Snowlines at the last glacial maximum and tropical cooling

An improved technique for the reconstruction of former glacier mass-balance and dynamics

“…The ELA is critical in examining glacier dynamics (Andrews, 1972(Andrews, , 1975Paterson, 1994;Benn and Gemell, 1997;Benn and Lehmkuhl, 2000;Harrison, 2005;: if a glacier is to remain in equilibrium, the net losses of ice from below the ELA must be equalled by transport of a similar net gain in ice from above the ELA. The ELA's of contemporary glaciers are strongly associated with regional temperature and snowfall (Osmaston, 1975;Sissons and Sutherland, 1976;Sutherland, 1984;Ballantyne, 1989;Locke, 1990;Ballantyne, 2002;Osmaston, 2005;Harrison, 2005), and therefore provide the sensitive link between glaciers and climate noted above.…”

“…The ELA's of contemporary glaciers are strongly associated with regional temperature and snowfall (Osmaston, 1975;Sissons and Sutherland, 1976;Sutherland, 1984;Ballantyne, 1989;Locke, 1990;Ballantyne, 2002;Osmaston, 2005;Harrison, 2005), and therefore provide the sensitive link between glaciers and climate noted above. A number of techniques have been used to infer the ELA of former glaciers, notably the area weighted mean altitude (AWMA: Sissons, 1974;Sissons and Sutherland, 1976), accumulation area ratio (AAR: Porter, 1975;Meierding, 1982), area altitude balance ratio (AABR: Furbish and Andrews, 1984;Benn and Gemell, 1997;Osmaston, 2005) and the maximum elevation of lateral moraines (MELM: Andrews, 1975).…”

“…However, whilst glacier mass-balance is sensitive to temperature changes through surface energy balance driving ablation, changes in precipitation (and thus accumulation) also have a residual impact (Kuhn, 1989;Kaser and Osmaston, 2002;Harrison, 2005;. This means that variations in former glacier ELA cannot be reliably used to derive quantitative palaeotemperature records unless an independent record of precipitation at the time of glaciation is available for comparison (Harrison, 2005;Benn and Ballantyne, 2005).…”

A stochastic process for the interannual snow storage and melting dynamics

“…Particular attention is given to the fluctuation in altitude of the end of summer snowlines (EOSS) with respect to the mean Equilibrium Line Altitude (ELA m ) [e.g., Paterson, 1994;Harrison, 2005]. This limiting line is defined as an average over many years of the EOSS location [Clare et al, 2002], and provides indications about the location in altitude of positive snow mass balance.…”

“…This limiting line is defined as an average over many years of the EOSS location [Clare et al, 2002], and provides indications about the location in altitude of positive snow mass balance. This has implications for recharge of glacial areas [Paterson, 1994], climate change [Beniston, 1997;Beniston et al, 2003], and the reconstruction of the last glacial maximum (LGM) and past precipitation [Harrison, 2005;Cherry et al, 2005].…”