Sediment analysis will reveal weather shifts

Nov 17, 2006 14:05 GMT  ·  By

An international team will make an expedition to a polar lake in Northeastern Siberia which may provide detailed record of Arctic climate along millions of years.

Knowing the natural shifts of the Arctic climate, like which traits are cyclic and which are stable, and how this region passed from a forested area to a cold permafrost covered zone would offer scientists an understanding of the future Arctic.

"The bottom line is the more we can learn about how the Earth system worked in the past, the more we can be prepared for the future," said Julie Brigham-Grette of the University of Massachusetts Amhers.

"This research will make a critical contribution to understanding climate change," says George M. Langford, dean of the College of Natural Science and Mathematics.

The study object is Lake El'gygytgyn, of roughly nine miles across, formed by a meteorite impact around 3.6 million years ago.

This lake was never covered by ice and thus has perpetuated a steady accumulation of sediment since the meteorite event.

The scientists will collect deep cores of this sediment (cylindrical columns of dense muck) that recorded details of the past Arctic climate.

In 2003, the researchers sank 16.7 m of sediments, going back to 300,000 years, and achieved the oldest continuous terrestrial record of the Arctic climate.

The goal of this expedition is to go through to the bedrock of the lake in order to get cores back to the meteorite impact.

Getting to the lake is quite an adventure as there are no roads in to the lake and the closest locality is situated at 250 km (155 miles).

In January of 2008, the team is planned to camp at the lake and will stay for 4 months.

"There may be 50 to 60 mile an hour winds, frigid temperatures and only caribou and wolves for neighbors," says Brigham-Grette.

The sediment is analyzed for pollen grains (this way, the species that had produced it), algae and bacteria, which are linked to specific temperatures, climate and habitat/ecosystem.

The cores will also be studied for changes in geochemistry, the magnetic orientation of the minerals and other parameters that recorded events of the Arctic's climate since 3.6 million years.

The data got from this lake can be compared with those achieved from core analysis of sediments from the north Atlantic and Pacific oceans, as well as tropical oceans, giving this way to the analysis of the past climate a global scale.

"Examining climate change is like reconstructing a puzzle-a 500 piece puzzle, and we have maybe 80 to 90 pieces," says Brigham-Grette.

"This work will fill in a lot of gaps in reconstructing why the Arctic is the way it is today and what it may be like in the future."