Woah. So what's with the adjustments? Fortunately, there is an explanation: They pick five neighboring stations, and average them. Then they compare the average to the station in question. If it looks wonky compared to the average of the reference five, they check any historical records for changes, and if necessary, they homogenize the poor data mercilessly. I have some problems with what they do to homogenize it, but that’s how they identify the inhomogeneous stations. OK … but given the scarcity of stations in Australia, I wondered how they would find five “neighboring stations” in 1941 … So I looked it up. The nearest station that covers the year 1941 is 500 km away from Darwin. Not only is it 500 km away, it is the only station within 750 km of Darwin that covers the 1941 time period. (It’s also a pub, Daly Waters Pub to be exact, but hey, it’s Australia, good on ya.) So there simply aren’t five stations to make a “reference series” out of to check the 1936-1941 drop at Darwin. ... Yikes again, double yikes! What on earth justifies that adjustment? How can they do that? We have five different records covering Darwin from 1941 on. They all agree almost exactly. Why adjust them at all? They’ve just added a huge artificial totally imaginary trend to the last half of the raw data! ... Those, dear friends, are the clumsy fingerprints of someone messing with the data Egyptian style … they are indisputable evidence that the “homogenized” data has been changed to fit someone’s preconceptions about whether the earth is warming. See http://wattsupwiththat.com/2009/12/08/the-smoking-gun-at-darwin-zero/ Also http://borepatch.blogspot.com/2009/12/how-to-create-scientific-consensus-on.html
- Just out of interest I decided to plot the raw temperature data for my home city of Brisbane, Australia from the GISS (ie the raw GHCN data) against the homogenized or adjusted GISS GHCN data. The temperature sensor is located at the Brisbane Eagle Farm Airport which is now our busy main international airport. The data used is the series available from 1950 to 2008. I have aniumated the result to highlight the difference. As you can see the raw data shows a downward trend of about -0.6 C per century. The unadjusted data however shows an opposite trend of +0.6 C per century. Intuitively as the airport grew from a quiet strip to a busy international jet airport one would think the more recent data would be adjusted downwards for the heat island effect. Instead we see that the data prior to 1978 is adjusted down and the data in recent times was adjusted up. See http://thedogatemydata.blogspot.com/2009/12/raw-v-adjusted-ghcn-data.html He has an overlay of Raw vs. Adjusted data that is simply stunning.
- A group called the Climate Science Coalition of New Zealand made a bombshell announcement: all of New Zealand's reported 1°C warming between 1850 and 2000 was due to adjustments. See http://www.climatescience.org.nz/images/PDFs/global_warming_nz2.pdf Also http://borepatch.blogspot.com/2009/11/man-made-global-warming-confirmed.html
- The link on the slide takes you to the analysis. Same in Detroit: http://thevirtuousrepublic.com/?p=4803 It also seems that Scandanavian scientists are having trouble replicating the IPCC results: http://wattsupwiththat.com/2009/11/29/when-results-go-bad/#more-13373
- An interesting question is how much of the 20th Century's warming came from adjustments, rather than from raw data ? A picture is worth a thousand words. What you're looking at is the annual adjustment made to the raw temperature, for each year in the 20th Century. You'll notice that almost no adjustments are made to years up to 1960, and then a very interesting shape appears in the graph. A hockey Stick. This is from the US National Oceanic and Atmospheric Adminstration (NOAA), for the lower (Continental) 48 US States. http://borepatch.blogspot.com/2009/11/man-made-global-warming-confirmed.html
- There is some reason to think that the adjustment process is completely broken. One analysis from Australia asks why ”average” the Darwin data to adjust it upwards when none of the 5 temperature stations in Darwin show warming? http://joannenova.com.au/2009/12/smoking-guns-across-australia-wheres-the-warming/
- Let's look at raw data. Where does it come from? There are thousands of weather stations all over the world. Some are in better locations than others. Good location: Rural, natural settings similar to what was there a century ago (picture on left). Bad location: in the middle of a newly-paved black asphalt parking lot, which soaks up the sun's heat is a way that the grass didn't, 100 years ago.
- Cities are hotter than the surrounding countryside. Growing cities change cooler rural land into warmer urban environment. This ”Urban Heat Island” is present in all cities – it's a problem for the temperature record when the city has been expanding quickly. Albuquerque, NM (1940): population 60,000 Albuquerque, NM (2000): population 600,000 Albuquerque is hotter today than it was 70 years ago. If we want to know whether the climate is changing, we need to know how much of the theremometer record is from Urban Heat Island, and how much is from climate change.
- This is a currently active weather station. It has been operating continuously at the same location for over 100 years. 100 years ago, the parking lot was a field of grass. 100 years ago, there were no air conditioner compressors pumping out hot exhaust 10 feet from the thermometer. You Can see that the site's recorded temperature has been increasing pretty dramatically since the 1930s. Did the Civilian Conservation Corps ”improve” the site during the Great Depression?
- Again, to avoid the charge of ”cherry picking” stations, let's look at the US Government's own data about site location. This is NOAA's published quality data for station siting. http://www1.ncdc.noaa.gov/pub/data/uscrn/documentation/program/X030FullDocumentD0.pdf See SurfaceStations.org for detailed information.
- One of the weakest parts of the pro-AGW discussion is the way UHI is dismissed almost out of hand. Very poor research is held up as definitive (temperature doesn't change in cities on windy days compared to still days). The opportunity for UHI to significantly bias temperature needs much more study, but right now it seems to only be coming from groups like surfacestation.org To me, this is a very serious weakness in the AGW hypothesis, and strongly suggests that AGW proponents are not interested in arguments that might falsify their theory. In other words, in actual science, which is founded on experimental falsification of hypotheses.
- We now need to shift from history to Chemistry. We've heard of the "Greenhouse Effect", where sunlight passes through the atmosphere to the ground, the energy is absorbed and re-emitted as heat, and the heat is trapped by the atmosphere. In more precise scientific terms, certain gases are transparent to visible light, but obaque (blocking) to heat (infrared) radiation. Carbon Dioxide (CO2) is one of a set of greenhouse gases, including methane and water vapor. One justification for the Hockey Stick that proponents of AGW theory used was that the Industrial Revolution began to produce large amounts of CO2 around 1850, which is when we saw the spike in temperature. There are a couple problems with this: 1. Correlation does not imply causation. Just because something happens at the same time as something else, doesn't mean that it's caused by it. If we see a big increase in, say, the number of lemons imported from Mexico, and simultaneously see a big reduction in the number of traffic fatalities, we shouldn't jump to the conclusion that Mexican lemons reduce traffic deaths. This seems obvious, but is really at the heart of the proposed policy mitigations like Kyoto, Cap and Trade, and Copenhagen.
- CO2 is a very - even surprisingly - weak greenhouse gas. What this means is that as you put more CO2 into the atmosphere, it has less and less of a greenhouse effect. This isn't really surprising, because this sort of "exponential decay curve" is the norm in nature - things tend to rapidly achieve equilibrium because this "negative feedback" keeps things from running away out of control. Chemistry (actually spectroscopy) tells us that CO2 is not really opaque to infrared except at a very narrow frequency band, and therefore "leaks" heat back into outer space at the edges of the bands. http://borepatch.blogspot.com/2009/09/14-reasons-why-anthropogenic-global.html
- Proponents of AWG know this, and have proposed a theory of "Positive feedback", where CO2's greenhouse power is multiplied, or "forced", sort of like Popeye after he opens a can of spinach. This forcing is reached after a particular CO2 concentration, and causes a "runaway greenhouse effect". There is a fatal problem with this: we simply don't ever see this in nature. The universe is stable because of negative feedback.
- There is, of course, a theoretical justification for positive feedback from the AGW proponents - the details are complex, and I don't want to get into them. Instead, is there a way that we can test the theory? There is indeed. We have measurements of both temperature levels as well as CO2 concentrations for at least the 20th Century. How do they match? Poorly (http://borepatch.blogspot.com/2009/09/14-reasons-why-anthropogenic-global.html): Rather than lots of science and math and stuff, he looks at what the proponents of AGW say. And find a lot to be desired: 5. The claimed “proof” of positive feedback is a model prediction of a hot spot in the tropics at mid troposphere levels. However all the experimental evidence from many, many measurements has failed to find any evidence of such a hot spot. In science, a clear prediction that is falsified experimentally means the underlying hypothesis on which the prediction is based is wrong. ... 8. If I adopt this 10:1 ratio by looking at the last 100 years worth of data I find 1910-1940 temperatures rising while CO2 was not. 1940 to 1975 temperatures falling while CO2 rising, 1975 to 1998 temperatures rising while CO2 rising and 1998 to 2009 temperatures falling while CO2 rising. Three quarters of the period shows no correlation or negative correlation with CO2 and only one quarter shows positive correlation. I do not understand how one can claim a hypothesis proven when ¾ of the data set disagrees with it. To me it is the clearest proof that the hypothesis is wrong.
- Actually, there's never been a consensus. The most interesting thing about this argument is that it's not a scientific argument. Science simply doesn't care about consensus, it cares about data and reproduceability of results. If your data is solid, and other people can get the same results, it simply doesn't matter if you run with the crowd or not. There's good reason to think that the raw temperature readings in the major climate data sets have been modified in a way that guarantees a global warming output. That would actually give you a consensus, although it wouldn't necessarilly be correct. Why and how the data was modified has not yet been well explained.
- It's not up to the AGW skeptics to propose an alternative theory to CO2 greenhouse forcing (although there's considerable activity particularly around solar cycles). The AGW hypothesis has to stand or fall on its own internal consistency, robustness, and ability to map to natural results and data.