Global warming would affect Southwest
Aug 13, 2009 2:26 PM, By Ron Smith, Farm Press Editorial Staff
Whether climate change will occur or not and whether changes result from human activity or not, cautious Southwest businessmen, including farmers and ranchers, should plan accordingly.
IRRIGATION MANAGEMENT may become more important in the future if climate changes affect the Southwest as much as some scenarios predict.
“We have some time,” said Gerald North, distinguished professor of atmospheric sciences and oceanography at Texas A&M University.
North, speaking at the annual Texas Ag Forum in June in Austin, said the Southwest agriculture industry should consider possible changes in business plans, “whether climate change occurs or not.”
He said research and observations, augmented by satellite surveys in recent years, indicate that climate change is occurring and that the Southwest will be vulnerable, with drought approaching levels of the 1930s Dust Bowl and the 1950s drought. “Data suggest annual precipitation could dip that low some years,” he said “Computer models indicate that precipitation in the Southwest will decline.”
He said Texas may be particularly vulnerable, in part because of its varied climate, part of which is sub-tropical. “In a worst case scenario, Texas rivers frequently will not make it all the way to the Gulf Coast,” he said. “Texas will get hotter. East Texas likely will be wetter; West Texas likely will be dryer.” He said I-35 could be the demarcation zone; West of the Interstate will be drier if climate change does occur.
Wildfires likely will be more common with a dryer climate. Also, as populations inch out into rural areas potential for wildfires increases, North said. “It’s too soon to tell if climate change will affect hurricanes but they could get stronger.”
North said temperatures over the past 20 years have been higher than at any time in the past 1,000 years.
He said he is not a preacher proselytizing about the imminent threat of climate change. “I’m neither an alarmist nor a skeptic. I started off as a skeptic but am now slightly on the conservative side.”
He said research and satellite observations over the past 15 years made him more aware of “the big picture.” Recent data, he said, show global air temperatures warming in a steep curve around 1980 and a “slight cooling recently. That may be a short break before it starts heating again. That represents the main thinking in the field, people in the best position to determine if (global warming) is man’s activity.
He said surveys show “95 percent of respondents who have published papers in journals, people in the field,” say global warming is influenced by human activity.
North said warming is occurring, “a little more toward the poles. We could expect an ice-free Arctic for a month or two a year within the next decade.”
He said observers have seen huge ice plates melt away on Antarctica. Greenland ice is also melting rapidly. A rise in sea level from melting ice “depends on the expansion of water and could be a foot or two. Or it could be big.
“Some studies indicate that even if the polar ice melts it could take 100 years to get sea levels to rise to its full rate. But sea levels will rise,” he said.
He said for the last 10,000 years carbon dioxide levels were “relatively steady. But since the Industrial Revolution we’ve seen a steep spike. We have a lot of carbon in the air from burning fossil fuels.”
The rate is so high that the natural system can’t absorb the carbon. “It takes 200 years to reduce the trend if we cut back,” he said. And the problem feeds on itself. As the earth become warmer it emits more carbon into the atmosphere.
A greenhouse effect is essential for life on earth, North said. “It’s essential to keep the planet warm enough. But with an increase in carbon dioxide or other greenhouse gas the outgoing radiation into space goes down; the planet warms and incremental increases in planet temperature result.”
North said the Southwest typically gets airflow that originates along the Equator, where it begins as moist air that generates frequent rainfall and creates the lush rainforests. As it circles westward and north, the air rises and becomes dryer as it drops into the Southwest.
He said the jet stream has been moving north for the last 40 years, leaving areas to the south dryer. “As temperatures rise, Texas will take a hit; at least parts of it will.”
He says two questions concern him. Is it warming and what’s the cause? “What to do about it is a value judgment and political. Some economists believe putting off some actions (on global warming) makes sense. Most economists favor a carbon tax instead of cap and trade.”
Mark Hussey, vice chancellor and dean for agriculture and life sciences at Texas A&M, said several different viewpoints exist on climate change and what to do about it. “In 50 to 200 years, some suggest Texas will be more forested because of climate change. Others say it will be more arid. Pessimists expect a desert.”
Regardless of what Texas looks like in a half a century or two centuries, Hussey said Texas A&M will “remain focused on providing technology to help producers remain competitive. If we do see climate change, Texas, because of its size and variability in climate, will be sensitive to that change.”
He said Texas is the leading producer of carbon in the country, “double any other state. A&M research is gauging the impact of carbon dioxide and climate change,” Hussey said. “We’re looking at communities, rangelands, cropping systems, carbon sequestration, tillage practices and conversion of croplands to grasslands. We are looking at the economic impacts and best use procedures.”
email: rsmith@farmpress.com
(New Course)
