Big, Fast & Global

Funding

In collaboration with colleagues at the University of Maine:

• Award Abstract # 1903175
• Collaborative Research: P2C2: Reconstructing Holocene Climate Change in the Southern Hemisphere from Southern Alps Mountain Glaciers and Tree Rings (NSF EAR 1903175)

Summary

This project establishes the record of Holocene climate variations, based on glaciers and temperature-sensitive trees, in the Southern Alps of New Zealand – on the opposite side of the planet from the North Atlantic region. Mountain glaciers are among Earth’s most sensitive climate recorders on timescales of decades and longer. Worldwide recession of mountain glaciers is an iconic illustration of global warming. Glacial landforms afford physical evidence of past glacier extent, and this effort will employ state-of-the-art cosmogenic dating techniques on those landforms to establish precise and accurate chronologies of glacier changes during and prior to the period of recorded observations. This work incorporates tree-ring chronologies of temperature-sensitive South Island species that afford continuous records of climatic fluctuations on annual timescales. Altogether, chronologies of glacier extent and tree growth will be used to develop a comprehensive record of past temperature variation in the Southern Alps for comparison to equivalent records in the Northern Hemisphere. The resultant temperature reconstruction will also provide a key metric for evaluating a suite of global climate and earth-system models developed by the National Oceanic and Atmospheric Administration Geophysical Fluid Dynamics Laboratory.

Role

The glacier and tree-ring records will be used as benchmarks to investigate results from the GFDL ESM2M preindustrial climate simulations. On the basis of this glacier, dendro, and modeling approach, the goal of this work is to determine whether Holocene climate variations were global or not, and therefore improve understanding of underlying drivers and the scope of natural climate variability in light of ongoing planetary warming.

Funding

In collaboration with colleagues at the University of Maine:

• Award Abstract # 2001401
• P2C2: Collaborative Research: Timing of the Glacial Termination in Southernmost South America (NSF EAR 2001401)

Summary

This research will examine the largest global warming event in the recent geological past: the transition from the last ice age to the present interglacial world. First, a climate record will be produced by documenting the age and location of landforms left by rapidly retreating glaciers at the end of the last ice age. These records will then be used, along with computer models, to test hypotheses about different components of the climate system that are thought to play important roles in rapid warming of Earth.

Despite significant progress, the origin of ice-age terminations remains unresolved. At the core of this issue is the precise inter- and intra-hemispheric timing of the end of the ice age, because such information yields clues as to the mechanisms that underlie the termination. The research team will test the hypothesis that the temperature rise of the last termination in southern latitudes was earlier and faster than previously recognized, so fast that it may require a major overhaul of existing hypotheses. The research project will document the timing and magnitude of the termination of the Cordillera Darwin icefield, in southernmost South America.

Role

These data will be compared with existing paleoclimate records at lower latitudes and with GFDL Earth System Model 2M to assess the feasibility of various forcing factors for the termination, such as an ocean bipolar seesaw, shifting of the southern hemisphere westerlies, and atmospheric carbon dioxide concentrations.

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