KNAU and Arizona News
Fri September 18, 2009
Major study shows Arctic temperature rise
By Laurel Morales
Flagstaff, AZ – Northern Arizona University geologist Darrell Kaufman recently published a major study showing Arctic temperatures have hit their highest levels in two-thousand years. The study published in the journal "Science" has received worldwide attention. And it's become part of the discussion leading up to the United Nations climate change conference in Copenhagen. It has also been the target of climate change critics. As part of the study Kaufman gathered data from remote lakes in Alaska. Arizona Public Radio's Laurel Morales has this story.
Kaufman and several graduate students recently took a float plane to Alaska's Allison Lake to study its mud. Kaufman shot video of the group floating out to the middle of the turquoise blue water on an inflatable platform. The students pulled sediment core samples from the bottom using a system of cables and pulleys.
KAUFMAN: We have now tapped the core tube in, filled it with mud and we have installed our chain hoist here. Caleb is cranking up for us. (fade down)
Kaufman and his students studied these long tubes of mud. Each layer represents a period of climactic history. They looked for conditions like how much algae grew in an ice-free period. He and several other scientists took the sediment samples and compared them to glacier ice and tree rings. They were then able to reconstruct a 2-thousand-year timeline of arctic temperatures to compare with computer climactic models. The analysis may be the most extensive to date.
In his office on NAU's campus he explains the study's major findings.
KAUFMAN: One was the overall cooling trend that took place during the first 1900 years that amounted to about a half degree Celsius. The second major feature was the remarkable warming that took place beginning around 1900 and extending into the late 20th century.
If you were to put the temperatures on a graph it would look like a hockey stick. Kaufman says the cooling trend should have continued through the 21st century. Instead, summer temperatures in the Arctic are now 2 and a half degrees warmer than what would be expected.
KAUFMAN: So not only is the warming unusual it's a reversal of the natural trend.
The analysis is among several recent studies that demonstrate industry greenhouse gas emissions have changed the Arctic's long climate trend.
Some climate change critics argue there was a warming trend at the end of the last ice age that Kaufman's study ignored.
KAUFMAN: We're not denying that climate changes. We're not denying that the arctic experiences relatively warm conditions. What we are saying is we know why we have those warm conditions factors like volcanic activity, like solar variability, like orbital changes, like carbon dioxide in the atmosphere cause climate to change. We understand that and that can help us to predict the future.
He says it's important to look at all the available records of climate change, which is what he and his co-authors did in this study. Kaufman was surprised by the vocal negative reaction to his research.
KAUFMAN: Either the people who are active on the blogs represent a very small subsection of the population or there is some serious misunderstandings about the nature of climate change and the evidence for it. Or the blogs are being led by people who have very strong ideological motives.
SFX: Class discussion
This reaction has been the impetus for Kaufman to dedicate more of his time to teaching about climate change.
KAUFMAN: Most people have made up their minds about climate change based on ideological lines. I think students young people have open minds and are hungry for information they can use to make decisions in the future.
Kaufman will teach an undergraduate Climate Change course in the spring. NAU has created a new school Earth Sciences and Environmental Sustainability in part to study phenomena like climate change.
In the meantime he and the other scientists involved in this study have received funding from the National Science Foundation to continue their research on Arctic climate change. Kaufman says he'd like to extend their records back even farther. They detected clues in the current research that showed arctic summers 8-thousand years ago are even warmer than they are now.
For Arizona Public Radio I'm Laurel Morales in Flagstaff.