Tamino’s post is comprehensive, but I wanted to check to see if I could extract any signal from the data myself.
The data is in the upper right of the following figure, and the FFT-based power spectral density (PSD) is in the lower left.
|FFT PSD lower left, Data upper right|
The PSD is nondescript with a red noise envelope shown by the solid line. Red noise is the embodiment of the Ornstein-Uhlenbeck process. This red noise shows very short correlation, at most a lag of one or two time units, as shown in the autocorrelation below.
|Autocorrelation function, centered at 1/2 time series length|
Hard pressed to find any real signal in such a time series. A simulation of Ornstein-Uhlenbeck red noise is shown to the left below, with a slice of the Greenland data to the right.
|Ornstein-Uhlenbeck red noise time series (left) and slice of data (right)|
Chylek claims that he can see 20 year AMO (Atlantic Ocean) oscillations in the data. Like Tamino, I see nothing but garden variety noise.