Bob Grumbine encountered a claim very similar to the one Hans Labohm makes on the well known skeptical website CO2-science which made him write this very educational post entiteled Misleading yourself with graphs. Do have a look yourself what happens if you extent Labohm's ten year period to a 150 year period.
Another way to be misleading with graphs is shown in the movie The Great Global Warming Swindle, in which there's claim the present day heating is a result of solar variance. A claim which is repeated on many skeptical websites.
It gets supported by graphs looking like this one :
|Great Global Warming Swindle manipulation|
It may be a little hard to see, but the graph stops thirty years ago. And in fact, on all skeptical websites this and similar graphs stop around this time. That's strange, isn't it ? The reason is clear :
The data of the last thirty years is available, and any real scientist usually will want to use all available data, as this will only make his proof stronger. So there's absolutely no reason why all those websites cut of the last three decades. This should ring an alarm bell.
But there's more : according to climate scientists, man's influence on earth's temperature is so strong that right now already we are in a period of antropogenic warming. The signal started to distinguisable from the natural signal somewhere in the nineties. As it stops in 1980, the period in which mankind actually significantly influences temperature isn't even on their graph...
So, aren't you curious what happens if you update the graph TGGS until present days ? This video gives the answer (start at 3:45 if you are impatient) :
Now it gets clear : they've cut the data at exactly the right point to support their claim, and ignore the data demonstrating their conclusion is wrong. The graph in TGGS is a fine example of a cherry pick.
Many more problems with the movie and some often to be heard skeptics claims can be found in this post : The Great Global Warming Swindle” is itself a Fraud and a Swindle.
The movie is very misleading. One of the conclusions one could make is that science should be done by scientists. It's hard to see a cherry picked conclusion without having a background showing the bigger picture.
With the Youtube movie i posted, anyone can see TGGS presents a misleading graph. Nevertheless, there are litteraly hundreds of websites where layman use the movie to support their claim science is wrong.
Of course, that's exactly what the skeptics were aiming for : misleading the layman. No scientist in the field gets fooled by the movie, but that never was the aim.
As the quote in the top left corner of my blog says :
The target audience of denialism is the lay audience, not scientists. It's made up to look like science, but it's PR. (David Archer)