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A century of climate change for Fairbanks, Alaska.

Article Excerpt
(Received 16 June 2008; accepted in revised form 21 November 2008)

ABSTRACT. Climatological observations are available for Fairbanks, Interior Alaska, for up to 100 years. This is a unique data set for Alaska, insofar as it is of relatively high quality and without major breaks. Applying the best linear fit, we conclude that the mean annual temperature rose from -3.6[degrees]C to -2.2[degrees]C over the century, an increase of 1.4[degrees]C (compared to 0.8[degrees]C worldwide). This comparison clearly demonstrates the well-known amplification or temperature change for the polar regions. The observed temperature increase is neither uniform over the time period nor uniform throughout the course of a year. The winter, spring, and summer seasons showed a temperature increase, while autumn showed a slight decrease in temperature. For many activities, the frequencies of extremes are more important than the average values. For example, the frequency of very low temperatures (below -40[degrees]C, or -40[degrees]F) has decreased substantially, while the frequency of very high temperatures (above 26.7[degrees]C, or 80[degrees]F) increased only slightly. Finally, the length of the growing season increased substantially (by 45%) as a result of an earlier start in spring and a later first frost in autumn. Precipitation decreased for Fairbanks. This is a somewhat counter-intuitive result, as warmer air can hold more water vapor. The date of the establishment of the permanent snow cover in autumn showed little change; however, the melting of the snow cover now occurs earlier in the spring, a finding in agreement with the seasonal temperature trends. The records for wind, atmospheric pressure, humidity, and cloudiness are shorter, more broken, or of lower quality. The observed increase in cloudiness and the decreasing trend for atmospheric pressure in winter are related to more advection and warmer temperatures during this season.

Key words: climate, Alaska, sub-Arctic, Fairbanks, 100 years, trends

RESUME. Il existe des observations climatologiques pour Fairbanks, a l'interieur de l'Alaska, echelonnees sur 100 ans. Cet ensemble de donnees est unique en Alaska en ce sens que les donnees sont de relativement grande qualite et qu'elles ne comportent pas d'interruptions majeures. Au moyen du meilleur appariement lineaire, nous concluons que la temperature moyenne annuelle s'est elevee de -3,6 [degrees]C a -2,2 [degrees]C au cours du siecle, ce qui represente une augmentation de 1,4 [degrees]C (comparativement a la moyenne mondiale de 0,8 [degrees]C). Cette comparaison montre clairement l'amplification ou le changement de temperature bien connu des regions polaires. L'augmentation de temperature qui a ete observee n'est ni uniforme pendant la periode visee ni uniforme au cours d'une meme annee. La temperature s'est en fait accrue pendant les saisons de l'hiver, du printemps et de l'ete, tandis que la temperature a baisse quelque peu l'automne. Pour bien des activites, la frequence des extremes est plus importante que les valeurs moyennes. Par exemple, la frequence de temperatures tres basses (en bas de -40 [degrees]C, ou -40 [degrees]F) a diminue considerablement, tandis que la frequence de temperatures tres elevees (au-dessus de 26,7 [degrees]C, ou 80 [degrees]F) n'a augmente que legerement. Et enfin, la longueur de la saison de croissance a augmente considerablement (de 45 %) parce que le printemps commence plus tot et que les premieres gelees de l'automne se manifestent plus tard. Les precipitations ont diminue a Fairbanks. Ce resultat est un peu contre-intuitif car Pair plus chaud peut contenir plus de vapeur d'eau. La date de l'etablissement de la couverture de neige permanente a l'automne a peu fluctue. Cependant, la fonte de la couverture de neige se produit maintenant plus tot au printemps, observation qui cadre avec les tendances caracterisant les temperatures saisonnieres. Les donnees relatives au vent, a la pression...

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