TRAVERSE CITY, Mich. -- Some of the Great Lakes' treasured national parks are showing ill effects of climate change that are likely to worsen in coming decades, from shoreline erosion to decline of certain wildlife and plant species, a former park system administrator said Wednesday.
Without changes in public policies and personal habits that pump greenhouse gases into the atmosphere, the parks could lose qualities that attract visitors and support unique ecosystems, Stephen Saunders, former deputy assistant secretary of the Interior Department, said in a report released by two advocacy groups.
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"Human disruption of the climate is the greatest threat ever to America's national parks," Saunders said. "Threads are being pulled out of the tapestry of these parks and the parks are beginning to lose their luster."
The Rocky Mountain Climate Organization and the Natural Resources Defense Council helped produce Saunders' report, which focused on five parks or lakeshores in the region: Indiana Dunes in Indiana; Isle Royale, Sleeping Bear and Pictured Rocks in Michigan; and Apostle Islands in Wisconsin. Together, they drew more than 4 million visitors in 2010.
Using federal temperature data and previous scientific studies, Saunders and colleagues said climate change was at least partially responsible for a series of unfavorable developments in the parks, which can serve as early warning systems for the wider environment.
The decade that ended last year was the hottest on record at Indiana Dunes on Lake Michigan, where records from a nearby weather station showed the average temperature from 2001-2010 was 1.6 degrees above the average for the 20th century, the report said. At Pictured Rocks on Lake Superior, the average from the most recent decade was 2.7 degrees higher than for the last century.
The worldwide average for the decade was 1.5 degrees above the average for the 20th century.
If climate models predicting further increases prove accurate, a typical summer day at Indiana Dunes could be as hot as present-day Gainesville, Fla., by the year 2099, the report says.
Winter ice cover on the Great Lakes declined 15 percent from the 1970s through 2009, and the reduction in the center of the lakes has been twice as dramatic, it says. Less ice means more evaporation, steeper drop-offs in water levels and bigger waves that cause shoreline erosion.
The report said other problems at the parks linked to climate change include population declines for the famed moose and wolves of Isle Royale, botulism outbreaks that have killed thousands of shorebirds at Sleeping Bear; and the first known appearance at Isle Royale of the tick that causes Lyme disease, which previously had not spread that far north because of cool temperatures.
"Change in nature is natural," said Dale Engquist, former superintendent of Indiana Dunes. But the effects of human-caused climate change "don't allow millennia or even centuries for adoption. The changes now will take place in only decades without time for nature to adapt."