Sectors

Regions:
Alaska
Appalacians
California
Eastern Midwest
Great Plains-Central
Great Plains-Northern
Great Plains-Sourthern /Rio Grande
Gulf Coast
Metropolitan East Coast
Middle Atlantic
Native Peoples/Native Homelands
New England
Pacific Islands
Pacific Northwest
Rocky Mountain/Great Basin
South Atlantic Coast & Caribbean
Southeast
Southwest

We are extremely grateful for the insights and suggestions made by the reviewers who took the time and opportunity to look over the regional summary when it was a work in progress. Below is a summary of the comments taken from these reviews. In many instances, several reviewers made different versions of the same comment s. These comments and the responses to them are listed under general comments. The names of the most of the reviewers are listed after the questions.


General Comments

Other studies have examined the potential impacts of climate change on the Great Lakes region. What makes this report so different?

The climate scenarios that were used in this study came from GCMs that included the effects of aerosols and which accounted for more realistic increases in CO2. Previous studies used older GCMs that did not account for aerosols and assumed an instantaneous doubling of CO2 levels

 

I have seen from other sources and references that the GCMs used in this report do not simulate very well some of the temperature and precipitation aspects for the current climate — particularly across Canada (just north of the Great Lakes region). How then can the results be credible for a time period 100 years into the future?

Almost all GCMs exhibit biases. A bias is an error (e.g., in temperature or precipitation) that appears over a given region — independent of how external forcing mechanisms are changing (e.g., increases in CO2). Many of the results in this report are obtained with respect to these biases. That is the bias is somehow considered. For example, to compute changes in lake levels by the year 2100, the change in model precipitation and temperature between the present and future time periods are added to the actual observed climate for the present. This future climate scenario is the one that is used to evaluate impacts on lake levels — thus accounting for model bias.

 

Why does this report focus on coping mechanisms rather than mitigation strategies?

This report and the study from which it was derived were spawned by a genuine scientific interest in understanding the impacts of climate change. We felt as a team that including a discussion of coping mechanisms was a responsible addition to the report, because these mechanisms suggest possible and appropriate actions regardless of whether climate is changing in the long term from increasing greenhouse gases or in the short term from natural interannual or interdecadal variations. We chose not to focus on mitigation strategies because including such strategies may suggest to some that we have some sort of political agenda in reducing CO2 emissions. As representatives of the scientific community, we felt that it would be outside our scope of scientific responsibility to recommend any political actions.

 

There is not a lot of information on stresses in each of the chapters.

The real focus of the report is on describing the potential impacts of climate change on the different sectors as were determined by our regional stakeholders. More information regarding the stresses on the sectors is provided in our Workshop Report.

 

There is not a lot of information on previous assessments in each of the chapters.

This assessment addressed stakeholder concerns more so than aspects that have been examined in previous efforts. Some of these concerns have never been addressed before — like the impact of climate change on respiratory illness in the Great Lakes region. Thus, there were not too many previous studies that were very relevant from a reference standpoint. Basic information regarding the methodology is for the most part referenced. For example, information about the agricultural models used (e.g., DAFOSIM) is available in the referenced literature.

 

There is not a lot of information on coping mechanisms in each of the chapters.

The real focus of the report is on describing the potential impacts of climate change on the different sectors as were determined by our regional stakeholders. More information regarding the coping mechanisms for the different sectors is provided in our Workshop Report.

 

The assessments do not have very detailed information.

We wanted to keep the report at a technical level where most of our stakeholders, including high school students interested in climate change, could understand most if not all sections of the report. In effect, we tried to write the report at the same technical level that one would find in a NOVA or National Geographic Presentation. A series of articles will be published in a special issue of Journal of Great Lakes Research in Spring 2001 that will contain much more technical information.

 

There is not much information on the assessment models used.

The emphasis on this report is on the results obtained from the various assessment models and techniques — primarily to keep the overall length of the report short. In all instances, the models and techniques are referenced so the interested reader can obtain more detailed information if so desired.

 

Why are all the results in English units?

Even though much of the world has already converted to SI units, many Americans still feel very uncomfortable and have trouble converting SI units to English units. Additionally, because all of the other regional assessment reports also were and are being written in English units, the results in our report are much easier to compare.

 

I read the Upper Great Lakes Regional Workshop Report. How come the sectors chosen for assessment don´t match the ones that stakeholders identified at your workshop?

The choices for the sectors that were studied in our assessment were based on a variety of factors including suggestions made by stakeholders who attended our workshop, availability of interested and trained researchers, availability of funds, and the existence of appropriate models or techniques to conduct the assessment. Thus, not all suggestions made by stakeholders could be addressed in this effort.

 

Why aren´t the economic impacts described throughout the report more quantitative?

A quantitative evaluation of the economic impacts given the short time, existing resources, and latest socio-economic projections was really beyond the scope of our effort. Thus, qualitative information was provided instead. Even a qualitative approach was beyond our scope in certain instances because of insufficient resources and knowledge.

 

Can I use text and graphics from this report for educational purposes?

Yes. We encourage all people interested in our report and especially teachers and others involved in education to use any text or graphics for educational purposes. The information may not be used in any way for profit without first obtaining written consent from the University of Michigan.

Chapter 1

What exactly is the overlay approach and why did many investigators use it for their analyses?

The overlay approach means that existing techniques and/or models, which have been used for previous assessments with different model output from older general circulation models (GCMs), were used with the latest model output from the most recent GCMs. This overlay of existing methodology onto new climate information implies that the new assessment information can be either interpolated or extrapolated from existing information.

Chapter 2

This chapter does not describe in sufficient detail the long term historical changes in climate for the region.

The purpose of our report was not to place the concept of global warming within the context historical changes or natural variations of climate in the Great Lakes region. Rather, our mission was to report how changes in temperature and precipitation patterns related to global warming would affect water levels, agriculture, etc . in the region. Thus, historical climate changes in the region were not explained in great detail.

Chapter 3

Why are the GCMs that were used not US models?

Because of the time-critical nature of this effort, both regionally and nationally, output from tested GCMs that was already available was used rather than waiting even several more months for output from a US model to become available. Output from the NCAR Community Climate Model (CCM3) has since become available and from a temperature and precipitation standpoint is consistent with output from the models we did use.
Why does the output for the two different GCMs that were used differ so much?
Because of the time-critical nature of this effort, both regionally and nationally, output from tested GCMs that was already available was used rather than waiting even several more months for output from a US model to become available. Output from the NCAR Community Climate Model (CCM3) has since become available and from a temperature and precipitation standpoint is consistent with output from the models that we did use.
How were the economic scenarios really used in your assessment?
The qualitative evaluation of some of the economic effects of climate change is based on the business as usual socio-economic scenarios. Not included in the report are qualitative economic evaluations based on good or bad economic scenarios. However, while readers may assume that economic impacts for these other two scenarios could be different — it is difficult to say whether the effects will be less or more severe for a given sector when considering a particular socio-economic scenario.
Most GCMs do not include the Great Lakes and the water surface temperatures projected by GCMs that do have the Great Lakes could be questioned unless a lake model is attached that represents the mixing and overturning of the lake water.
Lake temperatures were obtained using an independent (off-line) lake model that was forced by GCM output. It is true that a crucial parameter of lake-effect snowstorms is the lake-air temperature difference. However, because this study focused on intense storms, where lake-air temperature differences are presumably large, a small error introduced by incorrectly modeled lake surface temperatures should not greatly affect results. Additionally, the lake temperatures are not likely to be known more accurately than the air temperatures.
Do “lake-effect rain events” actually occur as such, or would increased temperatures decrease vertical temperature gradients and reduce the likelihood of precipitation?
The concept of lake-effect rain may be less familiar to much of the general public, although the physical processes are similar to those for lake-effect snow. Changes in stability were accounted for somewhat, again to the degree that GCMs can accurately simulate 850 mb temperatures. In the lowest 150 mb of the atmosphere, the temperature changes from global warming will likely be constant so that boundary layer stability will not change appreciably, so that lake-effect rains will likely be as if not more intense, especially when accounting for the increase in saturation vapor pressure with temperature.

Chapter 4

The Canadian Model used in your assessment shows that lake levels will not decrease as much as some of the earlier models suggested, and the Hadley Model used in your assessment suggests that lake levels will stay the same or increase. Don´t these results confuse the reader and suggest that the models have problems?

Close inspection of lake level projections from all of the previous studies (which were included for comparison) as well as from our study are actually very similar — with the common thread being that none of the studies show significant increases in lake levels. In that sense these results are not conflicting and should not confuse the reader.

Chapter 5

The results in this chapter were obtained for Lake Michigan. Is there any way to apply them to the other Great Lakes?

The model used to obtain the results for Lake Michigan was tuned with parameter values specific for Lake Michigan. While the quantitative results are not likely valid for the other lakes without retuning the model, qualitatively the results suggest that stratification will increase for all of the Great Lakes.

Chapter 6

Why does this chapter describe the impacts on land cover from climate change scenarios from old GCMs?

The results regarding climate change impacts on potential vegetation from the latest climate change scenarios was not available at the time the report was being prepared.
Was the fitting and optimization of the STASH model based on Great Lakes region parameters only, or on full (North American) range? Would this make a difference?
The STASH model was tuned with parameter values valid for the Great Lakes region.

Chapter 7

How valid are the results in this chapter for future corn, alfalfa, and soybean productivity yields given the uncertainties of interannual climate variability, pest infestations, and new pesticide, fertilization, and irrigation technologies?

Almost no evaluation of climate change impacts can account for all possible changes. Evaluating climate change impacts is still in its infancy, and while such complications from pests can be included hypothetically (e.g., increased pest scenario), the results become even more difficult to interpret. The best way to interpret these results is to consider that these productivity changes are expected if it can be assumed that many other features of the current agricultural system remain unchanged, which may or may not be likely.

Chapter 8

Why is there more emphasis in the report on the climate change impacts on respiratory illness than on heat-related morbidity and mortality?

This portion of the report was generated because of the recent increases in reported asthma cases in the Great Lakes region (and elsewhere) and because it has not been addressed much if at all in other studies.
REVIEWERS
D. Briane Adams, US Geological Survey   Dr. Susan Levine, University of Vermont
John D. Aber, University of New Hampshire   Michael MacCracken, Director, USGCRP National Assessment Coordination Office
Donn K. Branstrator, University Minnesota-Duluth   Dr. David Mladenoff, University of Wisconsin
Wally Brinkman, University of Wisconsin   Russ Moll, Michigan Sea Grant Program
Michael F. Burger, Ph.D. National Audubon Society of New York State   Michael R. Moore, University of Michigan
Dr. Russ Butler, University of Michigan   Michael A. McGeehin, PhD Centers for Disease Control and Prevention
Charlotte Caldwell, Indigenous Environmental Network   Thomas Nizol, National Weather Service - Buffalo Ofc.
Lynne M. Carter, USGCRP National Assessment Coordination Office   Fred Nurnberger, Michigan State University
Andrew Comrie, University of Arizona   Michael Palecki, Illinois State Water Survey
Julie A. Craves, University of Michigan-Dearborn   Dr. Jean P. Palutikof, Climatic Research Unit
Dr. Thomas Crow, University of Michigan   Brian Potter, North Central Research Station
Dr. Stewart J. Cohen, Sustainable Development Research Institute   Dr. Ronald L. Ritschard, University of Alabama in Huntsville
Dr. Yosef Cohen, Fisheries & Wildlife   Robert Rohli, Louisiana State University
Dr. Everett J. Fee, University of Calagary   Thomas Schmidlin, Kent State University
Dr. Otto Doering, Purdue University   Professor Richard H. Skaggs Department of Geography
Michael A. Donahue, Great Lakes Commission   Eugene Stakhiv, Phd US Army Corps of Engineers
Dr. Kirsty Duncan, University of Windsor   Alan Solomon, EPA at Corvallis
Betsy Foxman, University of Michigan   George Seielstad, Centers for Disease Control and Prevention
Gerry Galloway, International Joint Commission   Dr. Lisa G. Sorenson, Boston University
Dr. Robert H.Gray, University of Michigan   Dr. Eugene Takle, Iowa State University
Dr. Peter H. Gleick, Pacific Institute for Studies in Development   Stephen Thorp, Great Lakes Commission
Benjamin F. Hobbs, The Johns Hopkins University   Kerry Woods, Bennington College
Thomas C. Johnson Large Lakes Observatory    

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