Profound and continuing changes in Arctic ecosystems, initiated by record-setting changes occurring throughout the Arctic environmental system were found by a science team of 121 Arctic experts from 14 nations today in The Arctic Report Card. The Arctic amplification, a feedback loop of rapidly warming temperatures and rapidly melting snow and sea ice is transforming the Arctic environment to a new, warmer, state with less sea ice, more acidic sea water and profoundly altered ecosystems.
A major conclusion of the 2011 Report is that there are now a sufficient number of years of data to indicate a shift in the Arctic Ocean system since 2006. This shifted is characterized by the persistent decline in the thickness and summer extent of the sea ice cover, and a warmer, fresher upper ocean. As a result of increased open water area, biological productivity at the base of the marine food chain has increased and sea ice-dependent marine mammals continue to lose habitat. Increases in the greenness of tundra vegetation and permafrost temperatures are linked to warmer land temperatures in coastal regions, often adjacent to the areas of greatest sea ice retreat. A second key point in the 2011 Report is the repeated occurrence of 2010 Arctic winter wind patterns that mark a departure from the norm. These changes resulted in higher than normal temperatures in the Arctic, with record ice sheet mass loss, record low late spring snow cover in Eurasia, shorter lake ice duration, and unusually lower temperatures and snow storms in some low latitude regions. A potential indicator of recent atmospheric changes was record low ozone concentrations in March 2011. The 2011 Report Card shows that record-setting changes are occurring throughout the Arctic environmental system. Given the projection of continued global warming, it is very likely that major Arctic changes will continue in years to come, with increasing climatic, biological and social impacts.
Heat is stored in Arctic ocean waters that were formerly covered with ice. The stored heat is warming fall temperatures in the Arctic by as much as 6 Celsius (10.8 °F).
90 day temperature anomaly Sept 1, 2011 - Nov. 29, 2011 from NOAA reanalysis data.
These temperature anomalies are based on a 30 year average that was just raised by 1.39°F as we entered the new decade in 2011. It should be noted that this year this essay uses a new baseline interval for temperature anomaly departures using an average over the years 1981 through 2010. These include the recent warm years in the baseline average. In previous Report Cards the baseline average years were 1961 through 1990. The new baseline average is 0.77°C higher than the old baseline.
The strongest warm anomaly, greater than 3°C was over the Arctic ocean north of the Bering Strait adjacent Alaska.
Unusually strong north and south winds in fall and winter resulted in an Arctic-wide pattern of impacts, with warmer than normal temperatures of several °C over Baffin Bay/west Greenland and Bering Strait, and cooler temperatures over NW Canada and northern Europe. A new record low snow cover extent occurred over Eurasia due to persistent warm spring air temperatures.
So much snow and sea ice has melted that the Beaufort gyre, a dome of water north of Alaska, freshened by 5000km3 of melt water.
Relatively recent changes in upper ocean freshwater content (Fig. SIO10) in all Arctic Ocean basins were reported by Rabe et al. (2011). They showed that between 1992-1999 and 2006-2008, the freshwater content in Arctic basins increased by 8400 ± 2000 km3, and suggested that this was largely due to enhanced advection of river water from the shelves and net melting of sea ice.
Fig. SIO10. Objectively-mapped observed freshwater inventory (meters) from the surface to the depth of the 34 isohaline for the deep Arctic Ocean during July, August and September: (left) 1992-1999, (center) 2006-2008 and (right) difference between the 2006-2008 and 1992-1999 periods. Positive differences mean freshening. The locations of measured salinity profiles used for mapping are shown as black dots. The thick gray line represents the 1 m contour of the combined (maximum) statistical error estimate for both mapping time periods. Figures were modified from Rabe et al. (2011).
The complex physical changes in the Arctic triggered by the warming climate are causing the chemistry of the ocean to change in a way that is damaging to a number of lime-shelled organisms at the base of the food chain. Ocean acidification has advanced to a dangerous level where the water is undersaturated with respect to the mineral, aragonite, that makes up the shells of many small animals. When the water is undersaturated, the shells tend to dissolve if the organism doesn't internally decrease the acidity (increase the pH). Obviously, rising levels of CO2 in the atmosphere increase the problem of ocean acidification because they tend to increase the concentration of carbonic acid in sea water.
Undersaturation of the surface waters of the Canada Basin with respect to aragonite, a form of calcium carbonate found in plankton and invertebrates, was first observed in 2008 (Yamamoto-Kawai et al., 2009). This rapid and large decrease in aragonite saturation state was caused by a combination of increased atmospheric CO2 and melting of sea ice. The increased amount of open water (see the essay on Sea Ice) enhanced the uptake of CO2 from the atmosphere and the freshening of the upper ocean (see the essay on Ocean) decreased alkalinity, inorganic carbon and calcium ion concentrations (Yamamoto-Kawai et al., 2011). Although CO2 concentration in surface waters in 2010 and 2011 was not as high as in 2008 (Cai et al., 2009), these waters have continued to be undersaturated with respect to aragonite. The areal extent of undersaturated surface water in 2011 was similar to that in 2010.
Pacific walruses depend on sea ice as diving platforms for foraging on clams. As sea ice declines in the Alaskan Arctic, walruses are being forced to beach in northern Alaska during months they used to be foraging well out to sea. This physical change is threatening the Pacific walrus population.
Pacific walruses: Diminishing Arctic sea-ice, and specifically the retreat of the pack-ice beyond the continental shelf of the Chukchi Sea, has resulted in Pacific walruses (Odobenus rosmarus divergens) hauling out on land by the thousands along the Alaskan coast of the Chukchi Sea in the summer. While fall migratory aggregations (October-November) have been seen on the Alaskan coast in the past (notably at Cape Lisburne) the summer haul-outs are new and occur primarily north of Point Lay (Garlich-Miller et al. 2011).
The decline of sea ice around Alaska is also threatening the polar bear population in the Alaskan Arctic. The Canadian Yukon, which has also warmed and lost sea ice is also suffering polar bear declines.
The Pacific Arctic around Alaska is also suffering from a large decline in sea floor productivity as levels of carbon reaching the seabed decline. A 30% decline in biomass, apparently triggered by declining sea ice, has been measured in the past 20 years.
Over the last two decades specific marine sites have been occupied and re-occupied during both national and international ship-based projects. The data collected by these projects is forming a growing biologically-oriented time-series ranging geographically from the northern Bering Sea to Barrow Canyon. One of the most complete times-series is in the northern Bering Sea and includes sediment community oxygen consumption (Fig. ME6 upper panel), which is used as an indicator of carbon supply to the benthos. These data indicate a 30-50% decline over the last two decades coincident with ~30% decline in total infaunal biomass (Fig. ME6 lower panel). Other related evidence indicates a spatial shift northward in some fish distributions and marine mammal migrations, with direct impacts on habitat for ice-dependent species, such as walrus (citations in Grebmeier et al. 2012).
And a new study published today in Nature concludes that vast amounts of carbon stored in permafrost will be released more rapidly than models have predicted with a higher percentage of methane than models predicted. Because methane is up to 25 times as powerful a greenhouse gas than CO2, permafrost melting will be a major amplifier of global warming.
Recent years have brought reports from the far north of tundra fires1, the release of ancient carbon2, CH4 bubbling out of lakes3 and gigantic stores of frozen soil carbon4. The latest estimate is that some 18.8 million square kilometres of northern soils hold about 1,700 billion tonnes of organic carbon4 — the remains of plants and animals that have been accumulating in the soil over thousands of years. That is about four times more than all the carbon emitted by human activity in modern times and twice as much as is present in the atmosphere now.
The world community does not have the luxury of time to reduce greenhouse gas emissions. Rapid climate change is happening now in the Arctic. The changes in the Arctic are beginning to affect the climate, weather and ecosystems of whole northern hemisphere.