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RSS Close To 30-Year Average

June 8, 2013

By Paul Homewood




I did a quick post yesterday on the May numbers on RSS, which fell sharply to 0.139C. The RSS figures are anomalies from the 1979-98 baseline, and I pointed out that, against a baseline of 1981-2010, current temperatures are now only 0.039C higher.

I also mentioned that the 1981-2010 average had been artificially depressed by the two eruptions, El Chichon in 1982 and Pinatubo in 1991.

The above graph illustrates the effect these eruptions had. It is also worth pointing out that El Chichon coincided with the large El Nino of 1982/3. A paper by Alan Robock found :-

The eruption took place just as the largest El Nino of the century so far was beginning. (In fact the volcanic cloud in the stratosphere fooled the satellite sensors which monitor ocean temperatures into thinking ocean temperatures were normal, whereas they had warmed substantially. Thus, scientists were not aware of the El Nino until months after it had started.

As the MEI graph below shows, the 1982 El Nino was comparable to the 1998 one. Therefore, without the El Chichon eruption, the temperatures for 1982 & 83 would have been much higher than average.




Take the two volcanoes out of the equation, and it is clear that there is nothing unusual about current temperatures.




As Ken Gregory pointed out, my original calculation was based on the annual 1981-2010 baseline. Taking just the May figures, the anomaly works out slightly higher at 0.054C.

it will be interesting to see how the next few months work out.

  1. Kevin R. Lohse permalink
    June 8, 2013 4:48 pm

    Hi. At the risk of being pedantic, how can 2 naturally occurring events, in this case volcanic eruptions, artificially depress anything? Surely volcanic eruptions are natural events which affect global temperature change as do other naturally occurring events like ENSO, PDO and jet stream latitudinal movements?

    • June 8, 2013 5:53 pm

      I suppose I mean they are one off events, and should be taken out when looking at the underlying trends.

  2. Kevin R. Lohse permalink
    June 8, 2013 6:09 pm

    Thanks for taking the time to answer, Paul. How many other one-off events should be taken out? I’m positing a chaotic paradigm the mechanics of which we don’t really understand and am heading steadfastly towards the things that we don’t know we don’t know. So do we know what the underlying trends are, or are we still at the “pre-quantum” stage of Climatology?

  3. David Matz, Ph.D. permalink
    June 8, 2013 6:09 pm

    As I have looked at this data over the last few years, it appears to me that from the earliest satellite data until about 1996, there was a general variation around about -0.1. I haven’t analyzed it mathematically, but there is somewhere between no increase to maybe 0.1 degree over that period. The latter data, from about 2001 until today also appears about flat, but with a midpoint of about +0.25 deg C anomaly.

    In the period from 1996 until 2001, there appears to have been a step change increase. Of course whatever happened here is confused by Mt Pinatubo right before and an El Nino right after.

    When I have raised this observation on other blogs, I have been told that it can’t be, because there is no physical reason for this to happen. That’s like telling Einstein that his observation of light bending around the Sun can’t be right because Newton’s laws say that there is no physical reason for it to happen.

    Has anyone looked into this step phenomenon?

    • June 8, 2013 9:29 pm

      Bob Tisdale has done a lot of work on the interrealation of ENSO and ocean temperatures.

      He links these step changes to ENSO cycles and El Nino events. As well as the 1998 step change, there was a similar one when the PDO shifted in the late 70’s.

      In simple terms, he explains how large El Nino events release heat into the system. Although this explains the step changes, my difficulty with this theory is that, somewhere along the line, there has to be a compensatory, albeit slow, drop in temperatures as the extra heat escapes. If there is not, global temperature would carry on rising ad infinitum.

      Bob’s stuff is certainly worth a read though.

      • David Matz, Ph.D. permalink
        June 8, 2013 10:12 pm

        Thanks Paul.

        i agree that if there is a one time bump of heat, that it has to dissipate over time. I will check out the Tisdale paper right now.

        I still can’t wrap my head around a continually increasing CO2 concentration leading to an increase in temperature that has a totally different shape. Statisticians like to just look at the numbered and long term trends. That can be very deceiving. I’ll bet the correlation between Global Temperature and the US Federal Debt is just as good as the correlation between Global Temperature and CO2 concentration.


  4. Brian H permalink
    June 8, 2013 10:07 pm

    T^4 takes care of it.

  5. miked1947 permalink
    June 9, 2013 4:15 am

    So Basically the globe is at the same temperature it was in 1980! According to RSS! Or is that 1981?

  6. tckev permalink
    June 9, 2013 2:59 pm

    The more real data that get analyzed the more the chaos is seen.

  7. David Matz, Ph.D. permalink
    June 9, 2013 3:05 pm

    But Paul…. you know that your statement that “..against a baseline of 1981-2010, current temperatures are now only 0.039C higher.” is correct, but can be very misleading. The problem is that without about 20 years more data before that baseline started and into the future after that baseline ends, we cannot put that baseline in climate context. Plus, you can never draw any meaningful climate conclusions comparing any two points, although the “gloom and doom” guys do it every day.

    What we do know is that during the first 20 years which are included in that baseline calculation, the weather (and probably the climate) were “generally” about 2 degrees colder than that baseline. For the last 10 years,they have been “generally” about 0.15 degrees above it. There has been warming!

    Whether that warming continues over the next 20 years, accelerates until we burn to a crisp, or whether it dips back below the baseline for the next 20 years completing a normal global cycle, remains to be seen.

    But please don’t make statements that can lead people to believe that we are right back where we were in 1980. It’s those kind of statements next to pictures of Arctic shelves falling into the ocean that hurts the position of those of us who are saying that we shouldn’t blindly spend Trillions of dollars to reduce CO2 emissions to stop the earth from melting and then burning up.

    • June 9, 2013 3:47 pm

      True, but the fact that temperatures in the last half of the 30 yrs are higher than the first half, is an indication that current temperatures are lower than in recent years.

      It would be wrong to attempt to make projections based on a few months, or for that matter a few decades, but it is important to be able to put today’s temperatures into perspective.

      (And of course the graph makes all this totally clear!)

  8. June 11, 2013 3:37 pm

    The RSS figures are anomalies from the 1979-98 baseline, and I pointed out that, against a baseline of 1981-2010, current temperatures are now only 0.039C higher.

    The May 2013 RSS temperature anomaly of 0.139 C relative to the 1979-98 baseline is equal to 0.054 C relative to the 1981-2010 baseline, NOT 0.039 C. The May temperature anomaly is calculated relative to the average May temperature of each year of the baseline range. It is not calculated relative to the average temperature of all month of the baseline range, which is what you incorrectly did.

    The average May temperature anomaly from 1981 to 2010 was 0.0853 C. Therefore, the May 2013 temperature anomaly relative to 1981-2010 is 0.139 – 0.085 = 0.054 C.

    The average May temperature anomaly from 1979 to 1998 is exactly zero by definition.

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