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Are glaciers growing or retreating?

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The skeptic argument...

"Reports are coming in from all over the world: for the first time in over 250 years, glaciers in Alaska, Canada, New Zealand, Greenland, and now Norway are growing." (JamulBlog)

What the science says...

While there are isolated cases of growing glaciers, the overwhelming trend in glaciers worldwide is retreat. In fact, the global melt rate has been accelerating since the mid-1970s.

Glaciers respond directly and quickly to atmospheric conditions. As temperatures warm, summer melting increases. However, accumulation of ice in the winter also increases due to more snowfall. Air temperature tends to play the dominant role - there's a strong statistical correlation between air temperature and glacier fluctuations over large distances (Greene 2005). Generally, when air temperatures warm, glaciers recede.

Consequently, because they're so sensitive to changes in temperature, glaciers provide clues about the effects of global warming. Glacier mass balance is measured through a variety of techniques. Direct glaciological methods include ablation stakes, snow pits and snow probing. This data is then combined with independent geodetic surveys, collected and published by the World Glacier Monitoring Service (WGMS).

Over the period 1946–2005, the WGMS have monitored 228 glaciers. In the early years, just several glaciers were monitored. Over time, observations from more glaciers across the globe were added to the database, giving us a broader picture of global glacier mass balance. The highest quality glacier observations are ongoing, continuous and long term. There are 30 glaciers in 9 different mountain ranges that have been continuously measured since 1976 (11 of them reaching back to 1960 and earlier). These are considered 'reference glaciers'. Figure 1 shows the total number of glaciers monitored since 1946. The black and dark grey bar indicate the number of reference glaciers.

Figure 1: Observed glaciers from 1946 to 2006 (Zemp 2009).

What do these glacier observations reveal? The following table shows the mass balance of individual glaciers over 2002 and 2003. Negative values indicate shrinkage. We see that there are isolated glaciers that are growing. However, focusing solely on these few glaciers to indicate global glacier growth paints a very misleading picture. The vast majority of glaciers are receding. And importantly, the shrinking trend is increasing (eg - 77% in 2002, 94% in 2003).

WGMS Glacier Mass Balance over 2002 and 2003
Figure 2: Glacier Mass Balance over 2002 (blue) and 2003 (red). (WGMS)

What about the long term trend in global glacier mass change? There are several method to calculating global glacier mass change. One way is to use the average value of the 30 reference glaciers. Another is to calculate the moving average of all available glaciers. The results for both methods are displayed in Figure 3. The orange line is the average mass change of the 30 reference glaciers. The blue line includes all glaciers.

Figure 3: Cumulative mass balance curves for the mean of all glaciers and 30 'reference' glaciers (WGMS 2008).

Both approaches show consistent results (with all glaciers showing a slightly faster drop in mass compared to the 30 reference glaciers). There is strong mass loss in the first decade from 1945. Note that at this time, there were only several glaciers monitored - not quite a global sample. The mass loss slows down in the second decade so that around 1970, global mass balance was close to zero. Glaciers were in near equilbrium which indicates glacier shrinkage in the late 20th Century is essentially a response to post-1970 global warming (Greene 2005).

After 1975, glacier shrinkage continues to accelerate until present. The mass loss from 1996 to 2005 is more than double the mass loss rate in the previous decade of 1986 to 1995 and over four times the mass loss rate over 1976 to 1985. When you narrowly focus on a few cherry picked glaciers, you can be misled into an incorrect view of global glacier trends. When you take in the broader picture, you see that globally, glaciers are shrinking at an accelerating rate.

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Further viewing

Time lapse photography of shrinking glaciers:

Comments

Comments 1 to 3:

Quietman at 13:06 PM on 15 July, 2008
John
This is a strange claim: Global warming causing California glacier to grow (Wednesday, July 9, 2008)
"the seven glaciers on Shasta, part of the Cascade mountains in northern California, seem to be benefiting from the warming ocean"
Sam Spade at 13:51 PM on 4 June, 2009
Can the list of increasing glaciers be subdivided, by explanations, in a meaningful way?

I. WARMER POLAR SEAS GW EXPLANATION

The increased snowfall in central Greenland and Antarctica is due to the increased evaporation from the warmer polar seas around them.
Could this same reason apply to western Norway (Briksdal Glacier) and the west coast of South New Zealand (Franz Josef Glacier, Fox Glacier)?

"But Salinger said New Zealand glaciers were boosted by extremely high rainfall, with more than 10m a year falling west of the Southern Alps' main divide.
"Most glaciers, except for some in parts of Norway, were in areas of lower rainfall and were affected more quickly by rising temperatures." Taipei Times

And PIO XI Glacier(Chile) , and Perito Moreno Glacier(Argentina), are even further south...

Iam making my argument despite the following article...which goes into greater detail.
I am referring to the higher temperatures after several decades of GW. And simply extending the analogy: IF warmer seas lead to increased snowfall on Greenland and Antarctica, THEN...

"RECENT GLACIER ADVANCES IN NORWAY AND NEW ZEALAND...
"Norway and New Zealand both experienced recent advances, commencing in the early 1980's and ceasing around 2000, which were more extensive than any other since the end of the Little Ice Age. Common to both countries, the positive glacier balances are associated with an increase in the strength of westerly atmospheric circulation which brought increased precipitation..."
Norway=f(North Atlantic Oscillation)
New Zealand=f(Interdecadal Pacific Oscillation,
El Nino/Southern Oscillation)

II. MISCELLANEOUS GW EXPLANATIONS

The Karakorum Mountains are mentioned above.

???Alaska's increasing coastal glaciers???

"...Hubbard Glacier is the largest of eight calving glaciers in Alaska that are currently increasing in total mass and advancing. All of these glaciers calve into the sea, are at the heads of long fiords, have undergone retreats during the last 1,000 years, calve over relatively shallow submarine moraines, and have unusually small ablation areas compared to their accumulation areas."
"...were retreating throughout the Little Ice Age (AD1350 or 1450 to AD 1900) when most glaciers were growing." Jan 2003

Icy Bay glaciers, Alaska: "puzzled by the glaciers' advance because all three glaciers moved forward at the same time, possibly because of a high snowfall year in the upper reaches of the glaciers, or rainfall down low, that could lubricate the glacier's sliding surface, the bedrock beneath them." June, 2007
(January 2007 was the warmest globally, I believe,
so the La Nina hasn't started yet.)

Icy Bay is located near the Hubbard Glacier, on the Gulf of Alaska.
Note that all eleven of these increasing glaciers are located on the coast. I couldn't find an Alaskan map locating its glaciers. But Google Earth suggests that the largest glaciers are on the coast, and behind it; in an arc around the Gulf of Alaska.
Winter Land and Ocean Surface Temperature trend maps seem to indicate cooler water near the Gulf of Alaska, but warmer water way out in the north Pacific.
NOAA Wind Direction vectors for January pass thru the warm Pacific area, and head toward this coast.
Could the increasing Alaskan glaciers be attributed to Global Warming via the warmer waters in the north Pacific?

III. OTHER (NON-GW) EXPLANATIONS

Mount Shasta is mentioned above.
The Mount Shasta explanation would also cover two small glaciers nearby in the Trinity Alps.

"Since 1980, there has been an advance of more than 55% of the 625 mountain glaciers under observation by the World Glacier Monitoring Group in Zurich..."
A skepticalscience listing on this page, it is from a 2007-12-23 dated website. Obviously, '1980' seems pretty irrelevant. And,from the table above, 7% are increasing.

"Crater Glacier" is inside the Mount St. Helens crater.
"Shadowed by the crater walls and fed by heavy snowfall and repeated snow avalanches, it grew rapidly..."
This sounds like a special case, to me...a 'shadow' glacier.
"In addition, since 2004, new glaciers have formed on the crater wall above Crater Glacier, feeding rock and ice onto its surface below."

"Very high-elevation Mont Blanc glaciated areas not affected by the 20th century climate change..."
"...the mass balance of the glaciers is strongly controlled by precipitation, not temperature."

This list is from a skeptic website that, among many other things, lists articles about 'GROWING' glaciers.
I have not included the more recent, post La Nina, situations.

z4.invisionfree.com/Popular_Technology/index.php?showtopic=2050-884k-
Sam Spade at 11:10 AM on 7 June, 2009
........SKEPTIC SOURCES

My focus above was on increasing glaciers that were referred to by skeptics. I got them from an endless skeptic bibliography...that's split up into a hundred subdivisions.

z4.invisionfree.com/Popular_Technology/
index.php?showtopic=2050

GW skepticism being what it is, the counter argument was often also there, in the same article. In addition, there'd be some "google words", on which to continue.

The other skeptic source I know about is also subdivided; and includes some text, with a literature review.

appinsys.com/globalwarming/

A neophyte believer blogger's first source would likely be a skeptical argument website, like skeptical science.com. Is appinsys the first source for a neophyte skeptic blogger?
It would be useful to know where the other blogger is getting his information. For example, I've always been amazed at skeptics' ability to produce weather related fatality statistics. When I've never seen any. Until...

There's no hope for the cynical skeptic, who'll cherrypick anything anywhere. And the gullible skeptic can probably be reached only on his own entry level conspiracies. But I think the more open-minded ('skeptical') skeptic would eventually see through this disjointed collection of counter arguments...that don't add up to a realistic whole.

Are there any other useful skeptic sources?