Seems like a simple enough question. Take a peak at your thermometer, turn on a local all weather channel (we have 2 in the area), or hit accuweather.com. Simple. You will find that it is now 90°. At least here. But what if you wanted to find out the temperature for say......1998? And not just your berg, the world? What do you do?
One thing you cannot do is go to any online source or data averaging site! Why? It appears that even though the year is history and the past is unchangeable, in the world of Climate Change, that is not the case. "Turn on the wayback machine Sherman!".
From the time that it was the present, and Michael Mann/Al Gore used it in their infamous hockey stick/graph, the temperature has changed! Yes indeedy! Thanks to Steven Mosher, the reason is actually easy to understand.
In 1998, any data sites that had less than an arbitrary number of data points was not used in the calculation of the global temperature. So in 1998, the anomaly was .64 (.64 above a mean decided upon my the Climate Scientists). However, 12 years later, a lot more data sites had met the minimum number of data points to be used in the calculation of average global temperature (they had 12 years to gather additional data points for the "newbie" data), and viola! The Temperature for 1998 did not show an anomaly of .64, but of only .57!
So the "hottest" year was not so hot after all!
This interesting tidbit brought to you by GISS (Goddard Institute for Space Studies). It seems they have reduced the hottest year by almost a tenth of a degree - 12 years after the year was done and in the history books.
But their manipulation of the data does beg several questions and observations.
1. While we can usually tell with some degree of accuracy what the temperature was during the last ice age (notice how they usually say it was a range - like 10-15° cooler than today), we apparently do not know how cold it was to a 1/100th of a degree! And that is what is causing the hysteria about AGW.
2. We do have thermometers that can register 1/100th degree temperature changes around the world. Just not enough of them, nor enough years of history to be able to say that a ".61" anomaly is hotter than a ".59" anomaly. In other words, the first rule of averaging is that the number of digits in the average cannot exceed the accuracy of the numbers being averaged.
3. While I have no reason to doubt Steven Mosher about the GISS revision, it does beg the question, why are they reporting numbers that they have no statistical confidence in? And why are these numbers being used to drive mass hysteria about the coming apocalyptic hell fire we are damned to endure?
I doubt the temperatures for the Little Ice Age (LIA) or Midevel Warming Period (MWP) are going to change except when used to cook a hockey stick, but apparently you cannot trust the averages that GISS proclaims because in a few years, they will change the numbers. Based on more data sites becoming "reliable" due to more data points being available. While we can certainly say that 1998 was a hot year, there is no way, with any statistical accuracy to say HOW HOT WAS IT. (Unless you are Rodney Dangerfield).