Ninth International Conference on Permafrost ... - IARC Research

Recent Сlimatic Сhanges in YakutiaYu.B. SkachkovMelnikov Permafrost Institute, SB RAS, Yakutsk, RussiaIntroductionYakutia is the largest administrative region of the RussianFederation, occupying an area of 3.1 million squarekilometers. Most of the region is underlain by continuouspermafrost. Being the product of climate, permafrost is asensitive indicator of its long-term changes. In view of thepredicted permafrost degradation due to global warming andits negative consequences, it is extremely important to gaincomplete information on recent air temperature variations inthe region.During the past years, several works have been publishedon the general assessing of climate changes in Siberia andthe Far East over different periods of time (Ippolitov etal. 2007, Izrael et al. 2006, Pavlov & Malkova 2005, andothers). The present paper continues the previous researchmade by the author over the period 1966–1995 (Skachkov2001), and using the new data of the last decade, informs onthe current rate of climate warming in Yakutia.Data and Calculation TechniqueTo assess trends of the changes of the annual average airtemperature (T air) over the period 1966–2005 throughoutYakutia the following actions have been carried out:1. selection of 29 weather stations with accurateunceasing observation data (Fig. 1).2. calculation of the linear trend of the air temperatureand annual air temperature amplitude and their variance.3. assessment of the linear trends.The linear trends significance was estimated with theFigure 1. The plan of location of the stations selected for analysis.student criteria by the determination coefficient squaredvalue R 2 . The determination coefficient shows the linear trenddeposit in the general variation of the analyzed parameter. Theparameter variation trend would be considered significant ifits confidence level equaled or surpassed 95% (Р ≥ 0.95).With the sample size of 30 years, it conforms to R 2 ≥ 14%,and of 40 years, R 2 .≥ 12%.The period 1966–2005 is also nonrandom. In 1966, thehydrometeorological service of the USSR changed the gaugethat carried out measurements four times a day with theones that carried out measurements eight times a day; thusthe mean day parameters obtained from those observationsbecome more accurate. Secondly, WMO recommends a 30-year period as the main one for climate description. Thethird and most important reason: the beginning of the periodcoincides with the beginning of the observed warming. Thusthe series of observations 1966–2005 can be considered asclimatologically homogeneous regarding several factors.The temporal series data of the mean monthly airtemperature were used in the analysis. The meteorologicalobservation data were obtained from the climatologichandbook and monthly magazines and also from theUSA National Ocean and Atmosphere Agency database(http:www.ncdc.noaa.gov). Trend parameter calculationswere performed with Microsoft Excel 97.Results and DiscussionThe mean annual air temperature field analysis showsthat T airover the observed area widely varies from -16.7°С(Oymyakon) to -5.6°С (Vitim). High interannual variabilityof the mean annual air temperature is the peculiarity ofextreme continental climate endemic for the major territoryof Yakutia. The fluctuations of T airover the observed periodin the mean from all stations amount to 4–5°С. The lowestfluctuations of T air(-3.4°С) were noticed in Batamaya, andthe highest (-5.6°С), in Tiksi and Chulman.The global warming started in the end of 1960s over themajority of the Northern Hemisphere including Yakutia.From 1966 to 1989, the warming in this area passed on rathersmoothly and had almost zonational increment of the airtemperature. The highest increment values (1°С and more)are noticed in central and south Yakutia. Toward the north,there is noticed the decrease of temperature increment. Theair temperature trend values of the Laptev Sea shore, islandstations and northwest of Yakutia are subzero at this time(Skachkov 2001).The early 1990s saw spatially variegated temperatureincrease appear sharply throughout Yakutia. Southward ofthe latitude 64°N, the air temperature increment amountedto 1.5–2°С and more; northwest and northeast Yakutia was0.5–1°С. It is significant that the major contribution to the291