The greening of the Arctic..

More mosquitoes..?



Shifts in Arctic vegetation and associated feedbacks under climate change
[link to www.nature.com]


The green, green grass of the Arctic: Researchers predict dramatic boost in trees and shrubs due to global warming
[link to www.dailymail.co.uk]

[snip]

The Arctic is set to become a lush and green landscape due to global warming, researchers have predicted.

Experts say the wooded areas in the region could increase by 50% over the coming decades - and accelerate global warming in the process.

Researchers have unveiled the most accurate map ever of how vegetation could change in the region.


[link to en.wikipedia.org]
The Arctic's climate is characterized by cold winters and cool summers. Precipitation mostly comes in the form of snow. The Arctic's annual precipitation is low, with most of the area receiving less than 50 cm (20 in). High winds often stir up snow, creating the illusion of continuous snowfall. Average winter temperatures can be as low as -40 °C , and the coldest recorded temperature is approximately -68 °C . Coastal Arctic climates are moderated by oceanic influences, having generally warmer temperatures and heavier snowfalls than the colder and drier interior areas. The Arctic is affected by current global warming, leading to Arctic sea ice shrinkage and Arctic methane release.

Due to the poleward migration of the planet's isotherms (about 35 mi (56 km) per decade during the past 30 years as a consequence of global warming), the Arctic region (as defined by tree line and temperature) is currently shrinking.[9] Perhaps the most spectacular result of Arctic shrinkage is sea ice loss. There is a large variance in predictions of Arctic sea ice loss, with models showing near-complete to complete loss in September from 2040 to some time well beyond 2100. About half of the analyzed models show near-complete to complete sea ice loss in September by the year 2100.



from Jan 2010..

Trees invading warming Arctic will cause warming over entire region, study shows
[link to newscenter.berkeley.edu]

[snip]

“Broad-leaved deciduous trees are not as dark as evergreen trees and so are generally assumed to be less important. But broad-leaved trees transpire a lot more water through their leaves and are actually able to change the water vapor content and increase the greenhouse effect. As the air warms, it can hold more water vapor, and the greenhouse effect increases further,” Swann said. “So, broad-leaved trees end up warming the entire Arctic.”

More importantly, the researchers’ model predicts that the increased water vapor would melt more sea ice, resulting in more absorption of sunlight by the open ocean and dumping more water vapor into the atmosphere. This positive feedback will warm the land even more and encourage faster, more efficient tree growth and perhaps a faster expansion of trees into the Arctic.

All told, the model predicts an additional 1 degree Celsius increase in temperature over the Arctic as a result of this effect. Global warming already is predicted to increase temperatures in the Arctic between 5 and 7 degrees Celsius within the next 100 years.


Effects_of_Climate_Change_on_Arctic_Ecosystems_fact_sheet.pdf​
[link to docs.google.com (secure)]


[link to aob.oxfordjournals.org]

[snip]

This buildup of carbohydrates demonstrates that it is not the uptake of CO2 that limits growth, but the rate at which glucose can be utilized. This seems to be an important conclusion, implying that trees at the tree line are unlikely to respond appreciably to elevated CO2, simply because they are not short of the products of photosynthesis. They may well, on the other hand, respond to warming as this will increase the rate of cell division and therefore the rate at which the assimilated carbon can be utilized. Warming will also prolong the growing season and, in the already short growing season at the tree line, this effect will be proportionately greater than in lowland or more southern conditions.

Last Edited by Waterbug on 04/01/2013 10:02 AM