As far as I know, the null hypothesis is that a unit root exists and that the process is therefore stationary. I had found that thread you linked, and I'm the user who started the short but ongoing discussion in the comments. The linked post (listed in the right-hand column) is also mine, and is...
I have a time series of climate data that I'm testing for stationarity. Based on previous research, I expect the model underlying the data to have an intercept term, a positive linear time trend, and some normally distributed error term. In other words, I expect the underlying model to look...
I'm looking for annual mean temperature data for the city of Chicago for a large number of years, ideally over 100. I found this chart, which depicts the exact data I need from 1873 to 2011:
http://www.climatestations.com/images/stories/chicago/chiann.gif
which comes from this site...