Detail of time-stratigraphic record in ice cores • In some cores, where accumulation rate is high, sub-annual (seasonal) records are preserved • Allows exact age determination of ice, for thousands of years in the past
New West Antarctic Ice Sheet (WAIS) corecurrently being drilled Goals and justification for this new core and site: Need 80Ky record, from high-accumulation zone, with thick annual layers • Climate forcing by greenhouse gases • Role of Antarc. in initiating rapid climate change • Relationship between northern, tropical and southern climates • Stability of the West Antarctic Ice Sheet and sea level change
More detailed scientific questions : • Are the climate changes during the anthropogenic era unprecedented? • How has climate varied during the last 10,000 years? • Do solar variability and volcanic emission affect climate? • What was the role of the Antarctic in climate change as the last ice age was ending? • What are the interactions between terrestrial biology and biogeochemical cycles? • What are the interactions between southern ocean biology and biogeochemical cycles? • Are microorganisms metabolically active in ancient ice? • Does the biology within ice sheets reflect the climate when the icewas deposited?
What will happen to excess CO2 now in the atmosphere we run out of fossil fuel to burn(after a few centuries)? It will return slowly to the various “reservoirs” in which nature stores carbon on this planet • standing plants (small mass, rapid response) • soils (humus) • surface layers of ocean • deeper ocean • carbonate rocks (huge mass, v. slow response)
Ice cores - - not the only game in town.Other paleoclimate “proxies”: 1. Tree rings fine time resolution, fine areal emphasis 2. Corals rings like trees, but tell temp. & chem. of oceans 3. Ocean and lake sediments very long time record, coarse resolution 4. “Spelean realm”: stalactites, stalagmites Well dated, long records from groundwater. 5. Packrat middens Localized, long-term records from pollen