Is Arctic sea ice recovering or declining?
We've been hearing some arguments from global warming deniers, including everyone's favorite TV weatherman Anthony Watts, that Arctic sea ice has recovered this year. These claims are based on the fact that Arctic sea ice extent had a fairly large rebound in March.
However, according to the U of Washington Polar Ice Center, Arctic ice volume continues to decline.
So which is it - is Arctic sea ice recovering or declining?
- TrevorLv 710 years agoBest answer
Good morning Dana,
A common and easy mistake to make is to get area, extent, volume and mass mixed up.
Area is the area of solid ice - the amount of 'dry land' so to speak
Extent is the area enclosed by the limit of the ice (including all the holes, lakes, cracks etc)
Volume is the total space occupied by all the ice
Mass is the (gravitational) weight of the physical material
Were it not for the air trapped in the ice then volume and mass would be pretty much the same - only impurities, temps, densities etc prevent parity. The air trapped in the ice means that the mass is approx 90% of the volume.
I explained the above for the benefit of all, I know you're aware what mass, volume etc is.
In respect of the extent of the Arctic sea ice. At the moment it's not doing too bad. There was the unusual weather anomaly a few weeks ago that saw cold air parked over the Arctic for several weeks and this help to build the sea ice.
These last couple of years have seen a small advance in the general extent of sea ice, it's still way below the norm and the long term averages but not quite so critical as it was back in 07/08.
What we have been witnessing is a thinning of the ice. I can't recall the exact figures but ordinarily it would average 5m in thickness but currently sizeable portions of the sea ice are just 3m thick. It's this thinning of the ice which has affected the volume.
In short, it's correct to say that sea ice extent (and area) has rebounded slightly and it's also correct to say that volume (and mass) has decreased.
The indications are that the ice will start melting at a faster rate than usual and it's quite possible that this year we'll see record low or close to record low ice extent. Partly due to the progression of underlying warming but also because this is currently a strong ENSO period with a very high ONI.
For those who may be wondering - El Nino Southern Oscillation (ENSO) is a pattern of behaviour observed in the movement of ocean currents in the southern Pacific. This oscillation leads to warmer than normal global temperatures. ONI is the Oceanic Nino Index – a scale used to measure the strength of the ENSO. It’s quite likely that 2010 will see temperatures some 0.15°C higher than would otherwise have been expected.
- antarcticiceLv 710 years ago
I regularly post the monthly climate data from NOAA in reply to silly questions like "it's snowing were I am, global warming is over" and am also regularly criticized by one or several of the 'usual suspects', that a month is only short term data and means nothing (which ignores the fact that month after month has been warm, globaly)
In the case of the Arctic sea ice, deniers are now trying to use a months data for extent (directly after a Northern hemisphere cold spell (March), that they themselves kept telling us about, constantly) While they ignore the levels from Jan and Feb and the long term trend.
The reality of what is happening is covered in the NSIDC monthly report for April. Two things will happen as Summer returns, ice will decline again and given the growing area that is ~1m thick (single year ice) that decline may be quite large and deniers will simple find some other theory why this isn't happening and why some new group is making all this up so they can rule the world.
In other words they will continue to try and ignore reality and hope it goes away.
- JoeLv 510 years ago
Its misleading. I read a similar arguement from deniers in 2008, saying that there is more ice in 2008 than 2007, thus sea ice is increasing. Looking at a graph of sea ice extent shows they are deliberately being misleading:
From the NISDC website:
"The ice cover in 2008 began the year heavily influenced by the record-breaking 2007 melt season. Because so much ice had melted out during the previous summer, a vast expanse of ocean was exposed to low winter air temperatures, encouraging ice growth. Although still well below average, March 2008 saw slightly greater ice extent at the annual maximum than measured in recent years. However, the ice was also thin: less than a year old and vulnerable to melting in summer. Even the geographic North Pole was covered with thin ice, capturing the imaginations of many in the media and general public...
...Nevertheless, by August the rate of ice loss was much faster than average—even faster than in 2007—as the effects of a warm Arctic Ocean worked against the thin ice cover. The melt season became a race: waning sunlight versus rapid ice loss.
Ultimately, summer 2008 finished with the second-lowest minimum extent in the satellite record, 9% above the 2007 minimum and 34% below average. A more diffuse ice cover and a thinner pack nevertheless suggested a record-low ice volume (ice area multiplied by thickness) at the end of summer."
- 3 years ago
Arctic sea ice used to extend as far south as Washington DC and the South of France...Thankfully sea ice naturally recedes between ice ages... There is no evidence to support that Arctic sea ice has further declined due to global warming theory!
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- Noah HLv 710 years ago
Neither. Artic ice is responding to the effects of general climate change. Winters are several days shorter and summers are several days longer. This means that 'new' ice forms later and melts earlier. As the summers are slightly longer some 'old' ice melts as well but the 'new' ice doesn't have time to become 'old' ice so the total expanse of ice tends to diminish over time. While it's true that the 'new' ice may form over large areas it doesn't stick around very long, hence the argument that there's 'more ice' isn't valid...only 'old' ice counts. Also the artic waters are currently a degree 'warmer'. Ice forms at 32 degrees f. and melts at 32.1 degrees F. This means that around the edges of the Artic ice pack and some of the underside of the most southern portion of the ice pack tends to thin out year by year. The take a way here is that the 'old' ice floating around on the Artic Ocean has diminished and thinned over the last several decades and will continue to do as the general heat index rises. Every 1/10 of a degree of rise and every additional hour of 'summer' and every fewer hours of hard freeze winter works on this mass of ice. This is the Cliff Notes version of a complex heat and atmospheric equation, but it's as accurate as it can be without a lot of heavy duty math. Either way, it has nothing to do with Al Gore. Generally speaking the effect of our current accumulation of CO2 produced by burning fossil fuels has warmed both the oceans and the atmosphere slightly and that extra heat, small as it is has to go somewhere...it goes to melt the artic ice fields. Bummer for us!
- Anonymous10 years ago
In the winter months, the northern hemesphere gets colder. This caused ice to build up and for a short time, grow. In the summer months, the ice will melt. This isthe natural growth and decay of icecaps. But in the last few decades, the I've melts faster and in large quanities in the summer months then it grows in the winter. Long tern, yes the icecaps are melting.
The melting of the icecaps cause more, colder water to e put into a common cicle of ocean movement. This water is pushed all throughout the oceans, making them colder, which also gives the colder winter months this year then in previous years. The cold winter holidays, and snow in much of the USA, were caused by global warming.Source(s): Science class
- Anonymous10 years ago
This explains it very well. It has been in a decline the last 3 decades but there was a cold snap this year and there was some increase although it states that the ice is very thin and would melt off quickly. It seems overall it's declining while the Antarctic is increasing.
- booMLv 510 years ago
Seems to me that only the people who believe that extent in terms of square miles is the same as volume draw the conclusion that sea ice is recovering.
- oohhbotherLv 710 years ago
The top graph shoes 12 months - which is the yearly ebb and increase of the seasons. This shows that the earth has seasons.
The Polar ice center graph shows steady yearly declines over 30 years. This shows that the ice is declining.
- endpovLv 710 years ago
Shipping companies are planning on opening trade routes in the Arctic Ocean north of Canada...