Arctic sea ice extent has begun its seasonal decline towards the September minimum. Ice extent through the winter was similar to that of recent years, but lower than the 1979 to 2000 average. More importantly, the melt season has begun with a substantial amount of thin first-year ice, which is vulnerable to summer melt.
As mentioned earlier on this blog, Line Gordon and I are looking for a PhD student to be part of an international research project.
The student will develop a conceptual framework and empirical methods to investigate how globally driven hydrological changes could alter the social-ecological resilience of Arctic ecosystems. This research includes reviewing evidence for possible hydrologically triggered abrupt threshold changes or regime shifts in Arctic ecosystems, the synthesis of existing social, ecological and physical data to map social-ecological resilience in the Arctic, and the construction of minimal social-ecological models of Arctic regime shifts.
The proposed starting date is January 1, 2009 (although this can be negotiated). Applications will be taken until Oct 31th, 2008.
For more information see my previous post.
The official job ad and details are here.
From EO Newsroom
This image shows Arctic sea ice concentration on September 8, 2008, as observed by the Advanced Microwave Scanning Radiometer–Earth Observing System (AMSR-E) sensor on NASA’s Aqua satellite. The observations are collected on a pixel by pixel basis over the Arctic. The percentage of a 12.5-square-kilometer pixel covered by ice is shown in shades of dark blue (no ice) to white (100 percent ice). The gray line around the Arctic basin shows the median minimum extent of sea ice from 1979-2000. (The median of a data set is the middle value if you arrange the numbers in order from smallest to largest.)
The southern portions of the Northwest Passage through the Arctic (the western route from Europe to Asia through the islands of northern Canada) opened in early August. Then in early September, ice scientists confirmed that the waters around the Russian coastline—the Northern Sea Route— were navigable, but still treacherous, with shifting floes of thick, multi-year ice, that could coalesce rapidly. The image shows that the widest avenue through the Northwest Passage, Parry Channel, still harbored some ice, but the more circuitous, southern waterways were clear. On the other side of the Arctic Ocean, the passage around Russia’s Taymyr Peninsula, normally locked in by ice, was similarly open. According to a press release from the U.S. National Ice Center, “This is the first recorded occurrence of the Northwest Passage and Northern Sea Route both being open at the same time.”
The summer opening of the Arctic means that new uses of the Arctic are likely to emerge. International legal experts believe that “existing laws governing everything from fish stocks to bio-prospecting by pharmaceutical companies” are inadequate.
To date, the eight Arctic nations (the United States, Russia, Canada, Norway, Sweden, Iceland, Denmark and Finland) have limited discussions to existing agreements, such as the law of the sea. Environmental groups would like new laws, but others have suggested a more feasible, and adaptive response may be to strengthen the role of the existing Arctic Council to better govern a changing Arctic in a more adaptive way.
The shipping shortcuts of the Northern Sea Route (over Eurasia) and the Northwest Passage (over North America) would cut existing oceanic transit times by days, saving shipping companies — not to mention navies and smugglers — thousands of miles in travel. … Taking into account canal fees, fuel costs, and other variables that determine freight rates, these shortcuts could cut the cost of a single voyage by a large container ship by as much as 20 percent — from approximately $17.5 million to $14 million — saving the shipping industry billions of dollars a year. The savings would be even greater for the megaships that are unable to fit through the Panama and Suez Canals and so currently sail around the Cape of Good Hope and Cape Horn. Moreover, these Arctic routes would also allow commercial and military vessels to avoid sailing through politically unstable Middle Eastern waters and the pirate-infested South China Sea. An Iranian provocation in the Strait of Hormuz, such as the one that occurred in January, would be considered far less of a threat in an age of trans-Arctic shipping.
Arctic shipping could also dramatically affect global trade patterns. … As soon as marine insurers recalculate the risks involved in these voyages, trans-Arctic shipping will become commercially viable and begin on a large scale. In an age of just-in-time delivery, and with increasing fuel costs eating into the profits of shipping companies, reducing long-haul sailing distances by as much as 40 percent could usher in a new phase of globalization. Arctic routes would force further competition between the Panama and Suez Canals, thereby reducing current canal tolls; shipping chokepoints such as the Strait of Malacca would no longer dictate global shipping patterns; and Arctic seaways would allow for greater international economic integration. When the ice recedes enough, likely within this decade, a marine highway directly over the North Pole will materialize. Such a route, which would most likely run between Iceland and Alaska’s Dutch Harbor, would connect shipping megaports in the North Atlantic with those in the North Pacific and radiate outward to other ports in a hub-and-spoke system. A fast lane is now under development between the Arctic port of Murmansk, in Russia, and the Hudson Bay port of Churchill, in Canada, which is connected to the North American rail network.
Philip Higuera and collaborators suggests that based on paleo-ecological analysis of past fire regimes, climate change could lead to abrupt shifts in tundra fire frequency as climate change vegetation shifts from herb to shrub dominated tundra.
In their article (Higuera PE, Brubaker LB, Anderson PM, Brown TA, Kennedy AT & Hu FS. 2008 Frequent fires in ancient shrub tundra: implications of paleorecords for Arctic environmental change. PLoS ONE DOI: 10.1371/journal.pone.0001744) the authors write:
… paleorecords from northcentral Alaska imply that ongoing shrub expansion and climate warming will result in greater burning within northern tundra ecosystems. The geographic extent of fire-regime changes could be quite large, as shrubs are expected to expand over the next century in both herb and low shrub tundra ecosystems, which comprise 67% of circumpolar Arctic tundra ,  (Fig. 1). Over this same period, annual temperatures in the Arctic are projected to increase between 3–5°C over land, lengthening the growing season and likely decreasing effective moisture (in spite of increased summer precipitation) . How long might it take for the current shrub expansion to trigger a significant change in fire frequencies? Within the chronological limitations of our records, past shrub expansion and fire-regime changes at each site occurred within a few centuries (Fig. 2). The duration of this shift is consistent with the estimated rate of shrub expansion within a large area of northern Alaska [0.4% yr−1 for ca 200,000 km2; 10]. Based on a simple logistic growth model and the assumption of a constant expansion rate, Tape et al.  hypothesize that the ongoing shrub expansion in this region started roughly 125 years ago and should reach 100% of the region in another 125 years. Thus, if fuels and low effective moisture are major limiting factors for tundra fires, we predict that fire frequencies will increase across modern tundra over the next several centuries.
Despite these uncertainties, Alaskan paleorecords provide clear precedence of shrub-dominated tundra sustaining higher fire frequencies than observed in present-day tundra. The future expansion of tundra shrubs ,  coupled with decreased effective moisture  could thus enhance circumpolar Arctic burning and initiate feedbacks that are potentially important to the climate system. Feedbacks between increased tundra burning and climate are inherently complex –, but studies of modern tundra fires suggest the possibility for both short- and long-term impacts from (1) increased summer soil temperatures and moisture levels from altered surface albedo and roughness , and (2) the release soil carbon through increased permafrost thaw depths and the consumption of the organic layer , . Given the importance of land-atmosphere feedbacks in the Arctic –, the precedence of a fire-prone tundra biome should motivate further research into the controls of tundra fire regimes and links between tundra burning and the climate system.
Climate driven changes in vegetation cover across the most northern land surfaces on the planet will likely result in more carbon-releasing fires, according to a study published this week in PLoS ONE. Philip Higuera, currently at Montana State University, and colleagues examined charcoal and pollen samples from Alaskan lakes, which provide a historical record of plant composition and fire frequency between 14000 and 10000 years ago. Back then, the tundra was dominated by extensive thickets of resin birch Betula glandulosa, and the warming climate is likely to see its widespread return to areas currently occupied by somewhat less flammable herbs. The mass of tangled, resin-laden twigs could turn the area into a tinderbox, with the double whammy that such fires encourage vigorous birch regrowth, making it prone to further blazes. The likely consequence is that another source of carbon dioxide will enter the scene, as vegetation and long-frozen soil go up in smoke.
via SCB’s Journal Watch Online
The summer of 2007 was apocalyptic for Arctic sea ice. The coverage and thickness of sea ice in the Arctic has been declining steadily over the past few decades, but this year the ice lost an area about the size of Texas, reaching its minimum on about the 16th of September. Arctic sea ice seems to me the best and more imminent example of a tipping point in the climate system. A series of talks aimed to explain the reason for the meltdown.
The disappearance of the ice was set up by warming surface waters and loss of the thicker multi-year ice in favor of thinner single-year ice. But the collapse of ice coverage this year was also something of a random event. This change was much more abrupt than the averaged results of the multiple IPCC AR4 models, but if you look at individual model runs, you can find sudden decreases in ice cover such as this. In the particular model run which looks most like 2007, the ice subsequently recovered somewhat, although never regaining the coverage before the meltback event.
So what is the implication of the meltback, the prognosis for the future? Has the tipping point tipped yet? When ice melts, it allows the surface ocean to begin absorbing sunlight, potentially locking in the ice-free condition. Instead of making his own prognosis, Overland allowed the audience to vote on it. The options were
* A The meltback is permanent
* B Ice coverage will partially recover but continue to decrease
* C The ice would recover to 1980’s levels but then continue to decline over the coming century
Options A and B had significant audience support, while only one brave soul voted for the most conservative option C. No one remarked that the “skeptic” possibility, that Arctic sea ice is not melting back at all, was not even offered or asked for. Climate scientists have moved beyond that.
For more coverage see Nature’s Great Beyond.
Arctic sea ice has reached record low coverage in 2007.
From NASA EOS:
This image shows the Arctic as observed by the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) aboard NASA’s Aqua satellite on September 16, 2007. In this image, blue indicates open water, white indicates high sea ice concentration, and turquoise indicates loosely packed sea ice. The black circle at the North Pole results from an absence of data as the satellite does not make observations that far north.
Three contour lines appear on this image. The red line is the 2007 minimum, as of September 15, and it almost exactly fits the sea ice observed by AMSR-E. Depending on the calculations, the minimum occurred on September 14 (one-day running average) or September 16 (five-day running average). The green line indicates the 2005 minimum, the previous record low. The yellow line indicates the median minimum from 1979 to 2000.
In 2005 on Resilience Science, Line Gordon, wrote about recent research that we may have already passed tipping points in the Arctic.
NSIDC Arctic Sea Ice News Fall 2007 is providing weekly updates on the state of Arctic sea ice, which has reached record low coverage this year (the previous record low was in 2005).
The figure shows daily ice extent for 2007, 2005 and to the 1979 to 2000 average.
Is the home of polar bears, seals and Inuit communities already doomed? asks Jon Foley in Tipping Points in the Tundra a recent commentary Science. According to him, several recent sources of evidence show that feedback mechanisms seem to be kicking into high gear as the Arctic warms up. Temperature data illustrate, for example, that from the 1960’s to the 1980’s, the Arctic warmed by 0.15 degrees Celsius per decade, but since then the warming has been nearly 0.3 to 0.4 degrees per decade.
Recent evidence comes from Terry Chapin and his co-workers who have analyzed Arctic data on surface temperature, cloud cover, energy exchange, albedo, and changes in snow cover and vegetation. They concluded that the recent changes in the length of the snow-free season have triggered a set of interlinked feedbacks that will amplify future rates of summer warming. One of these feedbacks relate to that the snowmelt has advanced by around 2.5 days per decade which has lead to an increase in the amount of energy that is absorbed and transferred to the atmosphere. The resulting regional increase in temperature is estimated to be comparable (per unit area) to the global atmospheric heating that is projected from a doubling of CO2 levels in the atmosphere.
Chapin et al. also analyses the role of vegetation change for triggering positive feedbacks. Tall shrublands have increased rapidly in the surrounding region of the Arctic. Tree lines have also moved further north. Although the estimated contributions these have on warming were found to be small, the authors expect that they will continue to increase disproportionally in the future.