The theme of the week turned out to be a comparison of how the satellite and station data behave. I started out with the observation that the station data is responding less to ENSO events than it has in the past. It is a steady progression of decreasing response. Then I showed how the station data is poor in comparison to the satellite data at detecting the effects of volcanic eruptions. I asked how can the station data have better resolution at detecting global warming if it is significantly inferior at detecting the climate effects of a volcanic eruption or the ENSO.
Now I am going to show what happens to the two types of data if the above events are removed from the global temperature anomaly since 1979. That is 31 years of global temperature, but with the main events removed from the record. For the ENSO and volcanic events in the past 31, the station data has averaged only 60% of the response that the satellite data has. So what does the warming of the past 31 years look like if those events are removed?
I will start off by showing the temperature record without any modification. It is simply the averaged station (CRU and GHCN) and the satellite (UAH and RSS) temperature anomalies for the period from 1979-2010.
This should be familiar to most readers. The ENSO and volcanic events that have been discussed are clearly present in both the station and satellite records.
The next step is to remove the events at the magnitudes discussed in the previous articles. The 1983-1984 ENSO event was a little tricky as the sequential events had a recovery and overlap. There was also the 2nd year effect of the Mt. Pinatubo eruption. I used a 50% reduction in the initial drop for each set of data. Otherwise the clean up was the magnitude of the event response.
This is a less noisy chart. There is small reduction in the overall warming trend, but it is small for both sets of data.
Station Trend: Was 0.192 °C/decade Event Free: 0.185 °C/decade
Satellite Trend: Was 0.145 °C/decade Event Free: 0.128 °C/decade
So the trend is still warming for both sets of data and I would not consider the change to be significant.
There are two interesting items of note in the event free chart. The first is that the temperature of both data sets stepped up in the year 2001 and have been stable since. The trend for both sets is almost zero for the past 10 years. There was some minor ENSO activity that wasn’t removed, but both sets agree that it was not significant to global temperatures.
The other question is why is the station showing double the overall warming over the past 30 years? The two sets start off with an offset of ~0.2 °C. Since the satellite is not calibrated to the station data I see no problem with that, but for the past 10 years, the station data is showing a ~0.4 °C offset. Where did that 0.2 °C come from?
I have shown categorically that the satellite data is more sensitive to changes in atmospheric temperature. If the average sensitivity difference for the past 30 years is used, the station data should only have shown 60% of the warming that the satellite data has shown. The offset between them should be less now than it was 30 years ago. Instead the opposite has happened and the stations are showing 187% of the warming than the satellite data. Almost double the warming, from a data set that is statistically less sensitive to global temperature changes.
If increased levels of CO2 were causing warming, then the satellite should be detecting more warming than the station data. There is no event where the station data was significantly more sensitive than the satellite data. For the station data to show more warming than the satellite data in only general warming is opposite of the behavior in every other instance.
An analogy would be microscopes. The station data is a 60x microscope and the satellite data is a 100x microscope. In each case the 100x microscope provides better magnification of an object, except when the object happens to be the global warming bacteria. Then it suddenly the 60x behaves like it is a 300x microscope. That is the level of enhancement that would be needed to provide the additional global warming sensitivity to show 187% greater response than the satellite data provides.
If the assumption is made that the station has 60% the response of the satellite measurement, then this would be the expected behavior of the station data over the past 31 years.
Based on the typical station response the global temperature should now be slightly above 0.3 °C, that it is ~ 0.6 °C is the error that the station data is showing based on the analysis of the typical station response in comparison to the satellite response.
The problem isn’t that there is an offset, the problem is that the change in offset is counter to the change observed for every other event that has a measurable impact on global temperature. I can find to reasonable explanation as to why the station data is behaving in this manner. This problem is significant as it accounts for about half of the warming that the stations have observed. When the error is 50% of the observed change, there is a real problem.