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Still No Global Warming For 17 Years 10 Months

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  • #46
    Originally posted by tabibito View Post

    This has the "recent" temperature rises (section marked with the red curve underneath rising from left to right) mirrored and laid alongside past temperature falls. (red curve dropping from left to right). The black sections are what was projected, almost covering the red of actual recordings.

    Also, argument is that CO2 levels show an historic pattern of increasing after temperatures rise. I haven't been able to confirm that argument.
    This is worth a read:
    Last edited by firstfloor; 08-06-2014, 01:14 PM.
    “I think God, in creating man, somewhat overestimated his ability.” ― Oscar Wilde
    “And if there were a God, I think it very unlikely that He would have such an uneasy vanity as to be offended by those who doubt His existence” ― Bertrand Russell
    “not all there” - you know who you are


    • #47
      Originally posted by tabibito View Post
      Not arguing against that - I am satisfied that human activity is contributing and probably accelerating the process - but the question is trying to separate the significance of the human contribution. This current rising cycle started before the 20th century. (I think)
      The trend right at the start of the twentieth century was cooling; which reversed to give a strong warming trend from about 1910 to 1940 or so. Then there's a plateau, in fact a slight cooling dip, around 1945 to 1965 or so. From 1975 or so there was the start of a strong increase. The rate had varied; and as this thread points out over recent decades the increase in atmospheric temperatures has dropped off somewhat. (The "pause", or "hiatus", or whatever you call it.)

      There are various factors at work here of course. The early twentieth century warming starting from 1910 or so is quite strong.. and physically it's really hard to explain that as being entirely a human influence. A major factor here is almost certainly recovery from short term volcanic cooling, from Krakatoa and other big eruptions. The latter part of the twentieth century is pretty clear human driven; most of the other non-human influences over this time are for cooling rather than warming, so it's credible that more than 100% of that warming is human driven. We not only raised temperatures; we actually overcame a weaker solar influence to do so!

      Confounding everything, of course, is that there are substantially short term variations in temperature which are local to Earth rather than being driven by changes in the Sun or the atmosphere or by albedo. A big one (it seems; this is hard to measure well!) is ocean currents and exchanges of heat between the atmosphere at the ocean. So as temperatures increase, there are some significant "pauses" along the way; decades over which the warming doesn't show up well in temperature data. For this reason, trends measured over any short term period are not a good guide to long term trends. They may run higher than the underlying trend, or lower. We see both in the temperature record.

      The recent 17 year "pause" isn't really a pause. The OP uses a rather strange dataset (RSS lower troposphere temperatures) which is a bit of an anomaly from all the other temperature datasets available. All of them show warming over the last 17 years, but but not enough warming to represent a statistically significant trend. RSS is the odd one out, it shows a small decline (but again, not statistically significant). Curiously, the UAH dataset, which uses precisely the same satellite microwave data, shows warming. The difference is entirely due to ways in which two groups process the data. (Getting temperatures from satellites isn't easy.)

      The key to getting significant trends is to measure for longer periods. In the short term, we expect (and this shows up in both data and models) to get regular periods of time over which measured trends are substantially more, or less than the long term trend. It's called "natural variation"; but it's not actually random. It is largely chaotic; and hence we cannot predict well when you get the "pauses" and the "accelerations". But we will get them.

      Here is some example data. I'm using the HadCRUT4 temperature data from Met Office Hadley Center (UK). Blue is the temperature data itself. Black is a smooth of that data, using a Butterworth digital filter tuned to remove frequencies less than cycle per 17 years. The red cross is a regression trend line of the last 17 years, 95% confidence bounds. The dotted yellow is a rate of change taken as the slope of the smoothed data. It diverges at the end because the trend depends on data from the future, and I simply projected the trends from the 95% confidence bounds in red. Most likely it will end up somewhere in the middle.

      This is my own calculation, so I'm open to questions about it. It's a spreadsheet I put together for my own interest a while ago, and I can plot plenty of other datasets with it if anyone would like.


      For comparison, here is the UAH data (which only starts at 1979) and the RSS data (which is using precisely the same satellites; the discrepancy of these two datasets is not well understood as far as I am aware).


      Note that the trend over 17 years is not significant in either RSS or UAH. These are not measuring the same thing as surface temperatures; they are actually attempting to measure the atmosphere (lower troposphere). This data has much more variation than the surface, and you cannot hope to get a significant trend over 17 years. The atmosphere has too much variation to get a good idea of the long term trend from 17 years. The OP mentions Christopher Monckton citing the RSS dataset. (Just a caution; Monckton is right over at a far extreme of lunacy and ignorance with the science.) That's a bit of a giveaway; you get a better idea of what the pause is all about looking at the last 17 years in one of the surface temperature datasets. They all show warming; but over 17 years the confidence bounds include a possible flat trend within 95% confidence limits. So rather than "pause" I prefer to say that surface warming over the last 17 years is below statistical significance.

      The ideal thing would be to measure the ocean -- it has less short term variation and it is also where most of the heat goes. But that's really really hard. We would need to get accurate profiles across all depths, and all around the planet, and all through the year. We don't have that kind of resolution, alas. Indirect indications do show that the oceans are continuing to warm even as the atmosphere trends are showing a short term pause.

      It's a pretty safe bet that the current pause won't last. It's possible (though not at all certain) that 2014 will be a new record high. I definitely expect that one of the next five years will show a very clear record high global surface temperature anomaly. But we'll see....

      Cheers -- sylas


      • #48
        Originally posted by tabibito View Post

        This is the graph of Greenland temperatures - only one location in the world, but illustrative. Current temperatures nowhere near as high as they were about 900 years ago.
        Does it make sense to assume that both Greenland and the Scandes mountains should show scientific evidence of higher temperatures than recorded today, but that no such warming occurred elsewhere on the planet? We are not taking about temporary weather events; rather we are talking about extended periods of warming.


        • #49
          The graph for Greenland is highly misleading; it simply omits all the modern warming.

          It speaks of data up to 2000 AD. That's just wrong; it only goes up to 1855. That graph completely omits the modern warming peak. To add it in you would need to include a sharp RISE at the end of the graph, going up to above the level of "Medieval warming", but not as high as "Roman warming"; an extra about 1.44C. Here is the data plotted together with a marker for where the year 2000 SHOULD be.

          What is shown is a portion of the GISP2 ice core data. It is readily available from NCDC here.

          The data goes back some 50 thousand years; though the plot only shows the last 10 thousand, just after the really big jump in temperature coming out of the most recent ice age. The last data point is 95 years before present; and in GISP2 data, "present" is the baseline standard year of 1950.

          That 1950 is called the "present" is now a standard. This is in part because radiocarbon dating cannot work past this date due to the massive amounts of radiocarbon added to the atmosphere during nuclear bomb testing. I can try to chase up references on this if anyone is actually skeptical on this point; but I went through the whole issue here years ago. In the GISP2 and other ice core data, when dates are years before "present", the present is a 1950 standard. For scientists working with this data, this would simply be taken for granted. Unfortunately it is not explicit in the data file I have linked.

          The little red tick at the end of the graph is a dead giveaway that the original source of the graph is one confused individual called Don Easterbrook. He is trying to suggest that the little red bit corresponds to modern warming. It does no such thing. There is nothing special or difference about the little bit of red at the end of the data, and the data ends at 1855; well before modern global warming.

          This was pointed out by several people, who also contacted the original GISP2 researchers for clarifications and for the 1.44C rise of the modern period at this site. Read more here: Easterbrook's wrong (again)
          Attached Files


          • #50
            I just happen to be reading the "Climate Change Happens" chapter in The Great Global Warming Blunder: How Mother Nature Fooled the World's Top Climate Scientists, (Encounter Books, 2010), by Roy Spencer, principle research scientist at the University of Alabama; formerly a senior scientist for climate studies at NASA; he is co-developer of the original satellite method for precise monitoring of global temperatures from Earth orbiting satellites.

            Spencer makes the point that satellite instruments provide our only truly global source of temperature information. He says that the biggest headache he and his colleague have had in trying to monitor climate trends with satellites is not related to calibration but to the kind of Earth orbit the satellites are in. He says that that problem has been alleviated only since mid-2002 with the launch of NASA's Aqua satellite, which carries extra fuel to adjust its orbit periodically so as to maintain a constant observation time, year after year. He says that all measures of temperature variability are imperfect. And even if they were perfect, the huge amount of natural variability in the climate system―on time scales from yearly to millennial or longer―makes the definition of a temperature 'trend' very difficult. "While we can probably say with high confidence that the climate has warmed in the last 50 to 100 years, it is more difficult to say by exactly how much, still more difficult to say whether it is unprecedented or not, and impossible to say what any of this means for future temperatures."

            Spencer describes some kinds of chaotic behavior in the climate system, partly because they occur with some regularity. He mentions the fact that El Niño and La Niña events come around every few years, but they are not well enough understood to predict which years will experience an event. "When you do hear a forecast of El Niño or La Niña conditions for the coming month, it is only because an event has already started."

            Here is his theory: "My claim is that this chaotic behavior also occurs on much longer time scales. The chaotic climate fluctuation that I highlight in this book is known as the Pacific Decadal Oscillation, or PDO. Somewhat like El Niño and La Niña in the tropical Pacific, the PDO is a regional shift in weather patterns, but over the North Pacific Ocean. And rather than having a time scale of only a couple of years, the PDO changes phase much more slowly, every thirty years or so. This makes it a potential player in global warming."

            He goes on to say that since the atmospheric circulation is coupled with the ocean circulation, a change in one is almost always accompanied by a change in the other as they work together to move heat energy from where there is more to where there is less.

            "While the importance of the PDO to the global warming debate has been largely ignored, it's thirty-year time scale is long enough to cause climate change. This is comparable to the period in which the IPCC claims to have evidence of mankind's fingerprint on climate. To remind you, a major conclusion of the IPCC's 2007 report was: 'Most of the observed increase in global-average temperature since the mid-20th Century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations.' So, the IPCC is claiming to be confident that warming in the last 50 years is manmade, and since there was slight cooling from the 1940s to the late 1970s, they are mostly referring to the warming over only a thirty-year period!"

            Spencer presents a graph showing "Running five-month average values of the PDO index for 1900-2008" that has a marker to show the start time of satellite monitoring of the earth near the end of the 1970s. He says "Guess what? As shown [in the figure I just described -JR] that thirty-year interval [see end of paragraph above -JR] just happens to be the same period when the PDO was in its 'positive' or 'warming' phase."

            Spencer remarks that one would think that the IPCC reached its conclusion that mankind very likely caused the recent warming after ruling out natural climate variability, like that associated with the PDO as a cause. "But the truth is they never seriously investigated it. The IPCC has taken for granted that there are no natural variations in global average temperatures once one gets beyond a scale of 10 years or so. Specifically, the IPCC's most important (and incorrect) assumption is that the average cloud cover of the Earth always remains the same."

            He notes that the 2007 IPCC report does indeed mention the PDO, and other types of multidecadal variability, "but for some reason never asks the obvious question: Could these natural climate fluctuations cause a change in global cloudiness?"

            Spencer says we would need fifty years to prove or disprove the existence of a natural mechanism of climate change. Unfortunately, those measurements do not exist. Consequently the IPCC can correctly claim that there is virtually no published research to support natural sources of long-term climate change. "This is not arguing from evidence, though, but from lack of evidence." The lack of said evidence for natural sources of climate change "will require some digging. It's like trying to solve a murder mystery when one has very little to go on initially. Since a possible weapon (green house gas emissions) was found at the scene of the crime (warming), that's good enough for the IPCC to pin the rap on humanity."

            Spencer notes the fact that scientists write proposals to study the effect that anthropogenic global warming has had on any number of natural phenomena. "Is it any wonder that they find what they were paid to find?"

            Spencer repeatedly emphasizes the fact that there is no unique fingerprint of manmade global warming. "Any warming due to manmade greenhouse gas emissions looks the same as warming due to, say, increasing water vapor (Earth's main greenhouse gas) resulting from a warming of the oceans. The ocean warming could, in turn, be the result of low clouds changing how much sunlight is absorbed by the oceans, or by a change in how fast cold water wells up from the ocean depths. Therefore, while patterns of warming across the Earth in the past fifty years might be 'consistent' with manmade global warming, they are equally consistent with natural causes of warming."

            ETA: see here, and also click on the link within the article ― i.e., the one titled "PDO might explain most of the climate change"
            Last edited by John Reece; 08-07-2014, 04:52 AM.


            • #51
              UAH Global Temperature Update for July

              From Roy Spencer's blog

              Note the El Niño warming spike circa 1998-1999.

              I recommend extended browsing on Dr. Spencer's blog. See each of the six other bulleted categories under the Home/Blog section at the top of the page; also, the links to articles listed in the side bar of the Home/Blog page. All these features combine to form a gold mine of reliable information about global warming.

              A sample article from the list on the side bar is here.


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