parados wrote: I thought you had agreed a while back that a single year shouldn't be used to show trends. A 5 year moving average shows an increase. So.. why don't you be honest okie? Why don't you use the 5 year moving average instead of playing politics and trying to manipulate the numbers by using a single year? Using a 5 year moving average there is a very clear upward movement in the last 6-8 years.
Okay, where is your graph again, that shows this upward trend, using your 5 year moving average? The best I could do was this graph:
http://en.wikipedia.org/wiki/Image:Instrumental_Temperature_Record.png
You are correct, the red line or 5 year average is trending up, but a question here, the line quit 2 years ago. This brings up a question of clarification, do they plot the 5 year average at the midpoint of the 5 years, thus explaining the missing last 2 years, or is it an average of the previous 5 years? If it is the latter, it appears the graph is incomplete, and the red line probably is flat the last 2 years, illustrating the point I made.
To analyze it in a different way, the graph is tough to read but appears to show the average 2006 temperature is lower than the previous 4 years, and virtually the same as the 2001 temperature, and none of the past 8 years are higher than 1998, again illustrating the point that I made.
This is all splitting hairs, but that is the best we can do when looking at the past 6 to 8 years, but my point is that the trend seems to be more or less stalled out the last 6 to 8 years, and I stand by that. I have already said it is too early to tell which way the trend will go from here.
Also, the graph is of near surface air temperatures, not ocean temperatures or temperatures from higher in the atmosphere, etc., which are not as definitive in terms of an upward trend.
I admit to being a skeptic concerning almost everything, but I was looking at the following site:
http://en.wikipedia.org/wiki/Image:GHCN_Temperature_Stations.png
I realize this is dredging up something pretty basic, but I am quite curious how the spatial distribution of these weather stations are weighted and calculated into the global average. For example, I assume all of the stations are not equally weighted into an average, but instead weighted by the area of influence, and where one station may be located by itself for hundreds of miles or more, a skewed reading at that station would cause a fairly large skew to be thrown into the global average. With time, I would like to find out more about this, but it strikes me that this exercise alone could cause different answers depending upon the exact methods. We already know that folks have documented some pretty lousy situations at many weather stations, especially in urban areas where land use, heat islands, and other factors are causing faulty or skewed readings. We also have large variations in time of record for all of the stations, so that when the graph is extended over decades, the averages are really derived from apples and oranges, not apples to apples. When you start examining the nuts and bolts of this entire issue, there are so many questions that I seriously wonder just how well they have all been answered well enough to even derive the basic data reliably, let alone make grand conclusions from them.
