Ice Forcing in Arc Magmatic Plumbing Systems (IF-AMS)
Appreciation of how tectonic and earth surface processes are linked has advanced during the past two decades. In contrast, relationships between magmatism, climate, and the cryosphere via surface loading by ice remain less well understood due to limited observations. Thus, a question at the frontier of earth science is: how do changes in the climate system interact with the lithosphere and the magma reservoirs housed within it? To address this question, we conducting a novel blend of field observations, lab measurements, and numerical model simulations in an integrated study of links between the cryosphere, topography, and subduction zone volcanism. This will capitalize on recent advances, including: (1) understanding of the trans-crustal extent, physical state, and processes within magma plumbing systems, (2) improved precision and accuracy of geochronometers to determine rates of growth, erosion, and former ice configurations of volcanoes, as well as the timing of ice sheet retreat, and (3) numerical modeling to capture the dynamics of ice sheet growth and retreat and the response of subvolcanic magma reservoirs to ice- and sediment-driven surface loading changes.
Collapse of the Cordilleran Ice Sheet
Projections of future sea level rise rely on ice sheet models that are highly tuned to simulate the geometry and flow of the modern ice sheets despite uncertainties in the surface mass balance and unknown basal processes. Overfitting these models to the present day means that the sensitivity of the ice sheet to future warming is untested and unconstrained. Recent advances in cosmogenic dating as well as ice sheet modeling and uncertainty quantification now make it feasible to use reconstructions of past ice sheet changes to test and improve coupled climate-ice sheet models. While many ice sheets have been reconstructed with great detail, the deglaciation of the Cordilleran Ice Sheet is poorly constrained. Yet, this ice sheet offers great potential to constrain models due to its similarities to modern ice sheets, such as the southern Greenland Ice Sheet (mountainous, high accumulation and strong precipitation gradients, marine/land terminating).
Through a single, carefully designed effort combining widespread cosmogenic dating and ensemble modeling, we are developing the first large-scale reconstruction of Cordilleran Ice Sheet collapse – with data anchoring the model and the model filling data gaps. Our results will constrain ice sheet sources of deglacial sea level rise, the timing and magnitude of freshwater input to the oceans, and solid earth responses to deglaciation – key quantities of interest to Quaternary and ice sheet scientists, paleoceanographers, and geophysicists. These results will also be useful to refine ice sheet models used for future projections.
Holocene Alpine Glaciation
Glaciers are intrinsically linked to climate, and small alpine glaciers are particularly sensitive to climate perturbations and are unique amongst other climate archives because they record high elevation changes typically not widely represented by other climate proxies. In the high alpine regions it is well understood that glaciers were larger in the past few millennia based on exquisitely described and mapped glacial deposits just distal to present ice margins (Davis et al., 2009). These moraines demonstrate climate conditions that were once favorable for expanded ice positions, and are commonly associated with the so-called Little Ice Age (LIA) and/or ‘Neoglaciation’ of the late Holocene (Solomina et al., 2016). However, while the timing of the moraine construction is generally understood to have occurred in the last few millennia, the overall spatial pattern and precise timing of glaciation during the Holocene itself is still an open scientific question for many high alpine locations. Our group is working to better understand how alpine environments have responded major climate event of the Holocene, which provides a natural test case for understanding the sensitivity of alpine glaciers to past, and potentially, future climate changes.
