Post by KNOWTHIS on Jan 9, 2007 1:06:56 GMT -5
www.svherald.com/articles/2007/01/07/local_news/news5.txt
UA specialist: Scientists agree global warming is happening
There is no dissent in the legitimate scientific community that unprecedented global warming is under way and it is connected to the increased greenhouse gases in the Earth’s atmosphere, according to a scientist who spoke Saturday at a free lecture at the University of Arizona South.
About 60 people attended. University of Arizona climate science extension Specialist Mike Crimmons, Ph.D., talked about how the trends toward a warmer earth are expected by the world’s scientific community to affect the entire planet’s future and why. He also talked about the predicted impact on the weather in the American Southwest.
“There is really no debate over the causality,” he said.
The warming trend is evident and undeniably related to increased greenhouse gases in the earth’s atmosphere such as water vapor, carbon dioxide, methane, nitrous oxide and other trace gases, Crimmons said.
Though atmospheric content of greenhouse gases has cyclically climbed and dropped as ice ages have come and gone in the last several hundred thousand years, the content have never surpassed more than 300 parts per million.
That is, until the current trend emerged, he said. The atmospheric content of greenhouse gases is now about 380 parts per million.
“Those greenhouse gas concentrations are now in uncharted territory,” Crimmons said, even when compared with previous eras of high greenhouse-gas concentration in the Earth’s air.
Retroactive measurements to estimate the history of the Earth’s atmosphere and temperature are taken through tools and observations such as isotope reconstruction, coral reefs, old-growth tree rings and ice caps, he said.
It is not coincidental this trend of unprecedented increase in temperature, carbon dioxide-concentrations and carbon-emissions began in the 19th century with the start of the industrial revolution, he said.
Estimating how much humans contribute to the increased temperature and how much is caused naturally is important to study global warming, though the warming trend itself is a reality, Crimmons said. This enables scientists to understand how much humans can do to affect the trend.
Greenhouse gases accumulate mainly in the troposphere and are permeable to shorter-wave radiation from the sun as it enters the atmosphere. When energy is released from the Earth’s surfaces in a longer-wave form, its escape from the atmosphere is affected by those gases. This raises the atmosphere’s temperature.
The greenhouse gases are not “intrinsically evil,” rather, they are fundamental for life on this planet. Too much is still not good though, Crimmons said.
“Water vapor is indeed the strongest greenhouse gas,” he said.
At the current rate of warming, the planet is predicted to be about 7.2 degrees Fahrenheit warmer in 100 years, he said, though predictions vary, depending on various scenarios possibly occurring between now and then. Crimmons said such factors include the uncertain thermal reactions by the world’s oceans and the extent of Chinese and United States carbon emission mitigation efforts in that time, for example.
“We have to think about what is a temperature change we can live with,” Crimmons said.
Predicting a change in precipitation trends, as a result of global warming is much more difficult, he said. The estimation for the Southwest sounds familiar though — “The best idea is to plan on Arizona being an arid place, which it normally is, but temperatures will be warmer,” Crimmons said.
Predictions for the Southwest are that of much less snowfall and much more rainfall, and that is a problem for areas which depend on ice-pack runoff for water sources. Surface reservoirs which handle ice-pack run off wouldn’t be able to handle the subsequent floods, Crimmons said.
The Gulf Stream effect warms Northern Europe, and interruption of the Gulf Stream current caused by global warming — for which there is historical evidence — would make those lands colder, ironically. However, no such inverted effect could be expected for the Southwest, Crimmons said.
Also, because of the winter cold weather systems subsequently not reaching as far south, Southwest temperature increases would be more pronounced globally than in more northerly latitudes, he said.
Such predicted warmer temperatures would mean higher evaporation and transpiration rates, more stress on vegetation, water loss in reservoirs, less snow, more rain and less snow pack runoff in the spring.
It’s not too late, but there is no time to lose — “we need to demand action at the federal policy level,” Crimmons said. An understanding of the energy each of us use, and the true cost of that use is important on a local scale, he said, and complimented the state of California for its progressive attitude toward this issue.
“California is effectively acting as its own country now, coordinating with Europe,” Crimmons said.
While the nation must come together to understand and react to the situation, so must the global community, he said.
A man in the audience expressed pessimism that our bureaucracy is capable of any such humanitarian or environmentalist policy. Another man said he believed Saturday’s lecture to have been to optimistic, as he considered overfishing of the world’s oceans another terminal situation out of hand, catastrophically affecting the Earth’s food chain. Another woman complained that while all local elected officials were invited, only City Councilwoman Hank Huisking attended.
UA specialist: Scientists agree global warming is happening
There is no dissent in the legitimate scientific community that unprecedented global warming is under way and it is connected to the increased greenhouse gases in the Earth’s atmosphere, according to a scientist who spoke Saturday at a free lecture at the University of Arizona South.
About 60 people attended. University of Arizona climate science extension Specialist Mike Crimmons, Ph.D., talked about how the trends toward a warmer earth are expected by the world’s scientific community to affect the entire planet’s future and why. He also talked about the predicted impact on the weather in the American Southwest.
“There is really no debate over the causality,” he said.
The warming trend is evident and undeniably related to increased greenhouse gases in the earth’s atmosphere such as water vapor, carbon dioxide, methane, nitrous oxide and other trace gases, Crimmons said.
Though atmospheric content of greenhouse gases has cyclically climbed and dropped as ice ages have come and gone in the last several hundred thousand years, the content have never surpassed more than 300 parts per million.
That is, until the current trend emerged, he said. The atmospheric content of greenhouse gases is now about 380 parts per million.
“Those greenhouse gas concentrations are now in uncharted territory,” Crimmons said, even when compared with previous eras of high greenhouse-gas concentration in the Earth’s air.
Retroactive measurements to estimate the history of the Earth’s atmosphere and temperature are taken through tools and observations such as isotope reconstruction, coral reefs, old-growth tree rings and ice caps, he said.
It is not coincidental this trend of unprecedented increase in temperature, carbon dioxide-concentrations and carbon-emissions began in the 19th century with the start of the industrial revolution, he said.
Estimating how much humans contribute to the increased temperature and how much is caused naturally is important to study global warming, though the warming trend itself is a reality, Crimmons said. This enables scientists to understand how much humans can do to affect the trend.
Greenhouse gases accumulate mainly in the troposphere and are permeable to shorter-wave radiation from the sun as it enters the atmosphere. When energy is released from the Earth’s surfaces in a longer-wave form, its escape from the atmosphere is affected by those gases. This raises the atmosphere’s temperature.
The greenhouse gases are not “intrinsically evil,” rather, they are fundamental for life on this planet. Too much is still not good though, Crimmons said.
“Water vapor is indeed the strongest greenhouse gas,” he said.
At the current rate of warming, the planet is predicted to be about 7.2 degrees Fahrenheit warmer in 100 years, he said, though predictions vary, depending on various scenarios possibly occurring between now and then. Crimmons said such factors include the uncertain thermal reactions by the world’s oceans and the extent of Chinese and United States carbon emission mitigation efforts in that time, for example.
“We have to think about what is a temperature change we can live with,” Crimmons said.
Predicting a change in precipitation trends, as a result of global warming is much more difficult, he said. The estimation for the Southwest sounds familiar though — “The best idea is to plan on Arizona being an arid place, which it normally is, but temperatures will be warmer,” Crimmons said.
Predictions for the Southwest are that of much less snowfall and much more rainfall, and that is a problem for areas which depend on ice-pack runoff for water sources. Surface reservoirs which handle ice-pack run off wouldn’t be able to handle the subsequent floods, Crimmons said.
The Gulf Stream effect warms Northern Europe, and interruption of the Gulf Stream current caused by global warming — for which there is historical evidence — would make those lands colder, ironically. However, no such inverted effect could be expected for the Southwest, Crimmons said.
Also, because of the winter cold weather systems subsequently not reaching as far south, Southwest temperature increases would be more pronounced globally than in more northerly latitudes, he said.
Such predicted warmer temperatures would mean higher evaporation and transpiration rates, more stress on vegetation, water loss in reservoirs, less snow, more rain and less snow pack runoff in the spring.
It’s not too late, but there is no time to lose — “we need to demand action at the federal policy level,” Crimmons said. An understanding of the energy each of us use, and the true cost of that use is important on a local scale, he said, and complimented the state of California for its progressive attitude toward this issue.
“California is effectively acting as its own country now, coordinating with Europe,” Crimmons said.
While the nation must come together to understand and react to the situation, so must the global community, he said.
A man in the audience expressed pessimism that our bureaucracy is capable of any such humanitarian or environmentalist policy. Another man said he believed Saturday’s lecture to have been to optimistic, as he considered overfishing of the world’s oceans another terminal situation out of hand, catastrophically affecting the Earth’s food chain. Another woman complained that while all local elected officials were invited, only City Councilwoman Hank Huisking attended.