Posted on: Monday, February 28, 2005
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By Jan TenBruggencate
Advertiser Science Writer
The management of water resources and of severe rainfall events will be an important issue for Hawai'i and many other parts of the world in a future that includes global warming, according to Kevin Trenberth, head of the climate analysis section at the National Center for Atmospheric Research in Boulder, Colo.
Trenberth was in Honolulu recently for a climate meeting coordinated by the International Pacific Research Center, a part of the University of Hawai'i's School of Ocean and Earth Science and Technology.
Warming of the world's climate, to Trenberth's thinking, is inescapable.
"The evidence is very clear that we're changing the composition of the atmosphere," he said.
He believes that is translating to changes in the climate: "There's some real strange patterns going on right now," he said.
"NASA just reported that 2004 was the fourth-warmest year on record. The warmest was in 1998, when the temperatures were bolstered by an El Nino. The second- and third-warmest were 2002 and 2003. We continue to get warm years," he said.
The actual warming on average is slight, but what Trenberth finds significant is what scientists find when they look beyond the averages.
He said that for every degree of sea surface-temperature increase, there is a 7 percent increase in water vapor in the atmosphere. Between them, the warmth and the water vapor relate to the strength of tropical storms and an increase in heavy rainfall events.
Trenberth said that U.S. statistics already show an increase in the heaviest rainfall events — the ones that cause flooding.
"Changes in the character of precipitation is in my mind one of the most important things. It's the difference between gentle rains and gully-washers," he said.
The worst rainfall events, he said, would have a greater intensity but might not last as long as they did on average in the past.
The other side of the rainfall cycle is also increased, he said. "You also get stronger droughts. A lot of the heat (from increased temperatures) is going into drying out the soils."
But Trenberth does not want people to get the idea that a catastrophe is right around the corner.
"We're still talking about relatively modest increases over time," he said.
If you have an issue, question or concern about Hawai'i's environment, drop a note to Jan TenBruggencate, The Advertiser's Kaua'i Bureau chief and its science and environment writer. Reach him at jant@honoluluadvertiser.com, at (808) 245-3074 or at P.O. Box 524, Lihu'e, HI 96766.
