If this type of discontinuity was treated the same as a station elevation change it would introduce false warming by the amount of the discontinuity. (climateaudit.org)
If you hear a statement such as «They have dropped stations from cold locations so the result is now give a false warming bias» and your first reaction is, yes, that would have that effect, then please, if you haven't done so already, go and read Part 1A and Part 1B then come back here and continue. (skepticalscience.com)
A related criticism is that the decline in used station count has disproportionately removed stations from colder climates and thus introduced a false warming bias to the record. (skepticalscience.com)