[Mb-civic] CBC News - GREENHOUSE GAS LEVELS HIGHEST IN THOUSANDS OF YEARS: STUDY

[CBC News Online]

This email has been sent to you by harry.sifton at sympatico.ca
The following is a news item posted on CBC NEWS ONLINE
at http://www.cbc.ca/news
____________________________________________________
GREENHOUSE GAS LEVELS HIGHEST IN THOUSANDS OF YEARS: STUDY
WebPosted Thu Nov 24 18:56:51 2005

---Levels of carbon dioxide in the atmosphere are higher now than at any
time in the last 650,000 years, research on Antarctic ice cores suggests.

European scientists drilled ice cores from east Antarctica. They looked
for air bubbles, fossils and sediments to study carbon dioxide levels
dating back 100 million years.

"We have added another piece of information showing that the timescales
on which humans have changed the composition of the atmosphere are
extremely short compared to the natural time cycles of the climate
system," said lead researcher Thomas Stocker, a professor of climate and
environmental physics of the University of Bern in Switzerland.

The measurements suggest carbon dioxide levels jumped from 280 parts per
million two centuries ago to 380 parts per million today, they report in
Friday's issue of the journal Science.

Levels of other greenhouse gases such as methane and nitrous oxide also
rose dramatically since the Industrial Revolution, said study co-author
Ed Brook, a professor of geosciences at Oregon State University.

The record spans two full glacial cycles, showing a pattern of gas levels
lowering during cold periods and rising during warm periods.

Researchers are looking for longer climate records like the ice cores to
investigate global climate change.

A second study in the same issue suggests sea levels rose twice as fast
in the last 150 years compared to previous centuries.

Kenneth Miller, a professor of geological sciences at Rutgers University
in New Jersey, used shoreline data, tidal gauges and satellite data for
the study.

The study concludes sea levels are rising almost two millimetres per
year today compared to one millimetre annually for the past several
thousand years.

Copyright (C) 2005 CBC. All rights reserved.