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By Michael Melampy
 If you have seen an Inconvenient Truth, Al Gore’s documentary
about global warming, you are probably convinced that climate change
is at least something that we should be worried about and more likely
something that must be addressed sooner rather than later. Gore’s
film did an excellent job of outlining the process of climate change
and its likely consequences. However, the film was short on specifics
concerning the impact on biodiversity. Polar bears are going to be in
trouble, but they represent only the tip of the metaphorical melting
iceberg.
A number of studies published over the last decade, especially by entomologists,
have shown shifts in species ranges that seem to reflect the impact of
global warming. An article published in the journal Trends in Ecology
and Evolution (August 2006) by Thomas, Franco and Hill notes that butterfly
ranges are retreating uphill in the Sierra de Guadarrama mountains of
central Spain. The retreat corresponds with a 1.3°C increase in average
temperatures over the past 35 years. As the butterflies retreat, their
areas of distribution become increasingly restricted as higher elevation
peaks offer less land area with appropriate temperatures and host plants.
Although more data are needed to document the rate at which geographic
ranges are decreasing, continued warming could shrink ranges to the point
where populations and species become extinct. Population level extinctions
of the Edith’s checkerspot butterfly due to range shrinkage have
already been documented in California.
 Another group of organisms that is undergoing global decline suggestive
of the impact of climate change is the amphibians, particularly frogs.
In tropical Latin America, more than 67 species of harlequin frogs (genus
Atelopus) are presumed extinct according to Thomas et al. These were
common and widespread species found throughout the mountains of Central
and South America as recently as 20 years ago. Research indicates that
warming night-time temperatures and lowered maximum daytime temperatures
(due to increased cloudiness) have created ideal conditions for the spread
of pathogenic fungi that attack and kill the frogs.
While butterflies and frogs may not grab out attention the way polar
bears do, ecologically they may be more important than bears. Adult butterflies
pollinate a large variety of plants and their larvae are important herbivores.
As they go extinct, plant distributions and abundances are likely to
change in unpredictable and often undesirable ways. Likewise, frogs play
important roles as insect predators; their absence will have an impact
on insect abundance. By allowing climate change to continue, we are conducting
uncontrolled ecological experiments on a massive scale. Fundamental ecosystem
services, such as nutrient cycling and crop pollinaton, could easily
be disrupted to the point that our agricultural productivity declines.
Prudence would dictate that we heed Al Gore’s warning and take
prompt action to reduce human activities that contribute to climate change.
Photo 1 Credit: Nickles, Jon R, U.S. Fish and Wildlife Service
Photo 2 Credit: Smith, Charles H., U.S. Fish
and Wildlife Service
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