Paleo Slide Set: Polar Ice Cores
Fluctuations of ice conductivity

While ECM measurements highlight volcanic events and provide a seasonal signal 
that aids in dating the core, they also provide information about past climate. 
Just as ECM varies seasonally because dusty summers result in lower ECM readings, 
windy and dusty periods in the Earth's climatic history appear in the ECM record as 
periods of near-zero readings. This figure demonstrates the close correlation between 
cold climatic events (the Younger Dryas and Wisconsin Glacial [the Wisconsin is the 
term used in North America to refer to the last full ice age], in blue) and low ECM readings. 
Paleoclimatologists postulate that dust fluxes increase during colder periods because the 
glacial atmosphere is drier. Since dust stays in the air longer when the climate is dry, it 
is transported greater distances in the atmosphere, resulting in increased dust fluxes to sites 
like the Greenland Ice Sheet that are without local dust sources. 

Photo Credits:
Graphic by Thomas Andrews. Data from Kendrick Taylor 
DRI, University of Nevada-Reno