Since 1979, the Arctic has warmed nearly four times faster than the global mean . Recent mass loss from Arctic glaciers has contributed to sea level rise at a comparable rate to the vast Greenland Ice Sheet . The loss of glaciers is also expected to have numerous local impacts on hydrological, ecological, and human systems. Although it is virtually certain that glaciers will continue to lose mass over coming decades, large uncertainties remain in twenty-first century projections of ice loss from glaciers. These uncertainties have wide–ranging global and local scale implications including on projections of sea level rise and coastal flood risk, and for projections of the duration of freshwater supplies coming from glaciers. To address these limitations, my research program takes a cross-disciplinary approach and has drawn on tools from climate science, paleolimnology, glaciology, glacial geomorphology, remote sensing, and spatial analysis to provide a longer–term framework for anticipating the consequences of ongoing warming on the Arctic cryosphere.
Recent and ongoing research themes
Holocene climate and glacier reconstruction:
My recent work has largely focused on analysis of physical and geochemical properties of proglacial lake sediment to infer changes in glacier size over the Holocene. I use these sedimentary indicators alongside geomorphic evidence of past glacier extent (e.g., the positions of moraines and trimlines) to model past glacier surfaces and their associated equilibrium–line altitudes (ELAs; a mass–balance modulated parameter) to develop quantitative reconstructions of past climate conditions.
Historical climate and glacier change:
Owing to their remote and logistically challenging setting, direct field measurements on Arctic glaciers are very rare. Rather, most studies have relied on satellite imagery and other space–based observations to estimate glacier area, volume, or length change, but are inherently restricted to the satellite era, which began in the late 1970s. This limitation hinders our longer–term understanding of glacier sensitivity to climate perturbations, with implications for prediction of their response to sustained warming as anticipated for the future. I combine historical observations (e.g., air photos) with modern satellite imagery to extend the limited time frame of observational records of glacier change.
Assessing glacier lifespans:
I am working to develop the first Arctic–wide prediction of glacier lifespans by modeling when individual glacier equilibrium–line altitudes (ELAs) crossed, and will cross, critical topographic thresholds (which equate to glacier inception and death) from the mid-Holocene to 2100 CE. This work will thereby estimate how long individual glaciers have existed on the landscape and will identify which of the Arctic’s 50,000+ land–based glaciers are most at risk of melting away first under different future warming scenarios.
Circumpolar data synthesis:
To date, there are relatively few continuous records of glacier variations inferred from lake sediments over the Holocene across the Arctic—a vast area, which hosts a wide range of modern climates. I recently compiled all available lake-based glacier records (n = 66) from seven Arctic regions. The work summarizes evidence for when glaciers were smaller than today or absent altogether, and evidence for when glaciers regrew in lake catchments. Most importantly, the synthesis strongly reinforces that relatively modest summer warming (compared with projections of larger future climate change) drove major environmental changes across the Arctic including the widespread loss of smalll mountain glaciers.
Rantanen, Mika, et al. "The Arctic has warmed nearly four times faster than the globe since 1979." Communications Earth & Environment 3.1 (2022): 1-10.
Meredith, M., et al. "Polar Regions. Chapter 3, IPCC Special Report on the Ocean and Cryosphere in a Changing Climate." (2019).