In the global warming fiasco wars, there is so cotton picking much emphasis placed on trends. Headlines yell about how the temperature these days is so much warmer and how if this keeps up we are all gonna fry. Let me see if I can show you why I am so skeptical of these claims.
Data can be manipulated in so many ways. One of the easiest is by simply picking and choosing your data range. Now consider the following graph:
(Right click on chart and select open in another tab to see larger.)
This is a simple plot of the yearly temperatures at one of the coop weather stations from the year 1920 through 2013. As you can see there is nothing particularly exciting about it. If you look close the trend line (labeled linear value 1) is nicely flat. One might say that this chart shows that over the years, there is no sign of increasing or decreasing temps. They could say that as far as temperatures increasing goes, the trend is flat, or that the trend shows no increase in temperatures.
Now, consider this second chart:
What does this chart show? Well, to begin with it is the exact same data as the first chart. All I did was take that column of data in Excel and copy it two times. Then in the second column (value 2) I deleted the first twenty years worth of data. In the third column, I deleted all the way up until year 1960 (40 years data).
I put in trend lines for all chart series. In the first series (value 1) the trend line is flat, just like the initial chart. In the second series, you see an increase of what, about 1 degree Fahrenheit? Something like that. In the case of the third series however, it is what, much closer to 3 degrees Fahrenheit.
Now understand, this is the exact same data repeated for a total of three times. The only difference is where I choose to begin the series.
How are any of these charts going to tell you what all is going to happen? They are not going to. You see it is how you interpret that data tells you what is going on. But what this shows is how you can choose to display the data in a particular way as to what story it is going to tell.
Or I can say, no, go look at the first chart. There is nothing to worry about. There has been no major temperature change since 1920.
Take your pick. It is all the same data, simply presented a little differently.