THIRSTY CITY: The 20th century was unusually wet in the Atlanta region, according to tree ring records, which may have set unrealistic expectations for local water use.
Image: Wikimedia Commons/Atlantacitizen
At the height of the drought that gripped the southeastern United States between 2005 and 2007, the water level of the massive reservoir that provides Atlanta's drinking water dropped 14 feet below normal.
The dry spell intensified an ongoing legal battle among Georgia, Florida and Alabama over fresh water supplied by the Apalachicola-Chattahoochee-Flint River Basin, which runs through the three states.
But a new study suggests things could have been far worse.
Climate records gleaned from tree rings show the recent drought pales in comparison to droughts that hit the region in the 17th and 18th centuries. In fact, the research suggests that the 20th century stands out as an unusually wet blip in the 350-year history reconstructed using those tree rings.
"This is a reminder of what could happen," said the study's lead author, Neil Pederson, a forest ecologist at Columbia University's Lamont-Doherty Earth Observatory.
The study, published yesterday in the journal Environmental Research Letters, doesn't project whether climate change will make drought more or less likely in the future, he noted.
"The importance of this kind of work is showing that in these areas where there are a lot of people, severe droughts are not unusual," Pederson said. "We have to be prepared for that."
The new study draws on previously collected tree rings, including bald cypress samples analyzed by University of Arkansas scientists, and new samples taken throughout the Apalachicola-Chattahoochee-Flint River Basin.
Research began 'out of the blue'
"The study came about partly because one of the co-authors on this paper, Will Blozan" -- an arborist based in North Carolina -- "emailed me out of the blue one day and said, 'Hey, would you like to core some old-growth oaks just north of Atlanta?'" Pederson recalled. "I went, 'Yeah, wow, of course I would.'"
Later, the team tapped a stand of tulip poplars growing in north Georgia that were scouted by study co-author Jess Riddle, a graduate student at the State University of New York's College of Environmental Science and Forestry. Those trees ranged between 350 and 470 years old, Pederson said.
The tree-ring record the researchers cobbled together confirms earlier research that suggests the mid-18th and early 20th centuries were the driest periods in the southern Appalachian Mountains since at least 1700, while extending the record further back in time to document a "substantial" drought from 1669 to 1709.
And while the drought that hit the region in 1986 stands as one of the worst of the past 350 years, the 20th century -- when the agreements that govern the basin's water use were first established -- was the wettest period in the region since the late 1600s.
"We're developing our habits of how we use water during one of the wettest periods of the last 300 years," Pederson said. "That might not make us well-prepared for future droughts."
Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500
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6 Comments
Add CommentThe study can be found with supplemental data here:
Reply | Report Abuse | Link to thisA long-term perspective on a modern drought in the American Southeast: http://iopscience.iop.org/1748-9326/7/1/014034
Would Scientific American please consider linking to the original research that they report on? If people knew that a Scientific American story always had links to the original research it would probably increase your hit rate too.
Of the four categories illustrated projecting hydroclimatic change over the long term in the "JOURNAL OF QUATERNARY SCIENCE," only one - evaporation - is expected to increase in the Atlanta area. Precipitation, soil moisture content, and runoff are all projected to be approximately the same for the foreseeable future. Essentially, the current projection is for no expected change, neither more nor less drought, resulting from climate change.
Reply | Report Abuse | Link to thisRain depends on which the way the wind blows the moist air. (for the most part)
Reply | Report Abuse | Link to thisIt's not possible to predict, if the climate will, or will not change in the future. (It's to complicated to calculate all the necessary factors accurately)
Your vocabulary is wonderful, but what you say lacks any foundation based on facts. In case you haven't notice, weather is not all the predictable.
I'm not convinced about the tree rings that show water changes either.
That sounds shaky.
Dear Bops,
Reply | Report Abuse | Link to thisWhile your skepticism is impressive and trendy, it is too on shaky foundation. Try doing some research on predicting climate change. The models are getting better and predictions made a decade or two ago are generally on track [pointing to web sites sponsored by the oil industry do not count].
Second, you can learn a lot about this study by actually reading it yourself. The paper is open access. Download it. You might find it interesting.
More importantly, think about plant growth a little. Plants use photosynthesis to produce energy for themselves. This energy goes into plant growth. Trees are plants. Trees need energy to grow rings. The equation for photosynthesis is: Carbon dioxide + sunlight + _water_ = produce oxygen + carbohydrates (energy).
I'd say your foundation of knowledge is less than shaky.
Some good science untainted by the modern fad.
Reply | Report Abuse | Link to thisInteresting article and comments. Will global warming result in tropical moisture belts shifting into the Atlanta area? Does anyone have any reports on this?
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