Detecting the Global Warming Temperature Signal


When was the last time an article popped up stating that something was a “unequivocal” sign that global warming was upon us?  Okay, to be honest those happen just about every day.  There was even an article questioning if the earthquake in Japan might have been caused by global warming.  That is a textbook example of FUD.  That absurdity is….  well I have no further comment on it.

There are many different parts of the climate that can be looked at.  The sea level rise is a popular one, but it hasn’t been very cooperative lately.  The Arctic sea ice is still popular and will get lots of attention in this year.  Of course the Antarctic sea ice isn’t behaving in the same manner so that is a tough sell for the warming being global.   Blaming the lack of snow might work, until the increasing snow was caused by global warming.  Since the impacts of global warming seem to be a moving target it can be tricky knowing what is supposed to be an effect and what isn’t.

In the end it comes back the global temperature anomaly.  That is the key measure to the theory that CO2 levels will cause the Earth to warm up.  If the Earth reverses the warming and starts cooling for the next 100 years, then the theory is kaput.  So the ability to detect changes in the global temperature is the yard stick to measure the global effects of CO2 emissions.

That is why it is so important to have a reliable method to detect changes in the global temperature.  As I pointed out here, there seems to be a developing and increasing problem with the station data having the ability detect changes in the global temperature.  If the most commonly cited temperature sets cannot detect the easy changes in the climate, then how is it going to detect the subtle changes associated with the theory of global warming.

Besides the previous discussion about the station response to the ENSO cycle. I have also decided to compare it to other events that affect the Earth’s temperature.   Unlike the ENSO which happens every few years so there are lots of events to take a look at, other events are not as predictable and there are fewer to chose from.  The best other event to look at is volcanic eruptions.  These happen on a regular basis, but only a select few of them are large enough to affect the Earth’s temperature.

The eruption of Mt. Pinatubo in 1991 was one that had a strong effect on the Earth’s climate.  So how well did the station data detect the change to the Earth’s temperature?  Even more interesting is how well did the station temperature sets detect the change to the climate compared to the satellite temperature set?  The eruption took place on June 15th of 1991.  It took several months for the full effect of the eruption to impact the Earth as a whole.  For that reason it will be useful to look at the temperature for the year 1992 and compare it to 1991.

The Inconvenient Skeptic

(Green) Satellite response (Yellow) Station response. The eruption of Mt. Pinatubo caused global cooling due to a large amount of SO2 that was put into the stratosphere.

Much like the station temperature response has been less sensitive to ENSO events, the stations were less sensitive the eruption of Mt. Pinatubo.  The stations only detected 60% of the satellite temperature response in the exact same time period.

Nor is it possible to say that the satellite data doesn’t detect warming as well, because it also showed the temperature recovery that happened after the eruption.  Regardless of the cause, it is apparent that the satellites are more sensitive at detecting changes in the Earth’s temperature.  If the anomaly for the two satellite average and the two station average are compared for the 30 month period after the eruption, an even more unusual response is noticed in the station temperatures.

The Inconvenient Skeptic

For some unknown reason, the month of January shows significant increase in the global anomaly in both 1992 and 1993.  After that month the behavior is the similar.  Both sets of station data show this, but the greater effect is in the CRU data.

It is clear that the satellites show a significantly more sensitive response to the eruption of Mt. Pinatubo.  That by itself is very significant.  Whatever method shows greater precision at detecting a change in the global temperature should be the method of choice.  The evidence from the eruption and the ENSO events makes it clear that the satellites and not the stations are better at detecting changes to the global temperature.  To put it simply, they are more sensitive.

There have been two other major eruptions in the past 160 years.  The biggest of which was the eruption of Krakatoa in August of 1883.  Obviously there was no satellite data to compare to the station data, but both the CRU and GHCN have monthly data from that period.  Strangely the sets show almost no significant change in temperature in 1884 from 1883.

CRU:     1883: -0.417C,   1884:   -0.524C   for a change of -0.107 C.

GHCN:  1883: -0.167C,   1884:  -0.248C   for a change of -0.081 C.

That is less of a response than from the Mt. Pinatubo eruption.   It is known that the eruption of Krakatoa had a greater effect on the Earth’s temperature than Pinatubo, but once again the station data doesn’t show the response that it should.  It is not even possible to detect the signal of Krakatoa in these two temperature sources.  It is thought that the eruption caused a global drop in temperature of greater than 1 °C, but the best source I could find indicated a drop closer to 0.5 °C.  The official temperature records don’t show significant evidence for the eruption of Krakatoa.  That is a true lack of sensitivity.

The only eruption larger than Krakatoa in the past 1,000 years was the eruption of Tambora.  That eruption caused the “Year Without Summer” in 1816.  For that there is no official attempt to document the global temperature, but it had an effect on the Earth’s temperature that exceeded that of both Pinatubo and Krakatoa.

When it comes to volcanic eruptions, the satellite data is providing a greater measure of temperature response.  The station data did show some sensitivity to the eruption of Mt. Pinatubo, but to a statistically significant lesser degree.  The station data was even less sensitive to the eruption of Krakatoa.

The station temperature sets show poor sensitivity to both of these volcanic events.  They are showing less sensitivity to ENSO events.  If they are less sensitive at detecting changes to global temperature, then why would anyone trust them to detect far more subtle changes to the global temperature?

Posted in Anomaly and Climate and Measurement Methods by inconvenientskeptic on March 22nd, 2011 at 1:16 am.

6 comments

This post has 6 comments

  1. Hi there, I think there is a typo in your graph. Both sets of data are called Station response where I think the green data should be called Sattelite response. Otherwise good article.

  2. Joris Vanderborght Mar 22nd 2011

    This is really bad news because it seems to suggest that our data of the 19th century has not got enough precision to be used in climate studies.

  3. inconvenientskeptic Mar 22nd 2011

    Thanks Mike. I fixed it.

    Joris,
    It would seem that the 19th century data is not very sensitive or accurate.

  4. To answer John’s last dangling question:

    “..why would anyone trust them to detect far more subtle changes to the global temperature?”

    Simply put, it is because [the stations] FIT the CAWG narrative. Science/precision is irrelevant when the debate is over, right?

  5. Whose data is the best data? The warmist crowd will use the datat that fits their expectations. Anyone using other data that refutes their claims will be accused of doing the same. The difference is in the veracity of either claim. Sattelite data ought to be trusted becausee they are absent of so many of the variances that can affect the accuracty of earth-bound measurements. Sattelite data is the data that can be used best with the statement “all things being equal” because unlike the surface of this planet, LEO craft are subjected to tightly consistent conditions that make it easy to interpret the data as cleanly as possible. That simply isn’t the case with earth-bound measurement. Events like Mt. Pinatubo demonstrate the greater sensitivity and accuracy of sattelite data. By now it should be the de-facto means for measuring temperatures and calculating variances.

    The CAWG crowd can’t ignore this forever…though they will try mightily to do so.

  6. ReynaldoSiddoway Mar 6th 2012

    Enjoyed examining this, very good stuff, thanks .

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