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Arctic Temperature Trends

February 5, 2015
tags:

By Paul Homewood  

 

h/t Green Sand & Quinn The Eskimo

 

There’s a couple of items that are worth adding to yesterday’s post on Arctic temperature trends and adjustments.

 

 

1) NASA Report

Back in 2003, NASA published a report called “Dwindling Arctic Ice”, which included this graph:

 

arctic_temp_trends_rt

http://earthobservatory.nasa.gov/Features/ArcticIce/arctic_ice3.php

 

We can compare this with the latest version from GISS, using data from 1896 to 2000.

 

image

http://data.giss.nasa.gov/gistemp/tabledata_v3/ZonAnn.Ts+dSST.txt

 

 

The following differences stand out:

1) The current trend works out at 0.106C/decade, compared with 0.06C/decade in the 2003 version. In other words, nearly double.

2) Whereas the 5-year average in the 2003 version was higher for much of the 1940’s and 50’s than it was in 2000, the latest version reverses this.

3) in the 1960’s and 70’s, according to GISS, temperatures were still much higher than the early 20thC. NASA’s 2003 version, however, shows them at a similar level.

 

We can make one further comparison. NASA show a 65-year trend of minus 0.07C/decade, i.e from 1935 to 2000.

But latest GISS data gives essentially a flat trend for the same years.

 

image

http://data.giss.nasa.gov/gistemp/tabledata_v3/ZonAnn.Ts+dSST.txt

 

This is a clear indication of how much NASA’s historical account of Arctic temperature trends has changed over the last few years.

 

 

2) Observationally based assessment of polar amplification of global warming

Polyakov et al 2002

 

This paper again highlights the rapid rise in Arctic temperatures leading up to the 1940’s. It also emphasises multidecadal variability, and finds no evidence of polar amplification. 

 

ABSTRACT

 Arctic variability is dominated by multi-decadal fluctuations. Incomplete sampling of these fluctuations results in highly variable arctic surface-air temperature (SAT) trends. Modulated by multi-decadal variability, SAT trends are often amplified relative to northern-hemispheric trends, but over the 125-year record we identify periods when arctic SAT trends were smaller or of opposite sign than northern-hemispheric trends. Arctic and northern-hemispheric air-temperature trends during the 20th century (when multi-decadal variability had little net effect on computed trends) are similar, and do not support the predicted polar amplification of global warming. The possible moderating role of sea ice cannot be conclusively identified with existing data. If long-term trends are accepted as a valid measure of climate change, then the SAT and ice data do not support the proposed polar amplification of global warming. Intrinsic arctic variability obscures long-term changes, limiting our ability to identify complex feedbacks in the arctic climate system.

 

The paper concludes:

 

We examine arctic variability using long-term records of SAT from the maritime Arctic poleward of 62°N, fast-ice thickness from five locations off the Siberian coast, and ice extent in arctic marginal seas. Arctic atmosphere and ice variability is dominated by multi-decadal variability, which is exceptionally strong in the northern polar region, probably because of its proximity to the North Atlantic, which is believed to be the origin of the LFO. The highly variable behavior of arctic trends results from incomplete sampling of large-amplitude multidecadal fluctuations. Trends for LFO-modulated arctic air-temperatures are generally larger than northern-hemispheric trends, but over the 125 year record we can identify periods when arctic SAT trends were actually smaller or of different sign than northern-hemispheric trends. Arctic and northern-hemispheric air-temperature trends over the 20th century, when multidecadal variability had little net effect on computed trends, are similar and do not support the hypothesis of the polar amplification of global warming simulated by GCMs. It has been hypothesized that this may be due to the moderating role of arctic ice. Evaluation of fast-ice melt required to compensate for the two-fold enhancement of polar warming simulated by GCMs shows that the required ice-decay rate would be statistically indistinguishable from zero, given the substantial intrinsic variability observed in the data. Observed long-term trends in arctic air temperature and ice cover are actually smaller than expected, and may be indicative of complex positive and negative feedbacks in the arctic climate system. In summary, if we accept that long-term SAT trends are a reasonable measure of climate change, then we conclude that the data do not support the hypothesized polar amplification of global warming.

 

grl14565-fig-0002

Figure 2. Composite time series of surface air temperature anomalies (°C) relative to 1961–90 for the region poleward of 62°N. The plot displays the annual means (dashed blue), six-year running means (solid blue), 95% significance level (yellow), trend (dashed red), means for positive and negative LFO phases (horizontal green), and six-year running means using the 24 longest (century plus) records. Numbers at the bottom of the panel denote the number of stations used for averaging.

 

http://onlinelibrary.wiley.com/doi/10.1029/2001GL011111/full

 

Again, they show the strong warming leading up to 1940, with temperatures higher than by 2000.   

22 Comments
  1. February 5, 2015 5:45 pm

    As I mentioned on the previous posting on this subject – the data is 13 – 14 years old. Do they not have 21st century data, or, are they being selective in the time frame?

    • R2Dtoo permalink
      February 5, 2015 6:47 pm

      The papers were published in 2002 and 2003 – before climate science was totally corrupted. The disappearance of the warm 30’s and 40’s has occurred primarily since then.

  2. February 5, 2015 6:07 pm

    DMI has summer arctic ice maps drawn from fishing and whaling ship reports up through 1938 (WW2 interuption). Comparing 1923 to 1938 shows the shrinking extent of August ice edges comparable to the most recent decade. Larsens 1944 Northwest Passage transit in 83 days also shows this. That is strong qualitative aupport for the older temperature series, and not the new ones, simply because the present summer ice loss is qualitatively not unprecedented. Details with map reproductions in essay Northwest Passage.

  3. February 5, 2015 6:43 pm

    Reblogged this on Real Science.

  4. February 5, 2015 7:40 pm

    Before 1970s we had 4-6 temp. measurements a day, by a person, as opposed to continuous measurements, with a thermo-couple, once a second, + automatic recording from 1970 onward…
    Also, I could not find any temperature gauges’ recalibration records from before 1945.
    So, what do we really know with records going as shown in figure 2 of this paper. They are just trying to compare apples with pears.

  5. February 5, 2015 8:03 pm

    Reblogged this on Power To The People and commented:
    President Obama and Pope Francis There Is No Need To Doom Poor To Death by Fuel Poverty: Arctic & Antarctic Ice ‘not melting’ http://shr.gs/4eJgavZ

  6. February 5, 2015 9:54 pm

    Forcings (per unit area) have units Watts i.e. Joules/sec. To produce energy change (Joules), the forcing must exist for a time period. Temperature change is energy change divided by effective thermal capacitance. Thus a scale factor times the time-integral of the forcing produces the temperature change.

    CO2 has been considered to be a forcing. Because, during the previous glaciations and inter-glacials, the CO2 level and temperature went up and down nearly together, the temperature change is obviously not a result of a scale factor times the time integral of the CO2 level. This observation actually proves that CO2 has no significant effect on temperature at least up to about 280 ppmv.

    This same type assessment over the entire Phanerozoic (about 542 million years) demonstrates that ‘climate sensitivity’ (the average global temperature increase caused by a doubling of the CO2 level to 560 ppmv from the pre-industrial level of 280 ppmv) is not significantly different from zero.

  7. February 5, 2015 10:48 pm

    “This is a clear indication of how much NASA’s historical account of Arctic temperature trends has changed over the last few years.”

    No, it’s just a different measurement method. The 2003 plot you are showing, by Comiso et al, is based on satellite AVHRR data for the later years. It’s not NASA surface data. He’s explicit about the difference:
    “This study is unique in that previously, similar studies made use of data from very few points scattered in various parts of the Arctic region,” says Comiso. “These results show the large regional and seasonal differences in the trends that only satellite data can provide.”

    Unique.

    • February 5, 2015 11:46 pm

      Nick Stokes, your comment is interesting. But also irrelevant to this post, which is about provable by comparison inexplicable recent changes to the temp records for this region. Which are also not supported by regional historical qualitative info (my comment above). Do try to stay on topic.

      • February 6, 2015 2:40 am

        “about provable by comparison inexplicable recent changes to the temp records for this region.”
        But there is no comparison. One is GISS data. The other is part AVHRR. The older data is from a paper by Phil Jones, and relates to a different region (>60N). It is in no sense a GISS temp record.

  8. R2Dtoo permalink
    February 6, 2015 3:13 am

    Nick: A little story. In the early 60’s (ya I’m old) I was in charge of the Stevenson screen at a major US university. The thermometers were the best available, were calibrated by our physics department, and the screen was properly placed and maintained. I am 6’1″ tall, and at that time I had perfect eyesight. It pisses me off that you “modern” scientists think the data I recorded needs “adjustment”. It was just fine – the timing needs no TOBS, and UHI wasn’t involved. We also knew then that even properly sited stations varied in temperature over relatively short distances. We had read Geiger, Koppen and other early climate scientists. We also took courses in climate history, both from the geology department (paleo) and physical geography (historical). We knew what we were doing, and how to do it. Leave my data alone!

    • February 6, 2015 4:11 am

      Well, Rud has enjoined me to stay on topic, so I’m reluctant to respond. But generally, the original data is not disputed. It’s adjusted because something changed. The screen turned into a MMTS. Or moved to the field out the back. Your fine observations are just measuring something different to what is now measured. So they are brought into line.

      • February 6, 2015 4:39 am

        Nice try Nick. Total logic fail in response to R2Dtoo.

      • David A permalink
        February 6, 2015 4:43 am

        Yes Nick, they are brought into the “team” line. Still waiting for your explanation of the Iceland adjustments. Take just the one station, and explain what the code did to that one station. No need to explain how the entire homogenization system works, just explain how it works for one station,

      • Bill permalink
        February 6, 2015 4:45 am

        “So they are brought into line” Reminds me of the Borg: “You too will be assimilated!” 🙂

      • Bill permalink
        February 6, 2015 4:49 am

        In all seriousness, however, if older data is thought to be deficient, another way to handle it is with larger error bars. I’m thinking not just of temperatures, but, for example, the early 1970’s arctic ice data that was in the FAR (1st IPCC) report. I don’t like it when data is just “disappeared”. Reminds me of the Bureau of Truth in 1984.

      • February 6, 2015 5:30 am

        “In all seriousness, however, if older data is thought to be deficient,”

        It’s not deficient. Something has changed. We talked at WUWT about how in 1928, the Wellington NZ station moved from sea level to 100m. Nothing deficient about the old readings. There was just about 1C difference due to altitude. Adjust that, and you have a 160 year record. Thorndon (NZ) is an good as Kelburn. You just have to pick one standard.

      • February 6, 2015 6:56 am

        As an example from another field, here is a table of BHP share prices. Note the final column – price adjusted for dividends and splits. It’s not that the old prices were defective; it’s just that dividends and splits do not relate to the value of the company, or even to the total value you get from your investment. If you want to make historic sense of the raw prices, you have to keep making allowances. But the adjusted prices give a continuous picture of what a holding is worth.
        And if you don’t like the adjusted story, you can ignore it.

        Nick – you’re really struggling now!! Can we please just have your explanation of why Iceland’s temperatures have been altered? – Paul

      • February 6, 2015 10:42 am

        Hi Nick

        Will you explain the reason for data manipulation at Alice Springs?

        http://euanmearns.com/the-horrors-of-homogenization/

  9. February 6, 2015 9:17 am

    Nick says
    Adjust that, and you have a 160 year record. Thorndon (NZ) is an good as Kelburn. You just have to pick one standard.

    Hewnry says
    naaahhhh
    (nee, no,)

    You are still comparing apples with pears. You cannot compare current results with historic results.Show me a re-calibration certificate of a thermometer that is dated before 1945?

    https://notalotofpeopleknowthat.wordpress.com/2015/02/05/arctic-temperature-trends-2/#comment-37212

    Data collection and accuracy has changed a lot from 1970 onward.

    However, I think it is possible to look at data from 1974 onward and come to the conclusions that a) there is no man made global warming and that b) there is currently only natural global cooling.
    See last graph at the bottom of my last table, that summarizes the fall in global minimum temperatures.

    http://blogs.24.com/henryp/files/2013/02/henryspooltableNEWc.pdf

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