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Catholic Online interviews William Chapman of Cryosphere Today on global warming

By Marshall Connolly, Catholic Online (NEWS CONSORTIUM)
April 8th, 2013
Catholic Online (www.catholic.org)

This week, Catholic Online had the opportunity to interview William Chapman, senior research programmer for the Department of Atmospheric Sciences at the University of Illinois, Urbana-Champaign. Chapman maintains the Cryosphere Today webpages which are updated daily with data on the state of the polar ice caps and climate.

Chapman is a climate researcher, meaning he is a qualified expert in the field and has been aggregating data daily since the late 1970s.

COL: William, can you please tell us about yourself and what you do?

Chapman: I am part of a small research group at the University of Illinois that has been doing Arctic climate research for the past 30 years.  As part of this research, I started posting current ice and snow conditions in the Arctic and Antarctic on the Cryosphere Today website about 11 years ago.

COL: Can you share with us a little background on the Cryosphere webpages? What can we expect to find there?

CHAPMAN: The popularity of the Cryosphere Today has surprised us.  We get a lot of feedback from folks who appreciate being able to watch the day-to-day fluctuations of the ice and snow in the Arctic.  A few users have written us to tell us it is the first site they check with their morning cup of coffee.

The most popular products we provide are the images and animations of sea ice obtained from polar orbiting satellites.  We also include graphs of historic sea ice area and the departures from the daily averages.  We are presently adding several recently discovered sources of historic sea ice observations to our archive in order to put the recent decreases of Arctic sea ice into a broader historic context. 

COL: Those pages are rich with data. How much data have you accumulated?

CHAPMAN: We have daily data from satellites back to the late 1970s and at least some monthly observations back to the 1870s.  The monthly historic record is very reliable back to the 1950s but becomes more sparse in the early part of the 1900s.

COL: As an expert in your field, what conclusions are you comfortable with drawing from the data?

CHAPMAN: While Arctic sea ice in the winter months has decreased 5-10%, the summer sea ice is about 40% less than it was just a few decades ago.  The changes in summer are striking (see attached image).  This past summer, the sea ice area was the lowest it has been in recorded history, by far. 

Summer decreases in snow and ice are especially disconcerting because important climate feedbacks are in play during the summer months.  For example, as the temperature warms in the Arctic, the ice and snow melt.  Sea ice and snow are very reflective to sunlight.  The white color reflects much of the sunlight arriving in the Arctic surface back to space, keeping the Arctic cool.  As more sea ice is lost, it is effectively replaced by a very dark, very absorbing ocean.  Much more sunlight is absorbed by the dark ocean than the reflective sea ice.  This warms the surface even more and the feedback cycle continues.

COL: What's causing this? Is this natural or anthropogenic in origin, or is the verdict still out in your opinion?

CHAPMAN: While assigning attribution to these changes is a challenging problem, much of the research of the past decade points to a large anthropogenic contribution to the recent rapid changes in the Arctic.  Among the most convincing evidence are global climate modeling experiments that are performed with increased greenhouse gases and with stable greenhouse gases.  The experiments with steady greenhouse gases show level temperature and sea ice amounts in simulations of the past 50 years.  Experiments that increase the greenhouse gases to match the observed greenhouse gas increases show temperature increases and sea ice losses very consistent to what has been observed.  In my opinion, these experiments provide strong support to the idea that human influences, in particular the burning of fossil fuels and resulting increases in greenhouse gases, are responsible for the observed recent warming.

I realize there are those who are skeptical of any results from global climate models, but our group has done extensive evaluations of climate models and their performance simulating the recent Arctic climate.  While there is certainly room for improvement, in my opinion, they are sufficiently skilled to be trusted in basic experiments such as that described above.

COL: Why should we, as Americans living in the United States, thousands of miles away from the arctic, care about what happens up there?

CHAPMAN: There is a growing body of research showing that changes in the Arctic can have dramatic impacts in mid-latitudes.  In our own research, we observe that extensive sea ice loss during the summer can warm surface temperatures in the southwest United States and cool surface temperatures in the Northeast during the subsequent fall and winter seasons.  Weather patterns in the United States and Europe during this period are also altered.  The jet stream winds responsible for steering our weather systems from west to east are a result of the difference in heating from the equator to the North Pole.  As the pole warms, this equator-pole temperature difference gets smaller and, as a result, weather patterns adopt a more amplified, wavy pattern.  It was this type of extreme wavy pattern in the jet stream that aided in intensifying superstorm Sandy and moved it northwestward into the United States this fall, following the record low summer sea ice area.

COL:  Global warming seems to have some advantages, such as opening up the fabled northwest passage for sea-traffic. It's also greening the north with new trees and plant growth. It seems reasonable that residents of such frigid areas would have little problem  if their weather was a few degrees (F) warmer. Really, what's the problem when we look at it from that perspective?

CHAPMAN: Indeed, there are benefits to a warmer Arctic such as increased navigation opportunities   and growing season lengths.  The increased temperature and loss of sea ice brings its share of headaches to Arctic residents too.  In coastal communities in Alaska, increases in storm frequency, decreases in the buffering sea ice cover, and melting permafrost leave the coastlines vulnerable to erosion.  In fact, several entire coastal communities in Alaska are in the process of being moved inland because their towns are being swallowed by the encroaching Pacific Ocean and aided by a warmer climate. 

Inland communities do not escape the impacts of a warmer climate either.  Much of the buildings and infrastructure are built on permanently frozen soil in the Arctic.  As the temperatures warm above the threshold needed to sustain this permafrost, the underlying ground buckles, causing the buildings to crack and become unstable and uninhabitable.  To citizens of these communities, a longer growing season is the farthest from their minds.

COL: Isn't it true that the planet has been much warmer before? Certainly life didn't become extinct as a result of all that warming and the ice caps came back.

CHAPMAN:
Paleoclimate records suggest periods when the Arctic was a little warmer than the present-day climate.  These warm periods correspond to earth-sun orbital variations that strongly favor a warmer northern hemisphere.  The difference between those warm episodes and the present-day warming trends are that we are presently experiencing a rapid warming in the Arctic during a period where the earth-sun orbital variations are inconsistent with such a trend. 

With regard to extinctions and adaptation to recent and projected changes, paleoclimate records indicate the rate of warming the Arctic is experiencing, and is projected to experience in the coming century, is much more rapid than warming episodes in the past.  The ability of species to adapt to such a rapid change is not known.

William, thank you for your time. We wish you the best as you continue your important work into climate research.

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