The obvious to me is the graph above. Iceland would be a great spot to monitor if you didn't have many spots to monitor. The western coast of South America is another great spot if you are looking for long term climate trends, then I am an on the water kinda guy.
From the paper,
Out of those 17, only one station exhibits a warming trend which is significant against all three null models. The stations with significant warming trends are located mainly in Scandinavia and Iceland. I have been using the BEST Tmin data and diurnal data for a while since it would be more closely related to "greenhouse effect" impacts. The "greenhouse effect" reduces the rate of cooling and that would be most noticeable a night or Tmin. I am really anxious for the new global BEST data to hit the internet since that should use real marine surface air temperatures instead of a hodge podge of bucket, engine intake and spot coastal measurements. Once that is out, a lot of the mystery will see some light. Until then, Best Tmin temperatures from places like Iceland, Oceania, the Galapagos Islands and such tend to indicate that the oceans have been warming from well before 1950 in fits and starts. That is not exactly a great indication of CO2 forced climate change. More like natural internal changes with a dash of land use, IMHO, though you can tease out a tad of atmospheric forcing change likely due to CO2 influences. Now this paper is new and with "novel methods" will be questioned by many that often employ "novel methods" to get results in their "range of comfort". Time will tell and I would not be the least surprised to see a statisticalface plant or two in the discussions.