Vanishing of frogs, toads tied to global
warming
USA Today
By Traci Watson
January 12, 2006
A team of biologists and climate scientists says in a new study that it has
linked the extinction of a widespread group of animals to global warming.
Writing in Thursday's issue of the journal Nature, the scientists say that
more than 60 closely related frog and toad species have vanished from the
tropical forests of Latin America during the last few decades, partly because
of warming temperatures. The team says this is the first time such a connection
has been made.
The research team found a "near lock-step (link) between the timing of
losses and changes in climate," said lead scientist Alan Pounds of the
Monteverde Cloud Forest Preserve and Tropical Science Center in Costa Rica.
"It's a very striking pattern, and it's hard to find another explanation for
it."
The group did not identify the other contributing causes. Pounds and his
team say the warmer temperatures of the late 20th century led to better growing
conditions for a fungus that kills frogs and toads.
Other scientists expressed skepticism about the findings. Stephen Corn of
the U.S. Geological Survey said the dates recorded for extinctions may not be
entirely reliable. The University of Colorado's Cynthia Carey questioned why
the new work ignores extinctions of related species after 1998.
The Earth's average temperature rose roughly 1 degree in the 20th century
and could rise 10 more degrees by 2100, according to an international group of
scientists convened by the United Nations.
That group and other researchers attribute the warming trend to the use of
coal, oil and other fossil fuels, which emit carbon dioxide when burned.
Buildup of the gas in the atmosphere can trap heat.
Scientists already have evidence linking higher temperatures to changes in
the behavior or range of hundreds of species, such as flowers that bloom
earlier in the year.
Scientists in the U.N. group predicted in 2001 that global warming would
produce a wave of extinctions. They did not predict they'd see evidence so
quickly.
"None of us expected that we'd be seeing massive extinctions in five years,"
said Camille Parmesan of the University of Texas. She was not on the Pounds
team but found the link between extinction and global warming "very
convincing."
Pounds and his colleagues compared when a species was last seen with climate
data. They found that roughly 80% of the extinct species were spotted for the
last time just after a particularly hot year. For example, the Monteverde
harlequin frog hasn't been seen since 1988, one year after a warm year.
Pounds and his team theorize that the changes in the region's climate are
encouraging the growth of a parasite that spread around the world in the 1960s
and is a known killer of frogs and toads. Pounds said more work needs to be
done to nail down this possibility.
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