By Stacy L. Small, Ph.D. - Environmental Defense Fund Conservation Scientist The Intergovernmental Panel on Climate Change (IPCC) reported in 2007 that global air and ocean temperatures over the past 50 years are higher than any other 50 year period in the last 500 years; likely the highest they've been in the past 1300 years.
Furthermore, global temperatures will continue to rise over time as a result of heat-trapping greenhouse gas emissions – like carbon dioxide, methane, and nitrous oxide – that human activities have released into the atmosphere in the past half century.
This will have profound effects on virtually all of the physical phenomena of the world.
Change is Afoot
Human-induced global warming is already changing the world in many observable ways: altering wind patterns that influence tropical storms and drive ocean currents; increasing precipitation in some regions, drought in others; melting snowpack, glaciers, ice caps, and polar sea ice; and changing the timing and intensity of spring snowmelt runoff and floods.
Sea levels are rising because of thermal expansion of ocean waters and melting ice. In fact, some scientists believe that even the more dire predictions of sea level rise in the IPCC report appear to be conservative, when glacial melt is factored in.
These changes will visibly impact our most fragile, living ecosystems within our lifetimes and alter many current wildlife habitats beyond recognition. This could have fatal consequences for some of our most beloved and vulnerable species, especially those that have already become endangered from other human impacts.
Species at Risk
The IPCC predicts that up to 30% of all species are at risk of extinction at a global temperature increase of 1.5-2.5 degrees C. The IUCN has named three groups -- birds, amphibians, and warm-water reef-building corals -- as the most threatened species globally.
The North American ecosystems most immediately vulnerable to these radical environmental changes include coastal and marine zones and cold climates at high altitudes and northern latitudes, as well as arid western regions that depend upon snowmelt runoff for water.
However, all habitats and species on the planet will eventually be affected in one way or another by global warming, either directly or indirectly, in combination with other impacts, like development and pollution.
In addition, the timing of plant and animal life cycles ("phenology") is changing and in some cases, interdependent species are falling out of synch with one another. This is a special risk to migratory species that have evolved intricate migration behaviors timed with seasonal events across multiple locations.
Such precise migratory strategies enable these species to survive the winter elements, breed, and feed themselves and their young in synchrony with seasonal light, temperatures, weather patterns, and the life cycles of plants, insects and other animals.
Dire predictions are emerging daily for species that depend upon our most climate change-vulnerable habitats: especially those adapted to cold climates and coastal life and those that are highly specialized. Time is of the essence for all of these species; without action, we could lose many of them within our lifetimes.
Sources
- http://www.ipcc.ch/pdf/assessment-report/ar4/syr/ar4_syr_spm.pdf
- http://www.sciencemag.org/cgi/content/abstract/321/5894/1340
- http://www.nature.com/nature/journal/v453/n7193/abs/nature06937.html
- http://cmsdata.iucn.org/downloads/climate_change_and_species.pdf
- http://www.jstor.org/pss/2641830
- http://www.pnas.org/content/100/21/12219.full.pdf
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