While the global average temperature continues to rise, it does so disproportionately around the world: the closer to the poles one gets, the more drastic this temperature rise becomes, a phenomenon in climate science called Polar Amplification. This effect has become so drastic that some areas of the Arctic, such as the Barents and Chukchi seas, are up to 4ºC (7.2ºF) warmer than average. And now these temperature extremes are breaking climate data algorithms, such as in the case of climate data being recorded in Utqiagvik, Alaska.

At their December 4, 2017 meeting, the National Centers for Environmental Information (NCEI) found that all of the data for the town of Utqiagvik was missing entirely. This indicated that the climate data being recorded there had shown enough of a drastic deviation from the norm to have been flagged — and omitted — by their data sorting algorithm. Utqiagvik is more commonly known as Barrow: in 2016, the town voted to change Barrow’s name back the area’s traditional Iñupiaq name, Utqiagvik.

As one might imagine, day-to-day weather data isn’t going to flow evenly from one day to the next, with some days seeing an extreme deviation from the days coming before or after, or sometimes the data is simply recorded incorrectly. The NCEI’s climate stations across the United States employ an algorithm that watches for such deviations, comparing the incoming data against the average over other days, and also the data coming from neighboring climate centers: if the data matches closely enough to the other stations’ data, it is considered valid, but if it doesn’t, the information is excluded.

But the further north one gets, the fewer recording stations there are, meaning that the next station that the data needs to be checked against might be quite far off, and may actually be experiencing entirely different conditions. This was doubly so for Utqiagvik, situated near the northernmost point in the United States (at a latitude of 71ºN, or 2,078 km (1,291 miles) from the north pole), with the next closest station being in Wainwright, 140 kilometers (87 miles) to the southwest.

Upon investigating the data’s disappearance, the NCEI found that Utqiagvik’s data was flagged not because it was incorrect, but that the average monthly temperatures had indeed risen dramatically above the norm over the last three months of 2017: October, November, and December were 4.3ºC (7.8ºF) warmer than the 1979-1999 average. The preceding nine months, while cooler, were still recorded as being 1.1ºC (1.9ºF) over the average — twice the increase that the lower 48 states experienced over the same span of time.

This instance has prompted the NCEI to look into finding a way to adjust their algorithm to accommodate the disproportionate increase in temperatures being recorded in the Arctic, for instance granting more leeway in the deviation allowed for climate stations above 65th parallel north.