Comparing the Recession of Glaciers in the Torngat Mountains with Cirque Glaciers of the Canadian Rockies George Hill GE354 9 December 2015

Overview Description of Torngat and Rocky Mountain Localities Paleoclimates of Boreal Canada during the Holocene Mass Balance and Topographic Controls on Cirque Glaciers Glacier Recession

Importance of Study - Wide variety of forms - Indicators of global climate - Sources of fresh water - Torngat Mountains poorly understood Image Source

Torngat Mountains Extremely old rocks, Torngat Orogen, Granite and orthogneiss near coast → gneiss inland Mountains on coast Summers are rainy and foggy, winters dry and cold 195 ice masses, 1/3 under 0.05 km 2 and 8 above 0.5 km 2

Torngat Mountains

Canadian Rockies Monashee Mountains: assemblage of metasedimentary rocks overlying granite/gneiss batholiths, 2500 m of relief from valley floor Monashee Glacier size comparable to Torngats, < 0.4 km 2 Consistent precipitation, affected by maritime and continental air masses

Canadian Rockies

Paleoclimates of Canada During the Holocene Central Canada – Area from Ontario into BC – Stable, consistent conditions Labrador – Climate responsive to global trends (LIA, MWP, Dark Ages) – Winter temperatures strongly correlated to precipitation

Labrador Temperature and Precipitation Anomalies, past 2 ka

Topographic Controls Torngat Mountains – Backwall height associated with ELA – Minimum ice mass elevations correlated with proximity to ocean, same with backwall height Monashee Mountains – Backwall Height → shadowing – Avalanching and wind drifting

Backwall and ELAs in Four Large Torngat Glaciers MeanBackwall m a.s.l m Abraham Hidden Minaret Superguksoak Mean ELA After Rogerson, 1986

Mass Balance in Torngats Average -2.6 m over 3 years in large glaciers Mass balance was positive after a cool summer and snowy winter Mean annual temp was not a good predictor

Glacier Recession: Torngats Lost ~20% of area , ~53% since LIA Elevation was best predictor of recession – Topographic shading worse predictor Result of less snowy winters and warmer summer

Glacier Recession: Torngats From Way, 2014

Glacier Recession: Torngats Warm winters should be snowier Sea ice decrease is 20% per decade since 1968, so it must be warmer Snow cover has also decreased in duration at the end of the season

Glacier Recession: Monashees Have not receded appreciably in last ~50 years Glaciers without topography that favoured preservation did recede or disappear Not accurate predictors of climate change

Summary Cirque glaciers are highly variable and often influenced by topographic controls Labrador is more heavily influenced by global climate The recession of Torngat glaciers appears to be abnormal and still poorly understood Rocky Mountains cirque glaciers are preserved by topography and are not good indicators of global climate

References D'Arrigo, R., B. Buckley, S. Kaplan, and J. Woollett, 2003: Interannual to Multidecadal Modes of Labrador Climate Variability Inferred from Tree Rings. Climate Dynamics, v. 20, pp DeBeer, C. M. and M. J. Sharp, 2009: Topographic Influences on Recent Changes of Very Small Glaciers in the Monashee Mountains, British Columbia, Canada. Journal of Glaciology, v. 55, pp McCoy, W. D., 1983: Holocene Glacier Fluctuations in the Torngat Mountains, Northern Labrador. Géographie physique et Quaternaire, v. 37, pp Menounos, C. B., G. Osborn, J. J. Clague, and B. H. Luckman, 2008: Latest Pleistocene andHolocene Glacier Fluctuations in Western Canada. Quaternary Science, v. 28, pp Rogerson, R. J., 1986: Mass Balance of Four Cirque Glaciers in the Torngat Mountains of Northern Labrador, Canada. Journal of Glaciology, v. 32, pp Tennant, C., B. Menounos, R. Wheate, and J. J. Clague, 2012: Area change of glaciers in the Canadian Rocky Mountains, 1919 to The Cyrosphere, v. 6, pp Viau, A. E. and K. Gajewski, 2009: Reconstructing Millennial-Scale, Regional Paleoclimates of Boreal Canada during the Holocene. Journal of Climate, v. 22, pp. 316–330. Way, R. G., T. Bell, and N. E. Barrand, 2014: An Inventory and Topographic Analysis of Glaciers in the Torngat Mountains, Northern Labrador, Canada. Journal of Glaciology, v. 60, pp Way, R. G., T. Bell, and N. E. Barrand, 2015: Glacier change from the early Little Ice Age to 2005 in the Torngat Mountains, northern Labrador, Canada. Geomorphology, v. 246, pp

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