Last two posts were about the Global Average Temperature of the Earth. Reading it again I realized that I forgot to mention an important thing: not only did I assumed that there was some kind of Global Average Temperature, but also that there was only one dataset “measuring” it. In an accurate way, like in we could trust on it. In my believer years this was the NASA Giss dataset (largely based on the NOAA NCDC dataset).
There is obviously not only one dataset, there are at least five, probably even more. There are the surface based datasets like NASA Giss and HadCRUT, but also satellite based datasets like RSS and UAH. The results of these sets are not in the same league. There is some difference between them. Beside the different method of measuring, there is a difference in base period. The datasets don’t give real temperatures, but anomalies (departure from a base period). The base period for NASA Giss is 1951-1980 (wham in the middle of a cold period), RSS has 1979-1998 and UAH adopted 1981-2010 since 2010. NOAA NCDC uses 1971-2000.
Let’s go back to last post about the warmest November ever. In the media unsurprisingly only the NOAA NCDC dataset was used: November 2013 was 0.78 °C warmer than average over all years starting from 1880. NASA Giss had something similar with an anomaly of +0.77 °C, HadCrut had +0.59 °C, UAH had +0.19 °C (only 9th warmest since 1979) and RSS had +0.13 °C (only 16th warmest since its start).
Now comes the fun part. Alarmists say that the base period doesn’t really matter, it is the trend that counts. But when one is comparing the anomalies with each other then it is important. For example if you take the NASA Giss dataset and compile November 2013 against a different base period you will get different anomalies:
|Base period||250 km||1200 km|
|1951-1980 (NASA Giss)||0.73||0.77|
|1971-2000 (NOAA NCDC)||0.56||0.60|
|1880-2013 (complete period)||0.70||0.76|
This is exactly the same dataset. The only difference is the base period and we already get a range of 0.38 °C until 0.77 °C. That’s already half of the supposed warming. Measuring and calculating the global average temperature doesn’t seem to be the exact science that the media want us to believe it is.
So they found the highest number and they threw it into the public as if this was the only dataset that matters. Without mentioning other datasets. Without mentioning the high uncertainty of the measurements before 1979 or even 2003. No balance at all here. To be honest, I was not even surprised to find out that the media broad casted only the highest number of them all. I don’t think it is a coincidence they just took this dataset and sounded the alarm. Keeping the scare alive.