Ice cores show warming 'natural'
Brendan O'Keefe
January 07, 2006
HUNDREDS of thousands of years worth of climate records in ice cores show there is nothing unusual in a global warming trend over the past 25 years.
Marine geophysicist Bob Carter, a professor at Queensland's James Cook University and leading climate change sceptic, said the effects of human activity would barely register in the long-term history of climate change.
He told The Weekend Australian that ice cores from Antarctica "tell us clearly that in the context of the meteorological records of 100 years, it is not unusual to have a period of warming like the one we are in at the moment".
Dr Carter disputed the theory that human activity was making a current - natural - warm period hotter: "Atmospheric CO2 is not a primary forcing agent for temperature change." He argues that "any cumulative human signal is so far undetectable at a global level and, if present, is buried deeply in the noise of natural variation".
Fellow sceptic William Kininmonth, a former director of the Bureau of Meteorology's National Climate Centre, agreed. He wrote in a 2004 book, Climate Change: A Natural Hazard that there was "every reason to believe that the variabilities in global temperature and other climate characteristics experienced over the past century are part of the natural variability of the climate system and are not a consequence of recent anthropogenic activities".
But other leading scientists, who blame human activity for climate change, say the "denialists" are a one-to-99 minority.
Will Steffen, director of the Centre for Resource and Environmental Studies at the Australian National University, said: "There is no debate. The debate is over." The evidence that human activity had increased emissions of carbon dioxide into the atmosphere, adding to natural warming, was "overwhelming", he said.
For scientist and University of Adelaide academic Tim Flannery there was also no argument: humans had turned up the heating and only humans could keep a lid on it. The argument that human activity did not contribute to global warming was "not a credible hypothesis to build policy on", he said.
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