Global Warming Effects Around the World

Glacier National Park, MT, USA

Top Impact

Freshwater (Land ice)

Other Impacts

Ecosystems (Land)

Temperature (Air)

Historical comparison shows rapid retreat of Jackson Glacier in Montana

Montana's Glacier National Park is losing its namesake glaciers because of climate change. Scientists project that Jackson glacier—and other glaciers in the park—are likely to disappear within decades. For more comparison photos, go to

Key Facts

Global warming is shrinking the glaciers for which Montana's Glacier National Park is named. Climate change threatens the park's scenic beauty, wildlife, and economic value to the state.

  • Of the 150 glaciers in Glacier National Park in 1850, only 25 remain.2 Eleven of the park's iconic named glaciers have melted away since 1966.4
  • In 2003, scientists projected that all five of the named glaciers in Glacier's Blackfoot-Jackson basin could disappear by 2030.4,13
  • The park's wolverines, lynx, and mountain wildflowers are particularly vulnerable to loss of spring snow cover.4,16,17,18


Glacier National Park celebrated its one-hundredth anniversary in 2010. Since 1900, temperatures in the park have risen 2.4° F (1.3° C)—nearly twice the global average.2,3 The park now sees 16 fewer days each year at or below the freeze/thaw point compared with a century ago.3 Spring snowpack has declined since mid-century given western Montana's warming climate.4,5

Glaciers around the world have been retreating for the past century. The rate of retreat has increased in the past decade, and the total volume of glaciers on Earth is rapidly declining.6,7,8

According to the U.S. Geological Survey, of the 150 glaciers in Glacier National Park in 1850, only 25 remain.2 Eleven of the park's named glaciers have melted away since 1966.4

Glaciers are integral to Montana's ecology and economy. By storing water as ice, they provide a source of water during droughts, and after seasonal snows have melted in the summer, and they help regulate stream temperatures.2,3

More than two million people visited Glacier in 2009, making it the nation's eleventh-most-visited national park.9 Nearly three-quarters of the visitors come from outside Montana, and about three of 10 visitors to the state are drawn primarily by the park.4,10,11 Spending by these visitors directly and indirectly supports around 4,000 jobs.4,10

What the Future Holds

Unfortunately, this scenic area of Montana is likely to look very different 100 years from now. Scientists project that all five of the named glaciers in Glacier's Blackfoot-Jackson basin could be gone by 2030 if the amount of carbon dioxide in the atmosphere doubles.4,12 However, the glaciers could remain for a couple of centuries if they continue shrinking at rates that reflect the historical average.4,12

Besides melting glaciers, climate change is projected to bring shorter winters, earlier spring snowmelt, and warmer, drier summers to northwest Montana. If our heat-trapping emissions continue to rise at current rates, temperatures in the northwestern United States are projected to rise about 7.1° F (3.9° C) by the end of the century.4,13,14 In this scenario, West Glacier would be warmer than Santa Fe, NM, is today.4 If we make significant efforts to reduce our emissions, we could limit regional temperature increases to around 4.9° F (2.7° C).4,13,14

A recent study projected that by the end of this century, peak snowpack in the park could occur 41 days earlier than in the mid-twentieth century, and snow could cover the ground on 70 fewer days per winter.4,15 Shorter winters and the loss of glaciers could bring water shortages in the summer, and raise the risk of wildfires.4

A warming climate is also expected to roll back Glacier's carpets of mountain wildflowers. When the snow melts earlier in the spring, flower buds lose their protective insulation, and more are killed by frost.4,16

A changing climate will dramatically affect the park's ecosystem and the wildlife it harbors. Wolverines and lynx, which require spring snow cover to survive, are at particular risk.4,17,18 Climate change could also threaten habitat for grizzly bears, bighorn sheep, mountain goats, pikas, ptarmigan, and trout.4 As temperatures in Glacier rise, animals that do not now live in the park may move in, competing with existing species for food and habitat.4 Because the scenery draws virtually all the park's visitors, and nearly nine of ten report viewing wildlife as one of their activities, these changes could have economic implications as well.4,10



  1. Historical photograph courtesy of K. Ross Toole Archives, University of Montana, Morton Elrod. 2009 Photograph courtesy of Lisa McKeon, United States Geological Survey. Jackson Glacier 1911- 2009, Glacier National Park, Montana, United States. United States Geological Survey, Repeat Photography Project. Images available online at repeatphoto/ jackson.htm. Accessed 1 Sept 2010.
  2. Northern Rocky Mountain Science Center. 2010. Retreat of glaciers in Glacier National Park. Bozeman, MT: U.S. Geological Survey. Online at research/ glacier_retreat.htm. Accessed April 25, 2010.
  3. Pederson, G. T., L.J. Graumlich, D.B. Fagre, T. Kipfer, and C.C. Muhlfeld. 2010. A century of climate and ecosystem change in western Montana: What do temperature trends portend? Climatic Change 98:133-154.
  4. Saunders, S., T. Easley, and T. Spencer. 2010. Glacier National Park in peril: The threats of climate disruption. Denver, CO: Rocky Mountain Climate Organization; and New York, NY: Natural Resources Defense Council. Online at download/ GlacierInPeril_full.pdf. Accessed April 23, 2010.
  5. Mote, P.W., A.F. Hamlet, M.P. Clark, and D.P. Lettenmaier. 2005. Declining mountain snowpack in western North America. Bulletin of the American Meteorological Society 86(1):39-49.
  6. U.S. Global Change Research Program. 2009. Global climate change impacts in the United States. Edited by T.R. Karl, J.M. Melillo, and T.C. Peterson. Cambridge University Press.
  7. Steffen, K., P.U. Clark, J.G. Cogley, D. Holland, S. Marshall, E. Rignot, and R. Thomas. 2008. Rapid changes in glaciers and ice sheets and their impacts on sea level. In: Abrupt climate change. Synthesis and assessment product 3.4. Reston, VA: U.S. Geological Survey.
  8. Lemke, P., J. Ren, R.B. Alley, I. Allison, J. Carrasco, G. Flato, Y. Fujii, G. Kaser, P. Mote, R.H. Thomas, and T. Zhang. 2007. Observations: Changes in snow, ice and frozen ground. In: Climate change 2007: The physical science basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Edited by S. Solomon, D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor, and H. L. Miller. Cambridge University Press, pp. 337-383.
  9. National Park Service. 2009. Ranking report for recreation visits. Online at stats/ viewReport.cfm. Accessed April 25, 2010.
  10. National Park Service. 2003. Going-to-the-Sun Road rehabilitation plan/final environmental impact statement. Washington, DC. Online at archive/ glac/ pdf/ 2003roadeis.pdf. Accessed April 25, 2010.
  11. Oschell, C., and N. Nickerson. 2010. Niche news: 2009 3rd quarter nonresident visitor characteristics. Missoula, MT: Institute for Tourism and Recreation Research, University of Montana. Online at NicheNews10/ Q309AllTravelers.pdf. Accessed April 25, 2010.
  12. Hall, M.H.P., and D.B. Fagre. 2003. Modeled climate-induced glacier change in Glacier National Park, 1850-2100. Bioscience 53 (2):131-140.
  13. Mote, P., E. Salathé, V. Dulière, and E. Jump. 2008. Scenarios of future climate for the Pacific Northwest. Seattle, WA: Climate Impacts Group, University of Washington. Online at db/ pdf/ moteetal2008scenarios628.pdf. Accessed April 25, 2010.
  14. The emissions scenarios referred to here are the high-emissions path known as A1B and the low-emissions path known as B1 from the Intergovernmental Panel on Climate Change.
  15. Boisvenue, C., and S.W. Running. 2010. Simulations show decreasing carbon stocks and potential for carbon emissions for Rocky Mountain forests over next century. Ecological Applications, in press.
  16. Inouye, D.W. 2008. Effects of climate change on phenology, frost damage, and floral abundance of montane wildflowers. Ecology 89 (2):353-362.
  17. Schwartz, M.K., J.P. Copeland, N.J. Anderson, J.R. Squires, R.M. Inman, K.S. McKelvey, K.L. Pilgrim, L.P. Waits, and S.A. Cushman. 2009. Wolverine gene flow across a narrow climatic niche. Ecology 90 (11):222-3232.
  18. Gonzalez, P., R.P. Neilson, K.S. McKelvey, J.M. Lenihan, and R.J. Drapek. 2007. Potential impacts of climate change on habitat and conservation priority areas for Lynx canadensis (Canada lynx). Report to the U.S. Forest Service. Arlington, VA: Nature Conservancy. Online at workspaces/ climate.change/ climate.change.vegetation.shifts/ climate_change_Lynx.pdf. Accessed April 26, 2010.
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