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Regional-scale spatial variation in the change in equilibrium-line altitude (ELA) trend surface in the Queen Elizabeth Islands (QEI), Arctic Canada between the 'Little Ice Age' (LIA) and 1960 corresponds to Empirical Orthogonal Functions (EOFs) representing specific patterns of summer climate variability found in the modern record. Extreme warm (1953-1962) and cold (1965-1974) decades in the modern record were used as modern analogues of climatic conditions during the early twentieth century and the LIA, respectively. Because of the minimal influence of precipitation during both extreme decades, temperature is the variable upon which the fluctuation of the ELA is dependent. Hence, the ELA ?h pattern describes the spatial pattern of change in SAT across the QEI between the LIA and 1960. This pattern is consistent with the primary mode of variability of mean summer surface air temperature (SAT) in the modern record (ie, EOF-1, 1949-2002), the positive (negative) phase of which is strongly in place during the extreme warm (cold) decade. SAT anomalies in the QEI during the warm (cold) decade are positively correlated with a weak (strong) QEI-distal (QEIproximal) polar vortex, higher (lower) than normal SSTs in the North Atlantic, and one of the lowest (highest) periods of sea-ice extent during the twentieth century. The climatic conditions during the cold decade are believed to describe conditions, which if sustained, would lead to a LIA-type cold episode capable of long-term snowline lowering and perennial snow/ice expansion. The climatic conditions during the warm decade represent possible modern analogues for those that might have occurred during the early twentieth century in the Canadian High Arctic, which led to a substantial reduction in perennial snow/ice. [ABSTRACT FROM AUTHOR]

Changes in late Neoglaical climate resulted in extensive modification of Arctic terrestrial ice cover. A substantial reduction in terrestrial ice cover in the Queen Elizabeth Islands (QEI) following the 'Little Ice Age' (LIA) (~AD 1250-1900), is indicated by widespread, light-toned patches of poorly vegetated terrain, extending back to the modern ice mass. These patches display abrupt outer margins (trimlines), which record the former position and maximum extent of perennial snow/ice and, in many cases, mark the former equilibrium-line altitude (ELA). Trimlines surrounding terrain formerly covered by LIA perennial snow/ice were mapped using multispectral classification approaches applied to high-resolution satellite imagery. ELAs were reconstructed from trimlines associated with former perennial snow/ice produced by long-term snowline lowering. Between the end of the LIA and 1960, the area of terrestrial ice in the QEI decreased by 37% (62 387 km2). Most of this reduction (94%) occurred in the eastern QEI where the majority of the ice exists today; however, a 100% reduction in ice cover occurred on many of the western islands by 1960, an effect largely controlled by the subtle topography of these islands. The reconstructed LIA ELA trend surface was used with the 1960 mapped ELAs to calculate spatial variations in the change in height (Δh) of the ELA trend surface throughout the QEI during the first half of the twentieth century. ELA Δh between the LIA and 1960 reveal a high degree of local variability in the mountainous regions, ranging from 0 to >600 m; however a strong regional-scale pattern of change is shown over the QEI as a whole. [ABSTRACT FROM AUTHOR]