The data points at the top are at 16.6 year intervals.
Recent data is represented by a line.
The punch line is not the absolute temperature (as this wanders around a fair bit), but the gradient at the end.
Because the recent data is over a period of 166 years, you can turn the line into 10 dots which represent each 16.6 year 'line' average.
I think you should try this yourself. You will find that the averaging only smooths out brief transients between your new dots. In the case of the comic, it has no effect on the gradient at 2016.
Having more data doesn't change the average slope - it simply allows you to measure average slope over shorter distances.
So unless you think the joke was "haha we've been at this temperature before", I suggest it is you who is being ... what you said.
Because the recent data is over a period of 166 years, you can turn the line into 10 dots which represent each 16.6 year 'line' average.
I think you should try this yourself. You will find that the averaging only smooths out brief transients between your new dots. In the case of the comic, it has no effect on the gradient at 2016.
Having more data doesn't change the average slope - it simply allows you to measure average slope over shorter distances.
So unless you think the joke was "haha we've been at this temperature before", I suggest it is you who is being ... what you said.