Tree-ring-dated‘Little Ice Age’ histories of maritime glaciers from western Prince William Sound, Alaska

Abstract

Tree-ring studies at 13 glacier forefields in western Prince William Sound show‘Little Ice Age’ glacial fluctuations were strongly synchronous on decadal timescales. Cross-dated glacially overrun trees at eight sites indicate ice margins advanced in the early (late twelfth through thirteenth centuries) and middle (seventeenth to early eighteenth centuries)‘Little Ice Age’. Tree-ring dates of 22 moraines at 13 glaciers show two main periods of stabilization. The earlier of these, in the first decades of the eighteenth century, overlaps with the second period of glaciers overrunning trees and marks culmination of this middle‘Little Ice Age’ expansion. Stabilization of moraines on nine of the study forefields in the latter part of the nineteenth century delineates a third interval of‘Little Ice Age’ glacial advance. The detailed‘Little Ice Age’ record from land-terminating glaciers in western Prince William Sound is consistent on a timescale of decades with four other tree-ring-dated glacial histories from across the northern Gulf of Alaska. This coastal northeastern Pacific glacial record reveals the structure of the‘Little Ice Age’ in the region and provides a strong basis for comparison with other proxy climate records spanning the past 1000 years.

Subglacial methanogenesis: A potential climatic amplifier?

“…Some proglacial material is bulldozed into push moraines and thrust ridges during glacial advance, but a significant amount of sediment and vegetation is overridden by advancing ice [Winkler and Nesje, 1999;Motyka and Echelmeyer, 2003]. In support of this are numerous incidents of fossil carbon found in glacial till [Simpkins and Parkin, 1993;Punkari and Forsström, 1995;Wiles et al, 1999], and reports of Holocene forests being buried by advancing ice [Luckman et al, 1992[Luckman et al, , 1993Luckman, 1995;Motyka and Echelmeyer, 2003]. Simpkins and Parkin [1993] demonstrate that methane continues to be produced in these tills from OC that is 14 -17 ka old.…”

Tree ring-dated fluctuation history of Midui glacier since the little ice age in the southeastern Tibetan plateau

“…Tree-ring dating, as an accurate method, has been widely used to reconstruct past glacier fluctuations in many areas of the world, such as the Canadian Rockies [11][12][13][14][15][16], the Alaska [17][18][19][20], the Andes [21][22][23][24][25][26], the Alps [27], etc. On the southeastern Tibetan Plateau, there are a great number of temperate glaciers, which account for about 22.2% of the total glacier area in China [6].…”

Constraints on regional drivers of relative sea-level change around Cordova, Alaska

“…Late Holocene glacial advance culminated in the second millennium AD during the Little Ice Age (LIA), with early advances underway in Alaska from AD 1180--1330. The middle and late advances (c. AD 1540--1720 and AD 1810--1890 respectively) resulted in Holocene maxima for many land--terminating glaciers in the Chugach Mountains (Barclay et al, 2009;Calkin et al, 2001;Molnia, 2008;Wiles et al, 1999;Wiles and Calkin, 1994). The majority of Alaskan mountain glaciers have retreated and thinned from their maximum LIA positions.…”