Climate Crisis Has Already Altered Arctic Seasons
By Countercurrents.org
11 March 2013
Countercurrents.org
Bob Weber of The Canadian Press reported [1]:
Climate change has already altered seasons in the Arctic to make them more like southern regions, says newly published researc.
While tundra plant communities are already becoming shrubbier, scientists behind the paper say there's no way to predict what's going to happen as the change continues.
"We are doing a strange experiment," said Ranga Myneni of Boston University, co-author of the paper published on March 10, 2013 in Nature Climate Change.
It's long been known that climate change is proceeding more quickly in the Arctic than anywhere else — about twice the global average.
Myneni, one of an international group of scientists behind the research, decided to look at how that warming is happening. He and his fellow researchers found the effect was on the difference between the seasons.
The amount that temperatures change as the seasons pass depends on latitude, said Myneni.
"In any given year, you start with a horizontal line that's the temperature profile of the equatorial regions. Gradually, you build up a bell shape as you go further north."
But most of the warming that's happening in the Arctic is taking place in winter, with somewhat less happening in spring and fall and the least occurring in the summer.
"If you start warming the winters more, and the transitional seasons a little bit more, you're basically flattening out the bell shape," Myneni said. "The bell in the North is looking less like a bell shape."
In effect, he said, climate change is giving the Arctic the temperature profile of the south.
Using satellite data, the team found the change that's already happened is equivalent to about five degrees of latitude. They then averaged 17 different climate models to suggest that by the end of the century, Victoria Island will have the same temperature profile as Wyoming.
What effect that will have on the plants and animals of the North is anyone's guess, Myneni said. Shrubs are already growing further north.
Myneni points out that warmer temperatures don't mean more hours of daylight. Nor will they improve thin Arctic soils or prevent melting permafrost from destabilizing the land.
There are too many variables in play to guess what's going to grow in the North or how that will affect associated animals.
"The Arctic is a feast for two-and-a-half months," Myneni said. "There's a tremendous amount of food available."
Animals from birds to whales flock north to take advantage, but timing is everything.
"It's seasonality that is important," he said. "Once you change seasonality, the whole food web is connected to that. We could not predict what the next 90 years will hold in terms of biology."
More research on the future of the Arctic is needed to try and understand what's in store, said Myneni.
Irreversible melting of Canada’s Arctic glaciers
Canada's Arctic Archipelago glaciers represent the third largest ice body in the world after Greenland and the Antarctic. Should the Canadian ice caps melt completely, the global average sea level will rise by 20 centimeters. Since the year 2000 the temperature in this area has risen by 1 to 2 degrees Centigrade and the ice volume has already significantly decreased.
From London a report by SPX [2] said:
Canada's Arctic Archipelago glaciers will melt faster than ever in the next few centuries. Research by scientists has shown that 20 percent of the Canadian Arctic glaciers may have disappeared by the end of this century which would amount to an additional sea level rise of 3.5cm.
The researchers developed a climate model for the island group of the north of Canada in which they simulated the shrinking and growing of glaciers in this area.
The researchers show that the model correctly "predicted" the ice mass loss measured over the last ten years and then used the same model to project the effect of future climate change on Canada's Arctic Archipelago glaciers.
The most important result of the research is it shows the probable irreversibility of the melting process, according to lead author Dr Jan Lenaerts of Utrecht University who says, "Even if we assume that global warming is not happening quite so fast, it is still highly likely that the ice is going to melt at an alarming rate. The chances of it growing back are very slim."
One of the main reasons for the irreversibility lies in the fact that snow melting on tundra, and sea ice loss from around the glaciers, actually reinforce regional warming, with significant consequences on the glaciers of Northern Canada. Snow and sea ice reflect the sunlight, and when the snow and sea ice have disappeared, a large part of the sunlight will be absorbed by the land and the sea, which will significantly increase the local temperature.
In one scenario 20 percent of volume of the glaciers disappears by the end of this century. In this scenario the average global temperature increases by 3 degrees Centigrade but the rise in temperature around Canadian ice caps is 8 degrees Centigrade. Dr Lenaerts emphasizes this is not an extreme scenario.
Canada's Arctic Archipelago glaciers represent the third largest ice body in the world after Greenland and the Antarctic. Should the Canadian ice caps melt completely, the global average sea level will rise by 20 centimeters.
Since the year 2000 the temperature in this area has risen by 1 to 2 degrees Centigrade and the ice volume has already significantly decreased. If a fifth of the Canadian ice caps have melted by the end of this century, this leads to an additional sea rise of 3.5cm.
Co-author Professor Michiel van den Broeke of Utrecht University says, "Most attention goes out to Greenland and Antarctica which is understandable because they are the two largest ice bodies in the world. However, with this research we want to show that the Canadian ice caps should be included in the calculations."
Professor David Vaughan program leader of ice2sea, who is based at the British Antarctic Survey in Cambridge, says, "The Canadian archipelago is an area where climate is changing rapidly, and the glaciers here contain enough ice that we should not ignore their contribution to sea-level rise.
Added to glaciers in Alaska, the Russian Arctic and Patagonia, these apparently small contributions add up to significant sea-level rise.
A key success of this study was in showing that the model performed well in reproducing recently observed changes. That success gives us confidence in how the model predicts future changes".
The results of the research Irreversible mass loss of Canadian Arctic Archipelago glaciers will be officially published by Geophysical Research Letters this week. The research is part of the EU funded ice2sea program.
Tropical forest
Olive Heffernan reported [3]:
Tropical forests are unlikely to die off as a result of the predicted rise in atmospheric GHG this century, a new study finds. The analysis refutes previous work that predicted the catastrophic loss of the Amazon rainforest as one of the more startling potential outcomes of climate change.
In the most extensive study of its kind [ref.1], an international team of scientists simulated the effect of business-as-usual emissions on the amounts of carbon locked up in tropical forests across Amazonia, Central America, Asia and Africa through to 2100. They compared the results from 22 different global climate models teamed with various models of land-surface processes. In all but one simulation, rainforests across the three regions retained their carbon stocks even as atmospheric carbon dioxide concentration increased throughout the century.
The study provides “robust evidence for the resilience of tropical rainforests”, says lead author Chris Huntingford, a climate modeller at the UK’s Centre for Ecology and Hydrology in Wallingford. But uncertainties remain, he adds.
For one, it remains difficult to predict how climate will change regionally. Moreover, each global climate model represents climate somewhat differently.
The single simulation that predicted biomass loss for the Amazonian and Central American rainforests in the current study used a model called HadCM3, developed by the UK Met Office's Hadley Centre in Exeter. That same model produced the earlier prediction that climate change would lead to massive forest die-off in the Amazon [ref.2].
Climate scientist Peter Cox at the University of Exeter, UK, was one of the authors on the earlier study and is also involved in the new one. He explains that, unlike other climate models, HadCM3 predicts extreme drying over the Amazon basin in the future, which changes the outcome for the forests there. But in the light of new data and of improved modelling, the drying now seems a lot less probable. Scientists are more confident in the predictions from current studies, he says, as they are based on many more, and much more sophisticated, models.
“This has been a big issue in science for many years,” says forest ecologist Daniel Nepstad, who directs the Amazon Environmental Research Institute in San Francisco, “and the emerging view is that there is less sensitivity in tropical forests for climate-driven dieback”.
Uncertain assumptions
But Cox points out that much uncertainty still exists in how forests will respond to changes in climate. In another paper [ref.3], some of the same authors have shown that warming alone could have a massive impact on tropical forests; for every 1 °C rise in temperature, around 50 billion tonnes of carbon would be released from the tropics.
The fertilizing effect of carbon dioxide, which boosts plant growth, counteracts the release completely if it is as large as suggested by the models used in the new study. What scientists don’t yet know if whether that assumption holds up.
That tropical forests will retain their carbon stocks long term gives a major boost to policies aimed at keeping forests intact, such as the United Nations' REDD program on reducing emissions from deforestation and forest degradation.
But, warns Nepstad, there may be more immediate threats to forests in the next 20 to 30 years from extreme weather events. And those events will only become more common in a warming world.
Source:
[1] Canada.com, March 10, 2013, “Study finds climate change is making Arctic seasons more like south”,
http://www.canada.com/news/national/Study+finds+climate+change+making+
Arctic+seasons+more+like+south/8076177/story.html
[2] TERRA DAILY, March 11, 2013, “Glaciers will melt faster than ever and loss could be irreversible warn scientists”, http://www.terradaily.com/reports/Glaciers_will_melt_faster_
than_ever_and_loss_could_be_irreversible_warn_scientists_999.html
[3] Nature, March 10, 2013, “Tropical forests unexpectedly resilient to climate change”,
http://www.nature.com/news/tropical-forests-unexpectedly-resilient-to-climate-change-1.12570
References:
1. Huntingford, C. et al. Nature Geosci. http://dx.doi.org/10.1038/NGEO1741 (2013).
2. Cox, P. M. et al. Nature 408, 184–187 (2000).
3. Cox, P. M. et al. Nature 494, 341–344 (2013).
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