News stories about the Arctic always seem to say either that the Arctic is warming twice as fast as the global average, or that it’s warming nearly twice as fast as the global average. That’s not correct.
Arctic warming is more like three to four times as fast as global warming.
Some global temperature estimates (e.g. that from HadCRU) simply omit much of the Arctic, which makes it difficult to deduce how the Arctic has been warming. Others (specifically, NASA data, the extended HadCRU data from Cowtan & Way, and the data from Berkeley Earth) deduce pan-Arctic temperature from nearby measurements. This is based on the fact (not supposition but fact) that temperature change is strongly correlated in nearby areas, the correlation extending as far as 1200 km.
The warming rate since 1985 in the Arctic, at 6.48 °C/century (11.7 °F/century), is fully 3.4 times as fast as the global rate since 1985, 1.90 °C/century (3.4 °F/century).
What about the data from Cowtan & Way?
The warming rate since 1985 in the Arctic, at 8.25 °C/century (14.9 °F/century), is fully 4 times as fast as the global rate since 1985, 2.06 °C/century (3.7 °F/century).
[Read more here. The analysis in the original piece is much more detailed than what I have reproduced here. It's well worth a read]
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