A few interesting graphs to view.

The effect of the 2004 tsunami on temperatures in Sri Lanka. This looks like a gradual rise followed by a crash in temperatures.

    tempgraph --ghcn v2.mean --countrycodes v2.country.codes --start 1900 --countries "sri lanka"

However, upon closer analysis of the weather stations this interpretation is deceptive.

    tempgraph --ghcn v2.mean --countrycodes v2.country.codes --start 1900 --wmo wmo.txt --area "9.5N,79.8E,4N,82E" --kml sri_lanka.kml

Greenland appears to have been warmer in the early 20th century than it is today...

    tempgraph --ghcn v2.mean --countrycodes v2.country.codes --start 1870 --countries "greenland"

...but this seems to be explained by weather stations becoming more northerly.

    tempgraph --ghcn v2.mean --countrycodes v2.country.codes --wmo wmo.txt --start 1870 --countries "greenland" --equatordist graph_dist_to_equator.png

The decline in the number of active ground weather stations after the mid 1970s, which hitherto had been increasing exponentially, is probably due to the introduction of satellite based weather monitoring.

    tempgraph --ghcn v2.mean --countrycodes v2.country.codes --start 1900 --activestations graph_active_stations.png

Temperatures within the arctic circle.

    tempgraph --ghcn v2.mean --countrycodes v2.country.codes --start 1880 --wmo wmo.txt --latitudes "66.56N,90N" --minmax --fitline