A Few Things Ill Considered

A layman's take on the science of Global Warming featuring a guide on How to Talk to a Climate Sceptic.

Tuesday, April 11, 2006

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Warming Stopped in 1998

(Part of the How to Talk to a Climate Sceptic guide)

This article has moved to ScienceBlogs

It has also been updated and this page is still here only to preserve the original comment thread. Please visit A Few Things Ill Considered there. You may also like to view Painting With Water, Coby Beck's original fine art photography.



  • At April 11, 2006 4:08 PM, Anonymous Anonymous said…

    Thank you! I am learning so much from this blog and Real Climate, and I am very grateful.

  • At April 11, 2006 4:33 PM, Blogger coby said…

    I'm very glad you find it useful! :)

  • At April 16, 2006 7:55 AM, Anonymous Anonymous said…

    cheers for the info. - the 1998 arguement did seem a strange one

  • At April 19, 2006 3:38 PM, Anonymous Anonymous said…

    "at a global temperature not experienced in human civilisation"

    .. there is record that the Romans cultivated grapes in Britain though the weather is not really good enough which is why the British wine industry is small. It is also said that Britain was warmer during the Roman period, indeed it is generally believed by the British that it was warmer during Roman times and distinctly colder during the middle ages.

    Is it in fact not true that it was warmer in Britain during the Roman era? Was it that their wine making must have been a sorry endeavour?

    Anybody got any real beef on this?

    What gets me though, is the doomsaying ... trivially, the winters in England seem milder now than 30 years ago. The world is warming up. We can think of lots of losers, but also lots of winners. We don't know how much the world is going to warm up, and we don't know what that is going to do.

    We do know that whatever we do, CO2 levels will remain historically low - most of the world's carbon is going to remain locked up underground ( where the plants put it eons ago) whatever happens. We can be pretty sure that the world is going to remain cooler than it was throughout most of its life.

    Do we have good reasons to suppose we are facing a catastrophe? or will it simply get a bit warmer?

  • At April 20, 2006 11:18 AM, Blogger coby said…

    Regarding Britain during Roman occupation I would only caution about inferring a global climate from a regional one. The reconstructions being done in the peer review scientific literature are simply not finding evidence of a globally warmer period 2000 years ago, or indeed at any other time going back until the Eemian interglacial period. I am not familiar with climate in western europe at that time, so can't offer much about that.

    As for the specific evidence of grapes in England, they are growing there now and surely the economics of shipping wine was very different 2000 years ago so I don't know how much should be read into that.

    For your other questions I invite you to read these:

    Thanks for the comment (and sorry not to have responded right away)!

  • At April 21, 2006 1:21 PM, Blogger William M. Connolley said…

    Bob Carter's money is not as stupid as his words: he has refused to bet Brian Schmidt on odds that would be favourable if he really believed that GW had stopped.

  • At April 21, 2006 1:28 PM, Blogger coby said…

    Surprise, surprise. These guys don't even swallow their own tripe.

  • At May 27, 2006 6:26 AM, Anonymous Anonymous said…

    Just one comment... The author claims the article he sited "cherry-picked" years, yet the author goes and "cherry-picks" year to make a counter-point.

    The simple fact is noone knows. All the climatic models I've seen are mathematically wrong. The historical record of our climate is seems pretty clearly to follow a sin wave, yet all the models attempt to predict a dynamic, cyclical climate using linear trends.

    How can we trust the predictions for the next hundred years, when we can't get tomorrows weather accurate to a degree?

  • At May 27, 2006 6:53 AM, Blogger coby said…

    No, I didn't cherry pick, I picked. You have missed the entire point of the article.

    Which models have you looked at in this kind of detail, and what mathematical errors did you find? Obviously none, as you claim they are trying to predict the future with linear trends. I invite readers to review the past temperature trends here and see if it follows a nice sine wave.

    The last question you ask is answered here

  • At June 25, 2006 7:43 PM, Anonymous Anonymous said…

    Er, coby, actually, every time you picked "the start of a warming period" that was, in fact, cherry picking. Eg, just as invalid as picking 1998 because it is the "year it started cooling" (not that it did).

    Picking "the start of a record" is not cherry picking in the same way, but really, the _appropriate_ way to address this issue is to point out that there is significant year to year variation, and that therefore moving averages will show long term trends much more clearly than any difference between two points.

    I'm sure there must be a statistically approved way given a certain data set to choose the appropriate sized averaging window, but I don't know what it is... (some power series approach, perhaps?) it seems like 3 years is the minimum I've seen in the lit, 5 is common, and 10 is common (for paleo records, it tends to be even longer: one researcher told me he doesn't believe anything below a 25 year average, which is perhaps why the NAS report used "warmest 25 years of the past millenium" as their metric). Any of these approaches will deal with the "1998" "problem". As will waiting another year or two, unfortunately, when we blow past that temperature record...

  • At June 25, 2006 8:47 PM, Blogger coby said…

    every time you picked "the start of a warming period" that was, in fact, cherry picking. Eg, just as invalid as picking 1998

    Not really the same, as the starts of those warming periods are not based on individual years but are based on the five year mean in GISS and I'm not sure what smoothing they use in CRU. 1998 is not a peak on the trend line, it really is just a single year anomaly. Of course, looking at any particular window will never give you the full picture, any start and end is arbitrary. But arbitrary need not be useless and it is useful to isolate the late 20th century warming for comparative purposes.

    I agree with your point about inter-annual variation, I did make it but perhaps it is not prominent enough.

    I also heartily agree with longer averaging windows being more significant, and with waiting a few years for 1998 and 2005 to both be blown away as records. But there is a bit of urgency here too...!

    Thanks for the comment.

  • At July 06, 2006 4:13 PM, Blogger mulp said…

    Having just seen the Carter op-ed, I note that he doesn't claim that there is no climate change, merely no global warming, and then he warns of global cooling and calls for action to deal with that problem. Clearly what bothers him is that he thinks that the campaign to fight global warming might actually work.


  • At November 06, 2006 6:36 PM, Blogger coby said…

    Hi Robert,

    Mean global surface temperatures have not increased since 1998.

    Please reread this post, that is not a reasonable statement. It is correct that 1998 is about the same as 2005 but that is all you can say. If you insist on being ignorant of statistics, well then, warming has been quite dramatic since 1999, almost .3oC in 6 years. Yikes!

    What seems certain is that cooler Pacific sea surface temperatures bring more rainfall to Australia and moderate global temperature. A ‘cool phase’ of Pacific sea surface temperatures may have commenced in 1998.

    If global temperatures were being driven by oscillating ocean temperatures then global temperatures would be oscillating and land temperatures would be showing less change than oceans. Not.

  • At November 26, 2006 10:54 AM, Anonymous Anonymous said…

    There are a few things here and with the global warming debat I have a problem with.
    1. All climate models are based off of "surface" temperatures records, which most are near urban areas. So the data is faulty, cities and land use change of that sort trap heat creating warmer environments around the weather stations. These are called Urban Heat Islands.
    2. There was a warm period in which the Normans found 47(ish) winaries in England when they invaded and took over. Around this same period the Chinese found no ice in the artic (through sailing recored), and the Norse had farms in Greenland. The era is call the Medieval Warm Period, and it actually existed throughout the northern hemisphere. This is simple historic fact which has been ignored by climotoligist looking for some extra research dollars. If you would like more info on this, I would point you towards http://www.climateaudit.org/
    3. I would adives everyone to read into this more. Although, everyone will have their own opinion on these issues the media is not the place to look for this information. The media is full of bias and fearmongering. There are problems with all of the climate models, there are problems with what is reported from those models.
    3.CO2 is the ONLY thing these models take into consideration, and mostly ignore the most important greenhouse gas of call, water vapour. Satellites have only found a small rise in atmospheric temperature since the 1970's, yet surface data has shown a large rise in that same time. The oceans have remain relatively consistant through that time. Pre-70's there was a fear of the coming ice age, which thankfully never happened, in which some of the same scientists who were warning of that, are now warning of global warming, pretty big change in 30 years. There are always two sides to the coin.

    I could say more, but have run out of time...

  • At December 07, 2006 5:03 PM, Blogger coby said…

  • At April 20, 2007 12:01 PM, Anonymous Anonymous said…

    Especially since 2002 is the warmest (at least globally with the GHCN - ERSST data) I prefer to look at 1880 (-.2) to 2006 (+.3) off global mean for the period and it's clear to see the trend globally going from -.4 to +.3

    The only questions then left are what is the meaning (and/or import) of the sudden changes since 1980, what changing a total of .005C a year during the period means, what impact does increasing urbanization globally and additional industrialization in places like India and China contribute, why the drop from +.6 to +.3, and why not a constant increase from year to year, given the elevated CO2 levels.

    And of course, what to (or how much to) do about it.

  • At July 13, 2007 3:04 PM, Anonymous Anonymous said…

    I am very tired of you greenies calling anyone that disagrees with your assertions KOOKS. There is a debate that is ongoing. There is not a consensus. The only consensus is among the leftist environmentalists. I truly believe that any global temperature change is due to solar activity and natural causes. Those that believe that there is a anthropologic cause to global temperature change have blindly and steadfastly made their minds up and have hung the CLOSED sign on it. I have always believed that the green crowd has looked for one cause or another to scream about. The sky is falling. DDT, Acid rain, Pollution, The Ozone hole, blaa blaaa blaaaaaa. When the greater population loses interest in these causes a new flag is taken up. This has grown some legs. But the problem is that FACTS get in the way. It does look like the GW bandwagon is slowing down and is rolling to a stop. So whats next…….Ice age…Global cooling.

  • At July 16, 2007 9:00 PM, Blogger coby said…


  • At October 23, 2007 9:07 AM, Anonymous Anonymous said…

    The earth has gone thru periods where there were no polar caps at all for time line on cooling and warming check this outhttp://math.ucr.edu/home/baez/temperature/

  • At December 17, 2007 8:52 AM, Blogger Patrick Hadley said…

    I am sure you are interested to know that after the figures for 2006 and 2007 are included (see the Hadley Centre website) the five year moving average is now heading downwards.

    It it therefore correct to talk about a trend for global cooling without any reference to 1998.

  • At January 25, 2008 5:04 PM, Anonymous Anonymous said…

    i think my blood pressure went up a few degrees after reading many of your blog . I like how at the beginning of many of your posts, you automatically assume that anybody who opposes your opinion is more ignorant than you. i hate to think that people are influenced by people like you who are so horribly biased that they resort to name-calling, and will obviously never consider the other side

  • At February 27, 2008 11:29 PM, Anonymous Anonymous said…

    Hello friends,

    I'd like to inform everyone of a new discovery -- that global warming stopped in January 2008! Note that this result was obtained using the same cutting-edge methodology that concluded that global warming stopped in 1998.

    Which means... global warming came to an end 1998... and it came to an end again in 2008!

    Have fun,

    -- Frank Bi, http://globaldumbing.tk/

  • At April 04, 2008 5:49 AM, Anonymous Anonymous said…

    So, I guess that the UN is now part of the collection of fringe, right-wing nut-jobs who are cherry-picking data?


    When are you and your ilk going to be mature enough to accept that there is *legitmate* disagreement of opinion on this topic and actually apologize for all of the aspersions you've cast on those you've dubbed climate heretics?

    But I guess even that is asking too much. I'm curious to see how immature you get when the evidence against *man-made* global warming starts becoming harder to refute.

  • At April 04, 2008 7:51 AM, Blogger Unknown said…

    Anonymous. If you reread that BBC article you will in fact find that temperatures are expected to be lower this year because of an La Nina event, which reduces temperatures, the same as the El Nino raised temperatures in 1998. This is a natural cycle that will occur independently of global warming and doesn't detract from the argument at all, if you read the actual article (although the headline writer at the BBC got it all wrong)

  • At April 04, 2008 10:04 AM, Anonymous Anonymous said…

    And if you read what I said it is a direct response to this blog's assertion that the only way to claim the temperature stopped increasing in 1998 was to "cherry-pick" the data and that only a biased hack would do such a thing.
    The ariticle referenced, while still towing the standard political line, states clearly that no matter how you look at it the temperature trend over the last decade is flat or negative - in direct contradiction to the assertions of this blog and further pointing out the incorrect stance of the blogger.

    A further reading of my comment will also show that I made absolutely *no* comment about the larger warming trend outside of the evidence of the last decade, but *did* question the *man-made* component.

    Sorry you're so blinded by your political bias that you have to read inferences into my comment to criticize it.

  • At April 06, 2008 7:40 PM, Anonymous Anonymous said…

    Global warming will prove to be the biggest scam in our lifetimes.

    I just hope that sane minds will derail this hoax before too much damage is done.

    Countries are already wasting billions of dollars that might otherwise be going to help the poor or inproving peoples lives.

    Instead, we are denying 3rd world countries access to cheap energy resources because of the fear that they might spew more CO2 into the air.

    Do these environmentalists even understand that they are costing people their lives?

  • At April 20, 2008 2:21 PM, Anonymous Anonymous said…

    Sure the warming stopped in 1998. Or if you prefer (since 1998 was the all-time high ENSO year), it has stopped since 2001. Those are the facts. No interpretation needed.

    All four temperature records confirm this. Below is the link to one (Hadley).

    Download and plot the data into Excel and draw a linear trend line. You will see a very slight cooling trend, i.e. no more warming, despite the fact that atmospheric CO2 increased by 20 ppmv over the period.

    But it’s not only the “flat” period since 1998 (or 2001) that does not show a correlation between temperature and CO2 as David Whitehouse has pointed out, and Mark Lynas has not been able to refute in his response.

    The period 1976-1998 does indeed seem to show such a correlation. This period accounts for around 30% of the warming that has occurred since records began in 1850. CO2 rose by 30 ppmv over this period.

    The immediately preceding mid-century cooling period of post WWII boom and growing CO2 does not (temperature cooled while CO2 rose by 28 ppmv).

    The early 20th century warming accounts for 40% of the warming to date, with much lower CO2 increase (14 ppmv).

    And the late 19th century period with the most rapid rate of increase, which accounts for around 30% of the total warming, occurred before there was any real CO2 (2 ppmv increase).

    CO2 is assumed to be the culprit for the late 20th century warming, since model studies show that there is no other factor that can explain it.

    This assumption is flawed unless (a) one can demonstrate what the causes were for the other two warming periods, which together represent 70% of the total warming, (b) one can rule out that these same causes (rather than CO2) were responsible for the latest warming period and (c) one can explain why warming has now stopped despite increased CO2.


  • At April 22, 2008 8:09 AM, Anonymous Anonymous said…

    All the arguments I am reading in this blog are based upon circular thinking. I actually make a good deal of money off this global warming scam yet side with the dissident scientist who receive no funding from government grants. 97% of CO2 is naturally caused so to think that our 3% contribution will end the world sounds like a Christian fundamentalist waiting for the rapture. CO2 is not a cause of warming, rather an effect and it has been cooling since 98. It is so arrogant to think computer models can predict the weather when they can not accurately predict tomorrows. The butterfly effect is the monkey wrench in their predictions. The issue we face of extreme importance is why global warming is being marketed to the masses worldwide supported by junk science and government funding. Governments are not altruistic.

  • At April 24, 2008 1:28 AM, Anonymous Anonymous said…

    Thanks for posting this! I just watched bob carter's videos on youtube and was disturbed to see that certain people obviously have an agenda for the energy companies and are still going at it full force. Thanks for all the info, very helpful.

  • At June 10, 2008 1:02 AM, Anonymous Anonymous said…

    Running a data stream starting from and based on a spike is just bad statistics. For instance;

    Let's say I flip a coin ten times a day for 20 days. I am testing the math that the odds are even that I'd get a head or a tail.

    On the 10th day, I get a run of 9 heads and one tail.

    Rather than include the previous 9 days, I start my analysis from the 10th day with the 9-heads result. The next nine days are even odds, but because I decided to pick an anomalous run as my start point (excluding the 9th day, which had a run of 8 tails, say), I learn that it is more likely heads will turn up when a coin is tossed.

    If my agenda was to prove that heads are tossed more often than tails, this is how I would go about it. The fallacy is that my data pool is not large enough (and that I've deliberately picked an anomalous event from which to begin my statistical analysis).

    This is not a direct analogy to the issue at hand, but I hoped to demonstrate how statistics can be skewed by focusing on anomalies.

    If it turns out that 2010 is hotter than 1998, then in 2012, the global cooling fallacy will be propagated on the internet. As each year progresses, skeptics will say it's been cooling for n years now, and that we are no longer experiencing global warming.

    If then, as now, the years proceeding the hot spike are hotter than the years preceding it, the skeptics of the future will probably ignore that, too.

    So, look at the temperature record. Look at the 10 years before and the 10 years after 1998. When you know that 1998 was largely a result of an el Nino event, the largest el Nino of the century (estimated to have added 0.2C to the global annual temp for 1998), the warming trend over the entire 20 year series is clear.

    Alternatively, take out the 20 largest spikes, 10 hot and 10 cold, in the temperature trend back to 1880. In doing so, you get rid of some of the noise (weather), and will get a clearer resolution of the underlying trend, which is upwards over the series, including the last ten years.

    But even if you start from 1998 (a statistically incautious thing to do), the trend is still warming.


    You can, as the author of the above link did, take the start date at 2000 (I mean, why not? If we're going to pick 1998 and have to small a data pool, is there any reason left why we shouldn't choose any date after it?), and you'll also find a warming trend - not that starting at either '98 or 2000 is robust statistically.

    (For readers of the future, this post was submitted in 2008. If you're reading it in 2030, then you can now establish a robust climate trend starting from 1998).

    Some statisticians removed the temperature signature of all ENSO events (el Nino, la Nina) from the temperature record. This is a more specific version of removing the 10 highest and 10 lowest spikes, excising some of the noise from the record to make the underlying, longer term trend clearer.


    For further discussion on this I recommend this page which also lays out in more detail what the difference is between 'noise' and 'signal'.


    The 'noise' is the inerannual variability from things like ENSO events and volcanic eruptions. The 'signal' is the longer term trend underneath the noise.

  • At June 10, 2008 6:58 AM, Anonymous Anonymous said…

    There is an even simpler way of working out if there's been a cooling trend since 1998, that anyone should be able to get.

    We've got ten years of data now, from 1998 to 2007. So, all we have to do is add up the temperature of the first five years (A), and add up the temperature of the last five years (B). If the value of B is larger than that of A, then we have a warming trend. If B is less than A, it's been getting cooler over the last ten years. This is the simplest method I can think of to establish a trend for the period.

    Here are two global temperature data sets, one from NASA, and one from the UK Hadley Centre.


    The annual data are expressed as deviations from a mean value. That makes no difference for our purposes. So, add up the five years starting from 1998 (1998 - 2002) and then the five years to 2007 (2003 - 2007).

    Both temperature records show a warming trend over the last 10 years from 1998.

    Now, I don't suggest this is an appropriate way to determine temperature trends - starting with 1998 - but even working within that parameter, the trend has not been cooling or flat, it has been warming.

    Therefore, it is correct to say that of the years from 1998 to 2007, 1998 is the hottest (if you go with the Hadley Centre temperature record), but it is not correct to stipulate that global surface temperatures have been trending downwards or flat-lining since 1998.

  • At June 13, 2008 9:54 AM, Anonymous Anonymous said…

    Oops, the first link is the NCDC, not NASA - my bad.

    However, if you do the same simple calc with the NASA figures, you get the same result. Try it!



  • At June 29, 2008 9:13 PM, Anonymous Anonymous said…

    Hadley's (HadCRU temperature record) own analysis concurs with the conclusion that the globe has warmed from 1998 - 2007.

    "A simple mathematical calculation of the temperature change over the latest decade (1998-2007) alone shows a continued warming of 0.1 °C per decade."



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