Santa May or May Not be White. But the Arctic is, Increasingly, Green..
December 18, 2013
Satellites above the Earth are documenting a striking change in the Arctic. Not only is open water area increasing in the region, but adjacent land areas are growing “greener.” Since observations began in 1982, Arctic-wide tundra vegetation productivity has increased. In North America, the rate of greening has accelerated since 2005.
One of NOAA’s satellite remote sensors—the Advanced Very High Resolution Radiometer (AVHRR)—collects images of our planet’s surface, which scientists use to carefully measure the intensity of visible and near-infrared sunlight reflected by plants back up into space. From these measurements, they are able to determine the density of vegetation, or “greenness,” on land. The map above shows changes in greenness at the peak of the growing season between 1982 and 2012. All around the Arctic, the tundra has grown greener, with exceptions in western Alaska, and northwestern and northeastern Siberia.
The video below is a quick cliff notes version of the Arctic Report card released last week at the American Geophysical Union conference in San Francisco:
Arctic Report Card continued:
Increases in vegetation productivity are often connected to declining sea ice, increasing open water, and greater summer warmth in the Arctic. However, factors other than these can affect plant growth. Snow cover decline is thought to be among the main culprits behind the prolonged length of the Arctic growing season, which has increased by nine days per decade since 1982. Another factor in controlling the rate of greening in the Arctic is large-scale atmospheric circulation patterns. In Eurasia, lower temperatures and increased cloud cover in the summer lead to a more gradual greening compared to eastern North America, where cloud-free skies during the summer promote accelerated greening.
Overall, the greener, warmer, less icy Arctic of recent years is likely to be the new normal. One of the most obvious signs of this transformation is the spread of shrubs throughout the tundra. Across the Siberian tundra, tall shrubs and trees have expanded in landscapes at rates of up to 25 percent since the mid-to-late 1960s. Observations from Europe, Alaska, and Siberia in recent decades show that plant communities have become less diverse as mosses, lichens, and other shorter-growing vegetation disappear under the shade created by shrubs. The loss of lichens, in particular, could pose a problem for caribou and reindeer, which forage on them extensively.
A senior Glaciologist wrote me from south Greenland some months ago, “I was STUNNED to see the forests there this August..” and included some stills.
In addition, there is reason to be concerned about Santa’s Reindeer.
The heat is on for the world’s caribou with a new study warning the creatures could lose as much as 60 per cent of their range within 60 years.
Caribou, often called reindeer, are among the most numerous and mysterious animals in Canada, but many herds are in decline.
And while it might be fun to think they can fly with Santa, the report says there will be no escaping the rising temperatures transforming their habitat.
“The changes will be worse in North America than in Europe,” said Steeve Cote, a caribou expert at Laval University. He led the international study published Sunday in the journal Nature Climate Change.
It reveals a distinct genetic lineage of caribou found only in Canada. And it says the lineage “is likely to become increasingly fragmented, possibly disappearing from most of its present range.”
The scientists estimate 89 per cent of the “suitable area” for these caribou, which are found in Labrador, Quebec and Ontario and are a dietary mainstay for many First Nations people, could be lost within 60 years. That compares a 60 per cent loss in range predicted for the lineage that makes up the rest of the world’s caribou.
The study analyzed DNA from 1,300 caribou from across North America, Europe, Russia and Greenland. It is the most comprehensive look yet at how the animals responded to past climate change and how they ‘ll fare as temperature climb in coming decades due to the greenhouse gases being pumped into the atmosphere.
The map shows the current status of 24 major migratory tundra reindeer and caribou herds. Green indicates increasing populations; red indicates decreasing numbers; black and yellow indicate populations have remained stable either on the high or low end of their historic numbers. Only a few herds are increasing or are stable at high numbers; the most recent population estimates indicate that most herds continue to decline or remain at low numbers after severe declines.
Just as scientists try to figure out the causes behind climate cycles, wildlife experts are trying to understand what is behind cycles in herd populations. Local and traditional knowledge indicates that caribou go through periods of abundance and scarcity every 40-60 years. The size of individual herds has varied greatly since 1970 when population estimates began. Since it is normal for herds to vary in size over time, scientists are still uncertain whether the current low numbers are natural or perhaps driven by some of the rapid changes in the Arctic environment. For some herds, their current ranges are approaching the low end of their historic extent.
In the United States, there are four distinct herds of caribou in Alaska—two that are decreasing in number and two that are increasing. The Western Arctic herd—the state’s largest—reached a population low of 75,000 in the mid-1970s, and then rebounded during the 1980s and 1990s to reach a peak of 490,000 in 2003. The herd then declined to 325,000 in 2011. While the herd is still very large, the Alaska Department of Fish and Game says it may become necessary to reduce harvests in the future if this decline continues.
Many countries are attempting to stabilize population numbers through harvest management. Beginning in 2000, Greenland began to allow hunting to reduce caribou populations. Despite this, surveys indicated that the largest herd, the Kangerlussuaq-Sisimiut, remained at around 98,000 animals. The second largest, Akia-Maniitsoq, decreased from an estimated 46,000 in 2001 to about 17,400 in 2010. One possible cause might be differences in topography: hunting access is easier in the Akia-Maniitsoq territory compared to the rough, mountainous terrain that the Kangerlussuaq-Sisimiut inhabits.