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Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

April 2000

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Kelly Mella and Julia Barrett

Table of Contents
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The issue that's heating up

Global warming: It's a phrase we've been hearing on weather broadcasts and news reports, in science classrooms and around supper tables since the early 1980s. It's a vague concept that seems far removed from our everyday lives, something that concerns anonymous scientists digging into polar ice caps thousands of miles away – not us.

Wisconsin as we know it could experience drastic change as temperatures inch up globally.
© Robert Queen
Wisconsin as we know it could experience drastic change as temperatures inch up globally. © Robert Queen

But global warming and the changes it could cause in world climate should concern us.

The great majority of scientific research agrees that between now and the middle of the coming century the globe could very well warm up, and the results could significantly alter life in this little corner of the planet we call home. Credible scenarios show Wisconsin could face:

  • wetter winters and drier summers with longer, hotter and more frequent heat waves
  • weather and climate changes that could require farmers to raise different crops
  • dairy cattle beleaguered by heat exhaustion and growing pest populations
  • poor air quality and higher concentrations of ground-level ozone, an air pollutant that causes severe health problems
  • warmer and more shallow river waters – conditions that could hurt populations of cold-water fish like trout
  • denser algae blooms and lower oxygen levels in ponds and lakes
  • more frequent floods, droughts, forest fires and damaging storms
  • changes in tree species that could affect the forestry industry and wildlife populations
  • increases in disease-carrying insect populations

All of these potential changes are just that: potential. Because of the intricate interplay of a whole slew of climatic factors, it's difficult to predict what an increase in global temperature might bring. This publication dips into the ocean of global climate change theory, and attempts to fish out the bits pertinent to Wisconsin.

Table of Contents

What is global warming?

Historical records indicate the average global temperature increased by 0.5 to1° Fahrenheit (F) between 1890 and 1990. In the next 100 years, scientists predict the temperature may rise another 2 to 6° F. Such increases have occurred previously in Earth's history, but never over such a short time span. In fact, the average global temperature has risen more in the last century than at any time in the past 10,000 years.

What's causing this warming trend? Scientists agree the answer hinges on the six main human-influenced greenhouse gases in our atmosphere. These gases – carbon dioxide (CO2), methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride – make up about 1% of our atmosphere. They keep our planet warm by trapping the sun's energy and slowing its escape back into space. This heat-trapping ability is called the greenhouse effect, and it allows us to enjoy an average global temperature of 60° F. If our atmosphere lacked greenhouse gases, the Earth would be a cold gray lump of cosmic matter, and life as we know it would not exist.

Since the Industrial Revolution, however, atmospheric concentrations of the most important human-influenced greenhouse gases – CO2, methane and nitrous oxide – have increased at an unnatural rate. In the last 200 years, CO2 levels have risen almost 30%, methane levels have gone up 145%, and nitrous oxide levels have increased by 15%.

Gas-powered vehicles account for nearly half of Wisconsin's greenhouse gas emissions. © Robert Queen
Gasoline-powered vehicles account for nearly half of Wisconsin's greenhouse gas emissions. © Robert Queen

Where are all these "extra" greenhouse gases coming from? Us. Large-scale burning of fossil fuels for industry and motor vehicles, intense agricultural activity, mining, and other human activities pump more and more greenhouse gases into the atmosphere, creating a heightened greenhouse effect that leads to a higher average global temperature – global warming.

How do scientists study
past climate?
If scientists had to rely on written weather records for historical climate information, they would be in trouble. Such records only exist for the last 150 years or so. However, clues in the environment can provide information from thousands of years ago.

Ice cores – Ice in polar regions contains air bubbles trapped thousands of years in the past. Scientists can check the gases in the bubbles and provide a good estimate of the temperature at that time. Also, the thickness of the ice layers gives information about past climates.

© Robert Queen Tree rings – Trees can live for centuries, and for each year of their lives they add a ring of growth to their diameter. The width of these rings can give scientists information about climate during that year of growth.

Fossils – The bones
of long-dead animals indicate which species lived in certain areas and when they were there. Since each species has a set of food and temperature requirements, scientists can deduce the climate of their time and area.

Sediment cores – A column of sediment from a lake bottom contains pollen grains in each layer. The deeper the layer, the older the sediment. After determining the age of the layers, scientists can study what plants were growing when the sediment was deposited.

Archaeological records – Humans have left their traces throughout the world for ages. How they lived and what they needed to survive can provide important clues about the climates they experienced.

Normally, the elements that compose greenhouse gases (carbon, oxygen, nitrogen, etc.) cycle freely through the environment between sources and sinks. Sources release elements to the atmosphere; sinks store them. For example, carbon is stored in most life forms on Earth, including trees; trees are sinks for carbon. When trees are cut down and burned, this stored carbon is released into the atmosphere as carbon dioxide; thus, the burning of trees is a carbon source.

For two centuries, we've been releasing greenhouse gases into the atmosphere at unprecedented rates while destroying forests and other natural sinks that could absorb those gases. In our attempts to improve the quality of life, we've created a greenhouse that's a little too effective.

From global temperature to global climate

Because of human activities, the average global temperature may become 2 to 6° F warmer by 2100. While the prospect of a few more degrees of warmth may sound appealing to anyone who's endured a Wisconsin winter, it's important to realize the repercussions of such a change.

Consider that during El Nino, which tends to bring with it severe dry spells, storms and other dangerous weather events, average winter temperatures go up by only 0.5° F.

There is no longer much dispute over whether an increase in global temperature will affect global climate. Exactly how the climate will change, however, is a topic rife with debate. Researchers use computer models that mimic the Earth's climate to make educated predictions on what changes global warming may bring. The view they see is daunting: Nearly all regions of the globe would experience higher temperatures, but some, particularly inland areas in northern latitudes like Wisconsin, could get warmer than others. Some regions could become significantly drier while others would get more rain and snow.

More frequent and intense floods could drown dairying and other mainstays of Wisconsin's economy. © Robert Queen
More frequent and intense floods could drown dairying and other mainstays of Wisconsin's economy. © Robert Queen

Altered weather patterns could affect agriculture, forest make-up and wildlife populations. By 2100, ocean levels could rise as much as 3 feet, causing extensive coastal flooding that could disrupt food supplies, damage or destroy human dwellings, and displace millions of people. Extreme weather events like hurricanes, floods, droughts, and forest fires could become more frequent and intense. Local and regional economies as well as human health could suffer.

Wisconsin under the heat lamp

Because the models scientists use to study climate change are not sufficiently precise to offer specific predictions for an area as small as the state of Wisconsin, the following discussion is taken from predictions for the upper Midwest region. While it's fairly safe to say that global climate change won't turn our state into a tropical paradise, scientists agree that it could significantly alter the way we live.

Weather and climate

Researchers speculate the upper Midwest would generally become warmer and wetter, with the average temperature increasing by about 4° F. The increase doesn't mean we'd simply up the daily temperature by 4°; a more likely scenario is that summer heat waves would be longer and hotter, and nighttime winter temperatures wouldn't sink so low. Precipitation could increase by as much as 10% on average, but much of the increased precipitation could come in the form of intense storms, leading to local flooding and more runoff. Precipitation patterns could also change, with more rain coming in the winter and less in the summer. Less rain in the summer, paired with increased evaporation caused by warmer temperatures, could trigger severe summer droughts.

Water resources

Wisconsinites treasure our 15,000-plus lakes, and the scores of rivers, streams and wetlands that grace our state. Climate change could have tremendous effects on these waters, including the Great Lakes.

As warmer weather raises water temperatures, more algae blooms could clog lakes, endangering aquatic species. © Dale Lang
As warmer weather raises water temperatures, more algae blooms could clog lakes, endangering aquatic species. © Dale Lang

Lake Superior water levels could drop over time by 1 to 1.5 feet, while Lake Michigan levels could fall 3 to 8 feet. Such drops could result from longer and drier summers during which more of the lakes' waters would be claimed by evaporation.

Winters might have less snow and shorter periods of snow cover. Lowered Great Lakes levels could strike a heavy blow to industries like shipping and hydropower generation. Smaller inland lakes could also get shallower, and some ponds and wetlands might disappear altogether, jeopardizing wildlife habitat and our tourism and recreation industries. Finally, groundwater levels could drop significantly, threatening drinking water quality and quantity.

Water temperature could also be a problem. Warmer water would encourage algae blooms and other aquatic plant overgrowth in the summer, transforming clear blue waters into a thick, smelly pea soup that turns off boaters, anglers and swimmers, and makes survival difficult for fish and other aquatic species. Cold-water species like trout could decline in number or disappear from their traditional areas altogether. And decreased winter ice cover could disturb both lake ecology and the ice fishing season.


Should the weather warm significantly, crops like soybeans and corn currently grown in southern Wisconsin might have to be cultivated in northern fields, where thinner soils may not produce abundant harvests. © Robert Queen
Should the weather warm significantly, crops like soybeans and corn currently grown in southern Wisconsin might have to be cultivated in northern fields, where thinner soils may not produce abundant harvests. © Robert Queen

Anything that affects farming affects the state's economy. Some researchers predict that under the influences of climate change, southern Wisconsin farms might begin to resemble those in present-day Kansas. Wheat would do well, but the ideal range for corn and soybeans would shift northward, and these crops might not grow as well in the soils of northern Wisconsin. High levels of carbon dioxide in the atmosphere may actually increase crop production, because certain plants can become larger and more productive in a CO2-rich environment. However, gains in crop productivity might be counter-balanced by more frequent and severe droughts, and by more weed, pest and disease problems.

Dairy and other livestock farmers might see productivity decline as their herds suffer from heat stress, the feed supply is disrupted (from changing crop yields), and the water supply reduced. Warmer, longer summers might encourage the growth of pest populations that could further stress livestock and spread disease.

Forests and wildlife

As temperature and precipitation patterns change, habitat ranges for flora and fauna are expected to shift northward. Some species might be able to migrate with their ideal habitat, but others, especially those already endangered, could face extinction. Researchers predict that mixed northern hardwood and oak forests would be transformed to oak savannas and grasslands within 30 to 60 years. Typical northern forests could completely disappear from Wisconsin, along with the eastern hemlock and the sugar maple. Such radical changes in forest makeup could have far-reaching effects on the forestry industry, some types of hunting – and the very character of our state's landscape.

Human health

Weather changes could directly affect human health. More frequent and severe heat waves would threaten the elderly – especially those living alone – and people suffering from cardiovascular and respiratory diseases. The U.S. Environmental Protection Agency (EPA) projects that a 3° F warming could almost double heat-related deaths in Milwaukee during a typical summer, from 30 to about 55.

Aside from deaths caused directly by heat, climate change poses other health-related threats. A longer, hotter summer, along with increased emissions from power plants trying to keep up with greater air conditioning demands, would likely intensify air pollution problems. This could result in more, and more serious cases of asthma, emphysema and lung disease for Wisconsin residents. Wisconsin's allergy season could lengthen because some plants would flourish in the extended summer. Warmer weather might also be more hospitable to disease-carrying insects like mosquitoes and ticks, leading to more cases of Lyme disease, tick-borne encephalitis, and possibly even malaria. Finally, more frequent severe weather events like forest fires, floods and dangerous storms could cause injuries and take lives.

Responding to a global threat

Despite the uncertainty of predicting the effects of climate change, scientists and policy-makers are not sitting idly by. Wisconsin is working with other states and nations to understand climate change and find ways to limit or prevent the disruption and devastation it could cause.

The Wisconsin Department of Natural Resources (DNR) has completed several studies showing that the use of energy-efficient technologies could reduce the state's emissions of greenhouse gases with little or no net cost. One study showed that if Wisconsin adopted improved energy efficiency measures, we could realize a 12.5-million-ton decrease in the growth of greenhouse gas emissions by 2010 (compared to projected levels) and save $490 million in energy expenditures at the same time. Another study predicted that investing in energy efficiency measures could create a $490 million increase in disposable income, a $41 million increase in gross state product, and 8,500 new jobs in 2010. Based on these studies, the Wisconsin DNR created the Wisconsin Climate Change Action Plan. For more information, see Wisconsin Climate Change.

In 1992, 154 nations and the European Union adopted the United Nations Framework Convention on Climate Change, a voluntary agreement to stabilize greenhouse gas emissions at 1990 levels. In December 1997 at a United Nations meeting in Kyoto, Japan, some industrialized countries went a step further and agreed to the Kyoto Protocol, which requires developed nations to reduce their greenhouse gas emissions to an average of 5 percent below 1990 levels by 2008-2012. Specific reduction commitments vary among nations. If the protocol goes into effect, it will require the U.S. to reduce

Greenhouse gas emissions to seven percent below 1990 levels. However, at current rates our nation stands to increase its emissions to 30 percent above 1990 levels by 2010. Our country is already the world's largest emitter of greenhouse gases, contributing approximately 23 percent of global emissions despite having only 5 percent of the world's population.

What can I do?

The solutions to global warming may seem to be out of our hands, but we can take action – and many of the things we can do to reduce greenhouse gas emissions offer personal benefits as well.

Save the planet – take the bus! © Robert Queen
Save the planet – take the bus!
© Robert Queen

The biggest contribution individuals can make is to use less energy. By tuning cars, insulating homes and using energy-efficient appliances, we can decrease our use of fossil fuels and save money. We can carpool, use public transportation, or walk or bike to our destinations. These activities cut fuel consumption, decrease traffic congestion, decrease emissions of other air pollutants, and may even get our hearts pumping. Finally, we can purchase items with reusable, recyclable, or reduced packaging – all options that help decrease the amount of energy being used to make new packaging.

Those willing to invest even more in guarding against climate change have further options. Alternative energy sources like solar and wind power can supply home energy needs. Cars that use propane or natural gas – fuels that burn more cleanly than gasoline – are already on the roads. Hybrid cars, which use electricity from batteries along with gasoline for power, are entering the market. And solar-powered cars, as well as fuel-cell cars powered by hydrogen, may be available within the next 10 years.

Responding to the complexities of climate change won't be easy, but the State of Wisconsin has never backed down from a challenge. With cooperation from business, industry and individuals, Wisconsin can continue to serve as a national leader as the global warming issue heats up.

Hot stuff
For more information on global warming and climate change, peruse the following websites and publications:

U.S. Environmental Protection Agency – Climate Change

U.S. Global Change Research Program

United Nations Framework Convention on Climate Change

United Nations Environment Program

Intergovernmental Panel on Climate Change

Consortium for Integrated Resource Planning, Engineering Professional Development, University of Wisconsin, Wisconsin Department of Natural Resources and Leonardo Academy, Inc., The Economic and Greenhouse Gas Emission Impacts of Electric Energy Efficiency Investments: A Wisconsin Case Study. Report 4 of the Wisconsin Greenhouse Gas Emission Reduction Cost Study, February 23, 1998.

Intergovernmental Panel on Climate Change, IPCC Second Assessment: Climate Change 1995.

Intergovernmental Panel on Climate Change, The Regional Impacts of Climate Change: An Assessment of Vulnerability, 1998.

Office of Science and Technology Policy, Climate Change: State of Knowledge, October 1997.

United States Department of State, U.S. Climate Action Report, ISBN 0-16-045214-7, July 1997.

U.S. Environmental Protection Agency, Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-1997, EPA 236-R-99-003, April 1999.

Wisconsin Department of Natural Resources, Global Climate Change: Management Strategies for Wisconsin, Publication Number AM-066-91, December 1991.

Wisconsin Department of Natural Resources, University of Wisconsin Consortium for Integrated Resource Planning, and Leonardo Academy, Inc., Wisconsin Greenhouse Gas Emission Reduction Cost Study, Report 3: Emission Reduction Cost Analysis, Publication Number AM-269-98, February 1998.

Wisconsin Department of Natural Resources and the Wisconsin Climate Change Committee, Wisconsin Climate Change Action Plan: Framework for Climate Change Action, Publication Number AM 271-98, May 1998.

To order printed copies of "Warming trends" send an email message to Anne Urbanski requesting publication number AM-303-00. Include your name, address and number of copies desired.