The topic of climate change has attracted widespread attention in recent years and is an issue that numerous scientists study on various time and space scales. One thing for sure is that the earth's climate has and will continue to change as a result of various natural and anthropogenic forcing mechanisms.
This page features the trends in mean annual and seasonal temperatures for Alaska's first-order observing stations since 1949, the time period for which the most reliable meteorological data are available. The temperature change varies from one climatic zone to another as well as for different seasons. If a linear trend is taken through mean annual temperatures, the average change over the last 6 decades is 3.0°F. However, when analyzing the trends for the four seasons, it can be seen that most of the change has occurred in winter and spring, with the least amount of change in autumn.
Considering just a linear trend can mask some important variability characteristics in the time series. The figure at right shows clearly that this trend is non-linear: a linear trend might have been expected from the fairly steady observed increase of CO2 during this time period. The figure shows the temperature departure from the long-term mean (1949-2012) for all stations. It can be seen that there are large variations from year to year and the 5-year moving average demonstrates large increase in 1976. The period 1949 to 1975 was substantially colder than the period from 1977 to 2012, however since 1977 little additional warming has occurred in Alaska with the exception of Barrow and a few other locations. The stepwise shift appearing in the temperature data in 1976 corresponds to a phase shift of the Pacific Decadal Oscillation from a negative phase to a positive phase. Synoptic conditions with the positive phase tend to consist of increased southerly flow and warm air advection into Alaska during the winter, resulting in positive temperature anomalies.