Before moving on from Canada, just one more thing. Kevin reminded me this evening of two things. Big things. First Canada’s size (second largest country in the Northern Hemisphere) and therefore relative importance in climate terms. So why has it so few weather stations reporting into GHCN compared to the United States. For me one of Kevin’s maps says it all:
Map of stations in Canada and USA 1990-2010 with at least 10 years of data (and no missing months) (colours indicate temperature trends – key as below). Original here.
The other thing was something he mentioned in a blog comment elsewhere a few days ago. Something I had missed entirely….
Here’s what he means:
Map of stations in Canada and USA 1970-2010 with at least 10 years of data. Original here.
Striking isn’t it? I think somehow we might be coming back to this at some stage. But in the meantime I do feel the need to move on….
Digging in the Clay 
Could there be something with the switch from Fahrenheit to Celcius and rounding? Is there a step function in the data?
Barry, it’s not just a step change and the map above shows color data for rate of increase, so it is more than just a result of unit conversion.
It probably needs an investigation at the station level, but it might be quite an undertaking….
The reason I asked was that I didn’t know when Canada switched to metric and thought that there might be something to do with the different magnitudes in degrees.
Barry, Canada’s metrication was started in 1974. I think temperature was one of the realtively early conversions. That mid-70’s timing does conincide with the up slope for temperature (see previous postings, however the shape of the graph is similar in many parts of the world.
“Canada’s size (second largest country in the Northern Hemisphere)”
That would be second largest country on the planet – Russia still is the largest.
And we aren’t metric, we are sometimes metric, just enough to confuse by Americans & the Euros who visit.
@Fred,
You know one of the worst aspects of having a blog is that writing posts often gets squeezed into times when you are least lucid. Often you don’t write with the exactness you should.
My thinking in the scentence you quote was “country” “Northern Hemisphere” in terms of climate importance; I just happened to put them in the same sentence. Also in terms of high latitude thermometers and climate importance Antarctica is bigger (OK so it is a continent).
Ah, now I didn’t say you were fully metric – see you admit to some metrication.
Thanks for the comment and clarification
Metar Effect shows only where temps drop below 0.
In C, zero happens at 32F.
I don’t know about Canada, but there was a step change in Alaska in the mid 1970’s.
http://climate.gi.alaska.edu/ClimTrends/Change/TempChange.html
@Harrywr2, interesting link. That flip seems to be due to the PDO and it is noticeable that the temperature reconstruction at the site is looking at the total temperature change over 1949-2009 (50 years). Had they used 1939 (60 years) they may bot have had any warming, or even had cooling instead.