The summer sea ice extent and the sea volume over time are steadily decreasing. As this Climate Central Video shows, the receding Arctic summer sea ice is a positive feedback and at the same time, the sea ice is thinning.
In 2011 an MIT sea ice model showed the ice is thinning 4 times faster than the IPCC 2007 models estimated.
The PIOMAS model found 2012 to be a clear record in ice volume loss. The ice overall is thinning as multi-year old ice has been declining rapidly, as is shown by the drop in sea ice maximum in the PIOMAS graph.
As shown in this NOAA animation, after each summer minImum, the amount of ice build up over winter is declining steadily, meaning a tipping point has been passed, as James Hansen says happened in 2007.
The most recent published review of the science finds "the system may be poised to undergo rapid change" (The Arctic’s rapidly shrinking sea ice cover: A research synthesis, Julienne C. Stroeve, 2011).
A huge amount of sea ice (the size of Europe) has been lost already.
A 2011 study by Kinnard finds the duration and magnitude of the current decline in sea ice are unprecedented for the past 1,450 years.
James Hansen said, in 2009 that the Arctic sea ice had passed its tipping point.
ARCTIC SEA ICE
Less Arctic summer summer sea ice
= less cooling Arctic & high-mid latitude NH albedo
= increased Arctic warming (Arctic amoplification)
= more N. Hemis extreme weather & climate disruption &
= more Arctic methane CO2 & N2O emittted
= more global warming =less summer sea ice ....etc.
Loss of all sea ice throughout summmer
= large boost to Arctic warming from the latent heat effe
After 2001, the rate of ice loss switched to a faster rate, with another faster switch from 2007 to present making an ice-free summer Arctic look very likely by 2015. Less ice has been forming over the winter freeze, while more ice is being lost over the summer melt.
Why is the summer sea ice melting away so rapidly?
The reason for the apparent huge error in the model projections is multiple positive feedbacks.
Before the large 2007 sea ice decline, most scientists had estimated the sea ice would remain intact year round until near the end of this century. Scientists now agree on 2030, if not long before. The science consensus now is that the main reason is the loss of albedo cooling and the resulting heat absorption effect. Loss of sea ice causes more loss by more warming — a positive feedback loop.
The latest 2011 research by C. Kinnard suggests it is more complicated. "Arctic sea ice extent is now more than two million square kilometres less than it was in the late twentieth century, with important consequences for the climate, the ocean.... Observations show a more or less continuous decline for the past four or five decades.... Both the duration and magnitude of the current decline in sea ice seem to be unprecedented for the past 1,450 years.... Enhanced advection of warm Atlantic water to the Arctic seems to be the main factor driving the decline of sea ice extent on multidecadal timescales, and may result from nonlinear feedbacks between sea ice and the Atlantic meridional overturning circulation. These results reinforce the assertion that sea ice is an active component of Arctic climate variability."
Rapid Arctic surface warming, loss of Arctic albedo, melting of Arctic land ice and change in Arctic ocean currents have set up a complex positive feedback process causing the Arctic to lose sea ice from above and below at an increasing rate.
Perennial (year round) sea ice decline
Information published by the NSIDC suggests that low sea ice extent in the summertime may be having a direct effect on sea ice growth in the winter months. Warmer air temperatures and a lower-than-average sea ice extent were recorded in some areas of the Arctic Ocean in November.
In recent years, low sea ice extent in the summer has been linked to unusually warm autumn air temperatures, resulting from the larger areas of open water (due to ever increasing sea ice loss) that absorb more heat during the summer. This heat must escape back to the atmosphere in the autumn, before the ocean can freeze over. This escaping heat contributes to warmer-than-average conditions, which have been most apparent in October but may now be extending into November.
The Arctic Catlin Survey. Presenting the results (of direct ice thickness measurements by bore holes coupled with historic data) in October 2009, Professor Wadhams said, "The Catlin Arctic Survey data supports the new consensus view that the Arctic will be ice-free in summer within about 20 years, and much of that decrease will be happening within 10 years." (CNN)
A 2011 study looking into why the sea ice loss models underestimate the actual rate of loss, found that the Arctic is losing 10% of its permanent sea ice per decade since 1980, which is 4 times faster than models project. In general, the models project the summer sea ice will last until the end of the century but it is now agreed that projection is at least 50 years out. Direct records from Canada (Statistics Canada, December 2011) show the same and more. The largest decline is in the Northern Labrador Sea at a rate of almost 600 square miles or 17 per cent per decade, Hudson Strait down 16 per cent per decade, and Davis Strait down 14 %
When will the the Arctic start to be sea ice free?
What we really need to know is how fast summer sea ice surface albedo is being lost. From the PIOMAS volume loss, it certainly can be seen that the summer sea ice is on a heading to vanish by 2015.
However the Arctic is being heated and energized so fast that the inherent chaos of Arctic systems has to be increasing fast- making an accurate prediction an unlikely exercise. In such a situation, the worst possibility must be acted on.
The area of summer sea ice determines the amount of vital Arctic summer albedo cooling-as well as snow extent and Greenland ice sheet surface albedo.
Decades ago, Arctic ice covered about 6 million square miles of sea in the winter, and would shrink to about 3 million square miles in the summer. The rate of summer melt increased enormously around 2005, however, and today Arctic summer ice covers only 1.3 million square miles.
The PIOMAS sea ice volume estimate model shows the 2007 tipping point. Even assuming a linear change in rate (which excludes projected abrupt change) summer sea ice is headed for collapse in matter of years.
Arctic sea ice is measured in two ways- as surface ice cover and also as ice volume or the thickness of the ice. There are two kinds of ice cover measurement- extent and area. Extent includes small patches of open water within the general ice cover, while area (at a record loss for 2012) takes the small patches out of the estimate. The area then best indicates sea ice albedo.
A 2009 review of the sea ice science by D. Perovich found that both summer and year round (perennial) sea ice are in rapid decline since 2000. This means that following the total loss of summer sea ice all the ice year round will melt away.
Cryosat satellite confirms rapid recent sea ice thinning trend.
Salt connection Cold, salty water from first year ice melt may be forcing the relatively warmer water to the surface, where it's speeding up the decay of more ice.
There are two very different predictions on the future rate of Arctic sea ice loss. Most of experts relying on their sea ice computer models say the Arctic will have year round ice cover for at least several more decades – though the model projections vary widely. There is one model developed by Wieslaw Maslowski, of the Naval School that in 2006 projected an ice free Arctic as early as 2016 and results of the revised model published in 2012 gave 2016 ± 3 years to reach a nearly ice-free Arctic Ocean in summer.Leading Arctic Expert Prof Peter Wadhams has been advising that it could be by 2020 extrapolating the very rapid decline in sea ice volume.
Ice free Arctic may be years , not decades away Overland NOAA Science 2012 NOAA Extrapolating the sea ice decline is a valid method to predict future sea ice loss-results have ice free summer Arctic in years rather than decades as most models project.
Frequently Asked Questions Arctic sea ice NSIDC
Damocles project : sea ice could be gone in 10 years.
Arctic sea ice fluctuations pose significant impact on local climates. Changes in sea ice cover alter surface heat and radiation fluxes, surface and atmospheric temperatures, precipitation characteristics, storm tracks, cyclonic activity, as well as local and synoptic scale atmospheric circulation. These modifications are known today to propagate to the lower latitudes with potentially significant consequences for global climates.
Several contribitions to the sea ice melt positive feedback,
that results in more warming,
Loss of snow and sea ice reflectivity of solar energy (ice albedo feedback).
Both thinning and loss of extent reduces sea ice albedo.
Thin sea ice also lets more solar energy through the ice warming it from inside
Heat energy absorption by exposed dark open water and land surface
Loss if sea ice insulation of water.
Latent heat of ice
The is a big factor to come. The point about summer conditions is that as long as there is SOME ice present on the sea surface, however thin the layer, then the ocean temperature below it is held to 0 degrees C because the absorbed solar radiation melts the bottom of the ice rather than warming the water. Also the atmospheric temperature is held to close to 0C because warmer air melts the surface snow layer on top of the ice and is thereby cooled. The sea ice, even when thinned, continues to act with 100% efficiency as an air conditioning system for ocean and atmosphere alike. BUT, as soon as the sea ice layer goes, this process ceases and the sea can warm up rapidly. Latent heat is an enormously powerful buffer - the amount of heat that you have to pump in to melt 1 kg of ice will subsequently heat that same amount of melted water to 80C.
Is the loss of sea ice reversible?
A couple of scientists have suggested that if the summer sea ice melts away- it is reversible, meaning the ocean surface could re-freeze. It is based on a model. In reality itis impossible because even if all GHG emissions suddenly stopped the global temperature would continue to increase for a long time, so the idea of the Arctic refreezing is impossible, without local geoengineering to cool the Arctic.
The best option by far is low scale local Arctic cooling while there is still a thin ice cover.
2014 Linkages Between Arctic Warming and Mid-Latitude Weather Patterns: Summary 2013 Workshop
NSIDC Interactive map
PDF: Arctic Sea Ice Tipping Elements, T Lenton, 2012
VIDEO A New Climate State: Arctic Sea Ice 2012
The extent of Arctic summer sea ice has declined about 1 million sq. miles since the 1970s.
The sharp decline in summer Arctic sea ice is unprecedented, and consistent with human-induced climate change. (USGCP Climate Change US 2014)
Abrupt loss of sea ice cover (e.g. 2007) have been projected by some models
While the Arctic has been losing sea ice that Antarctic sea ic not the massive land ice) has been gaining. A 2012 NASA study finds even with the Antarctic gain the planet is losing sea ice fast.
Average Sea Ice Extent Winter maximum 15 million sq. km /5.8 million sq. miles Summmer minimum 7 million sq. km./2.7 million sq. miles) (NSIDC)
IPCC AR5 WG1 2014 Arctic
The Arctic sea ice floats on the Arctic Ocean. Its winter average area is15 million square km/5.8 million sq. miles) Its average low summer area 7 million square km/2.7 million sq. miles.(NSIDC
Scientists warned years ago the Arctic summer sea ice is the air conditioner for the entire Nothern Hemisphere.
Models project abrupt declines and Arctic summer sea ice is in an overall extreme raipd decline.
Models project a rapid very decline summer sea ice from 2020 and possible near zero by 2035 for worst and even best case scenarios, so with possible abrupt loss (as in 2007, 2012) late summer ice free could occur any year from now. However it is the decline in albedo cooling that matters, and that declines rapidly on the currwnt worst case emissions.
TEDEd Why the Arctic is climate change's canary in the coal mine - William Chapman (animation)
NASA Video: Arctic sea ice extent & thickness
2019 Rapid decline of Arctic sea ice volume: Causes and consequences