Editor's note: This is the tenth excerpt from the National Parks Conservation Association's latest report on how climate change is impacting national parks. This section focuses on how climate change can jeopardize the future of caribou in Alaska and such units of the National Park System as Denali National Park and Preserve, Gates of Arctic National Park and Preserve, Noatak National Preserve and Kobuk Valley National Park. The entire report can be found at this page.
Caribou have been on the landscape for more than 400,000 years. For roughly the past 12,000 years, they have been hunted by humans — ﬁrst the paleo-Indians, now the First Nations’ cultures along with many other Alaskans. Resilience to hunting, to weather, and to predators has enabled the caribou to remain an integral part of both the natural landscape and the human culture. The greatest test of their resilience, though, stands to be climate change.
Caribou travel great distances, in some cases traversing more than 200,000 square miles annually, in their search for adequate vegetation. For example, although the Denali Herd spends almost the entire year in Denali National Park and Preserve, the Porcupine Herd roams between the Arctic National Wildlife Refuge in northeast Alaska and the Northwest and Yukon territories. The Western Arctic Herd, one of three herds that visit Gates of the Arctic National Park and Preserve, crosses a jigsaw-puzzle mix of federal, state and tribal lands, including not just Gates of the Arctic but also Noatak National Preserve and Kobuk Valley National Park as well.
Climate change will affect all these areas. Indeed, already many impacts can be seen throughout Alaska. Ice ﬁelds are shrinking, ice sheets are breaking up, forest ﬁres and insect outbreaks are increasing, permafrost is melting, and coastal villages are disappearing into the sea. For caribou, one of the Earth’s great iconic species, these climate-related shifts are expected to bring many changes, some good, some not so good, and some unknown. Cows and calves require lush spring vegetation for vital nutrients during the critical period around calving and early development. Climate change will affect when that spring vegetation appears, potentially putting the green-up out of sync with calving, and leaving adults and newborns without adequate nutrition. With climate-change forecasts predicting a warming of as much as 5 degrees centigrade throughout the Arctic, a trend that is likely to lead to earlier plant germination, will caribou be able to advance their biological clocks and keep calving when food is most available?
Some think earlier springs could also lead to an earlier than normal vegetation die-off in the fall, which could create a lack of forage when caribou are trying to fatten up for winter. Lack of proper nutrition in the fall decreases a pregnant female’s chance of successfully bringing her calf to term. Climate change doesn’t mean climate uniformity. While a trend to warmer weather could mean less snow in some areas, it could mean heavier snows elsewhere that could force caribou out of their traditional calving grounds. Warmer temperatures also bring occasional rain to regions that used to only see snow in the winter. These thaw and refreeze events create a tough layer of ice that places forage out of reach.
Also complicating life for caribou is the prospect of more frequent tundra ﬁres. These ﬁres, predicted to increase in number if not in size as the climate warms, could adversely impact lichens that caribou rely on in winter. Even without ﬁre lichen patches might shrink under current climate-change scenarios. Lichens prefer poor soils, but with permafrost thawing there is expected to be better soils, which will encourage and support different vegetation that could drive out lichens. Already there have been documented increases in shrub cover over north-western Alaska, and some studies indicate that caribou won’t eat shrubs. All these factors — timing and types of vegetation, ﬁres, and lichen decline — are poised to interfere with the herds’ reproductive cycles and nutritional needs. More problems could arrive in the form of parasites.
With so many potential changes in store for caribou, it’s crucial that the National Park Service, other federal agencies, state agencies, and tribes collaborate in monitoring the health of both caribou herds and vegetation across their ranges. For example, a better understanding and mapping of the present-day status of caribou winter ranges can help play a role in developing ﬁre management plans that balance active ﬁre suppression in areas with valuable lichen resources against letting wildﬁres burn themselves out. Wildlife and human life are so intertwined in Alaska, just as national park lands are so intertwined with other federal, state, and tribal lands. Climate change threatens to send shudders, if not outright shatter, some of these connections if nothing is done to slow, and hopefully reverse, its course.
We Can Safeguard Caribou from Climate Change
Stop contributing to climate change
Caribou in Alaska could decline if we fail to reduce carbon dioxide pollution and global warming that is altering the timing and variety of foods caribou need to produce healthy calves in the spring and to survive the winter.
Give caribou freedom to roam
Even with the vast territory available to Alaska’s caribou herds, traditional calving grounds and winter feeding areas may become unsuitable due to climate change impacts on vegetation; identifying suitable new habitat and ensuring the path is clear for caribou to get there should help caribou cope as climate change alters their landscape.
Adopt “climate smart” management practices
By coordinating the work of resource managers from the National Park Service, other state and federal agencies, and tribes, to monitor and map caribou herds and the vegetation they depend on, we can make smarter decisions about fire management and other land management practices that will help caribou overcome the climate challenges they face.
Tomorrow: Wolverines of the Northern Rockies
Jennie Hoffman, PhD, Senior Scientist, Climate Adaptation, EcoAdapt
Eric Mielbrecht, MS, Senior Scientist and Director of Operations, EcoAdapt
Lara Hansen, PhD, Chief Scientist and Executive Director, EcoAdapt
NPCA GRATEFULLY ACKNOWLEDGES FINANCIAL SUPPORT FOR THIS REPORT FROM THE FOLLOWING:
Merck Family Fund
Ruth and Ben Hammett