Understanding the complexity of climate science is best left for the experts, and most certainly not for the poll-driven politician. New research is carefully monitored by peers within the scientific community, and by the time the general public hear about it, there is a fairly good chance it has been so critiqued and commented-upon that it is relatively reliable. So when Eric Steig of the University of Washington recently published new ice-core research, one can imagine he did so with some trepidation. The research, published online April 14 in the journal Nature Geoscience, makes a bold claim in a day and age where any climate change-denier will grasp hold of even the most insignificant and scientifically-dubious claim.
Steig’s research suggests that the thinning of Antarctic glaciers on the West Antarctic Ice Sheet cannot necessarily be placed at the feet of human-caused global warming, despite the recent acceleration and contribution to sea level rise.
“If we could look back at this region of Antarctica in the 1940s and 1830s, we would find that the regional climate would look a lot like it does today, and I think we also would find the glaciers retreating much as they are today,” said Steig.
This photo from December 2010 shows a one-meter long section of the West Antarctic Ice Sheet Divide core, with a dark layer of volcanic ash visible.
Source: Heidi Roop, via the University of Washington
Previous research done by Steig with UW colleague Qinghua Ding has shown that rapid thinning of Antarctic glaciers was accompanied by rapid warming and changes in atmospheric circulation near the Antarctic coast, and mostly cam during the 1990s in response to El Niño conditions in the tropical Pacific Ocean.
Steig and Ding’s new research shows that the 90s were not necessarily all that different from other decades – such as the 1830s or 1940s – that also shared similar temperature spikes and could also be traced back to unusual El Niño activity.
Their research is based upon a new ice-core derived from the West Antarctic Ice Sheet Divide that provides data going back 2,000 years, and was combined with other ice-core records that data back approximately 200 years.
Importantly, however, is the fact that this new research does not diminish the effect human-caused global warming is having on the Antarctic Peninsula (link to other Antarctica article I submitted). Steig clearly states that the rapid ice loss on the Antarctic Peninsula is almost certainly a result of human-caused global warming.
The reality is, the effects of climate change are not the same everywhere; even from one part of a continent to another. Steig’s research focused on the West Antarctic Ice Sheet, where the evidence does not suggest human-caused global warming has been involved. While changes in recent decades have been unusual and at the “upper bound of normal,” Steig said, they cannot be considered exceptional. “The magnitude of unforced natural variability is very big in this area,” Steig said, “and that actually prevents us from answering the questions, ‘Is what we have been observing exceptional? Is this going to continue?’” Steig believes that the next few decades for the West Antarctic Ice Sheet will be greatly influenced by whatever happens in the tropics.