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SIERRA VISTA — Climate change is a little too tame.
Climate disruption seems more fitting, said the city of Tucson’s sustainable development administrator.
David Schaller talked about some of the local efforts to solve the global problem of climate change along with local scientists during a forum sponsored by the Unitarian Universalist Church of Southeastern Arizona Social Action Committee and Earth Charter U.S. at the University of Arizona South on Saturday.
Zach Guido, associate staff scientist for Climate Assessment for the Southwest at the University of Arizona, explained the science of climate change and its impacts.
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For hundreds of thousands of years, Earth’s temperatures have shifted naturally within a 20-degree Fahrenheit range because of the Earth’s changing alignment and distance from the sun, he said.
Measurements show Earth’s carbon dioxide levels have fluctuated between 180 and 290 parts per million during the past 700,000 years, he said. But those levels have been only increasing beyond those ranges in recent decades.
“We are currently at 383 (parts per million),” Guido said.
In Earth’s atmosphere, greenhouse gases such as carbon dioxide are a part of a balancing act. Too little and Earth would be too cold.
“If we had too many, we’d be like Venus and it would be too hot,” he said.
Whether or not carbon dioxide has been the cause or effect of rising temperatures, carbon dioxide amplifies rising temperatures.
Besides increasing carbon dioxide levels, other indicators such as tree rings point to one conclusion, he said.
“It’s getting warmer.”
A pattern of increasing temperatures has also been seen locally, based on temperatures taken at Fort Huachuca and Sierra Vista since 1955, he said.
Scientific scenarios predict Arizona temperatures to rise by three to four degrees in the winter and up to six degrees in the summer within the next 40 years, he said.
It’s less clear how precipitation will be affected, but snow is likely to decrease and less snow pack will mean drier landscapes, making wildfires a more common danger, Guido said.
Besides higher temperatures, carbon dioxide levels could change the make up of local flora, said Mitchell Pavao-Zuckerman, associate research scientist for the University of Arizona’s Biosphere 2 and B2 Earth Science.
Since he began learning about climate change in 1980s, he said it’s been “scary and interesting” to see those effects begin to happen.
One example came from the Edith’s Checkerspot butterfly. A 1996 study showed the butterflies began going extinct in their southern range in California as blooms began coming out earlier, which was before the butterflies had emerged.
In other studies, carbon dioxide levels have been raised to see the effects on plant species. In one study, carbon dioxide is shown to increase the growth and toxins in poison ivy. In another study, increased carbon dioxide levels increased non native grasses, Pavao-Zuckerman said.
“The native species doesn’t do as well,” he said.
There is no “magic bullet” to solve these issues, he said. The challenge will be to come up with local solutions to a global problem.
Some are simple fixes. Having a white reflective roof, compared to darker shingles, can reduce home temperatures by 20 to 30 degrees, he said.
The city of Curitiba, Brazil has found a way to reduce it’s fuel consumption by 25 percent less than other cities of its size in Brazil by making its public transportation more convenient for users. An estimated 70 percent of all trips in the city are provided by its public transportation system, he said.
But cities much closer than Curitiba are offering other examples as well.
David Schaller, sustainable development administrator for the city of Tucson’s Office of Conservation and Sustainable Development, talked about the efforts in Tucson.
In 2006, the city of Tucson joined the Mayor’s Climate Protection Agreement, which was started by Seattle’s mayor in 2005 and has been adopted in 884 cities since, he said. The idea behind the agreement is to make the Kyoto Protocol a city goal.
One goal is to reduce greenhouse gas emissions by 7 percent of their 1990 levels by 2012. A recently completed greenhouse gas inventory by the city shows the city’s greenhouse gas levels increasing 34 percent from 1990 to 2006.
But a reduction has been seen in some sectors, he said. Residential and industrial greenhouse gas emissions were reduced between 2005 and 2006.
Whether it was an early indication of economic downturn or effective reduction efforts isn’t yet known, he said.
The city will soon be forming a climate change mitigation and adaptation plan.
“Even if we’re not going to get a 41 percent reduction in the next four years, we have to start,” Schaller said.
The forum was a part of the Earth Charter Global Community Summits on Climate Change. This is the first year a group in Sierra Vista has participated.
Herald/Review reporter Laura Ory can be reached at 515-4683 or by e-mail at laura.ory@svherald.com.
ON THE NET
• Earth Charter U.S.: http://www.earthcharterus.org/
Paul Arnold wrote on Oct 12, 2008 10:00 PM:
There is not one of these "experts" who knows what a quadratic equation is. Not one could define a BTU (British Thermal Unit).
Twenty yours ago it was nuclear winter, then global warming, now climate change. 1900 we were running out of oil!
ONE CRISIS AFTER ANOTHER.
Anything to panic the voters.
IT IS ALL A MONUMENTAL LIE!
AWAKE AMERICA, the ENEMY IS WITHIN THE GATES! "