| Popis: |
Three glaciers of the Kigluaik Mountains are very small and the only ones on the Seward Peninsula and surrounding west-central Alaska, but they are important climatically. They display the typical recession in response to recent warming, as well as moraine evidence of Little Ice Age worldwide cooling peaks of the 17th and 19th centuries. The terminal moraine of Grand Union glacier, dated lichenometrically at about A.D. 1645, indicates that equilibrium line altitudes fell about 170 m from present levels at this time, or one half the amount estimated locally for late Wisconsin glaciation. Periglacial landforms throughout the Kigluaik Mountains display ample evidence of the earlier Neoglacial cooling of the Holocene. Minimum (lichenometric) ages from active tongue-shaped rock glaciers and protalus ramparts, as well as maximum 14C ages for pingo development are compatible with a wide range of published proxy climate data indicative of middle to late Holocene cooling, particularly from about 4000 to 3000 yr ago. Increasing warmth of the late 20th century is showing its direct effects on Grand Union glacier, the only active glacier remaining in this transitional maritime-continental climatic regime of western Alaska. With an estimated net mass balance of -0.8 m water equivalent, it is, along with the other two stagnant glaciers of the Seward Peninsula, projected to disappear by about A.D. 2035. |
