Bill
11-16-2007, 08:44 PM
This is interesting, altho apparently bad news for the trees.
The article says that rising co2 may delay the trees entering into dormancy, causing them to be hurt as our short falls suddnly turn into cold winters with cell-killing freezes.
I kinda miss the clearer fall colors of the past. Oh well, who needs trees, we'll all be living in megacities.
http://www.livescience.com/environment/071116-autumn-delay.html
A gray, grim landscape used to greet residents of the Northeastern United States each November, but autumn's riot of red, orange and yellow came late this year. Delayed fall foliage also occurred in Chicago and parts of Europe.
Some say droughts and a warm summer played a role, while others wonder more broadly about global warming. In fact, it's rising levels of carbon dioxide, not the warmer temperatures fueled by the greenhouse gas, that have been delaying the transformation of green leaves, at least in Europe for a few decades, a new study suggests.
In the past 30 years, leaf color change across Europe has gradually occurred later and later, with a delay of about 1.3 to 1.8 days per decade. Like the early onset of spring blooms, this phenomenon has been explained as a result of Earth's rising temperatures.
But the correlation between rising temperatures and leaf color change, known as autumnal senescence, isn't as strong as it is for the spring bloom.
Researchers at the University of Southampton in England suspected that the rising carbon dioxide levels responsible for global warming might directly be influencing the timing of the autumnal color change.
They conducted two large forest experiments in which poplar trees were separated into two plots, with one plot exposed to ambient levels of carbon dioxide and the other exposed to elevated levels. (The elevated concentration was 550 parts per million—the predicted atmospheric level for 2050—while current ambient levels of carbon dioxide are 375 parts per million.)
The researchers found that trees exposed to elevated levels of carbon dioxide retained their leaves and stayed greener longer than those exposed to ambient levels.
The article says that rising co2 may delay the trees entering into dormancy, causing them to be hurt as our short falls suddnly turn into cold winters with cell-killing freezes.
I kinda miss the clearer fall colors of the past. Oh well, who needs trees, we'll all be living in megacities.
http://www.livescience.com/environment/071116-autumn-delay.html
A gray, grim landscape used to greet residents of the Northeastern United States each November, but autumn's riot of red, orange and yellow came late this year. Delayed fall foliage also occurred in Chicago and parts of Europe.
Some say droughts and a warm summer played a role, while others wonder more broadly about global warming. In fact, it's rising levels of carbon dioxide, not the warmer temperatures fueled by the greenhouse gas, that have been delaying the transformation of green leaves, at least in Europe for a few decades, a new study suggests.
In the past 30 years, leaf color change across Europe has gradually occurred later and later, with a delay of about 1.3 to 1.8 days per decade. Like the early onset of spring blooms, this phenomenon has been explained as a result of Earth's rising temperatures.
But the correlation between rising temperatures and leaf color change, known as autumnal senescence, isn't as strong as it is for the spring bloom.
Researchers at the University of Southampton in England suspected that the rising carbon dioxide levels responsible for global warming might directly be influencing the timing of the autumnal color change.
They conducted two large forest experiments in which poplar trees were separated into two plots, with one plot exposed to ambient levels of carbon dioxide and the other exposed to elevated levels. (The elevated concentration was 550 parts per million—the predicted atmospheric level for 2050—while current ambient levels of carbon dioxide are 375 parts per million.)
The researchers found that trees exposed to elevated levels of carbon dioxide retained their leaves and stayed greener longer than those exposed to ambient levels.