As long as humans do not mess it up, the Earth's climate is set at fair for the next 15,000 years. That is according to information extracted from the oldest ice core ever drilled.
That already shows that the amount of CO2 in the air during stage 11 was similar to our own pre-industrial level3. As Earth's orbit was much the same then, this suggests that stage 11 was very like our present balmy interglacial, and that without the effects of global warming we would probably have to wait some 16,000 years for another ice age. "It's a wonderful window into the future as well as the past," says Raynaud.
While some scientists are interpreting these new results to mean that a new ice age is still a long way off one ice-core scientist from the University of Colorado sounds less certain about our ability to predict the next ice age.
Recovery of a new ice core in Antarctica that extends back 740,000 years -- nearly twice as long as any other ice core record -- is extremely important and will help scientists better understand the Earth's climate and issues related to global warming, according to a University of Colorado at Boulder professor.
The new ice core, announced June 9 by the European Project for Ice Coring in Antarctica, or EPICA, reaches far enough back in time to give scientists "a first shot at looking at climate and greenhouse gases during interglacial periods when humans had nothing to do with climate change," said geological sciences Professor James White.
"This has the potential to separate the human-caused impacts from the natural and place it in a much clearer context," he said.
A commentary on the new ice core written by White will appear in the June 11 edition of the journal Science. One of the world's leading ice-core scientists, White has conducted dozens of studies of ice cores from both Antarctica and Greenland. He is director of the CU-Boulder Environmental Studies program and a fellow of the CU-Boulder Institute of Arctic and Alpine Research.
Concern about the effects of human-caused greenhouse gas releases into the atmosphere has led many scientists to conclude that humans are changing the atmosphere. Drilling deep into polar regions and extracting ice cores can tell scientists about the Earth's climate during the distant past, before technology and farming became a factor in releasing such gases.
Ice cores can tell scientists about concentrations of greenhouse gases such as carbon dioxide and methane, dust levels in the atmosphere, volcanic eruptions and estimates of temperatures and precipitation.
"We're living in an unusual time," White said. "In the past 430,000 years, the percentage of time that the climate was as warm as it is today is quite small, about 5 percent to 10 percent, and before that time, it appears to never have been that warm.
"Humans have been active in messing with the carbon cycle for a long period of time," he said. "Here we are warming the planet, while at the same time, climatologists will tell us that we are perhaps long overdue for a glacial period."
The average number of years spent in a warm period between ice ages -- like our current climate -- has been about 6,000 years, White said. But the current interglacial period has lasted for 12,000 years. Only one other interglacial period has exceeded that length of time -- it lasted for about 28,000 years -- and it happened about 450,000 years ago.
The EPICA core will provide the first complete record of that period and will allow scientists to study it in more detail than ever before, White said.
"Ice cores are the ultimate preservation tool for information about past environments," White said. "Whatever happens on the Earth that changes the atmosphere -- the big events -- is recorded in the ice and it stays there."
Another exciting aspect of the EPICA ice core is that at 740,000 years, scientists have not yet reached the bottom of the ice sheet, he said. "The possibility of a million-year ice core is out there and a million years ago is a really significant period in the Earth's climate history."
Prior to a million years ago, there was no large-scale glacial/interglacial pattern and the Earth had a more steady climate controlled by the sun, he said. Something happened at around that time to cause the Earth to have larger variations in its climate.
"One of our biggest scientific questions is: Is glaciation overdue?" White said. "For our future it is very important that we understand how these huge glaciers start."
The fact that we are overdue, by historical standards, for another ice age may be due to human intervention. See my previous post Farming And Forest Destruction Prevented Ice Age 5000 Years Ago.
The more we understand the climate the better we are going to be able to predict both naturally-caused and human-caused future changes in the climate. At the same time, our ability to intervene in the climate to engineer different outcomes will increase. Along with our increasing understanding and ability to intervene will come increased demands for climate engineering to either reverse the effects of other human interventions or to prevent natural trends from playing out.
If the theory that human farming practices have already prevented an ice age then this will have a profound effect upon the debate about human influences on climate. A radical program to neutralize human influences on the climate would literally bring on an ice age. Only a small minority of environmental radicals are going to support an effort to produce that outcome.
|Share |||Randall Parker, 2004 June 09 03:06 PM Climate Trends|