Killer freeze of '07 illustrates paradoxes of warming climate

Mar 03, 2008
Killer freeze of '07 illustrates paradoxes of warming climate
Oak leaves show damage from the "Easter freeze" of 2007. Some tree species were more affected by the freeze than others.

Widespread damage to plants from a sudden freeze that occurred across the Eastern United States from 5 April to 9 April 2007 was made worse because it had been preceded by two weeks of unusual warmth, according to an analysis published in the March 2008 issue of BioScience.

A destructive spring freeze that chilled the eastern United States almost a year ago illustrates the threat a warming climate poses to plants and crops, according to a paper just published in the journal BioScience. The study was led by a team from the Department of Energy's Oak Ridge National Laboratory.

The "Easter freeze" of April 5-9, 2007, blew in on an ill wind. Plants had been sending out young and tender sprouts two to three weeks earlier than normal during an unusually warm March. Plant ecologists, as well as farmers and gardeners, took note of the particularly harsh turn of the weather in early April.

"The warm weather was as much a culprit for the damage as the cold," said lead author Lianhong Gu of ORNL's Environmental Sciences Division.

"We see the paradox in that mild winters and warm, early springs make the plants particularly vulnerable to late-season frosts," Gu said. Gu's team observed satellite images and field data to establish the extent of the 2007 spring freeze. They also assessed the long-term and short-term effects on the terrestrial carbon cycle with respect to plant activity in normal years. Short-term effects were "profound," Gu said.

"In the period just after the freeze we saw a large reduction in the fraction of absorbed photosynthetically active radiation, which is a sensitive indicator of plant growth," he said. "We also noted that the regrowth in the following weeks and months did not result in the levels of plant development in previous years."

Gu's team hypothesized that the freeze could have long-term effects on forest carbon uptake because of damage the cold did to the prematurely developed plant tissues, which could affect future growing seasons. The associated carbon and nutrient losses may affect growth in future years.

Beyond devastated horticultural crops, the study noted that some species suffered more than others. Yellow poplar trees were "surprisingly" slow to put out flushes of new leaves, and white oaks were particularly hard hit with freeze damage to both new leaves and flowers. On the other hand, trees located along shorelines--where the water stores heat--and underneath dense canopies seemed to be protected from the cold.

Compounding the stress on plants, as noted in the International Panel on Climate Change's fourth assessment report, is the prospect of prolonged droughts, which also occurred in the region last summer.

"This freeze should not be viewed as an isolated event; rather, it represents a realistic climate change scenario that has long concerned plant ecologists," Gu said.

Authors on the paper include Gu, Paul Hanson, Dale Kaiser, Mac Post and Bai Yang of ORNL; Ramakrishna Nemani of NASA's Ames Research Center; Stephen G. Pallardy of the University of Missouri at Columbia, and Tilden Meyers of the National Oceanic and Atmospheric Administration's Air Resources Laboratory in Oak Ridge. The DOE Office of Science's Biological and Environmental Research program funded the studies.

Source: ORNL

Explore further: Pact with devil? California farmers use oil firms' water

Related Stories

'Map of life' predicts ET. (So where is he?)

Jul 02, 2015

Extra-terrestrials that resemble humans should have evolved on other, Earth-like planets, making it increasingly paradoxical that we still appear to be alone in the universe, the author of a new study on ...

A tale of two (soil) cities

Jul 01, 2015

As we walk along a forest path, the soil beneath our feet seems like a uniform substance. However, it is an intricate network of soil particles, pores, minerals, soil microbes, and more. It is awash in variety.

Reducing agriculture's greenhouse gas emissions

Jun 23, 2015

The overwhelming scientific consensus is that gases produced by human activity are affecting the global climate. But even if you don't believe the current warming of the global climate is caused by humans, it's only common sense that cutting back on h ...

Straw-insulated houses beat petroleum-based alternatives

Jun 18, 2015

Everybody knows one of those houses; freezing cold in winter, stiflingly hot in summer and energy guzzling all year round. Better insulation is the key to recapturing the comfort of home while cutting energy bills.

Fossils explain how life coped during snowball Earth

Jun 15, 2015

Researchers have discovered what they think are fossils of a unique red algae species that lived about 650 million years ago during a brief respite between some of the most extreme ice ages the world has ...

Recommended for you

Gimmicks and technology: California learns to save water

Jul 03, 2015

Billboards and TV commercials, living room visits, guess-your-water-use booths, and awards for water stinginess—a wealthy swath of Orange County that once had one of the worst records for water conservation ...

Cities, regions call for 'robust' world climate pact

Jul 03, 2015

Thousands of cities, provinces and states from around the world urged national governments on Thursday to deliver a "robust, binding, equitable and universal" planet-saving climate pact in December.

Will climate change put mussels off the menu?

Jul 03, 2015

Climate change models predict that sea temperatures will rise significantly, including in the tropics. In these areas, rainfall is also predicted to increase, reducing the salt concentration of the surface ...

As nations dither, cities pick up climate slack

Jul 02, 2015

Their national governments hamstrung by domestic politics, stretched budgets and diplomatic inertia, many cities and provinces have taken a leading role—driven by necessity—in efforts to arrest galloping ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

bigwheel
not rated yet Mar 03, 2008
I knew these global warming idiots would find a way to blame
cold weather on warm weather, makes perfect sense. Somebody
please neuter them before they breed.
DrPhysics
not rated yet Mar 04, 2008
They use o be aptly called 'ecochondriacs'. As they read more of their own press clippings, they will evolve into eco-fascists.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.