A study released this month by Cambridge University indicates the
advance of the treeline in the Arctic is moving slower than previously
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 news
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, Earth’s surface temperature has risen an
average of 1.3 degrees F, but the average is greater in the far north.
Rees’ study coordinated experts from across various Arctic nations,
primarily in northern Europe. But Canada, Alaska, Russia and Scandinavia
also participated.
“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 --
suitable soil, the absence of animals that destroy saplings, and the
ability of trees to produce viable seeds.
Scientists are paying close attention to the Arctic tree line
for several 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.
Click here for more on the study.
In a similar story that came out last November, scientists at
Columbia University’s Lamont-Doherty Earth Observatory noted that the
white spruce of Alaska’s boreal forest have been growing faster in
recent decades, boosted by warming temperatures.
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