Assessing the Impact of Climate and Ocean Changes on Glacier Mass Balance
The recent recognition of dramatic ice loss in the polar regions underscores the importance of outlet glacier dynamics on the overall stability of ice sheets. Ice loss from the Greenland Ice Sheet tripled from 1996 to 2007, and over half of that loss was caused by an acceleration of the outlet glaciers. Accelerated surface melting and synchronous retreat due to warmer air temperatures has been well documented in Greenland, yet we still know very little about rates of submarine melting and how these may be influencing retreat, mainly because investigating the marine realm of many glaciers is difficult. We collaborate with researchers at UBC, in the US, and in Chile to combine geophysical observations with spatial analysis and numerical models of ice-ocean and ice-climate interactions, by collecting oceanographic data in both temperate and polar fjords to define fjord circulation patterns and determine melting rates. Subaqueous melting is compared with the results with surface mass balance measurements and climate models to achieve new insights into a) the role of ice-ocean interactions in outlet glacial systems and their impact on the mass balance of the ice masses that feed them, and b) the role of regional moisture and temperature variability on glacier health.
Identifying the Signatures of Climatic Change in Glaciated Landscapes
Landscapes produced by glaciers are of particular interest because they create topographic and sedimentary archives recording a wide range of important climatic and non-climatic variables. The erosion by ice, the flux of sediment from glaciers and the imprint of glaciers on the land are dominantly controlled by meltwater discharge and thermal regime. Glaciers advance and retreat in response to changes in climate, and the reconstruction of former distributions and extents of alpine glaciers can thereby serve as a proxy of past climatic conditions. Understanding the relationships between glaciers, climate, erosion, glacial sediment yields and landforms is also necessary if we want to decipher the response of ice masses to past climatic changes from complex sedimentary and topographic archives. This project identifies the factors controlling erosion and sediment yields through glacial advances and retreats, and determines those factors that reflect climatic forcing and those that reflect either tectonic forcing and/or non-climatic dynamics of the glaciers. Our group takes an integrated fieldwork and modeling approach, including mapping and dating glacial and paraglacial deposits, using modern climate data to understand the basic mechanisms of climate variability in mountain landscapes, and developing a coupled mass balance, flow and erosion models to reconcile differences between current and former glacier dynamics and regional patterns in climate and topography.
Effects of glacier retreat on hazards
Glacier thinning and retreat drives the destabilization of steep valley walls and can lead to massive rock avalanching. When such a landslide collapses into a standing body of water it can trigger a powerful local tsunami. A compelling example of this phenomenon took place on October 17, 2015, when the largest landslide in North America in decades occurred in Taan Fjord in SE Alaska, triggering a tsunami over 180 m tall. The cause of the landslide was the rapid retreat of Tyndall Glacier during the latter half of the 20th century, a phenomenon that drove rapid thinning of the glacier, de-buttressing of valley walls, and destabilization of ice-marginal deposits and bedrock. With a number of colleagues from across Canada and the US, including MSc. student Haley Williams, in summer 2016 we completed the first real-time field observations to establish a benchmark dataset on a tidewater glacier that will be used to assess the hazards caused by large, catastrophic events, including evaluating the magnitude of landslide mass transferred to the fjord, the glacier dynamic response to the addition of supraglacial landslide debris and the paraglacial response to such events.
Warming trends are exacerbating this risk in glaciated coastal regions around the world. The prevalence of large rock avalanches that have resulted from glacier thinning and retreat elsewhere in coastal Alaska, British Columbia, and the Yukon has increased dramatically in the past decade. Hence, it is very likely that similarly large and tsunamigenic landslides will occur in other BC and Alaskan fiords in the near future, posing significant risk to lives and infrastructure.
Projecting Impacts of Climate Change on Freshwater Resources
Understanding the impact of regional climate change on the mass balance of glaciers throughout high mountain regions such as the Himalaya or the BC Coast Mountains is essential to predicting future meltwater contributions to river discharge. In collaboration with researchers in the US and in India, we are working on determining the significance of climate change on glacier health in the Indus and Ganges Rivers watersheds, by 1) investigating the role of debris cover, avalanching and summer snow accumulation on the mass balance and melting of Himalayan glaciers, 2) calculating the contribution of glacial melt to the river, 3) determining margins of error for numerical calculations by comparing climate data from global datasets and local climate data collection and 4) understanding the potential implications of future climate change based on IPCC projections. We are also working on assessing the role of proglacial lake formation on the mass balance and hydrologic regimes of Bridge Glacier in BC. We use climate stations, streamflow measurements, and glacier flow data as well as GIS analysis to model the total volume of melt from glaciers in these watersheds.
Socio-ecological dimensions of cryospheric change
This project is focused on 1) characterizing how changes in the high mountain cryosphere––particularly climate-related changes in snow/glacial hydrology––propagate through interlinked socio-ecological systems and 2) the development of principles for responding to cryospheric changes in ways that are both socially and ecologically tenable. The project aims to provide actionable governance recommendations for supporting human well-being and ecological resilience in the context of a rapidly changing cryosphere.