The temperature of permafrost is measured at the shallowest depth where the temperature does not change throughout the year. This chart shows permafrost temperatures recorded at ten sites in Russia, Alaska, Canada and Svalbard. Most of these temperature sequences show warming, typically by between 0.5 and 2 centigrades over the last two to three decades, with greater temperature increases at colder sites. The range in permafrost temperatures between sites is 1 centigrades less than it was 30 years ago.
These changes are linked to changes in average air temperature. Over western North America, the rate of warming has slowed since 1998, which was the year with the highest air.