|Asunto:|| (En ingles) 22-SEP: Nuevas evidencias para el calentamiento global:|
|Fecha:||Viernes, 29 de Septiembre, 2000 21:02:11 (-0400)|
|Autor:||Jose Rafael Leal <trastor @..........net>
Nuevas evidencias para el calentamiento global:
UT Austin biologist develops new evidence for global warming
September 22, 2000
Mary Lenz, Office of Public Affairs
Office of Public Affairs
P O Box Z
FAX (512) 471-5812
AUSTIN, Texas -Dr. Camille Parmesan, an assistant professor of biology at
The University of Texas at Austin and an expert on non-migratory butterfly
species, has worked with world climate experts to document new evidence of
global warming. The research will be featured in the Sept. 22 issue of the
According to scientists with the National Oceanic and Atmospheric
Administration (NOAA) and the National Center for Atmospheric Research,
temperature and precipitation records collected for the past century point
to a slight increase in warmer weather throughout the world, accompanied by
an increase in both the number and the severity of extreme weather events.
The scientists documented that rising temperatures and extreme weather also
are having an impact on population, behavior, distribution and even the
physical appearance of a wide variety of animals and plants in the wild. Dr.
David R. Easterling, scientific director of NOAA's National Climatic Data
Center in Asheville, N.C., is lead author on the paper.
Parmesan said the paper is especially significant because it coordinates
data collected through the years on climate change with basic research on
wildlife and with recent trends in wildlife attributed to climate change.
Scientist have plenty of evidence that extreme weather events can cause
everything from bleaching of coral reefs and smaller beak size in some
species of birds to changes in mating behavior of African elephants.
Parmesan said the increasingly rapid extinction rate of species around the
globe make it critical "to understand the specific impacts of climate change
on those trends."
Parmesan said that, over many decades, a series of extreme weather events is
believed to underlie a gradual range shift in the Edith's Checkerspot
(Euphydryas Editha), a butterfly named for the checked patterns on its
black, orange and cream-colored wings. This butterfly, found in the western
part of North America, has moved northward and to higher altitudes over the
past 100 years. Parmesan linked extreme weather events to the permanent
disappearance of entire local populations of the colorful insects.
Parmesan said when reviewing research by other biologists, what really
surprised her was that "every time (a Checkerspot) population went extinct,
it was connected with an extreme climate year. The l976-77 California
drought caused a lot of local population extinctions, and 20 years later
they were still extinct." Due to the l983 El Nino, the snow never melted in
some areas of Northern California's Gold Lake and the butterflies never
emerged, she said.
Extreme weather events, from hurricanes to blizzards, are nothing new. But
in the past, populations of animals were larger. When, for example, they
shifted territory in response to a drought, they didn't run into farmland or
urban areas. "Especially when you are talking about an endangered species
that already is restricted to a very small habitat, one severe weather event
can wipe out an entire species," Parmesan said.
Weather records reviewed for the study document an increase in the average
global temperature of about 0.6 degrees centigrade since the beginning of
the 20th century and a decrease in the number of days each year below
freezing. Climate researchers have been looking for a link between the
changes and increasing greenhouse gases from human activities. While some
uncertainty remains, the evidence of such a link, especially in the past few
decades, is growing stronger.
Parmesan said a one or two-degree increase in global temperature in the next
century doesn't sound like very much, but the increase "makes local extreme
weather events even more extreme. In a particular year, the maximum high
temperature in the summer could be 10 degrees hotter, and precipitation
increasingly is coming down as floods," Parmesan said. "This is something
that is happening now."
For more information, contact Dr. Camille Parmesan at the College of Natural
Sciences section on integrative biology at (512) 471-5209. For images of
Edith's Checkerspot butterflies, contact Marsha Miller at (512) 471-3151.