Post by marchesarosa on Mar 17, 2012 9:51:42 GMT 1
Trees not invading as fast as earlier predicted
by Carey Restino 16th March in The Arctic Sounder
www.thearcticsounder.com/article/1211trees_not_invading_as_fast_as_earlier
A study released this month by Cambridge University indicates the advance of the tree line into the Arctic is moving slower than has previously been predicted.
The study, which was released March 17 by Gareth Rees, a researcher with the university's Scott Polar Research Institute, says the relationship between climate change and tree growth is more complicated than initially thought.
"To generalize our results, the tree line is definitely moving north on average but we do not see any evidence for rates as big as 2 kilometers per year anywhere along the Arctic rim," he said in a release. "Where we have the most detailed information, our results suggest that a rate of around 100 meters per year is more realistic.
In some places, the tree line is actually moving south. The predictions of a loss of 40 percent of the tundra by the end of the century is probably far too alarming."
According to the report, the Earth's surface temperature has risen an average of 0.7 degrees Celsius, but the average is greater in the higher latitudes. Rees' study coordinated experts from across various Arctic nations, primarily in northern Europe. But areas of Canada, Alaska, Russia and Scandinavia have been included as well.
"What we are saying is that when you take the step from a climate model to a vegetation model, we may be doing that in a way that exaggerates what is actually happening," he said. "Furthermore, the response around the Arctic rim is by no means uniform."
In addition to temperature, other conditions must be considered, the study said. Suitable soil, for example, as well as the absence of animals that destroy saplings, and the ability of trees to produce viable seeds, must be considered.
Scientists are paying close attention to the Arctic tree line for a variety of reasons. Trees impact the earth's climate in several ways - they are darker than tundra and therefore absorb sunlight and increase temperature. Trees also transpire more than small plants, having an impact on the hydrological cycle of the earth.
"We understand a bit about what's going on, but definitely not enough," Rees said.
For more on the study, visit www.cam.ac.uk/sciencefestival .
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I've always wondered why the IPCC's palaeoclimatologists, who tend to deny that the Arctic was warmer in the past, do not seek out the evidence of tree stumps to the north of the existing tree line.
That's what a real empirical scientist would do to test his hypoothesis!
by Carey Restino 16th March in The Arctic Sounder
www.thearcticsounder.com/article/1211trees_not_invading_as_fast_as_earlier
A study released this month by Cambridge University indicates the advance of the tree line into the Arctic is moving slower than has previously been predicted.
The study, which was released March 17 by Gareth Rees, a researcher with the university's Scott Polar Research Institute, says the relationship between climate change and tree growth is more complicated than initially thought.
"To generalize our results, the tree line is definitely moving north on average but we do not see any evidence for rates as big as 2 kilometers per year anywhere along the Arctic rim," he said in a release. "Where we have the most detailed information, our results suggest that a rate of around 100 meters per year is more realistic.
In some places, the tree line is actually moving south. The predictions of a loss of 40 percent of the tundra by the end of the century is probably far too alarming."
According to the report, the Earth's surface temperature has risen an average of 0.7 degrees Celsius, but the average is greater in the higher latitudes. Rees' study coordinated experts from across various Arctic nations, primarily in northern Europe. But areas of Canada, Alaska, Russia and Scandinavia have been included as well.
"What we are saying is that when you take the step from a climate model to a vegetation model, we may be doing that in a way that exaggerates what is actually happening," he said. "Furthermore, the response around the Arctic rim is by no means uniform."
In addition to temperature, other conditions must be considered, the study said. Suitable soil, for example, as well as the absence of animals that destroy saplings, and the ability of trees to produce viable seeds, must be considered.
Scientists are paying close attention to the Arctic tree line for a variety of reasons. Trees impact the earth's climate in several ways - they are darker than tundra and therefore absorb sunlight and increase temperature. Trees also transpire more than small plants, having an impact on the hydrological cycle of the earth.
"We understand a bit about what's going on, but definitely not enough," Rees said.
For more on the study, visit www.cam.ac.uk/sciencefestival .
-----------
I've always wondered why the IPCC's palaeoclimatologists, who tend to deny that the Arctic was warmer in the past, do not seek out the evidence of tree stumps to the north of the existing tree line.
That's what a real empirical scientist would do to test his hypoothesis!