Let's see, there's the fact that global warming isn't due to cars & manufacturing. There's the thing about things "could be" worse. That means they "could be" better or they "could be" the same. Then there's the part about unprecedented followed by precedence.
Journalism certainly isn't what it used to be.
Journalism certainly isn't what it used to be.
07 Oct 2004 20:39:28 GMT Source: Reuters
By Maggie Fox, Health and Science Correspondent
WASHINGTON, Oct 7 (Reuters) - The U.S. West, already suffering from a long drought, could be in for worse if past patterns hold up, experts said on Thursday.
A study of tree rings showed that a 400-year-long drought dating back 1,000 years ago occurred during a time when the planet was warmer than usual -- like today.
If the pattern holds up, it could mean a cruel drought, the researchers write in this week's issue of the journal Science.
"The western United States is experiencing a severe multiyear drought that is unprecedented in some hydroclimatic records," the researchers, led by Edward Cook of the Lamont-Doherty Earth Observatory in New York, wrote.
"Using gridded drought reconstructions that cover most of the western United States over the past 1,200 years, we show that this drought pales in comparison to an earlier period of elevated aridity and epic drought in AD 900-1300, an interval broadly consistent with the 'Medieval Warm Period'," they added.
"If elevated aridity in the western United States is a natural response to climate warming, then any trend toward warmer temperatures in the future could lead to a serious long-term increase in aridity over western North America."
Cook, an expert in tree rings and climate, said the culprit seems to be a weather pattern called La Nina.
It is marked by upwelling of cold water from the bottom of the Pacific in eastern tropical waters. Climate models show this reduces rainfall in the U.S. West.
"Modeling results now suggest the same thing may have happened during the so-called Medieval Warm Period 800 to 1,000 years ago," Cook said in a telephone interview.
During that time the world was a little warmer than average.
"It looks like the long period of elevated aridity in the Western United States that has been reconstructed from my tree rings could very well be associated with prolonged La Nina-like conditions," Cook said.
Cook said he did not know how long it would last.
"This says nothing about what the future is going to be. But if warming increases in the future we ought to at least consider the possibility that we are going into a more drought-prone period than we have seen over the last few hundred years," he said.
"It's a bit of a cautionary tale. We ought to at least think about the likelihood of this happening in the future. How one prepares for this is anyone's guess."