Life on the Rocks: A Portrait of the American Mountain Goat

Chapter Eight: The Global Challenge

Even as some threats to species may be regulated and ameliorated at the local level, others cannot. A growing global challenge now confronts alpine environments and their wild residents, including the mountain goat. The evidence is undeniable that our planet is warming, atmospheric accumulation of greenhouse gases is largely responsible, and Earth’s ecosystems and biodiversity are already suffering the effects. These realities are well-documented in countless scientific publications and summarized in comprehensive reports of the Intergovernmental Panel on Climate Change (IPCC). The IPCC was established in 1988 by the United Nations to assess current scientific, technical, and socio-economic information worldwide about the risk of climate change caused by human activity, its potential environmental and socio-economic consequences, and options for human adaptation to these climatecaused effects. Thousands of experts in climate science and related fields from 120 countries contribute to the panel’s assessments. Although some consequences of the planet’s warming may bring welcome changes on local scales—most notably for those who aren’t fans of parkas and mukluks—negative consequences will predominate. For example, warmer and CHAPTER EIGHT The Global Challenge DOI: 10.5876_9781607322924.c008 146 T H E G L O B A L C H A L L E N G E longer growing seasons and the fertilization effect of rising CO2 levels will accelerate growth rate of plants, potentially boosting crop yields and increased consumption of CO2 (a major greenhouse gas and fuel for photosynthesis). However these benefits will be offset by increasingly variable precipitation patterns, withering heat and drought, geographical shifts in food production zones, and plagues of agricultural pests. Our warming climate is impacting biota from the poles to the equator. But it’s at the highest latitudes and altitudes that the changes are most dramatic. Annual temperatures of polar regions and the arctic alpine are climbing at triple the rate of other regions of the globe. Conditions have always been most frigid at these geographic extremes, and by definition their life forms are cold-adapted. The whitebark pine is one such species adapted to ice-box temperatures and blistering winds that shape the upper treeline across much of the mountain goat’s interior range. Yet from Colorado to British Columbia the tree is dying. In the Greater Yellowstone Ecosystem, almost half of whitebark pines are now dead. More broadly, vast tracts of Rocky Mountain spruce and pine forests have become eerie landscapes of arboreal skeletons after dying orange needles fall from gray, lifeless limbs. Their ongoing demise has been traced to increased pine blister rust and mountain pine beetles formerly held in check by the winter deep freeze. Temperatures are no longer cold enough long enough to beat back the pests that attack and kill trees that are increasingly weakened by warm, dry summers. Dead forests become tinderboxes for wildfires that have been raging across western wildlands as the wildfire season has lengthened by weeks. Such effects not only destroy commercial forests, they accelerate the addition of CO2 to the atmosphere and change ecosystems in numerous ways and more rapidly than many species can adapt. It’s a big deal to the Clark’s nutcracker, which makes a steady diet of the whitebark’s pine nuts, and also to threatened grizzly bear populations in Wyoming, Montana, and Idaho who relish the cones as a high-energy, pre-denning food source. The bears get them not by climbing trees, but by raiding winter food caches diligently stored by red squirrels. Additional reverberations ripple throughout the alpine zone’s web of life from the loss of this single species of tree. Warmer conditions are expected to advance phenological events such as flowering and fruiting of plants demanding species dependent on them to reset migration timing , breeding, and other biological cycles. The transformation is altering distributions of whole plant communities, changes scientists have been measuring on the ground and with the aid of satellite imagery in recent years. Trends over the past three or four decades show an accelerating expansion of species’ geographic range boundaries toward the poles or to higher elevations by progressive development of new local populations . Concurrently, opportunistic, weedy, or highly mobile species are invading new (overleaf ) Dying whitebark pine (Pinus albicaulis) has become a common sight in the subalpine zone of the mountain goat’s range as unchecked disease and parasites attack heat-stressed trees. (Photo by author) The Clark’s nutcracker’s (Nucifraga columbiana...