NZ glaciers holding their own (just)

by Gareth on November 9, 2010

NIWAParkPass2010.jpg

New Zealand’s glaciers just about held their own over last summer, showing a very slight gain in mass on average according to NIWA’s annual end of summer snowline survey, released today. The Park Pass glacier (above) in the Mt Aspiring National Park between the Hollyford Valley and the head of Lake Wakatipu (map) is one of the 50 index glaciers in the NIWA survey. From the press release:

“A moderate El Niño developed in the tropical Pacific in spring last year. This brought more southwesterlies, with normal to below normal temperatures through last summer and into autumn this year. The overall effect was to hold snowlines in a near steady state this year,” says [NIWA scientist] Dr Hendrikx. The previous two years (2007–08 and 2008–09) had seen end-of-summer snowlines rise significantly as not enough snow fell to compensate for melting.

The impact of the El Niño shows as a (very) small uptick at the end of the ice mass graph, but the overall trend remains strongly downwards.

NIWAglaciermassbalance2010.gif

The full report (with lots of pictures from the aerial survey) can be downloaded from the NIWA web site. The Park Pass photo above was taken on March 6th this year on the fourth leg of NIWA’s alpine flight, and shows some spectacular icebergs in the proglacial lake. The extent of the glacier’s retreat can be seen in the Google Earth imagery at Mauri Pelto’s From A Glacier’s Perspective blog post on the nearby Donne Glacier. With a strong La Niña now influencing weather patterns in NZ, it’ll be interesting to see how the glaciers fare. I wonder if I can blag a seat on the 2011 flight? ;-)

{ 95 comments… read them below or add one }

R2D2 November 9, 2010 at 2:29 pm

“The impact of the El Niño shows as a (very) small uptick at the end of the ice mass graph, but the overall trend remains strongly downwards.”

I would dispute this. It would be nice to have the raw data to do a simple signifigance test. I note if the report was done in 1988 or 1998 one could remark the trend was “strongly upwards”. So a significance test is needed to prove the trend.

Anyhow, I also note that you have removed a line and all the notes from the graph. In the report a second line marked ‘raw’ shows an increase in MBI since 1978. This line is scaled to adjust for the fact that melting years remove more ice than freezing years. The authors multiply every decreasing year by 1.92 in order to achieve the downward trend. To give the authors credit they do a sensitivity analysis of this assumption and show this in figure 11. Using a scaling factor of only 1.5 results in ice balance today equal to that of 1978.

What data did you plot your graph with Gareth? Are you able to please post the data?

Gareth November 9, 2010 at 2:37 pm

The graph was supplied by NIWA, and is as shown on their web page.

I note with some interest that R2, having skimmed the report, considers himself enough of an expert on NZ’s alpine glaciers to “dispute” NIWA’s conclusions. What breathtaking self-importance…

R2D2 November 9, 2010 at 3:02 pm

Sorry, yes it is on their web page.

I dispute the conclusion that you draw from it Gareth, that it has a “strongly downwards” trend. I don’t dispute any of the conclusions or comments of the authors.

You are the one who dispute the comments of the authors, who say, “On average, the latest survey indicated very slight positive mass balance for the index glaciers for the 2009/2010 glacier year, i.e. the snowlines, the equilibrium line altiudes (ELAs), were slightly lower than average.”

Gareth November 9, 2010 at 6:48 pm

See diesoli’s comment below. I’m merely echoing the NIWA statement.

RW November 9, 2010 at 2:57 pm

Idiot. Go and join Weatherzone instead of trolling here – some of their dimwits might swallow some of your nonsense.

R2D2 November 9, 2010 at 4:24 pm

RW. How rude.

So you don’t like people posting comments that actually critique the posts written? Anyone who points to any flaw is a ‘troll’? Would you prefer an environment where everyone operated a group think mentality and never paused to critique their own view point?

bill November 9, 2010 at 3:09 pm

Wow, R2 – channelling Ian Plimer on the pseudo-informed pontification scale! Are you able to prove you actually know anything about it? Thought not! And you’re like John D – read the bloody links, man, the graph you’re casting aspersions at Gareth about is right there on the NIWA page! Sheesh!…

R2D2 November 9, 2010 at 4:25 pm

I know nothing about glaciers. I will be the first to admit that.

I know a thing or two about statistics. I know the difference between a trend and random noise. If the data set was posted I would be able to determine this.

Greg November 9, 2010 at 6:18 pm

You can eyeball the numbers off the chart. There’s software that does this, but I can’t remember what it’s called.

Go ahead. Fit a trend line.

Gareth November 9, 2010 at 6:47 pm

Actually, all the numbers are at the back of the NIWA report…

R2D2 November 9, 2010 at 10:34 pm

Any random data set can have a trend line fitted to it. What is useful is not the trend line but the significance of that trend

Mike C November 10, 2010 at 1:41 am

Well R2, there is an easy answer here.
Grab the data from the report, fit a trend, check if it is significant and then come back and tell us what you found. I’m interested to see the answer.

Lank November 9, 2010 at 3:46 pm

Gareth you initial description….. “just about held their own” is just plain false. Clearly, the ice has ‘gained in mass’ over last year.
Why do you not just say that the ice has increased? You obviously have a need to put on an alarmist spin for a trend that clearly does not indicate significant ice melt.
How much CO2 emmissions will result if you ‘blag a seat on the 2011 flight’?

diessoli November 9, 2010 at 4:16 pm

“Why do you not just say that the ice has increased?”

Because a short term gain is not a trend.
I don’t see that Gareth has added any spin.
From the report:
This slight gain is insignificant when compared with the losses experienced since the glacier monitoring started in 1977. “This small average gain helped to hold some glaciers in a steady state over the last glacier year,” says NIWA’s snow and ice scientist, Dr Jordy Hendrikx. The overall average downward trend of the last 33 years, since the survey started, is still evident. “Our monitoring is showing a general decline over the long-term and that is consistent with the obvious shrinking of some of the South Island’s largest glaciers as ice melts in the glacier trunk and calves off at the terminus.”

D.

R2D2 November 9, 2010 at 4:27 pm

“Because a short term gain is not a trend.”

But a short term decrease is? What do you define as short term?

John D November 9, 2010 at 5:14 pm

@R2D2

Note in the linked pdf and the article above that these are adjusted figures to account for the difference between ablation and accumulation.

Fig 10 in the pdf shows the raw data, and Fig 11 shows the sensitivity of the scaling factor to the graphs.

The methodology is explained in the pages 29-31 of the pdf.

Lank November 9, 2010 at 5:28 pm

Gareth states …”the overall trend remains strongly downwards” but if you look at the data 1977-2007 the trend is flat, or if anything is……. ‘upwards’.

Gareth November 9, 2010 at 6:53 pm

Your eyeball isn’t very good at doing regression analysis, is it? You can say that the 2007 ice mass is about the same as 1977, but that doesn’t mean that there isn’t a downward trend over that period, because end points are misleading. Plot all the data, and see what you get…

R2D2 November 9, 2010 at 10:39 pm

But end points are equally misleading for the data set 1977-2010. There are 16 data points above 0 and 17 below, if you pick a random end point you are pretty much 50% likely to get an upward trend! The truth is there is no significant trend in that data set.

Gareth November 10, 2010 at 9:03 am

Worth pointing out, perhaps, that the graph is for end of summer mass balance, not cumulative mass change. For that you need something more like the graph here

Lank November 10, 2010 at 11:49 am

Yep good point Gareth – That graph tells an important story. In the first 20 years the mass balance was essentially the same, a flat line. Last 10 years the mass balance was also ‘flat’.
What is your point?…. Dropping of ice over one or two years in a 33 year record tell very little.

Same Ordinary Fool November 9, 2010 at 6:42 pm

“NZ glaciers unusual
Worldwide glaciers are regarded as a useful indicator, but New Zealand glaciers are complicated because they have their sources in areas of extremely high precipitation. Glaciers in parts of Norway are similar…”

Does the NIWA summary adequately express the differences with the global glacier situation? Maybe a global glacier mass change graph should also be included.

http://www.skepticalscience.com/himalayan-glaciers-growing-intermediate.htm

Gareth November 9, 2010 at 7:00 pm

Thanks for the link: here’s the graph on that page:

The report does describe the NZ glacier environment in detail, but doesn’t put it into the global context. That’s better left to the WGMO.

Terry Jackson November 9, 2010 at 8:05 pm

Gareth:
I tryst you realize this is a pathetically small sample, The last textbook I consulted listed the annual precipitation at Alaska’s North Slope at somewhere around 3″ per year. . NZ will differ. Input minus output. But the bright side is you get to grow wine grapes. That is really neat, but you seem to long for the days when grapes would not grow, at least at your location.

Someone recently compared the Dakotas and Alberta/Saskatchewan as the Saudi’s of food production. It only applies in a climate as warm or warmer than we enjoy today.

There are some potential benefits to warming, and some downsides. Time to recognize both.

Where is Phil Scadden?

Terry

Gareth November 9, 2010 at 8:19 pm

“Pathetically small sample” of what? The NIWA survey is pretty extensive. If you mean the WGMO graph, you’ll find it’s indicative of global behaviour. Take the selection of glaciers up with them.

Dappledwater November 9, 2010 at 8:50 pm

Someone recently compared the Dakotas and Alberta/Saskatchewan as the Saudi’s of food production. It only applies in a climate as warm or warmer than we enjoy today.

Someone?. And the many trillions of dollars worth of land and infrastructure that will be rendered useless by global warming?.
C’mon at least apply wee bit of critical thinking.

cynicus November 9, 2010 at 10:02 pm

Indeed, the promise of new farm lands is a fallacy, but not the only one…

“Higher temperature in the North yields new farmland” is just another iteration of the “CO2 is plant-food” crock. Those who use it simplify too much. It assumes that temperature (or more CO2) is the only driver to more productive farms, but forgets that available soil moisture, pests and minerals etc. are equally important parameters.

adelady November 11, 2010 at 1:21 pm

“Soil moisture” relies on there being soil in the first place.

A lot of these northern permafrost and ice covered areas have not a lot beneath them that a farmer would recognise as useful soil. And the very short growing seasons imposed by the high latitudes are more suited to fast turnaround vegetables than grains even where soil is available..

Thomas November 10, 2010 at 10:23 am

People who believe that the northern plains can grow as much as the tropics will be disappointed to realize that even if and when the climate warms enough to grow more food in northern Canada, its light does a lot of the trick. And no warming up north will alter the amount of sunlight available there over the year. The winters will be just as dark as they are now and the growing season will therefore never match the two or sometimes three harvests in the tropics. So anybody who thinks we can simply shift humanity to the high latitudes if push comes to shove is sadly mistaken.

Mauri Pelto November 10, 2010 at 5:14 am

Many New Zealand glaciers have lost volume rapidly in the last 12 years. This is a good indicator that the snowline model is a reasonable proxy for glacier mass balance. New Zealand glaciers have by far the highest ratio of advancing glacier over the last decade of any region, yet volume overall has been declining significantly. That this is due to local moisture increase is supported by the loss of glacier ice to the south on Heard Island and to the north in New Guniea .

David November 10, 2010 at 8:23 am

R2,
you are wasting your time in this echo chamber of 16 people!
They just accept everything they are told without critical review. They havent even worked out that feedbacks are still the “dont know” part of climate science. They just blindly rely of computer models and want to commit billions of dollars “just in case”.
Blithley ignoring the pressing needs of the poor all over the world who need things like good drinking water.
Meanwhile WUWT has just passed 60 million page views….
Seriously , a blog of 16 ignorant and rude people vs millions who disagree.
Tell us about your “concensus” again.

Sits back and waits for the post to be suppressed.

RW November 10, 2010 at 9:24 am

You’re delusional.

Dappledwater November 10, 2010 at 9:43 am

has just passed 60 million page views

Which affects atmospheric physics how?. If this blog is so insignificant, why bore us with your superstitious ramblings?.

Gareth November 10, 2010 at 9:53 am

Poor effort David. Comparing µWatts to Hot Topic is pretty meaningless. A fairer comparison would be with an NZ sceptic blog. For the record, the last time Tim Selwyn ran his NZ Blogosphere survey, HT was at #13, and our readership has increased a fair bit since then.

(Aside: Watts likes to rely on Alexa web stats. They’re pretty meaningless outside the US, because they only count visits from people who have installed an Alexa “toolbar” in their browser. Alexa suggests that over 60% of HT’s readers come from the US, for instance — which is nonsense. Over the last month, 47% of visitors came from NZ, 17% from the US, 6% from the UK, 8% from Australia and 5% from Canada. I think it’s rather interesting that half of our readership is international…)

Thomas November 10, 2010 at 10:32 am

Oh dear David…. You forget one rather important thing here: Uncertainty in science always goes BOTH WAYS!!!
In other words, while indeed there may be feedbacks which have yet to be counted correctly or other factors which we have yet to weigh with a smaller error bar, the resulting uncertainty goes to both sides of the debate. While there may be a glimmer of hope that we might come out better than the very conservative IPCC consensus reports, there is a considerable chance that we might be off far worse actually.
The idea that uncertainty can be claimed by the head in the sands brigade for their ‘do nothing’ campaign is simply totally fraud.

BTW the fact that many people indulge themselves with sites like WUWT speaks for the strong desire of so many to cling to straws in their hope that we can simply go on as we were, happily growing exponentially, without ever needing to face the consequences.
Denial is sweet as long as it lasts…. and for the die hard libertarian conservatives, there is simply no room for ever allowing the realization to take hold that unregulated market behavior is at the core of the problem.
You might find this post interesting:
http://rationallyspeaking.blogspot.com/2010/05/why-do-libertarians-deny-climate-change.html

John D November 10, 2010 at 11:33 am

Have you seen the results from the SciAm survey?

Examples responses:

3. What is causing climate change?
natural processes 77.7% of votes

4. The IPCC, or Intergovernmental Panel on Climate Change is
a corrupt organization, prone to groupthink, with a political agenda: 83.7% of votes.

5. What should we do about climate change?
Nothing, we are powerless to stop it 69.1% of votes

8. How much would you be willing to pay to forestall the risk of catastrophic climate change?
Nothing: 79.5% of votes.

http://www.surveymonkey.com/sr.aspx?sm=ONSUsVTBSpkC_2f2cTnptR6w_2fehN0orSbxLH1gIA03DqU_3d

Phil Scadden November 10, 2010 at 12:27 pm

We are doomed. I assume this was only american’s who seem to be particularly reality-challenged. From those numbers that nothing will change in US till costs of climate change are hitting them hard enough to face facts.

Actually just checked – this wasnt a proper survey – just a poll of those self-selected ones who filled it out. Furthermore, when I tried to find it, I see it was being advertised all over denialist websites whereas I didnt see any news of it in science sites (apart from Sciam).

JohnD – what idiots think tells you nothing about reality except for about the nature of idiots.

John D November 10, 2010 at 12:33 pm

when I tried to find it, I see it was being advertised all over denialist websites whereas I didnt see any news of it in science sites (apart from Sciam).

Funny that, eh?

What does that tell you about the science sites, given that the survey results are genuine?

Does the word “denial” spring to mind?

Thomas November 10, 2010 at 10:14 pm

JD you realize that your little poll only proves one thing: People are susceptible to believe what they want to believe and in general not scientifically literate.
It proves that those who worked so hard on orchestrating this whole smear campaign against the truth are culpable beyond reasonable doubt and will hopefully one day be held to account.
Besides if you were to advertise a poll on a pentecostal church website on the question of the age of the Earth you can probably guess what the answer will be.
In fact a 2008 Gallup poll worked out that 44% of US adults agreed with the statement “God created human beings pretty much in their present form at one time within the last 10,000 years or so.”
You will perhaps agree that what 44% of Americans believe has no influence on how nature works….
However if the denial campaign indeed succeeds to keep a sizable percentage of voters ignorant of the truth then indeed we may be doomed….

John D November 10, 2010 at 10:40 pm

Thomas,
The survey was run after the article on Judith Curry. The SciAm portrayed her as a heretic because she claims that the IPCC is prone to group think, is corrupt, etc.

Maybe the readers were simply agreeing with her?

Gareth November 10, 2010 at 12:35 pm

Given that the survey was promoted at µWatts, I dare say Anthony’s rather suggestible readers piled in to distort the result. Web polls like that are meaningless. More credible would be the Pew Center poll of US opinion.

Sam Vilain November 10, 2010 at 12:47 pm

One survey also found that 57% of respondents to one survey (n = 1,700 or so) said that :

God’s intervention could save a family member even if physicians declared treatment would be futile.

Doug November 10, 2010 at 11:12 am

My mother always suggested that when faced by rude people don’t say anything just simply leave.

Goodbye David, don’t let the door hit you on the way out.

John D November 10, 2010 at 12:42 pm

Doug,
Is this an admission that you are a rude person?

It is certainly how it reads to me.

David November 10, 2010 at 2:18 pm

“My mother etc”

Not my words. You get confused easily dont you. I note the other day I was called a ‘moron” and a “nutter”
How nice.
And no moderation.

Thomas
“while indeed there may be feedbacks which have yet to be counted correctly”

Or indeed counted at all!!! You still dont get it do you.

Thomas November 10, 2010 at 10:36 pm

I get it all right. Its you who seem to believe in fairies.

Besides you did not get what I was saying at all: Uncertainty goes BOTH ways. The IPCC for example has not counted release of methane from arctic permafrost and seabed hydrates because we can not yet quantify this well enough. However we do know that significant amounts of the gas will be released if the area continues to warm at present rates.

What risk are you willing to take on the future then??

If we were told that some mad scientists had created a device that had a 50% chance of accidentally warming the earth by 10 degrees over 200 years, wiping out a large percentage of species, raising sea levels by 6 meters and condemning a sizable percentage of humans to starvation, would you be so “libertarian” about them and let them tinker on with their experiments or would you stop the nonsense?

If we carry on as we are today we know for certain that the earth will warm by several degrees and there is a good chance that we might condemn the system to heat by perhaps two digit figures, possible feed backs assumed. So you are willing to bet the Earth on your slim chance that things are not as bad as science tells us?

Gambler!

Doug November 11, 2010 at 2:12 pm

My point is that if you find us rude go somewhere else were there are a better class of people. Why come here and to be abused? You must realise we think little of your opinion and you are not convincing us of your arguments, because we follow the actual science and know you don’t have any.

John D November 11, 2010 at 2:29 pm

Doug,
We are discussing science here.

The resident trolls are adding nothing of any consequence.
You are merely pumping out the usual propagandist arguments.

Doug November 12, 2010 at 7:38 am

Great present some science and I will consider it. I have access to the journals and will read anything you suggest and come back with a response – on the science

John D November 12, 2010 at 8:56 am

I note with some sadness that one of the authors of the referenced papers is a friend, Clive Heydenrych, who along with Trevor Chinn and Jim Salinger did a lot of the original survey work for NIWA

Clive has advanced cancers and is currently in a hospice. He is only just turned 50.

Gareth November 12, 2010 at 10:01 am

Very sad, JD. I trust he is being well looked after.

R2D2 November 10, 2010 at 11:05 pm

So still not one admission that the glacier record shows no trend?

Thomas November 10, 2010 at 11:16 pm

Have you done your homework and put the data through a linear regression yet? The you will see the trend.

R2D2 November 11, 2010 at 9:23 am

Do you mean the numbers in Appendix 1? They don’t seem to match the graph. The data set is incomplete, it looks like some tricks are required to fill in the gaps in order to get to the graph displayed. If the data used for the graph was available it would be much easier. If I am being slow and these are in the report please point me to the page number.

John D November 11, 2010 at 9:30 am

@R2D2 – I am guessing that the numbers in the appendix are the raw figures. Note that there is an adjustment to account for ablation / accumulation that I mentioned in a previous comment.

Dappledwater November 11, 2010 at 9:45 am

it looks like some tricks are required to fill in the gaps – R2

You need to make up your mind. Earlier in this thread you wrote:

I know a thing or two about statistics- R2

Like Thomas I’m waiting for you to run a linear regression and post the results.

R2D2 November 11, 2010 at 10:25 am

Sorry I just use the term ‘trick’ in the same sense as Phil Jones (ie “Mike’s nature trick”).

Dappledwater November 11, 2010 at 1:01 pm

Sorry I just use the term ‘trick’ in the same sense as Phil Jones – R2

No you wrote:

it looks like some tricks

Which implies you either don’t know, or were casting aspersions at the scientists involved.

R2D2 November 11, 2010 at 1:42 pm

That was not my intention. When the data for 1990 only contains 2 observations statistical ‘methods’ are needed to estimate the data. For the record I have not read anything in the report that would give me reasons to cast “aspersions at the scientists involved”. If I have given this impression I apologise.

diessoli November 11, 2010 at 10:03 am

Here are the values used to create the graph. It’s an accumulated index where the negative indices are scaled with 1.92 (reading the text under discussion is often helpful)
18
-56.88
-116.4
-95.4
-53.4
-74.52
57.48
167.48
247.48
261.48
296.48
277.28
280.28
-178.6
-113.6
11.4
147.4
214.4
365.4
410.4
534.4
453.76
123.52
-158.72
-67.72
-282.76
-178.76
-93.76
19.24
-67.16
-60.16
-313.6
-496.0
-493.0
The linear trend is -0.86 per year.

I’d be happy to include a plot with the trend, but it seems attachments are not supported (or are they Gareth?).
D.

R2D2 November 11, 2010 at 10:38 am

When I do a regression on that data (fairly simple just ask the computer to do it) I get:

Coefficient = -8.32
Adjusted R2 = 0.08
t stat = -1.98

Given this is a one sided test any t-stat that is less than -1.64 will result in a rejected hyopthesis (that the coefficient is 95% likely to be less than 0). The null hypothesis that there is no trend can not therefore be rejected.

John D November 11, 2010 at 10:53 am

You should also bear in mind that the trend is highly sensitive to the adjustment factor of 1.92 (see Fig 11 in the pdf that I mentioned previously)

R2D2 November 11, 2010 at 11:00 am

On page 30 the authors discuss this assumption. It would be interesting to know the confidence on this scaling factor. The authors do not seem very confident in it hence the sensitivity analysis. This added variable will further add to the insignificance of the trend (it is harder to reject the null because not only could the trend be zero under present assumptions, present assumptions could be wrong).

John D November 11, 2010 at 11:14 am

The scaling factor of 1.92 is an average of sorts. The pdf refers to the possibility of a more accurate assessment by calculating a scaling factor of each individual glacier.

I presume that glaciers dynamics vary considerably in NZ. e.g the Tasman is long and narrow, whereas the Fox and Franz have large accumulation zones and small ablation zones. I am guessing that the scaling factor would very considerably for these two examples.

R2D2 November 11, 2010 at 11:45 am

All very good points John D. But even without that information Gareths assessment that the trend is “strongly downwards” is alarmist to the point of ridiculousness.

R2D2 November 12, 2010 at 10:06 am

OK so I said I knew a thing or two about statistics but I actually made a very basic mistake when I posted the above and I should now eat humble pie. I guess that’s the risk of revisiting a basic task that you haven’t done in 5 odd years.

No one seems to have noticed it though so I hope no one is callous enough to now rub my face in it. The above statement has an error, and I am willing to admit it, so hopefully that is enough. The statement that there is no “strongly downward” trend in the data still holds true. There is however a slightly downward trend in the data.

Gareth November 11, 2010 at 10:46 am

Only blog admins can post images AFAIK. If you want to forward me your image, I’ll upload it and post.

I’ve also asked one of the report’s authors to clear up one or two points (specifically the difference between this year’s graph, and the one published two years ago).

John D November 11, 2010 at 8:57 am

The trend is desribed in the executive summary (page i) of the NIWA report (pdf from the link above)

The glaciers have shown a varying pattern of positive(22 years) and negative (12 years) mass balance over the 34 year monitoring period

John D November 12, 2010 at 10:21 am

You have to love how my verbatim quotes from the NIWA report gets thumbs down.

I guess that really does define the meaning of Ad Hominem!

diessoli November 12, 2010 at 1:17 pm

Maybe because you quoted the wrong sentence. The trend is described in the following two sentences:
However, some of the index glaciers with well-defined permanent ice areas have clearly lost ice during the course of the 34 year monitoring period. This mass loss has occurred during large negative mass balance years and has not been replaced during the positive mass balance years.

D.

bill November 12, 2010 at 1:35 pm

Fixed that for you, John -

You have to love how my cherry-pick verbatim quotes from the NIWA report gets thumbs down.

I guess I really have no idea of that really does define the meaning of Ad Hominem!

John D November 12, 2010 at 1:43 pm

Bill,
I read the article and analysed the data myself.
The trend is quite clear from the graph. The trend is mirrored in the NIWA statement I quoted.

You can fit any straight line and find a trend. I could fit a linear trend to a portion of a sine wave if I wanted.

Mauri Pelto November 11, 2010 at 2:44 am

I see a trend and it fits the global pattern. Note that the mass balance of glaciers globally took a downward turn in the 1990′s, that is when the snowline began a persistent period of higher elevations in New Zealand. True the trend is not as negative. Glaciers do not have a memory of the previous year as sea ice does when it comes to the mass balance of the current year. Globally after 19 consecutive years of mass balance loss the trend is robust and of concern. Each year there are locations around the globe where conditions permitted positive glacier balances, but each year those locations are in the minority. In 2010 both New Zealand and the ,North Cascades were close to equilibrium. That is not the case in Alaska, Alps, Himalaya for the year.

R2D2 November 11, 2010 at 9:16 am

“Globally after 19 consecutive years of mass balance loss the trend is robust and of concern. Each year there are locations around the globe where conditions permitted positive glacier balances, but each year those locations are in the minority”

Likely a very true statement. But it does not justify the claim that the NIWA report shows a “strongly downwards” trend for the mass ballance of New Zealand glaciers.

Gareth November 11, 2010 at 10:57 am

The trend is downwards, and in context (ie the loss of ice in NZ since records began) continues. Here’s a picture:

As you can see, when Julius von Haast first sketched the Cameron Glacier in 1864, there was a lot more ice than in the photo, taken in 2005. More info and links in this recent post.

R2D2 November 11, 2010 at 11:02 am

Wow Gareth you are onto something! The majority of ice retreat seems to have happened before 1977!

Gareth November 11, 2010 at 11:11 am

Not news.There was a period of strong ice loss in the 1950s.

R2D2 November 11, 2010 at 11:17 am

1950s? But isnt that before the majority of CO2 emissions??

Again, the report notes (section 5.1) that some glaciers are exhibiting loss of ice inherited from a previous climate. These glaciers have a 100 yr response time and are excluded from the survey. So yes Gareth the Haast glacier is retreating, from the little ice age (which I take it you think either didn’t exist or was limited to Europe).

Gareth November 11, 2010 at 11:47 am

The Cameron Glacier, R2. The “little ice age” seems to have been a global phenomenon, as you might expect from an event thought to have been driven by high levels of volcanic activity and low solar irradiance (with, by today’s standards, low levels of CO2), but be careful how you interpret “response time” (see point four in this Wishart post).

Dappledwater November 11, 2010 at 12:16 pm

So yes Gareth the Haast glacier is retreating, from the little ice age

So how does the little ice age figure into all the yo-yo-ing advance/retreat cycles for the Franz Josef?. And all those areas sampled in the NIWA graph above?.

In 1907 the Franz Josef Glacier was advancing, and a viewing platform was built for tourists to look over the front of the glacier. It continued to advance, and the viewing platform was swept away in 1909

Franz Josef Glacier: advances and retreats

Are you now claiming the 20th century was part of the Little Ice Age?.

Your contrarian talking points lack coherency. As always.

R2D2 November 11, 2010 at 12:24 pm

Dappledwater: the point was from the report.

John D November 11, 2010 at 12:44 pm

So how does the little ice age figure into all the yo-yo-ing advance/retreat cycles for the Franz Josef?

The Franz is very short and steep and responds quickly to snow accumulation on the neve, unlike the Tasman which is long and shallow angled.

Lank November 11, 2010 at 11:54 am

Gareth – the Haast sketch in 1864 clearly shows snow covering the morrain. This is not glacial ice as you can see the hummock texture of terminal morrain outlines covered by snow. If you took a photo showing the same scene after a snowfall last winter then you would see much the same as Haast in 1864.

Gareth November 11, 2010 at 12:04 pm

Nonsense. Follow the links in the original post, or just look at the ice level in the valley behind. The ice loss is clear and obvious to any visitor to the valley.

Gareth November 11, 2010 at 11:07 am

PS: Those genuinely interested in how NZ’s glaciers “work” and respond to climate signals will find this post at Journeys To The Ice interesting. In particular, the podcast is fascinating.

Lank November 11, 2010 at 11:43 am

Gareth – R2D2 makes a good point. Glaciers have a very long response time. The ice movements we see now relate to a time well before significant man-made CO2.
Surely all the fuss about retreating icecaps as ‘proof’ of AGW is hovering on thin ice?

Gareth November 11, 2010 at 12:40 pm

You don’t understand response times. Read the reference I offered to R2.

R2D2 November 11, 2010 at 1:00 pm

Gareth in that ‘reference’ (which is in reality your own soap boxing), “Wishart’s error here is a big one — a very basic misunderstanding of the meaning of “response time”. He appears to think it means that the ice somehow has to wait for a period before it can start melting — he calls it “thermal lag”. This is, not to put too fine a point on it, complete rubbish. If the climate warms, ice starts melting straight away and the glacier starts losing mass. No lag. No heat mysteriously stored away for hundred or thousands of years before making itself felt. Current melting is not a “delayed reaction” to events a long time ago, it’s a direct response to current weather and climate change as it happens.”

Again, I am no expert in glaciers, but I think you are misrepresenting Wishart here.

No one is saying glaciers ‘wait’ 100 years before they start melting. Only that not all the melting can happen overnight.

Simple analogy. I open the door on my freezer and leave it open. Every minute I measure the change in ice mass. The warming has happened once and once only. Yet the ice mass accelerates for about 2 hrs then decreases as the amount of ice is diminished to zero. Applied to glaciers we can see the change in temperatures will result in melting over a period of time.

But again, we are off topic and I am being tricked into arguing pointless issues. I agree the world has warmed. I agree this should result in changes to glaciers (either more precipitation or more melting or both). I just don’t agree that you need to misrepresent this NIWA report to claim a ‘strong trend’.

If you want to change the discussion now to talk about melting that happened in 1950 I don’t see what that has to do with AGW other than to show modern variation is no different to historical variation.

Dappledwater November 11, 2010 at 1:08 pm

But again, we are off topic and I am being tricked into arguing pointless issues.

Now you know how we feel.

Gareth November 11, 2010 at 1:42 pm

No misrepresentation involved. Simply read what Wishart claimed happened — that the current ice loss was due to the medieval warming! The basic point is that glaciers respond to the here and now, though the time it takes them to reach a new equilibrium (however you choose to measure it) can be long or short.

Your freezer analogy is incoherent. All the time the door is open heat is entering the freezer.

NZ has lost about half its ice mass since European settlement. Within that big picture there have been periods of ice loss and gain superimposed on the overall trend. I didn’t misrepresent the report, I made a statement about the overall trend which is supported by the facts. Your nit-picking changes nothing. Listen to the podcast reference I provided. You will hear a real ice expert, and his opinion is that if NZ warms by a couple of degrees, all NZ’s ice will eventually disappear.

RW November 11, 2010 at 12:48 pm

Poppycock.

Dappledwater November 11, 2010 at 11:49 am

Glaciers have a very long response time.

Yes. Consequently the loss of ice from this current Anthropogenic Global Warming episode will persist for a very,very long time.

R2D2 November 11, 2010 at 12:00 pm

So is anyone willing to admit that “The impact of the El Niño shows as a (very) small uptick at the end of the ice mass graph, but the overall trend remains strongly downwards” is a very alarmist statement given the conent of the report?

RW November 11, 2010 at 12:49 pm

Absolute rot.

R2D2 November 11, 2010 at 1:01 pm

?

So you think there is a strong trend in the data set?

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