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Global Warming and the Great Lakes Region In the opening scene of Holling Clancy Holling's classic children's book, Paddle-to-the-Sea, a young boy stands at his cabin door in the Nipigon country north of Lake Superior. It is late winter, and the season's first flock of Canada geese is flying overhead. "Geese!" he cries. "They come back too soon!"
Those words, written by Holling nearly 60 years ago, have a familiar ring today. For the geese — and many other birds — now come back "too soon" to the Great Lakes region on a regular basis. In Holling's home state of Michigan, at least 15 bird species have advanced their spring arrival dates in the upper peninsula by one to eight weeks since 1965.
Why? Some researchers believe the birds are responding to long-term changes in climate that may be due to global warming. In fact, scientists have noted similar changes in other parts of the world. A study in England, for example, found that many birds there laid their eggs an average of 19 days earlier in 1995 than in 1971.
Impacts at a Glance
- Global warming could reduce the habitat available for cold water fish such as trout and salmon in lakes and streams.
- Lake levels in the Great Lakes could drop significantly, affecting wetlands, water quality, recreational facilities, and shipping.
- Forests may change, with some species shifting their range northward or dying out, and other trees moving in to take their place.
- Endangered species such as the Kirtland's warbler could lose habitat.
- Ducks and other waterfowl could lose breeding habitat.
- Changes in the timing of migration and nesting could put some birds out of sync with the life cycles of their prey species.
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Wildlife researchers are concerned that such behavioral shifts could be harmful for some birds. Insect-eating migratory birds that return too early in the spring might have trouble finding food, especially during late-season snowfalls and cold snaps. Similarly, birds that lay their eggs earlier might have poor nesting success if their young hatch before favored prey species become available.
Birds are not the only organisms responding to changes in the climate. Scientists reported in 1997 that plant growth in northern latitudes has increased by more than 10 percent since 1981 due to longer growing seasons. The growing season in latitudes where the effect is strongest — including the northern Great Lakes region — may have lengthened by 8-16 days. This sounds like a change for the better, but it will take time to see the effects.
Ecosystems respond to environmental trends in complex ways. Scientists have not yet determined how the longer growing seasons and warmer temperatures might affect competition among tree species in a forest, or what the changing climate might mean for northern plants that are near the southern end of their geographic range.
The Great Lakes-St. Lawrence basin, which includes the five Great Lakes, the St. Lawrence River, and their surrounding watersheds, contains 20 percent of the world's freshwater. The basin covers 295,000 square miles and includes huge forests and wilderness areas, rich agricultural land, lakes, streams, rivers, mineral deposits, and a world-class fishery. It also is home to a diverse range of plants and wildlife, including endangered and threatened species such as the Canada lynx, gray wolf, peregrine falcon, Kirtland's warbler, and Karner Blue butterfly.
Encompassing portions of Minnesota, Wisconsin, Illinois, Indiana, Michigan, Ohio, Pennsylvania, and New York, plus the Canadian provinces of Ontario and Quebec, the basin is home to more than one-tenth of the population of the United States and one-quarter of the population of Canada.
The region supports a multibillion-dollar outdoor recreation and tourism industry, with a number of popular national parks and recreation areas such as Isle Royale National Park; Voyageurs National Park; Superior National Forest; Indiana Dunes National Seashore; the Boundary Waters Canoe Area Wilderness; and Quetico, Algonquin, and Killarney Provincial Parks in Canada.
"It appears that global warming could have negative impacts on many of our region's strengths, assets, and resources."
- The Honorable Anthony Masiello, Mayor of Buffalo
NY June 1998 |
If scientists' projections are accurate, global warming could bring substantial changes — both positive and negative — to the region and its inhabitants in the years ahead.
Birds, plants, and other forms of life in the Great Lakes region have always been exposed to changes in climate and weather. But the changes underway now, and those projected for the future, are different. Climate scientists believe the Earth will experience an average rate of warming during the next 100 years that will be faster than any seen in the last 10,000 years. For the Great Lakes region, that means the next century could bring one of the greatest environmental transformations since the end of the last ice age, perhaps rivaling the dramatic changes wrought by humans after Europeans settled the region nearly 400 years ago.
If a Nipigon boy in the year 2050 were to place a small carved wooden canoe into the headwaters of Lake Superior, his Paddle-to-the-Sea might eventually reach the ocean just as the one in Holling's book did. But the sights and sounds along the way — the fish in the brooks, the trees lining the marshes, even the shape of the shorelines — might be very different from what Holling painted and described in 1941.
What is Global Warming?The Earth's climate has changed in the past, and will continue to change naturally in the future. Ice ages, long warm periods, and short-term fluctuations in temperature and precipitation are all elements of the global climate's natural variability.
Today, the average global temperature is rising. Is that natural? Some of the temperature increase can be explained by natural factors. But many scientists believe that a portion of the warming trend may be caused by humans. Human activities are creating a buildup of greenhouse gases — primarily carbon dioxide, methane, and nitrous oxide — in the atmosphere. The heat-trapping property of these gases is undisputed. Although scientists do not know exactly how the Earth's climate responds to increases in greenhouse gases, they do know that the current warming trend is consistent with changes that would be expected from the increase in greenhouse gases.
Scientists generally believe that the burning of fossil fuels and other human activities are the primary reason for the increased concentration of carbon dioxide in the atmosphere. Fossil fuels burned to run cars and trucks, heat homes and businesses, and power factories are responsible for almost 99 percent of U.S. anthropogenic carbon dioxide emissions and about 20 percent of our nitrous oxide emissions. Of the carbon dioxide emissions, industrial activity accounted for 33 percent in 1997. Personal and commercial transportation accounted for 30 percent, and residential and commercial energy use accounted for 19 and 16 percent, respectively. Increased agriculture, deforestation, landfills, industrial production, and mining also contribute a significant share of carbon dioxide, methane, and other greenhouse gas emissions.
Average global temperatures at the Earth's surface have increased 0.6-1.2°F since the late 19th century. The 10 warmest years in the 20th century all occurred in the last 15 years. Snow cover in the northern hemisphere, floating ice in the Arctic Ocean, and the areas covered by mountain glaciers have all decreased. Globally, sea level has risen 4-10 inches during the past century. Worldwide precipitation over land has increased by about 1 percent, and the frequency of extreme rainfall events has increased throughout much of the United States.
Although it is impossible to predict future changes in climate with certainty, many scientists believe that the continued addition of greenhouse gases to the atmosphere is likely to raise the Earth's average temperature by several degrees in the next 100 years. Rising global temperatures are expected to raise sea level and change precipitation and other local climate conditions. Changing regional climate could alter forests, crop yields, and water supplies. It also could threaten human health and harm birds, fish, and many types of ecosystems. |
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