TESTIMONY OF DR. SYUN-ICHI AKASOFU BEFORE THE UNITED STATES SENATE COMMITTEE ON APPROPRIATIONS HEARING ON ALASKA NATIVE VILLAGES AFFECTED BY FLOODING AND EROSION JUNE 29, 2004
Presented by S.-I. Akasofu Director, International Arctic Research Center University of Alaska Fairbanks 930 Koyukuk Drive Fairbanks, Alaska 99775-7340
Thank you for the opportunity to testify at this important hearing today.
Today, I would like to address the cause and effect of climate change on the coasts and coastal communities of Alaska.
First of all, it is important to recognize that prominent climate change has been in progress in the Arctic during the last several decades. During the past few decades, the area of the Arctic Ocean sea ice has shrunk approximately 5-10%, but at an accelerating rate, and its thickness is decreasing (from about 4m to 3m). Many Alaskan glaciers are receding; the Columbia Glacier is receding at a speed of more than 10m per year. Permafrost temperature in Alaska is changing. Air temperature records show an increase of 1°C (~2°F) per decade in Siberia, Alaska, and Canada; the global average increase is about 0.6°C (~1.2°F) per century.
The Arctic is quite unique in that climate change is prominent in comparison to the rest of the earth. It is generally believed that various ice forms in the Arctic cause positive feed-back in enhancing climate change.
Many of these climate change phenomena in the Arctic could be interpreted as results of ‘warming.’ Scientists have been seriously debating whether or not the cause of the ‘warming’ is natural or man-made? Here, ‘man-made’ means the greenhouse effect. It is fair to say, both. Then, the question is how much each is contributing? I do not think that any decent scientist can claim explicitly how much the greenhouse effect is contributing to the present arctic ‘warming’ trend.
I would like to summarize several important findings of the arctic research community.
The shrinking sea ice in the Arctic Ocean appears to be related to inflow of warm North Atlantic waters into the Arctic Ocean. The strength of the inflow varies as a part of the North Atlantic Oscillation (NAO), which is a natural phenomenon; it has multi-decadal periods and has been intense during the last several decades, so that it is not accurate to claim that the present shrinking of sea ice is all man-made. It is not certain if NAO is enhanced by the greenhouse effect.
Some of the past records on glaciers indicate that glaciers in Alaska and Greenland began receding as early as 1900 or earlier (e.g. the Portage Glacier), well before the CO2 increase became serious. Furthermore, the collapse of the Columbia Glacier is partly due to mechanical causes. In Norway, glaciers are advancing.
Permafrost temperatures decreased until about 1970 and then began to increase. The increase appears to have slowed down recently. Meanwhile, the amount of CO2 has been increasing monotonically since 1900.
These are a few examples to show that it is not appropriate to claim all ‘warming’ trends are caused by the greenhouse effect. The collapse of houses built on permafrost is certainly man-made (heating), not a direct consequence of the greenhouse effect. There is too much confusion on such issues.
Computer modeling has been improved greatly during the last decade or so. However, the computer is a very imperfect “earth” when we conduct CO2 experiments with it. For example, clouds cause warming by trapping infrared radiation, but cause cooling by reflecting solar energy back to space. Scientists are still debating which is more important. A computer behaves exactly as we instruct. Until we understand quantitatively all major processes related to climate change, a computer cannot provide reasonably accurate prediction on future climate. Computer modeling is now predicting the shrinking of sea ice in the Arctic Ocean in 2050 or 2100. However, the models cannot reproduce the seasonal changes; observations show the maximum shrinking in summer, while computer simulations indicate it to be in the winter. There are still many contradictions of this kind. We have too many unknown factors in instructing the computer. There is still too much unknown to rely completely on the computer to predict the temperature in 2100.
Many scientists find ‘warming’ trends, but can’t refer to their causes explicitly, and the press takes excerpts from these to claim that all warming is man-made. The scientific consensus is that large natural variations are superimposed on any trend caused by greenhouse effects. I would like to repeat that any decent scientist cannot claim explicitly how much the greenhouse effect is contributing to the present arctic ‘warming’ trend.
What is important here, aside from the debate on the cause of the ‘warming’, is that climate change is in progress and Alaskans have to face the trend seriously. Since the subject of coastal erosion is not my specialty, I consulted with several of my colleagues including Dr. Orson Smith, School of Engineering, UAA, Dr. John Walsh, International Arctic Research Center, and Dr. Glenn Juday, UAF.
Coastal Erosion
Sea level rise caused by global warming is expected to be about 40cm (~16 inches) in 2100. With the present rate, it is not the most serious threat in the near future.
The most important threat comes from the expected retreat of sea ice, exposing coastlines to wave/surge effects.
According to the National Weather Service, there were 7 damaging coastal flood events during the last six years. Among them, five were caused by cyclones that were born in the open region of the Arctic Ocean and moved in the SW direction. Both Kivalina and Shishmaref are affected by this effect. This is a new trend. Furthermore, according to National Weather Service research, a number of intense cyclones over the entire Arctic have been increasing in recent years. However, it is hard to prove that such a trend is caused by global warming.
In this report I would like to mention that Mr. Kenneth Toovak, Sr., Barrow, is of the opinion that the present bank-building in Barrow is not working. I would also like to add also that Dr. Orson Smith has made various presentations on the subject of design criteria in preventing coastal erosion.
Permafrost Melting and Others
The temperature of permafrost is near the melting point (0°C/32°F) in the interior of Alaska, so that permafrost in the Interior is quite sensitive to climate change, in particular to the present warming trend. As you are well aware, thawing of permafrost causes considerable damage to house structures, roads, forests, and other structures.
In addition to the warming trend, the precipitation has decreased considerably in the Interior during recent years, causing a variety of effects on vegetation. Trees are suffering directly from this effect and also indirectly from insects.
Mission of the International Arctic Research Center
An important responsibility of scientists at IARC and the arctic research community is to reduce uncertainty of the present prediction of:
the southern edge of sea ice of the Arctic Ocean
the occurrence of extreme events
permafrost temperature
temperature and precipitation
shift of the tree line
The first two studies will be able to bring fruitful collaboration as we combine efforts of scientists and engineers at both UAF and UAA.
Thank you again for the opportunity to present this testimony today, and thank you for your interest in this important issue. Please feel free to contact me if you have any additional questions.
