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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.
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:
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.
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%.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.