“Fish and wildlife–more so than humans–are governed by the temperatures of their environments, because they can’t change them like we can,” says Virginia Burkett, a senior scientist with the U.S. Geological Survey and former head of the Louisiana Department of Wildlife and Fisheries. “And there’s no real disagreement about that bottom line: Changes are coming. They’re already happening.”

A Matter of Degree
Those changes are the consequence of an increase in daily temperatures already under way and expected to average between 2.5 and 10 degrees by 2100, according to the latest report of the International Panel on Climate Change (IPCC), which includes the top climate scientists from the U.S. government. While climate changes have been part of the planet’s history, the IPCC says an unnatural and historic acceleration is taking place due largely to the so-called greenhouse effect, caused by an atmospheric blanket of heat-trapping carbon dioxide and water vapor. Human activity, such as the combustion of fossil fuels and the removal of forests, intensifies the effect. A rise of just a few degrees may seem insignificant to sportsmen used to adjusting home thermostats that much with the touch of a button. But such a change can rip­ple through an ecosystem with dramatic impacts on fish and wildlife.

Anyone doubting that need only consider Minnesota, where sportsmen have already felt the heat.
Over the last 40 years, average temperatures in Minnesota have risen by 12 degrees in the winter and 4 degrees in the summer, forcing moose to spend more time immersed in water to cool down, and less time feeding. The result has been a weaker herd, more susceptible to disease and less successful at breeding, says Dave Schad, director of the state’s Division of Fish and Wildlife. Between the 1980s and 2003, the moose population in northwest Minnesota dropped from 4,000 to 237, forcing the end of hunting seasons. The northeast population has experienced a similar drop, and the hunting season there has been curtailed.
Another icon of the Minnesota outdoors, the walleye, is facing a similar crisis. The small increase in water temperatures will be fatal to walleyes in some shallower lakes, while in others it will kill the species’ primary food sources.

Those are just two in a sweeping tide of changes to the sportsman’s world that have been outlined by a large and growing list of scientific papers and reports from fish and game agencies, as well as from conservation groups such as the Wildlife Society, Trout Unlimited, Ducks Unlimited, and the National Wildlife Federation. The general themes are unsettling:

* Waterfowl face an uncertain future. Climate models indicate that prairie potholes, responsible for as much as 80 percent of the continent’s duck production, will become drier and hotter. The worst-case scenario of long-term wetlands loss on the prairies could reduce waterfowl populations by 50 percent before the end of the century. “Predictions of wetlands loss cover a wide range (from 9 to 69 percent by 2080), but they all point in the same direction,” says Mike Anderson, a senior scientist for Ducks Unlimited Canada.

* Coastal regions will experience significant impacts due to an acceleration of sea level rise expected to average almost 2 feet on all U.S. coasts by 2100, according to the federal Environmental Protection Agency. Worst-case models show increases over twice that. The Wildlife Society reports that sea level rises could drown the nation’s most productive estuaries, dramatically reducing fish production as well as wiping out vital wintering waterfowl marshes along the northern Gulf coast and Atlantic seaboard.

* Species in cold-weather climates will be affected earliest, and most severely, because they are less tolerant of high temperatures. The lack of snow and warmer winters correspond to temperature increases that will be sharpest in the higher altitudes of the Mountain West, and northern latitudes including the Great Plains and Great Lakes.

* Coldwater fisheries are seen as the most immediately threatened. According to TU, rising water temperatures resulting from warmer air will wipe out trout populations in many areas of the country where their habitat is currently marginal. This includes the southern Appalachians as well as parts of the desert Southwest. But the greater challenge nationally to trout will come from degraded habitat caused by the runoff from increased winter flooding and more frequent and severe wildfires.

* Salmon will also suffer. An independent scientific council study reports that 40 percent of the rivers in Oregon and Idaho and 22 percent of those in Washington will be too warm for salmon by 2090. The already stressed bull trout in these drainages will succumb much earlier.

* Western game will be subject to massive shifts. In the forests, winter temperatures be­low 0 degrees always limited damage from cyclical bark-beetle infestations. But now the insect numbers are reaching historic proportions. The dead, dry trees will inevitably lead to huge fires, forcing displacement of deer, elk, and upland birds, as well as silting streams with ash and soil runoff during postfire rains.

* In the Upper Midwest, researchers say the northern pine and birch forests could vanish or be replaced by red oak and maple, having an impact on deer and upland birds such as grouse.

No state or region will be exempt from upheaval, although some sportsmen may like their new world. Midwestern anglers who long for flathead cats and largemouth bass may be very happy to see walleyes and trout replaced by those warmwater species. And waterfowlers in the central latitudes will surely have longer and better hunting when ice and snow no longer force most ducks south for the winter.

Wildlife scientists say there is no stopping some of the changes. The causes of global warming can only be slowed by global ac­tion—a process they support, but one they know they have little control over.

In the meantime, they have shifted their attention, and much of their research, to meeting the management challenges that global warming is sending their way. As the Wildlife Society urges, managers are beginning to recognize climate change as a factor in wildlife conservation efforts.

“We have to make sure we have management practices in place that will help lessen the impact of a warming climate as it happens,” says Doug Inkley, a senior scientist at the National Wildlife Federation. “For instance, we know trout will be stressed, so we should start improving protections for riparian habitat now. We need to be asking ourselves, ‘What things can we do today that will prevent some negative impacts in the future?'”

The global warming debate should end. Now it’s time for action.