One of the first things you learn in a higher education science curriculum is the topic of “significant digits”
It is a tough concept to grasp for some, but it basically means you cannot have more accuracy than your measuring device.
If all you have is a yardstick, it is impossible to tell me how long something is to a thousandth of an inch. You could tell me something is a yard and a half or 2ft. 3and 1/2 inches (if your yardstick is marked to inches), but you cannot tell me something is 3.0005 inches.
Similarly, if all you have for hundreds of years of temperature data is tree rings and ice cores, you cannot tell me temperature has risen 0.06 degrees.
And that is the claim of the global warming religious zealots- temperatures went up 0.06 degrees. I knew that was bull$hit the first time i saw such accuracy depicted.
This is a tool to achieve a political agenda, and nothing else.
If you look at most professional level digital thermometers they are accurate to between +/- .08C degrees so anything more precise than that is impossible.