Norway's Gro Brundtland said it will take a worldwide effort to slow and ultimately reverse global climate change.
While conceding the task is daunting, Brundtland believes it's achievable by the middle of this century, if the world's nations can put aside their political differences and pull together.
"We can turn this around (reducing air pollutants) 60 to 70 percent by 2050," said Brundtland, during a telephone interview from her hotel in Nice, France. "We can change the (temperature) curve downward with a concentrated effort.
"It has to be done. We still will have (climate change) effects to deal with, but it is possible."
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That's the message Brundtland, a United Nations special envoy on climate change, will carry to Stockton on Thursday, when she's scheduled to speak at the University of the Pacific.
As a special envoy, Brundtland represents the 2,000 scientists who serve on the U.N.'s Intergovernmental Panel on Climate Change. That group shared the Nobel Peace Prize with former Vice President Al Gore last week for helping increase worldwide awareness about global warming.
A variety of chemical compounds in the atmosphere might act as "greenhouse gases," warming temperatures in the process.
As sunlight passes through the gases and strikes the ground, some is reflected back into the atmosphere as infrared radiation. Greenhouse gases absorb this radiation or heat and trap it in the atmosphere.
Some of these gases -- water vapor, carbon dioxide, methane, nitrous oxide -- can occur naturally; others result from human activity or products, such as propellants used in aerosol cans.
But there's no question, according to Brundtland, that human activities and products have dramatically heightened the greenhouse gas effect.
The Intergovernmental Panel on Climate Change reported earlier this year that global warming is "very likely" caused by man. Many scientists around the world share that opinion.
"The scientific evidence is indisputable," Brundtland said. "Major changes in climate are due to man's activities. And scientists today say climate is changing faster than they previously thought. That's why we must have a worldwide approach."
Brundtland has been a player on the world health and environmental stages since the mid-1970s.
A medical doctor and scientist, Brundtland was the first woman to serve as environmental minister, and later prime minister, of Norway.
From 1998 to 2003, she was director-general of the World Health Organization.
Brundtland said global warming, if it remains unchecked, also will have serious consequences for human health.
Worldwide warming temperatures, she said, will give rise to new diseases and allow others that have been controlled or eradicated to return and spread to new locations.
Malaria and other tropical diseases and viruses, for example, could move into regions of the world where it never before existed.
"We're seeing malaria coming back in places where it had disappeared," she said. "We're also seeing it turn up in places where it never has been before."
Diseases could make comeback
Brundtland said other diseases such as smallpox, which have been virtually eradicated worldwide, also could return with a vengeance.
Brundtland was at the WHO in February 2003, when the SARS (severe acute respiratory syndrome) virus first surfaced in Asia.
In just a few months, the illness spread to more than two dozen countries in North America, South America and Europe before it was contained.
"We started tough actions," Brundtland said. "We restricted travel to the areas where the outbreak occurred and by June, the virus was stopped in its tracks."
The WHO reported that 8,098 people contracted the virus. Of those, 774 died. In the United States, just eight SARS cases were confirmed.
Brundtland said international cooperation -- scientists sharing data and theories and working cooperatively -- was the key reason behind the relatively quick containment of the disease.
That same approach is needed, she said, to combat and ultimately reverse global warming.
Although Brundtland said she's not familiar with all of the climate change consequences facing California's Central Valley, there are similarities between it and other agricultural areas whose water supplies are dependent upon melting mountain snow.
The same airborne pollutants that scientists say will reduce the size and location of the Sierra Nevada snowpack by the end of this century are causing similar headaches worldwide.
"There are no borders at work; we all breathe the same atmosphere," Brundtland said. "You cannot isolate one country or one state. What one nation or one state tries to do on its own (to reduce air pollutants) will never be sufficient."
Brundtland will speak at 6:30 p.m. Thursday in the Faye Spanos Concert Hall. The lecture will be broadcast the next day over the Pacific iTunes U site. It can be accessed by going to itunes.pacific.edu, but you must have iTunes installed on your computer to access it. Bloggers may send questions until noon Thursday to DeanSIS@pacific.edu.
Bee staff writer Michael G. Mooney can be reached at firstname.lastname@example.org or 578-2384.