Arctic sea ice declined rapidly through most of June and now lower even than 2007 was at this time of year. The NSIDC has now expressed a concern that the Arctic may become ice free within 30 tears.
Overview of conditions
See the posting titled “Arctic may be ice-free within 30 years“
Figure 6 shows the daily change in extent (averaged over the prior week) and figure 7 compares the recent extents as a percentage of the 2003 – 2010 extent for the same day of the year. The data for this analysis were downloaded from “IJIS” (the IARC-JAXA Information System) reporting the AMSR-E sea ice extent on a daily basis since 2002.
EurekAlert: The least sea ice in 800 years
New research, which reconstructs the extent of ice in the sea between Greenland and Svalbard from the 13th century to the present indicates that there has never been so little sea ice as there is now. The research results from the Niels Bohr Institute, among others, are published in the scientific journal, Climate Dynamics.
There are of course neither satellite images nor instrumental records of the climate all the way back to the 13th century, but nature has its own ‘archive’ of the climate in both ice cores and the annual growth rings of trees and we humans have made records of a great many things over the years – such as observations in the log books of ships and in harbour records. Piece all of the information together and you get a picture of how much sea ice there has been throughout time.
Climate Dynamics: Unprecedented low twentieth century winter sea ice extent in the Western Nordic Seas since A.D. 1200 doi:10.1007/s00382-009-0610-z
We reconstructed decadal to centennial variability of maximum sea ice extent in the Western Nordic Seas for A.D. 1200–1997 using a combination of a regional tree-ring chronology from the timberline area in Fennoscandia and δ18O from the Lomonosovfonna ice core in Svalbard. … The present low sea ice extent is unique over the last 800 years, and results from a decline started in late-nineteenth century after the LIA.
Scientists from around the world will convene at the University of New Hampshire June 2-5, 2009, to discuss key findings from the most ambitious effort ever undertaken to measure “short-lived” airborne pollutants in the Arctic and determine how they contribute in the near term to the dramatic changes underway in the vast, climate-sensitive region.
The two-year international field campaign known as POLARCAT was conducted most intensively during two three-week periods last spring and summer and focused on the transport of pollutants into the Arctic from lower latitudes.
One surprise discovery was that large-scale agricultural burning in Russia, Kazakhstan, China, the U.S., Canada, and the Ukraine is having a much greater impact than previously thought.
A particular threat is posed by springtime burning – to remove crop residues for new planting or clear brush for grazing – because the black carbon or soot produced by the fires can lead to accelerated melting of snow and ice.
Soot, which is produced through incomplete combustion of biomass and fossil fuels, may account for as much as 30 percent of Arctic warming to date, according to recent estimates. Soot can warm the surrounding air and, when deposited on ice and snow, absorb solar energy and add to the melting process. …
The work presented at the POLARCAT meeting will benefit the eight-country Arctic Council, which recently voted to jointly undertake efforts to reduce emissions of black carbon, ozone precursors, and methane in order to slow climate change and ice melt in the Arctic. The data will provide more robust results for governments to use in the development of mitigation efforts with the highest likelihood of benefiting Arctic climate.
The latest Arctic sea ice data from NASA and the National Snow and Ice Data Center show that the decade-long trend of shrinking sea ice cover is continuing. New evidence from satellite observations also shows that the ice cap is thinning as well. …
Summers in the Arctic may be ice-free in as few as 30 years, not at the end of the century as previously expected. The updated forecast is the result of a new analysis of computer models coupled with the most recent summer ice measurements.
“The Arctic is changing faster than anticipated,” said James Overland, an oceanographer at NOAA’s Pacific Marine Environmental Laboratory and co-author of the study, which will appear April 3 in Geophysical Research Letters. “It’s a combination of natural variability, along with warmer air and sea conditions caused by increased greenhouse gases.” …
Geophysical Research Letters: A sea ice free summer Arctic within 30 years? Geophys. Res. Lett., 36, L07502, doi:10.1029/2009GL037820.
September 2008 followed 2007 as the second sequential year with an extreme summer Arctic sea ice extent minimum. Although such a sea ice loss was not indicated until much later in the century in the Intergovernmental Panel on Climate Change 4th Assessment Report, many models show an accelerating decline in the summer minimum sea ice extent during the 21st century. Using the observed 2007/2008 September sea ice extents as a starting point, we predict an expected value for a nearly sea ice free Arctic in September by the year 2037. The first quartile of the distribution for the timing of September sea ice loss will be reached by 2028. Our analysis is based on projections from six IPCC models, selected subject to an observational constraints. Uncertainty in the timing of a sea ice free Arctic in September is determined based on both within-model contributions from natural variability and between-model differences
On January 1, 2009, an article by Michael Asher entitled “Sea Ice Ends Year at Same Level as 1979” appeared on the Daily Tech website. We have received many requests for confirmation and clarification on this article from media outlets and interested individuals regarding the current state of the cryosphere as it relates to climate change and/or global warming.
One important detail about the article in the Daily Tech is that the author is comparing the GLOBAL sea ice area from December 31, 2008 to same variable for December 31, 1979. In the context of climate change, GLOBAL sea ice area may not be the most relevant indicator. Almost all global climate models project a decrease in the Northern Hemisphere sea ice area over the next several decades under increasing greenhouse gas scenarios. But, the same model responses of the Southern Hemisphere sea ice are less certain. In fact, there have been some recent studies suggesting the amount of sea ice in the Southern Hemisphere may initially increase as a response to atmospheric warming through increased evaporation and subsequent snowfall onto the sea ice. (Details: Warmer Air May Cause Increased Antarctic Sea Ice Cover)
The “National Snow and Ice Data Center (NSIDC)” has regularly-updated “Arctic Sea Ice News and Analysis” here.
The NSIDC has a good introduction to the science concerning sea ice at their “Education Center”, here.
The NSIDC has a good introduction to the science concerning sea ice at their “Education Center”, here.
PNAS: Nonlinear threshold behavior during the loss of Arctic sea ice
In light of the rapid recent retreat of Arctic sea ice, a number of studies have discussed the possibility of a critical threshold (or “tipping point”) beyond which the ice–albedo feedback causes the ice cover to melt away in an irreversible process. The focus has typically been centered on the annual minimum (September) ice cover, which is often seen as particularly susceptible to destabilization by the ice–albedo feedback. Here, we examine the central physical processes associated with the transition from ice-covered to ice-free Arctic Ocean conditions. We show that although the ice–albedo feedback promotes the existence of multiple ice-cover states, the stabilizing thermodynamic effects of sea ice mitigate this when the Arctic Ocean is ice covered during a sufficiently large fraction of the year. These results suggest that critical threshold behavior is unlikely during the approach from current perennial sea-ice conditions to seasonally ice-free conditions. In a further warmed climate, however, we find that a critical threshold associated with the sudden loss of the remaining wintertime-only sea ice cover may be likely.
While news of this year’s ice loss in Arctic waters was not as stunning as last year, the trend to thinner and newer sea ice continued to surprise scientists around the world on many fronts:
- On September 12, the sea ice extent in the Arctic Ocean dropped to 4.52 million square kilometres, coming close to last year’s record low of 4.13 million square kilometres. …
- For August 2008, the rate of sea ice melt was the greatest ever. Satellite images showed ice declining at a rate of 84,686 square km per day in August, compared to 63,191 square km per day a year earlier.
- In 2008, vast stretches of water in the western Arctic, including the Beaufort Sea, were almost clear of ice. …
- Canadian Arctic waters had much less permanent ice compared to the same time last year. …
- More stunning news in 2008 was the dramatic disappearance of nearly one-quarter of the massive, ancient ice shelves on Ellesmere Island. …
- The calving of glaciers from Greenland led to nearly 1,000 icebergs off Canada’s east coast, more than in the previous four years combined. …
- Also noteworthy, the ice extent in the Baltic Sea was the lowest since records began in 1720. Latvia and most of Finland had their warmest winter since 1925. Norway’s winter temperature was the second highest on record.
Naval submarines have collected operational data of sea-ice draft (93% of thickness) in the Arctic Ocean since 1958. Data from 34 U.S. cruises are publicly archived. They span the years 1975 to 2000, are equally distributed in spring and autumn, and cover roughly half the Arctic Ocean. … Annual mean ice draft declined from a peak of 3.42 m in 1980 to a minimum of 2.29 m in 2000, a decrease of 1.13 m (1.25 m in thickness).
While the 2008 Arctic sea ice extent was larger than that for 2007, the total volume was down.
28 October 2008
The thickness of sea ice in large parts of the Arctic declined by as much as 19% last winter compared to the previous five winters, according to data from ESA’s Envisat satellite.
28 October 2008
Last winter, the thickness of sea ice in large parts of the Arctic fell by nearly 19 per cent compared with the previous five winters. This followed the dramatic 2007 summer low when Arctic ice extent dropped to its lowest level since records began.
Annual Review of Marine Science: Loss of Sea Ice in the Arctic
Donald K. Perovich and Jacqueline A. Richter-Menge, Annu. Rev. Mar. Sci. 2009. 1:417–41: doi 10.1146/annurev.marine.010908.163805
(Thanks to Daryll Williams for the link)
The Arctic sea ice cover is in decline. The areal extent of the ice cover has been decreasing for the past few decades at an accelerating rate. Evidence also points to a decrease in sea ice thickness and a reduction in the amount of thicker perennial sea ice. A general global warming trend has made the ice cover more vulnerable to natural fluctuations in atmospheric and oceanic forcing. The observed reduction in Arctic sea ice is a consequence of both thermodynamic and dynamic processes, including such factors as preconditioning of the ice cover, overall warming trends, changes in cloud coverage, shifts in atmospheric circulation patterns, increased export of older ice out of the Arctic, advection of ocean heat from the Pacific and North Atlantic, enhanced solar heating of the ocean, and the ice-albedo feedback. The diminishing Arctic sea ice is creating social, political, economic, and ecological challenges.
There is now legitimate concern that we may have reached a positive-feedback “tipping point” for Arctic sea-ice melting and that we may see a summertime ice-free Arctic well before 2050.
Daily Updated AMSR-E Sea Ice Maps from the University of Bremen Institute of Environmental Physics