Glaciers are one of the natural environments most often used to illustrate the impacts of climate change. It is fairly indisputable that in a warming world, glaciers melt faster. Yet two recent studies published in top scientific journals (more here and here) suggest that in the Himalayas the rate of mass loss has been small and overestimated, and that further west, in the Karakoram range, the glaciers are actually slightly gaining mass.
Is there a conflict between these studies and the wider body of research indicating that, worldwide, glaciers have been receding for several decades?
To answer this question, we need to look a little more carefully at what the studies show, and to place them in the context of global changes to land and sea ice. Both studies cover a relatively short period of time: eight to nine years, over roughly the last decade. The Himalayas experience large variations in snowfall from year to year depending on the strength of the monsoon. But in atmospheric sciences, trends in climate are generally determined from records that span at least 30.
To obtain observations over these longer time scales is a challenging task for glaciologists. There are more than 160,000 glaciers on the planet, less than 120 of which have continuous, long-term measurements taken. These ground-based measurements have been supplemented by data from airborne and satellite sensors. The combined records indicate that most, but not all, glacier systems have been losing mass for at least the last four decades, and that the rate of loss has been accelerating since the 1990s for key regions including Patagonia, the Canadian Arctic, Alaska and, most important of all for sea-level rise, from the great ice sheets covering Antarctica and Greenland.
These two ice giants contain 99.5% of all land ice on Earth, and store enough ice to raise global sea level by around 64 metres. The evidence that mass loss in Greenland and west Antarctica has been accelerating since the early 1990s is irrefutable.
Likewise, Arctic sea ice that used to cover around 9m sq km of ocean at the end of summer has, after 30 years, reduced at such a rate that the Arctic Ocean seems likely to be ice-free in summer by the middle of this century. The most recent predictions for the European Alps, for which there are comprehensive observations, suggest that glaciers will have shrunk in area by 80-96% by 2100.
With glaciers and ice sheets covering such a diverse range of latitudes (from the tropics to the poles) and altitudes (from sea level to over 6,000 metres), it is not surprising that there are regional variations in their behaviour. Such variability should not, however, distract from the broader and more important story unfolding, which is one of profound and likely irreversible changes to global land and sea ice cover. Taken as a whole, the evidence for sustained changes to the cryosphere is clear.
The impacts these changes are having on water resources, sea-level rise and climate feedbacks are already observable and significant. Some recent predictions of the increase in sea levels by 2100 exceed one metre. Loss of Arctic sea ice results in enhanced warming of the Arctic Ocean due to a strong positive feedback.
Most glaciologists believe we are witnessing unprecedented changes to land and sea ice. The burning question is not if, but how fast, land and sea ice will disappear, and what we can do to mitigate and adapt to these changes.
• Prof Jonathan Bamber is director of the Bristol Glaciology Centre
Comments
15 April 2012 7:00PM
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15 April 2012 7:31PM
Exactly - these are the exceptions that prove the rule. Just because in 2010 it was arctic temps in the UK at December did not mean it wasn't the warmest year on record.
Global warming will mean some areas of the world get colder, but most will not and just to underline this, the arctic ice is melting and in the summer will soon be ice free, and the northwest passage will be open.
Oh - and the seas are getting warmer, so the "once in a life time" Hurricane Irene that hit New York, is not at all going to be once in a life time.
15 April 2012 7:41PM
64 metres! 64 metres!
I'm going to need a bigger boat.
15 April 2012 7:43PM
I'm waiting for someone to pitch in with the 'discredited' report on Himalayan glaciers. However, the Karakoram is a sub-set of Himalaya glaciers. So I thought it best to point it out.
15 April 2012 7:44PM
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15 April 2012 8:08PM
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15 April 2012 8:17PM
[years]. Let's just note that
So, in reaching your conclusions about the retreat of glaciers, you are relying upon (which by your own admission is less-than-perfect) data about less than one-in-a-thousand of these glaciers?
Weasley. You mean that extrapolating from the dodgy (and no doubt, erm, shall we say 'filtered and normalised') data you have, to x 1000+ actual glaciers allows you to pronounce scientifically on the state of all 160,000?
.
1. If the ice-sheets of Antarctica and Greenland contain 99.5% of all land ice on Earth, and you are concerned about potential sea-level rise, why bother even mentioning the other 0.5%?
2. If the evidence that "mass loss in Greenland and west Antarctica has been accelerating since the early 1990s is irrefutable" then not only have you not presented that evidence, but even if you had:
(i) 1990 was less than 30 years ago, so by your own criterion is not a signifier of a 'climactic trend'
(ii) If your concern about loss of ice in Antarctica and Greenland is a rise in sea level, then if there *has been* a signifinant loss of ice in the last couple of decades, it would have manifested itself in a rise in sea levels. No?
And it hasn't.
15 April 2012 8:44PM
A hurricane hitting New York is neither unprecedented nor rare.
We did this one on the other thread: 84 hurricanes and tropical storms have hit New York since the 17th century: that's about one every 5 years on average.
15 April 2012 8:46PM
It wasn't "discredited". It was just discredited.
15 April 2012 8:51PM
Good.
Do we really want the ice cap and glaciers to be growing?
An ice age is not a good thing!
15 April 2012 8:55PM
@TurningTide
"Response to Gelion, 15 April 2012 7:31PM
Oh - and the seas are getting warmer, so the "once in a life time" Hurricane Irene that hit New York, is not at all going to be once in a life time.
A hurricane hitting New York is neither unprecedented nor rare.
We did this one on the other thread: 84 hurricanes and tropical storms have hit New York since the 17th century: that's about one every 5 years on average."
Yes we did do it on another thread.
And those US agency figures showing Hurricane figures that I published showed that Hurricanes are more frequent over the last 30 years than at any other time in recorded history - because the seas are warming.
15 April 2012 8:55PM
Why have these two sentences been put together, as though there was some connection between them? Surely the author isn't trying to imply there's any probability of the sea level rising by 64 metres anytime soon?
15 April 2012 8:56PM
@TurningTide
15 April 2012 8:55PM
These two ice giants contain 99.5% of all land ice on Earth, and store enough ice to raise global sea level by around 64 metres. The evidence that mass loss in Greenland and west Antarctica has been accelerating since the early 1990s is irrefutable.
Why have these two sentences been put together, as though there was some connection between them? Surely the author isn't trying to imply there's any probability of the sea level rising by 64 metres anytime soon?"
Why won't they? The Arctic is going to be ice free very soon in the summer.
15 April 2012 8:57PM
They show that more hurricanes have being detected over the past 30 years, due to better monitoring, not that more have actually occurred.
But please don't keeping mentioning Irene as though it were something unusual: it wasn't, as the data shows.
15 April 2012 8:58PM
The Arctic being ice-free (again - it's been ice-free before at various times over the past few thousand years) is worlds away from the entire Greenland and Antarctic ice sheets melting.
15 April 2012 9:00PM
Well done for having mastered simple subtraction! However 22 years is a lot more than 8 years and is well on the way to 30. I'd hazard a guess that 22 years could show a more reliable trend than 8, no?
No. Do you deny that sea level has been rising on a global basis? If you accept that it has then you must accpet that at least in part that rise may have been influenced by ice-melt in Greenland and Antarctica. You shouldn't assume that because London isn't yet underwater that it therefore bever will be - only a tiny amount of Greenland and Antarctica's ice has melted yet.
15 April 2012 9:02PM
@TurningTide
"And those US agency figures showing Hurricane figures that I published showed that Hurricanes are more frequent over the last 30 years than at any other time in recorded history - because the seas are warming.
They show that more hurricanes have being detected over the past 30 years, due to better monitoring, not that more have actually occurred.
But please don't keeping mentioning Irene as though it were something unusual: it wasn't, as the data shows."
----
You know why I mention Irene - because the media in the US were so concerned about it that Obama had to go on TV and declare it a once in a life time event.
You know it's not going to be so, warming seas mean warmer seas further north, which means stronger and more frequent hurricanes going north and hitting the north east of the US. Obama was wrong to say once in a life time.
In no way does anyone other than you feel that New York gets hit by 5 year cycle hurricanes - although the figures might say that in terms of storms - but Washington and NYC are going to be hit by hurricanes because the seas are warming ...
15 April 2012 9:06PM
@TurningTide
15 April 2012 8:58PM
Why won't they? The Arctic is going to be ice free very soon in the summer.
The Arctic being ice-free (again - it's been ice-free before at various times over the past few thousand years) is worlds away from the entire Greenland and Antarctic ice sheets melting."
It is a marker and whether you like it or not, the climate figures clearly show that the world is getting warmer, year on year.
Why would the Greenland ice sheet not melt? It's next to the Arctic. I agree the Antarctic is another matter, but Greenland is very open to melting.
15 April 2012 9:12PM
The fact that the Himalayan glaciers are not melting make a mockery of articles such as this one where Suzanne Goldenberg claimed to be watching a glacier die and claimed it was "evidence of the increasing pace of climate change"
15 April 2012 9:29PM
To quote Achim Steiner, the UN Environment Programme leader
'We haven't even begun to understand the damage we are bringing to bear on the sustainability of our planet'
"We are able, and we must change course."
"A classic illustration is the ... luxury of this continued debate about scientific uncertainty with climate change. If even 10 per cent of what the IPCC [the UN's Intergovernment Panel on Climate Change] said were to come true, it should actually make us sit up and say immediately, 'change course!'."
15 April 2012 9:33PM
Um, what 'fact'?
15 April 2012 9:34PM
Ice-free over the past few thousand?
15 April 2012 9:37PM
One big denier trick is to focus and pump the heck out of what (they think) supports their case and ignore the overwhelmingly larger bulk of evidence that doesn't.
In this case, they ignore the fact that Greenland, Antarctica and the world's glaciers and ice caps are losing more than 530 billion tons of ice mass annually and the melting has sped up dramatically in the last few years (Jacob et al, 2012).
But no, denier mindset dictates that we ignore the 99% (the rest of the world) and focus on the 1%, which in this case, is the Himalayan ice caps....
15 April 2012 9:38PM
Someone made an error in part of it and apologised. The report is not totally 'discredited', hence the quotes. Deniers regularly make errors and fail to apologise. So, who should be considered more trustworthy?
15 April 2012 9:39PM
Subset of
15 April 2012 9:41PM
I was generalizing to make a point.
15 April 2012 9:47PM
I actually agree with your implication that it is unlikely that we will get anything close to 64 metres rise in sea level in the near future. However, what I took from these two sentences was much simpler than you - you take the most extreme interpretation as the obvious implication.
My interpretation - almost all of the land ice is in two places and the mass loss of sea ice in these two places is accelerating. So yes sea levels could rise - we don't know how much but it could be really significant for those in vulnerable low lying areas. That, it seems to me is not histrionic but in my view a reasonable conclusion based on that information.
15 April 2012 9:49PM
What parts of Greenland were being farmed in the 1-2 centuries before the middle of the 13thC? I guess this may help to put a little more perspective on the extent to which we may be observing cyclical rather than uni-directional change.
15 April 2012 9:53PM
I see on Cryosphere Today that the total global sea is currently at the 30 year average.
15 April 2012 9:56PM
Correction to above: ...total global sea ice area currently at 30 year average.
15 April 2012 10:07PM
Lucky old sceptics -- the Himalayan glaciers give them some more data to cherry pick.
15 April 2012 10:13PM
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15 April 2012 10:16PM
Somewhat less than is currently being farmed is the answer. Currently some 1% of the land surface can be used for growing crops. There may have been a point at which a similar amount was available after the Norse arrived but for the last hundred years or so I doubt that it was anything like that. Certainly the range of crops being farmed there now is a great deal larger than then, I don't recall accounts of apples, strawberries, broccoli, cauliflower, cabbage and carrots being cultivated then. To be fair, potatoes weren't part of the European diet then, not having been discovered, but today some 10% of consumption is from local produce. You should remember that the concept of farming was somewhat different back in the Norse day. Less emphasis on growing things and more on keeping the cattle (=prestige/wealth) alive with the result that arable areas were rapidly stripped of fertility.
No evidence whatsover for cyclical change if you're looking for some cycle shorter than Milankovitch's.
15 April 2012 10:25PM
Sorry deniers, but our world is melting.
Land Ice:
About 148 billion tons of annual land ice loss comes from glaciers and ice caps outside of Greenland and Antarctica and 385 billion tons of annual land ice loss comes from Greenland and Antarctica -- a total of more than 530 billion tons. The annual ice loss is now accelerating rapidly. The total global land ice mass lost during the study period (2003 - 2010) was about 4.3 trillion tons, adding roughly 0.5 inches to global sea level. (Jacob et al, 2012)
According to GRACE data, the Antarctic ice mass loss has now increased dramatically, up from 103 to 246 gigatons per year. So no, deniers, it isn't warming in the Antarctic.
Sea Ice:
1. Maximum Extent: The winter months prior to, and around the **maximum** Arctic sea ice extent reached in March, 2012 and it was:
- 9th lowest out of the 34 years of satellite data
- 530,000 kilometers below the 1979 to 2000 average extent.
March sea ice extent from 1979 to 2012 showing a decline of 2.6% per decade.
2. Minimum Extent: The **minimum** extent of Arctic sea ice reached in September 2011, was:
- the SECOND LOWEST on record
- 2.38 million square kilometers below the 1979 to 2000 average minimum.
Monthly August ice extent for 1979 to 2011 shows a decline of 9.3% per decade.
3. Volume: Sea ice volume takes into account both sea ice thickness and extent. Last year's sea ice volume on September 2011 was:
- the LOWEST on record
- 66% lower than the mean over this period
Arctic sea ice volume 1979 - 2012 from PIOMAS
15 April 2012 10:35PM
This graph actually suggests that over the last few years things have improved.
In fact it suggests that March was almost at the 1979-2006 average.
http://arctic-roos.org/observations/satellite-data/sea-ice/observation_images/ssmi1_ice_ext.png
15 April 2012 10:39PM
Cripes. Even my measly O level physics says that's a lot of energy to turn that ice into water. Has the sun started shining brighter? I don't think so, as my yearly tan indicates otherwise.
15 April 2012 10:45PM
Yaaaaaaaaaaaaaawn ...
15 April 2012 11:36PM
Utter rubbish.
The Antarctic is now losing mass and at an increasing rate.
"...Gravity data collected from space using NASA's Grace satellite show that Antarctica has been losing more than a hundred cubic kilometers (24 cubic miles) of ice each year since 2002. The latest data reveal that Antarctica is losing ice at an accelerating rate, too...."
http://www.nasa.gov/topics/earth/features/20100108_Is_Antarctica_Melting.html
link
If you are going to spout off about climate change at least get your most basic facts right. Otherwise you will appear to be just another ...er..."skeptick"...liar.
15 April 2012 11:50PM
I looked it up a while back.
The latent heat of fusion (heat required to melt ice at 0C) is 334kJ/kg.
The specific heat capacity (energy to raise the temperature of water by 1C) is cp = 4.1855 [J/(g·K)
Thus the energy required to melt a given mass of ice is equivalent to that required to heat the resulting water from 0C to 80C
From this we can see that the global ice melt is absorbing...
(530x10^12) x(334) kJ = 177x10^18 J
A whopping 177EJ per annum!
15 April 2012 11:52PM
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/global.daily.ice.area.withtrend.jpg
link
Yep. "currently" being the operative word. It was even briefly above average back in 2008. Woop de doo - we're all saved and it's all due to you proving climate change is a hoax by spotting one month's ice anomaly.
Oh wait! I've just had a closer look and according to the same Cryosphere today page (linked above) it is on a long term trend downwards and has been for decades now.
I guess that was just an innocent oversight on your part.
15 April 2012 11:57PM
What percentage of the total melt, if any, is caused by AGW?
16 April 2012 12:21AM
Earlier, I wrote:
Then I posted data of the planet's ice loss including ice caps and glaciers, Greenland and Antarctica and Arctic sea ice.
Then Murphed comes along with this rebuttal:
A perfect example of that denier trick... focus on what you think supports your case and ignore the overwhelmingly larger bulk of evidence that doesn't.
Murphed's graph shows the Maximum ice extent, where this year is closer to the average (but still 530,000 kilometers short). Ignoring all the other data (the 530 billion tons of melting land ice, the disintegrating Arctic sea ice volume, etc) Murphed erroneously concludes from his cherry-pick that "over the last few years things have improved". What???
To recap (once again), and in context this time. This is the state of the overall cryosphere:
Land ice:
Melting fast (including the Antarctic) to the tune of 530 billion tons of mass loss annually.
Sea ice:
The Arctic Maximum Extent in 2012 was 9th lowest on record and 530,000 kilometers below the 1979 to 2000 average, declining at a rate of 2.6% per decade.
The Arctic Minimum Extent reached in 2011 was the SECOND LOWEST on record and 2.38 million square kilometers below the average minimum, declining at a rate of 9.3% per decade.
The Sea Ice Volume in 2011 was the LOWEST on record and a whopping 66% lower than the mean over this period.
Does that sound like "things have improved" to you?
16 April 2012 12:30AM
A record that only began in 1979, on a planet that is 6 billion years old.
Does that sound like a worthwhile statistic to you?
16 April 2012 12:33AM
A minor point on your otherwise highly informative post.
I just tried to do some fag packet calculation based on your figures, and billion is an ambiguous amount.
I'm assuming you are using 10^9, so 530Gt is a clearer way to express it
16 April 2012 12:56AM
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16 April 2012 1:03AM
You betcha.
The global warming due to our addiction to burning fossil fuels is happening exponentially faster than anytime in the past. Seeing as the Arctic sea ice minimum is declining at a rate of 9.3% a decade and the volume is dropping even faster and Greenland and Antarctica are losing ice mass at increasing rate every year, it doesn't take a genius to figure out where we'll be in a few decades. You don't think that this is worthwhile to know??
So yes, it's worthwhile statistics. Of course it is.
16 April 2012 1:06AM
That's .075%, hardly seems meaningful.
16 April 2012 1:15AM
Could China and its massive weather modification decrease the moisture of the glaciers? Is it warming, or is it getting very dry?
16 April 2012 1:15AM
30 years out of 6 billion?
That is like one second from my life!!
I haven't breathed in the last second, therefore it could mean I will never breath again. Should I be in a panic? does the last second provide a meaningful amount of time to tell if I am never going to breath again?
Or is it just too small of a time period to gain any meaningful information from, especially when it is highly likely that my breathing is a cyclical action and I will breath again?
Oh, I just breathed!! Just needed longer than a second. ;-) all good.
16 April 2012 1:18AM
So you are confident in the past 6 billion years arctic sea ice has never declined faster in any 33 year period?