[Marxism] New confirmation of global warming

Louis Proyect lnp3 at panix.com
Fri Nov 25 07:42:05 MST 2005

Core Evidence That Humans Affect Climate Change
Ice drilled in Antarctica offers the fullest record of glacial cycles and 
greenhouse gas levels.
By Usha Lee McFarling
Times Staff Writer

November 25, 2005

An ice core about two miles long — the oldest frozen sample ever drilled 
from the underbelly of Antarctica — shows that at no time in the last 
650,000 years have levels of the greenhouse gases carbon dioxide and 
methane been as high as they are today.

The research, published in today's issue of the journal Science, describes 
the content of the greenhouse gases within the core and shows that carbon 
dioxide levels today are 27% higher than they have been in the last 650,000 
years and levels of methane, an even more powerful greenhouse gas, are 130% 
higher, said Thomas Stocker, a climate researcher at the University of Bern 
and senior member of the European team that wrote two papers based on the core.

The work provides more evidence that human activity since the Industrial 
Revolution has significantly altered the planet's climate system, 
scientists said. "This is saying, 'Yeah, we had it right.' We can pound on 
the table harder and say, 'This is real,' " said Richard Alley, a Penn 
State University geophysicist and expert on ice cores who was not involved 
with the analysis.

Previous records, from an ice core drilled at the Russian Antarctic station 
Vostok, extended back 440,000 years. Extracting and analyzing that core was 
a major achievement, but the core stopped short of a time period scientists 
are anxious to study because it was like today's.

Climate scientists called the analysis of the older records spectacular 
because they were so clear and said they would become "canonical" additions 
to the climate record. "It's really important," Ed Brook, an ice core 
expert at Oregon State University said of the new research. "Those 200,000 
years were a lot harder to get than the previous 400,000 — and those were 
hard enough."

Ice cores are plugs drilled from glaciers and ice sheets. They are composed 
of tens of thousands of layers of fallen snow and air bubbles compressed 
over time. Ice cores are among the most powerful tools available to climate 
scientists. The chemistry of the ice reveals temperatures from the distant 
past, while bubbles within the ice are minuscule time capsules that capture 
air and greenhouse gases as they existed hundreds of thousands of years ago.

The ice core was drilled by the European Project for Ice Coring in 
Antarctica from a high plateau in East Antarctica called Dome C that rises 
about two miles above sea level. It is one of the driest, coldest parts of 
the continent, where summer temperatures can fall to 50 degrees below zero. 
Temperature records from the core were published in 2004, and scientists 
have been waiting for an analysis of the core's gases.

The last time carbon dioxide levels were as high or higher than today was 
probably tens of millions of years ago, Alley said. Over millions of years, 
carbon dioxide levels shift because of slow geological processes, such as 
weathering of rocks, swallowing of crust into subduction zones and the 
release of gases from volcanoes. But these processes are much slower and 
more gradual than the current rapid increase of carbon dioxide into the 
atmosphere from the burning of fossil fuels, Alley said.

Scientists are enthusiastic about the ice core because it includes about 
eight full glacial cycles. The Vostok sample had four. Glacial cycles occur 
roughly every 100,000 years and include long periods of cold, when ice ages 
occur, and brief, warm interglacial periods, such as the current one. The 
cycles are controlled by shakes, wobbles and tilts in the Earth's orbit 
around the sun that determine the amount of sunlight falling on and warming 
the planet.

The Vostok core showed that warm interglacial periods lasted about 10,000 
years. Because the current temperate interglacial period has lasted about 
12,000 years, many scientists had speculated that the planet was overdue 
for an ice age.

But the new core shows that the interglacial period of 440,000 years ago, 
when the Earth's position relative to the sun was similar to what it is 
today, lasted nearly 30,000 years and was not ended by natural decreases in 
carbon dioxide, Stocker said. The work suggests that the next ice age is 
about 15,000 years away.

"Anyone counting on an ice age to head off global warming, or hoping to 
justify human greenhouse-gas emissions as a useful attempt to head off the 
next ice age, will find no comfort in the ice-core record," Alley said.

The latest findings also run counter to a theory presented two years ago by 
William Ruddiman, a professor emeritus of environmental sciences at the 
University of Virginia, that humans who lived five thousand or more years 
ago are responsible for delaying the next ice age because their activities 
— forest clearing and rice growing — started to raise greenhouse gas levels 
when they should have been naturally declining.

"This claim can no longer be upheld," said Stocker, because the ice core 
shows greenhouse gases do not naturally decline after 10,000 years in the 
longer interglacial periods like today's.

Scientists are eager to look further back into earth's climatic past. About 
a million years ago, the earth shifted from ice age cycles that were 40,000 
years long into cycles that were 100,000 years long. This shift from a "40K 
world to a 100K world" is a major mystery, said Oregon State's Brook, and 
will require a core that reaches deeper into the ice and much further back 
in time.

Brook is co-chairman of a joint European and American group that hopes to 
start drilling in coming years a core that could produce ice and bubbles 
that are 1.2 million to 1.5 million years old.

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