Read here and here. Let's say you are a NASA climate scientist and have been on record for a very long time that the world is warming due to human CO2 emissions - despite the evidence to the contrary. And let's say you decide to produce a new study to absolutely prove your case by showing how the oceans are heating due to an energy imbalance.
"Improving observations of ocean temperature confirm that Earth is absorbing more energy from the sun than it is radiating to space as heat, even during the recent solar minimum. This energy imbalance provides fundamental verification of the dominant role of the human-made greenhouse effect in driving global climate change."
Finally, let's say you want to enhance your study with graphs that will bolster your case. Then you would use the below graph if you're a NASA scientist with a political agenda, with the actual empirical science being a lower priority. (click on images to enlarge) (image source)
Notice the 1980 starting point for the above graph. Why do you think a NASA scientist would start the graph at 1980 when there is data all the way back to 1955? Oh, here's why. (image source)
Obviously, the ocean heat data prior to 1980 reveals both large increases and decreases of an inconvenient nature that the NASA scientist does not want to bring any attention to.
Of course, if the NASA scientist wasn't just pursuing a political agenda he might of also have brought attention to the fact that the majority of ocean basins (5 of 7) have recently been losing heat, or are flat, in direct contrast with his hypothesis that they are gaining from a CO2-caused energy "imbalance." (image source)
And, if the NASA scientist really desired to mislead policymakers, he would be sure not to include the sea surface temperatures as shown below. Gee, global sea temps seem to be highly variable with a recent significant decline, which neither condition seems to match the NASA "analysis" that oceans are overheating because of an energy "imbalance." (image source)
Wouldn't it be great if we could still trust that our government scientists are objective and truthful, sans their personal and political agenda bullshit?
Updated 4/24/2011: Anthony Watts calls Hansen on the bullshit cherrypicking also. And he describes the new Hansen Mt. Pinatubo hypothesis 'total bollocks.'