Arguments
Recent Comments
Prev 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 Next
Comments 34701 to 34750:
-
scaddenp at 13:31 PM on 29 August 2014Antarctica is gaining ice
I fail quite to understand what point you are making here? Sealevel rise from Antarctica comes from the loss of ice sheet, not ice shelves. The main issue with the loss of ice shelves is the buttressing effect on glaciers. Where shelves have been lost, glacial calving rates have gone up. If you want to see what is the real issue, start with this paper. It is discussed in the NASA press release here.
-
Rob Honeycutt at 10:55 AM on 29 August 20142014 SkS Weekly Digest #34
sw @1... a) No, Christy merely pulled a fast one on you by improperly applying baselines. LINK
b) The models are not failing. LINK
sw @2... a) Engineers are not climate scientists. Next time you have an electrical problem in your home, are you going to call a plumber?
b) Religion is faith in something without any evidence. Climate change has 150 years of research and data behind it.
c) Mann's original graphs (MBH98/99) only go back to the MWP, not past it. You should actually read the paper. Or better, read any of the dozen papers that have been written on the same subject since 1999.
d) Why was Greenland green? When? 65 million years ago? 250 million years ago?
e) Christy again? Really?
f) Yes you are. I don't suspect any of these posts will survive the next hour.
-
jetfuel at 10:29 AM on 29 August 2014Antarctica is gaining ice
I did some research on smithsonian.com and found out that Antarctica is much larger than the US lower 48 in area. The Ross Ice shelf is about the size of Texas. It lies on a shallow sea and the shelf is less than a km thick. It has always been melting from underneath. The study of Ice shelf loss recently done over a long period found that 85% of all ice shelf loss was from along the penninsula. There, the sea is warmer, has more currents, and the shelves are numerous, small, and farther from the S. pole. The shelf sits on the ocean anyway and won't add much to sea level rise because it is not on land. Right now, these shelves are surrounded by possibly the most extensive sea ice ever since records started being kept. The ice shelves are mostly the thinnest ice cover thickness areas of Antarctica, sit over the ocean, and are a small fraction of Antarctica'a huge area. They also get heavy snowfall and if they were to melt significantly, there would be an abrupt end to the melt as the area that has ocean under ice would be used up, leaving the vast majority of Antarctica's land ice still totally protected from the warm water of the sea being underneath. Really nothing new here, as this water has always been underneath the ice.
-
2014 SkS Weekly Digest #34
<snip>
Moderator Response:[PS] Welcome to Skeptical science. Please read and thoroughly digest the comments policy. Note particularly, "Make comments in the most appropriate thread". No gish gallops like your one. "No sloganeering.".
Use the search function on the top left to find appropriate place to comment. Stick to topic and produce evidence to back your position. References to peer-reviewed literature are best.
If you just want a rant there are plenty of other sites which would welcome your comment. Stay here if you want to discuss actually the science.
-
Klaus Flemløse at 03:55 AM on 29 August 2014Southern sea ice is increasing
@12
I have tried to include a discontinuity at September 2006 in the sea surface temperature(sst):
In this case the fit is better and the SST is increasing, but not significantly. Is the discontinuity comming from an error in sea ice cover data?
Can someone tell me if there is a know error in NOAA data around 2005-2010 ?
What am I going to believe?
Moderator Response:[RH] Need to keep the width of the images limited or they break the page formatting. I added a zoom so you can see the details (or at least I thought I did). Edit: Okay, next best thing is an added link to the full sized image. ;-)
-
Temp record is unreliable
Ashton - Marohasy's article is an online publication through the Sydney Institute, "a privately funded not-for-profit current affairs forum encouraging debate and discussion", in Sydney Papers Online, which is most definitely not a peer-reviewed publication.
Your above claim about its review status is wholly in error. And there is no sign that anyone with knowledge or expertise on the temperature records had critical input to the article.
-
ianw01 at 23:18 PM on 28 August 2014Athabasca Glacier: a tragic vanishing act
michael sweet @17:
It would seem that my comments misled you: I'm not interested in listening to deniers over experts. I was just seeking to better understand the relationship between glaciers and river flows, primarily because that is likely going to be the way that Albertans experience global warming in a way that might change a significant number of minds.
Andy Skuce @18:
Thanks for the interesting link. The point it makes about the boost to flows from glacial melt masking the coming problems is important. (It is similar to the storage of heat deep in the oceans in that it delays unavoidable consequences.) And your analogy about the behaviour of glaciers as well managed dams concisely describes their value.
Tom Curtis: @19:
Good point about the relationship between land area and freezing level in the mountains - I had not considered that.
jimb @20:
Nope! :-)
Bob Loblaw @27:
Good catch! I'm not sure where that typo came from.
-
John Mason at 19:52 PM on 28 August 2014Climate Change: the Terminological Timeline
And just for completeness, here's the abstract in Science:
-
Tom Curtis at 19:50 PM on 28 August 2014Temp record is unreliable
Ashton:
1) Read my posts more carefully. I did not say anybody was brainwashed to reject AGW. Rather, I ironically suggested that those who disagree with Marahosy had been "brain washed" to emphasize the fact that, considering who they were, that was not the case and that their independent finding of a positive temperature trend in the Brisbane valley using satellite data was truly independent, and indeed refuted Marohasy.
2) Given that Marohasy accuses BOM of fraudulently tampering with data, something you apparently have no problem with, your taking of offense even at your misinterpretation of what I wrote is simply hypocritical and not worthy of notice.
3) Marohasy has not written any peer reviewed reports on the temperature data. Rather, she has merely echoed the results of an Australian blogger on her blog, and in emails to the Australian, and to a Minister in the Abbot government. I believe it was you, not she who made up the cannard about her findings being from a peer reviewed report.
4) In contrast, the appropriateness and proper conduct of the BOM methods have been peer reviewed, and reported on in a publicly available document. It has also been peer reviewed in the scientific literature.
5) I have been downloading raw temperature data for stations nearby to Amberly today, and in the process noticed that Marohasy has clearly cherry picked her examples. The most telling point is that she cites airport (29.53 km from Amberley) to support her case, but neglects Ipswich (4.73 km away) and two stations at Gatton (37.99 and 38.61 kms distant), all of which show strong positive trends (contrary to my mistaken rememberance in my previous post). A number of other local stations also show positive trends. The key point here is that Marohassy neglects those stations, even though they are in the majority and are often closer and more climactically similar to Amberley than those she does cite.
6) I note you do not report on past and present times of jacaranda blooming in Western Australia. I on the other hand have linked to reports of the phenomenon in Sydney, Ipswich, have verified it in Brisbane, and can confirm it for Grafton (sorry. lossed the link), Camden San Diego (California), Florida (normal flowering time from April to June) and Los Angeles.
-
John Mason at 19:50 PM on 28 August 2014Climate Change: the Terminological Timeline
GP Alldredge, thanks. I've figured out what happened here. The original paper published in Science had "climatic" in its title. It was later incorporated into the book, "Climate change: critical concepts in the Environment (vol.1) published in 2002, where the term "climate" is instead used. Luntz must have nobbled the publisher!!
The link on that screengrab now points to the relevant Google Books page, as it was wrongly pointing to some much more recent NASA document. Trying to do too many things at once, as usual!
-
Tom Curtis at 18:49 PM on 28 August 2014Climate Change: the Terminological Timeline
John Mason @6, just to books in the Google Book collection.
-
Ashton at 18:39 PM on 28 August 2014Temp record is unreliable
Apologies again I should have noted that Dr Marohasy's paper was peer reviewed and asked if the reviewers were "evidently brainwashe"?
-
Ashton at 18:36 PM on 28 August 2014Temp record is unreliable
Apologies Ton Curtis should read Tom Curtis
-
GP Alldredge at 18:09 PM on 28 August 2014Climate Change: the Terminological Timeline
Just an historical correction: The actual title of Wallace S. ("Wally") Broecker's 1975 paper in Science is "Climatic Change: Are We on the Brink of a Pronounced Global Warming?"--that is, "climatic" rather than "climate". (I just copied and pasted that title here from my PDF copy downloaded from the Science online site.)
In a further historical note, that 1975 paper was not the first appearance of the term "global warming" in the scientific literature, as was asserted by Stefan Rahmstorf in his 28 July 2010 RealClimate post "Happy 35th birthday, global warming!". I cannot account for the term not being found earlier according to the ISI database search Stefan cited in that posting. But in a short time with Google Scholar I found and verified at least three prior to 1975; my search was not exhaustive, so there may be others even earlier. The earliest of the three I found was:
J. Murray Mitchell Jr. (1961). "Recent Secular Changes of Global Temperature", Annals of the New York Academy of Sciences, Volume 95 [Issue topic: "Solar Variations, Climatic Change, and Related Geophysical Problems"], pages 235 -250, October 1961. [The term "global warming" appears in the half-page Introduction, viewed at http://onlinelibrary.wiley.com/doi/10.1111/j.1749-6632.1961.tb50036.x/abstract.]
Mitchell was reporting an update he performed as a follow-on to Willett's 1950 report of global temperature rapid increase in the early 20th century up through a pentad centered on 1937 (1935-1939), which had still strongly increasing temperatures. Mitchell used Willett's methodology (but with corrected latitudinal weighting, and extended it with data for the 4 pentads centered on 1942, 1947, 1952, and 1957 (1955-1959). Thus, ironically he was using "global warming" to describe what Willett observed, but the added span of data in Mitchell's analysis fell in much of the 1940-1975 mid-century "hiatus", so he was finding that slight "global cooling".
But even though Broecker's 1975 paper is not the first instance in the scientific literature of "global warming", it may well be the first coupling of a form of "climate change" and "global warming" in the title of a scientific paper, and title aside, it is a seminal paper whose 35th birthday was noteworthy.
My nit-pick on the subject of Broecker's 1975 paper's title aside, I add my thanks to John Mason for this posting.
-
Ashton at 18:08 PM on 28 August 2014Temp record is unreliable
Tom Curtis asks "so who are you going to believe etc" and then goes on use derogatory terms such as "evidently brainwashed" obviously suggesting any one who may question his conclusions is unsound. Naturally one would assume the three independent teams of temperature experts are more likely to be correct, although one might question the importance placed by Ton Curtis on his Jacaranda observations which could be local and ask why the Jacarandas are not flowering early in Western Australia. However, one is given cause for pause when the reasons given by the BoM for their adjustments are refuted by those who actually worked where the stations in question are sited. Are those who refute what the BoM says "evidently brainwashed"?
-
John Mason at 16:46 PM on 28 August 2014Climate Change: the Terminological Timeline
Interesting Ngram results there. Can the same tests be applied to the mainstream media?
-
Ashton at 16:29 PM on 28 August 2014Athabasca Glacier: a tragic vanishing act
I'm a unsure whether is allowed. If not my apologies. I was referring to the recent, peer reviewed, paper by Jennifer Marohasy which has been discussed in the Australian. I went to the link supplied above where Tom Curtis is in the process of crtitiquing her paper.
-
Bob Loblaw at 11:01 AM on 28 August 2014Athabasca Glacier: a tragic vanishing act
Another short comment - this time about stream flows.
A minor correction to ianw01@16 - the rivers flow east through Alberta.
As for tracking the use and supply of water: Canada has a detailed agreement between the federal and provincial governments covering water usage in rivers flowing out of the mountains and across the prairies. There is even an intergovernmental board to deal with it: the Prairie Provinces Water Board (PPWB). Each province must recognize the rights of downstream users.
The Athabasca River actually forms part of the Mackenzie River Basin (which empties into the Arctic Ocean), so it by-passes the most populated portions of the prairies. As a result, it does not appear to be part of the PPWB mandate. The existence of the PPWB does indicate that river flows are taken seriously in this part of the world, though.
-
jmorpuss at 10:51 AM on 28 August 2014Climate Change Impacts in Labrador
As population grows and demand increases for energy supply, the Artic will keep loosing ice because this will ramp up http://rt.com/news/154028-arctic-russia-ships-subs/
-
Bob Loblaw at 10:48 AM on 28 August 2014Athabasca Glacier: a tragic vanishing act
Hopefully the moderators will accept one more temperature discussion. It does get on-topic to the Athabasca glacier area, eventually!
For the off-topic temperature information, there is another weather station nearby, at Saskatchewan River Crossing. Across the continental divide in British Columbia, there is also weather data collected at Yoho Park. Both are valley bottoms, so limited in usefulness. Environment Canada is not in the habit of trying to maintain stations at high altitudes in the mountains.
Yoho Park is on the "wrong" side of the mountains. Saskatchewan River Crossing is a Parks Canada site, only recording since 1976, and historical data is hard to find on-line (i.e., I couldn't in easily-digestible form...) The metadata I could find suggests it's not a high quality observation station.
For glacier work, research data is probably the best bet. Peyto Glacier is a little further southeast - about half way between the Columbia icefields and Banff, It has an extensive record of ice mass balance research. The Wikipedia page (linked above) includes a reference to a fairly recent paper by Scott Munro, titled "Temperature trends in the Peyto Glacier weather station record", but the link appears to lead to a dead end. I did find this link to some information about the paper, and this link to a newsletter that briefly mentions the conference presentation. In that last link, it refers to an 11-year record, which is much too short for extensive trend analysis.
-
Athabasca Glacier: a tragic vanishing act
Ashton - I'm reading unsupported armwaving on your part. More important at the moment, I believe that your issues with homogenisation are far more topical on the Temperature Record thread, not here, as you have said nothing about glacier melt in your posts.
Moderator Response:[PS] Yes, please put any concerns over the temperature record in the thread pointed to. They are offtopic in this thread. This applies to any follow-ups. Ashton, if you have issues with homogenisation, then please provide specific examples of your concern so others can evaluate what you are claiming. There are numerous spurious claims about this process and without specifics, it is not possible comment further.
-
Ashton at 07:28 AM on 28 August 2014Athabasca Glacier: a tragic vanishing act
Of course you are correct in that there are closer stations the point I was trying,perhaps not very well, is that stations close to stations that are being homogenised are sometimes disregarded in the homogenisation process while stations further removed are not. This is usually justified by explanations of why closer stations were less suited to the homogenisation process than those further away even though the closer stations often had longer records than those eventually used in the hmogenisation process.
-
Tom Curtis at 06:07 AM on 28 August 2014Temp record is unreliable
ronswanson @301, I am in the process of drawing together a blog post on her criticisms of the Amberley temperature record (because it is geographically close to my location). In essence here claim is that three seperate teams (BOM, GHCN, BEST) have looked at the Amberley data and despite all using distinct methods, have all concuded the slight cooling trend in the raw data is spurious, but that her non-mathematical examination is superior to the consensus of the experts. To do that she compares Amberly to the nearby Archerfield station, but not to the even nearer Ipswich station (available from BEST) that shows the positive trend she says does not exist, or the also nearby Gatton stations (one of which shows the positive trend, and one of which does not)- and certainly not to stations in the wider region which do show the trend.
She says it is ridiculous to consider the discrepancy found independently by three different teams by mathematical analsysis exists because no change in the metadata is recorded at that time, even though BOM warns that the metadata is incomplete and has not had all paper sources entered into the relevant digital database on which she relies.
She also neglects to mention that satellite data over the relevant periods shows a temperature trend consistent with the homogenized BOM (and GHCN and BEST) data, but inconsistent with her data. Presumably climate change deniers John Christy and Roy Spencer are also homogenizing their data to show a trend as well:
She also claims that there are no natural phenomenon consistent with the warming trend, neglecting to mention that Jaccaranda trees in the area are flowering a month earlier than they used to, a fact attributed to global warming. (My attention was first drawn to the early flowering of the Jacaranda's by my mother, who studied in Brisbane in the early fifties, and comments every year when the jacaranda's start blooming on their early flowering.)
So, who are you going to believe - three independent teams of temperature experts, and the (evidently brainwashed) deniers with the satellite data who have so cleverly rejigged the DNA or 78 year old jaccaranda trees to hoodwink us - or former right wing think tank member, Jennifer Marahosy who obviously couldn't have a political reason for her beliefs (unlike those well known lefties, the Jacarranda's).
-
Temp record is unreliable
ronswanson - I will also point out that your question seems to indicate that you have not read the opening post nor any of the links provided. I would suggest you do so, as you might find them informative.
-
Temp record is unreliable
ronswanson - There is a significant literature on this, for example these papers. For a more informal discussion Victor Venema has written a great deal on the subject. The BEST temperature record project applies a closely related methodology to identify individual station break-points, although they simply separate the data into separate non-overlapping station records rather than correcting a single record for regional consistency.
Station moves occur, as do equipment changes, both of which change the absolute temperatures recorded at the station affected and thus bias anomalies. Homogenization looks at nearby stations that do not experience simultaneous changes to detect and measure how the temperature anomaly offsets have changed for the modified station, and corrections are applied accordingly. Hansen and Lebedeff 1987 demonstrated strong correlations in observed temperature anomalies over distances over 1000km, meaning that nearby station anomalies are very reliable indicators for identifying individual station changes.
As I've said before, It could be argued (and has by people like Marohasy) that it’s better to look at raw temperature data than data with these various adjustments for known biases. It could also be argued that it’s worth not cleaning the dust and oil off the lenses of your telescope when looking at the stars. I consider these statements roughly equivalent, and would have to disagree.
Ignoring known and correctable biases to search out some subset of raw data that seems to support your thesis IMO indicates either (a) deliberate distortion or (more charitably) (b) a huge misunderstanding of science and statistics accompanied by confirmation bias. Either way, such claims are simply not meaningful.
-
Andy Skuce at 05:39 AM on 28 August 2014Athabasca Glacier: a tragic vanishing act
Ashton, if you read the comments (4,5,6,8) you will see that there are other weather stations closer by and others in the region with longer and more complete records than the Jasper station referred to by Jrexx. Seasonal changes and precipitation changes matter as well as annual temperature trends for glacier growth/shrinkage and these factors can vary rapidly with location and altitude in this part of the world. The fact that lower elevations have generally (but not always) higher temperatures says nothing about temperature trends.
-
ronswanson at 05:04 AM on 28 August 2014Temp record is unreliable
Jennifer Marohasy has been really attacking homogenization this year. Recently she wrote a "paper" detailing her criticisms, directed at a few stations in Australia, who, after homogenization, experienced cool to warm trend shifts. Anyway, I was wondering if anyone was on top of this or could direct me to some information that might clear this up.
http://jennifermarohasy.com/wp-content/uploads/2011/08/Changing_Temperature_Data.pdf
Thanks :)
-
Tom Curtis at 04:56 AM on 28 August 2014Climate Change: the Terminological Timeline
Rocketeer, 1896 actually, but it has been corrected. Thanks.
-
rocketeer at 04:54 AM on 28 August 2014Climate Change: the Terminological Timeline
Nice work by Tom and andy. Of course, Tom meant 1886 rather than 1986. For my wn contribution to the list of old CC references:
T. C. Chamberlin, Journal of Geology, October-November, 1897, A Group of Hypotheses Bearing on Climatic Changes
-
Tom Curtis at 04:38 AM on 28 August 2014Climate Change: the Terminological Timeline
A more bulk approach to the analysis can be provided by the Google Ngram, which tracks relative usage of terms in books:
The Ngram is started in 1896, the year of Arrhenius' famous paper on the greenhouse effect. In the entire 113 years shown, in only three years does "global warming" get more use than does "climate change", in 1948 and 1950, and again in 1991.
-
Andy Skuce at 04:33 AM on 28 August 2014Climate Change: the Terminological Timeline
Thanks for an interesting article, John.
You can use the Google Books Ngram tool to search for word frequencies over time within books. A simple search of "climatic change" (blue), "global warming" (green) and "climate change (red) from 1980 to 2008 looks like this:
For a bigger and more readable version click here.
As John's selection of papers suggests, "climatic change" was the term of choice prior to 1988. Its usage peaked in 1991. "Climate change" and "global warming" both took off in 1987 (around the founding date of the IPCC), with "climate change" becoming the dominant term in the mid-1990s (before the "pause" started).
-
Ashton at 04:22 AM on 28 August 2014Athabasca Glacier: a tragic vanishing act
Moderator `in your reply to Johannesrexx@1 you said:"though I am not quite sure of the relevance of a station that is nearly 100km away and 2400m lower"
Surely the distance of 100Km is comparable to the distance between stations in the temperature "homogenisation" carried out by the Australian BoM, distances considered by the BoM as entirely appropriate. The fact that the station referred to is lower might indicate it has a higher temperature readout than the temperature at the glacier.
-
Tom Curtis at 04:03 AM on 28 August 2014Athabasca Glacier: a tragic vanishing act
sotolith7 @14, the original research you seem to be relying on is Hormes et al (2001) and Joerin et al (2006). What in fact happened to the theory (to answer MA Rodger's question) was Schnedejoch, and more particularly the discussion of the Schnidejoch finds by Grosjean et al (2007). Specifically, Grosjean et al show the continuous presence of ice in the Schnidejoch Pass (based on the argument I presented above). They discuss the apparent discrepancy with Hormes et al and Joerin et al, saying:
"At first glance our conclusion differs from the conclusions drawn from exposed trees in the forefields of melting glacier tongues (Jo¨rin et al., 2006). However, the conclusions by Jo¨rin et al. (2006; see also by Hormes et al., 2006) refer to the AD 1985 level:‘glaciers in the Grimsel [and Alpine] area were smaller than at 1985 AD during several times for the last 5000 years’; while our conclusion reads: ‘in the year of 2003 AD, the ice field at Schnidejoch has reached the smallest extent since the last 5000 years’.
This is not a contradiction. We argue that this difference is explained by the dissimilar response lags of the two types of archives compared: ice mass balance near the LA (Schnidejoch) responds immediately to sub-decadal climate variations, while Alpine glacier tongues respond with a multi-decadal lag to climatology (20–60 years (Jo¨rin et al., 2006); importantly this fact also applies to the study by Hormes et al. (2006)). Differences between the equilibrium states of fast and slowly responding climate archives are typically large during phases of rapid changes. Indeed while the ice field at Schnidejoch is in equilibrium with the state of the atmosphere of the most recent years, the glacier tongues have not yet fully responded to the excessively warm years of the last 15 years, when (1) solar radiation at the Earth’s surface has increased owing to brightening of the atmosphere (globally 6.6 W m-2 10 yr-1 between 1992 and 2002, Swiss Plateau 7.2 W m-2 10 yr-1; Wild et al., 2005), (2) anthropogenic greenhouse forcing with related strong water vapour feedback enhanced the downward longwave radiation in Europe (+1.18 W m-2 yr-1, data 1995–2002; Philipona et al., 2005) which increased temperatures, and (3) negative trends in the specific mass balance of Alpine glaciers accelerated (Zemp, 2006)."
In short, the discrepancy is explained because (1) the two results use different reference years and there as been a large change in atmospheric forcing and temperature between those two years, and (2) glaciers respond slowly to changing conditions so that the current glacial extents (let alone those of 1985) are not in equilibrium and will retreat quite a bit further before they are.
It should be noted that the finds in Schnidejoch do not directly contradict the results of Hormes et al or Joerin et al in that different microclimates in different alpine valley are known to result in slightly different responses to temperature changes at different times. Note that Schnidejoch responded rapidly to warmth in recent times, and the potential of decay precludes decades long exposures of the artifacts found in the pass. That therefore precludes glacial retreats in the past 5000 years greater than the current equilibrium state of Alpine glaciers (although greater than the current retreat due to slow response times).
Finally, Grosjean is not a complete answer to Hormes and Joerin in that they also show a higher altitude treeline. Treelines, of course, also respond slowly to changes in temperature. Nicolussi et al (2005) estimate early 2000 treeline levels to reflect climate conditions in the 1980s. Since the 1980s, climate change has resulted in a 1 degree C increase in temperatures at the alpine treeline since the 1980s, with a projected further rise of the treeline by 200 meters as the result (Gehrig-Fasel et al, 2007) . Returning to Nicolussi et al, they find:
"In the space of the last 4000 years the dendrochronological tree-line record is not continuous, probably due to human impact. Tree-line positions similar to or slightly above the 1980 tree-line are established for the time periods approx. 1000 to 640 b.c. and a.d. 1 to 330 respectively. For the time period between approx. 7100 and 2100 b.c. the dendrochronologically analysed logs show nearly continuous evidence of a tree-line above the 1980s limit. Very high elevation of the tree-line, between 120 and 165 m above the 1980s level (2245 m a.s.l.) and even higher than the a.d. 2000 tree-species-line (2370 m a.s.l.), are recorded for the periods 7090–6570, 6040–5850, 5720–5620, 5500–4370 b.c., approx. 3510–3350 b.c. and 2790–2590 b.c. Additionally, a tree-line which was located at least 50 m above the 1980s limit can be shown for the periods 6700–5430, 4920–3350 and 3280–2110 b.c. The dendrochronological record from the Kauner valley, showing high and very high tree-line positions between approx. 7100 and 2100 b.c. with only two gaps (around 6490 b.c. and from 3350 to 3280 b.c.), suggests that summer temperatures as observed in the late 20th century were at the normal or the lower limit of the temperature range which can be assumed for long periods of the early and middle Holocene epoch."
So, treelines above the 1980s level were found 4000 years ago, or older, with two small episodes of treelines matching the 1980s level after that. No trees were found as high as the projected stable treeline for current alpine temperatures (with the highest, being from the early holocene, and about 30-40 meters below that level).
Consequently, the Hormes and Joerin results are accurate, but consistent with early 2000 temperatures exceding stable alpine temperatures at any time in the Holocene. Of course, those temperatures have been only been occuring for a decade, and decadal temperature fluctuaions above that in the early to mid holocene, and specifically prior to the earliest remains from Schnidejoch are quite likely. Those elevated NH temperatures, however, are a direct consequence of the milankovitch cycles that lead to much higher NH summer insolation at that time. Further, soon anthropogenic warming will take alpine temperatures above even those early holocene peaks - indeed much above them.
-
EOttawa at 03:43 AM on 28 August 2014Climate Change: the Terminological Timeline
Thank you for putting this together. As you say, a picture(s) is worth a thousand words.
-
jimb at 03:17 AM on 28 August 2014Athabasca Glacier: a tragic vanishing act
lanw01
Suppose you received the following notification from your water supplier;"Based on past usage, your yearly water requirement is 50,000 gallons. Because of changing circumstances, we will deliver that amount to your home beginning on January 1st and ending on March 31st. Please adapt your usage to this changed delivery schedule." Could you cope?
-
Tom Curtis at 03:09 AM on 28 August 2014Athabasca Glacier: a tragic vanishing act
ianW01 @16:
" If summer river flows are dependent on glacial meltwater, then those flows would have been lower before the 1800's, assuming there was roughly no net melting of the glaciers then."
Summer flows are not due to glacial melt but due to melt of the seasonal snowpack. In the 1800s, the seasonal snowpack would have extended to a lower altitude, and the upper limit of snow melt would also have been at a lower altitude but there would still be a large snow melt in summer to provide summer river flows. In fact, due the shape of mountains, a lower snowpack would have occupied more area, and hence is likely to have had a greater volume of snow melt. Hence the initial premise of your argument does not hold.
-
Andy Skuce at 03:05 AM on 28 August 2014Athabasca Glacier: a tragic vanishing act
Ian, I deliberately avoided discussing the importance of glaciers for river flows; it's complicated. There is a good article at Yale 360 on this. Melting glaciers, smaller snowpacks that melt earlier in the year as well as increased demand for water in the N American West, all combine to cause a supply problem. It's not all about glaciers.
If you had to devise a water management scheme not involving dams--one that evened out water flows, providing more water in summer, more water in dry, hot years, less in cool years and in years with heavy snowfall--the chances are that you would come up with something like a glacier. Possibly, in some areas, part of the role of glaciers in modulating water flow can be compensated for by building artificial reservoirs in mountain valleys.
It is true that receding glaciers are contributing positively to river flows. But relying on that is like basing your retirement income on capital withdrawals rather than interest. That will indeed work, but only for a while.
-
michael sweet at 02:42 AM on 28 August 2014Athabasca Glacier: a tragic vanishing act
lanw01,
Too often in these discussions we hear uncritical arguments made without considering the consequences of what is being suggested. Deiners frequently do not think through their arguments.
Certainly it can be argued that total river flow will be the same as it was. Unfortunately that is not the only consideration. In these areas it rains a lot in the winter and spring and little in the summer. If all the rain runs off there will be floods in spring and drought during the summer. What great conditions for agriculture!! Who needs all that food anyway? The forests are also damaged by the drought in summer. The volume of water is too great to hold back using dams (which cause their own problems in any case).
We already see increased springtime floods in the US Midwest caused by too rapid melt of snow.
Think through your suggestions so that they make sense. Perhaps if you listened to experts, who have thought through the issues, you would have different ideas than when you listen to deniers who do not think of the consequences of their actions.
-
ianw01 at 01:08 AM on 28 August 2014Athabasca Glacier: a tragic vanishing act
Back to the Athabasca glacier, and the melting of glaciers in the Rockies: I wonder when (or if) the current trends will significantly affect river flows heading west through Alberta. That would make climate change more apparent to the population of the province.
Consider this: If summer river flows are dependent on glacial meltwater, then those flows would have been lower before the 1800's, assuming there was roughly no net melting of the glaciers then. And one could argue that once the glaciers are gone, we'll be back to the same point: no net melting of glaciers, just the seasonal snowpack.
So, what is wrong with a contrarian position that says that net melting of glaciers is no big issue, it is just a temporary and unsustainable boost to river flows during those centuries?
Of course there are other issues related to changes in precpitiation that come with climate change - let's leave that constant for current discussion purposes.
I conclude that the changes in the freezing level in the mountains will reduce their ability to seasonally store and delay the water flow in the river. Therefore floods and droughts should become more common.
However, it is not also true that the loss of the glaciers is not fundamental to river flows?
Too often in these discussions I hear that glaciers are needed for good river flows, yet at the same time we do not want them to melt. We can't have it both ways.
-
One Planet Only Forever at 00:21 AM on 28 August 2014Global warming denial rears its ugly head around the world, in English
Lloyd,
The ideology many adhere to is greed related, or created to justify greed. As such, the person you are struggling to get to change their mind may be one of those I would eventually stop trying to convince ... because their greed based ideology means they cannot be reasoned with. Their mind is clearly made-up as will be their relentless arguments. I would move on to find people who are less informed or misinformed. There are plenty of those around who will change their mind when made more aware and given a reason to. Mind you some of those people read discussions like the one you are having and can learn to better understand much more by seeing the example of unreasonable reluctance as well as becoming more aware of the climate science facts. So the question becomes when to stop the effort to convince a person who clearly is not interested in changing their mind (because they see no personal benefit from accepting what better understanding climate science requires people to accept, their greed motivation actually makes them see a personal loss coming from acceptance of the science).
-
MA Rodger at 23:52 PM on 27 August 2014Athabasca Glacier: a tragic vanishing act
sotolith7 @14.
Perhaps you didn't read past the take-away headline to where it said "controversial". And certainly you didn't read the dateline. I suggest you do your "quick search" and the adjust it so it isn't "Any Time".
I suppose there is one question worthy of asking - What did happen to the "Green Alp" theory?
-
sotolith7 at 19:56 PM on 27 August 2014Athabasca Glacier: a tragic vanishing act
ok, that "sometimes said" was weak, but I think it's correct that it's notorious, as a quick search shows:
from -
http://www.spiegel.de/international/spiegel/the-coming-and-going-of-glaciers-a-new-alpine-melt-theory-a-357366.html
"The Alpine glaciers are shrinking, that much we know. But new research suggests that in the time of the Roman Empire, they were smaller than today. And 7,000 years ago they probably weren't around at all."
Many thanks for the detailed explanations.
-
Tom Curtis at 19:14 PM on 27 August 2014Athabasca Glacier: a tragic vanishing act
A small addition to my preceeding post.
One of the people who has pushed the idea that the finds show the pass to have been warmer in the past is Steve McIntyre, who, did so based on German news reports in 2005.
Meanwhile, scientific papers had this to say:
"During the hot summer of 2003, reduction of an ice field in the Swiss Alps (Schnidejoch) uncovered spectacular archaeological hunting gear, fur, leather and woollen clothing and tools from four distinct windows of time: Neolithic Age (4900 to 4450 cal. yr BP), early Bronze Age (4100-3650 cal. yr BP), Roman Age (1st-3rd century AD), and Medieval times (8-9th century AD and 14-15th century AD). Transalpine routes connecting northern Italy with the northern Alps during these slots is consistent with late Holocene maximum glacier retreat. The age cohorts of the artefacts are separated which is indicative of glacier advances when the route was difficult and not used for transit. The preservation of Neolithic leather indicates permanent ice cover at that site from ca. 4900 cal. yr BP until AD 2003, implying that the ice cover was smaller in 2003 than at any time during the last 5000 years. Current glacier retreat is unprecedented since at least that time. This is highly significant regarding the interpretation of the recent warming and the rapid loss of ice in the Alps."
(My emphasis)
Note that the dating discrepancy between my account above in the abstract quoted in this paper was due to a redating of the oldest remains after this 2007 paper was published.
-
Tom Curtis at 18:59 PM on 27 August 2014Athabasca Glacier: a tragic vanishing act
sotoloth7 @10, you are refering to the finding of ancient artifacts in the schnidejoch pass between Italy and Switzerland. The story is that in recent times the pass has been so icebound that it was even forgotten that it was a potential route across the alps. The finding of neolithic, bronze age and iron age artifacts, however, prove that the pass was used in ancient times, which is supposed to prove the region was warmer in those times.
Cutting through the denier dross, the key facts are:
1) Artifacts have been found in the pass, mostly of organic material (bark, wood, plant fibres, leather);
2) The artifacts are found when the current ice which holds them melts, thus revealing them;
3) Once uncovered by the ice, organic artifacts decompose rapidly. Hafner (2011) states:
"Organic finds have only a limited chance of being preserved once they are no longer encased in ice and become exposed to the elements. Once objects are free of the ice, they remain covered by snow for almost nine months of the year; for the remaining months, however, they are exposed to frequent rain and snowfall alternating with intense sunlight and strong winds. Artifacts lying on the surface are blown away by the wind or exposed to UV radiation, which makes them brittle. Compared to the lowlands, there are probably fewer active decomposers at 2700 m asl and at such low temperatures. Nevertheless, unprotected fragile artifacts such as leather or textiles would likely not have survived more than a few years. Timber fragments lying exposed on the surface of the scree would probably have survived considerably longer, perhaps for 50 to 100 years."
(My emphasis)
4) Some organic artifacts found in the pass are very ancient. Hafner itemizes the most ancient artifacts:
"The oldest objects from the Schnidejoch include a fragment of a bowl made of elm wood (Fig. 6) and several fragments of arrows. Five pieces of leather and wood dating from around 800 to 1000 years later can be attributed to the second Neolithic time slot from 3700 to 2900 BC.
The third Neolithic time slot, between 2900 and 2200 BC, yielded particularly numerous and spectacular finds. An almost complete bow kit was found over the course of a few years in many pieces that were likely from one kit. The bow kit consisted of a complete bow, 1.6 m long, made of yew wood (Fig. 7); a bow string made of an unidentified material, probably of animal origin; a bow case made of birch bark (Fig. 8); numerous complete arrow shafts, as well as many fragmented ones (Fig. 9); and two arrowheads. This Neolithic equipment was supplemented by a leather legging (Fig. 10). This item of clothing exhibited obvious seams stitched with plant fibers and repairs in the form of patches. This large piece of leather measuring 89 cm × 60 cm—probably one of the largest preserved prehistoric leather fragments ever found—was analyzed using various methods."
5) The artifacts were found within a short distance of the summit of the pass. As seen in the picture below, the summit of the pass (rather than the mountain) is marked by a small rige of stone, with the artifacts being found around the small ice patches immediately below that ridge, mostly on the northern side. Because they were found so close to the summit, they are unlikely to have been moved by ice while burried, and were almost certainly deposited within meters of the locations in which they were found.
Bringing together these six points, it becomes evident that the pass is currently largely ice free in summer. Further, it has not been largely ice free for more than about 100 years since 4300 BC (6300 years ago). If it had been, the earliest (wooden) finds would have decomposed and not been found. Further, it has not been largely ice free for more than a few years since 2900 BC (4900 years ago). If it had been, the five pieces of leather from the second period would also have decomposed. Therefore, taken together the finds are strong evidence that prior to the first discovery of artifacts in 2003, the summit of the pass had been largely ice free for at most a decade in the preceding 5000 years. Put in other words, since that first discovery in 2004, near ice free summers at the summit of schnidejoch pass have equalled or exceeded the number of such near ice free summers in the preceding 5000 years.
Deniers take this stunning fact and turn it into (apparent) evidence that the pass was warmer in the past.
Obviously they are playing a pea and thimble trick. In this case the trick is the assumption that the pass must be ice free to be traversed. The assumption is not true, with passes traversible with shallow snow - even knee deep snow - without undue difficulty. In contrast, the pass does need to be almost completely ice free to reveal artifacts dropped into the snow in previous millenia. In fact, because the pass can be crossed even with snow present, and because even short periods of ice free summers would have caused the decomposition of the remains, the presence of organic remains is strong evidence the pass has not been nearly ice free in the 5000 (and probably 6000) years preceding 2004. The object of the pea and thimble trick is to make evidence of the unusual warmth of the early 21st century look like evidence that it was not unusually warm at all.
-
Athabasca Glacier: a tragic vanishing act
Sotolith7:
The regional climate in Europe may have been warmer during Roman times, but not globally. Here is a reconstruction of the northern hemisphere temperature for the last 2000 years. The Medieval warm period and the Little ice age are apparent, but nothing in this period comes close to the recent warming.
-
sotolith7 at 16:47 PM on 27 August 2014Athabasca Glacier: a tragic vanishing act
It's sometimes said that the alpine glaciers (in Europe) were not as extensive in Roman times as they are now, and that passes which are still blocked by glaciers now were free then (Hannibal is alleged to have used one of them).
Was it globally warmer then?
Moderator Response:[Rob P] - "It is sometimes said" is hardly a sound starting point. Certainly glaciers in the Northern Hemisphere appear to have advanced in the late Holocene - known as the late Holocene neoglacial cooling. This was likely due to orbital factors as the Earth was slightly closer to the sun (eccentricity), and it's axial tilt (obliquity) & wobble (precession) meant the the Northern Hemisphere summer was warmer about 9-10,000 years ago than it is now.
Although likely warmer than today, globally there probably wasn't a great deal of difference in temperature because of the increased seasonality. The global sea level trend through the mid-late Holocene effectively rules out global temperature approaching anything like modern-day.
-
Lloyd Flack at 15:32 PM on 27 August 2014Global warming denial rears its ugly head around the world, in English
I think it would be easier to reason with denialists if they were primarily motivated by greed. But it’s ideology, something much harder to get through.
Most of them treat beliefs about global warming as part of their side’s political position. They refuse to recognize integrity when it comes challenging beliefs that they have made part of their self-image. Self-image and idealism are much more dangerous than greed because they are insatiable and people are very protective of them.
I’ve been arguing on another site with a denialist who wants to believe that adjustments to temperature records are done for corrupt reasons. But is your behaviour all that different? Yes, you are taking a factually correct position about nature. But you are giving in to your biases about opponents. And this can damage your credibility even when you are right. -
chriskoz at 14:05 PM on 27 August 2014Athabasca Glacier: a tragic vanishing act
johannesrexx@1,
I don't comment on your Athabasca glacier's cooling trends (others said enough) but your statement:
'they actually ride tour busses onto the glacier'
brings the feelings of outrage. I visited Athabasca in 1998 and when I saw this 4WD vehicle on huge, mining truck-like wheels full of tourists, whizzing past me, I felt disgusted at its noise and smell of diesel. I said no way that this contraption would mount the actual ice. But to my disbelief, it not only mounted the ice but kept going on it further and further until I lost its site. Then I took binoculars and found not only it (some 3 km away) but a second vehicle coming back.
IMO, those "bus tours" caring people so spoiled and so thoughtless about their envirinmental destruction, that even mankind AGW fades in comparison. A spoiled pleasure for essentially nothing: too lazy to set foot but be part of a noisy, smelly vehicle. I'm really disappointed that those "tours" are still continuing and are not banned yet, which is a symbolic mirror image of the emissions continuing unconstrained.
-
One Planet Only Forever at 13:33 PM on 27 August 2014Global warming denial rears its ugly head around the world, in English
Lloyd Flack,
In case my reply to Trakar did not clarify my position and comments, I offer the following.
I did not say that I start out such a discussion by declaring a person who is not fully aware and better understanding of the climate science to be greedy. I said a person who actually is willing to better understand the climate science could have been tempted into believing what a greedy person wanted them to believe. They may have simply been more interested in sports or entertainment. And when they become more aware and better understand the climate science those people will also understand that they were being fooled if they had believed something other than the better understanding based on fuller awareness.
However, anyone who persists at resisting better understanding the issue, refusing to accept the actual facts of the matter, is almost certain to be committed to be greedy. And it would be a waste of time to try to change their mind because their mind is already made-up as will be all their claims against better understanding (made-up).
Acknowledging these facts of the matter is not being sanctiminous, and frankly does no harm. A committed greedy person will never better understand something that is contrary to 'their interest'. And they do not need to be convinced, they just need to end up being disappointed when the reasonable rational considerate majority understand what is actually going on and decide what is acceptable without considering their input (because their input would be better understood to not be relevant).
I admit that does not 'attempt to please everyone'. But this is definitely an issue where allowing greedy people to set the standard of acceptability, or have any influence on the exercise of setting such standards, will not produce an acceptable result.
-
Andy Skuce at 11:37 AM on 27 August 2014Athabasca Glacier: a tragic vanishing act
HK and michael sweet
Thanks for that. One thing that you have to be careful about is that the weather in the high mountains is different than in the plains and the mountain valleys. In winter for example, it is not uncommon for it to be 20 degrees colder in Banff or Calgary than 1300m higher up on the ski hill, due to the cold arctic air that can penetrate from the plains up the valleys. Preciptation is also very different at altitudes relevant for glaciers than in the valley resort towns The winter weather in Banff is also much more variable from year-to-year than the summer weather and has a higher trend of warming. NASA monthly data for Banff here.
I did find a weather station record on the BEST site at Sunwapta, about 30 km N of the Athabasca Glacier and 150 metres lower in elevation.
The data are a little fragmentary, but an upward trend is apparent:
Plotted in the context of regional and global trends, we see that the local annual temperature trends are not markedly different:
However, my caveats about seasonal trends and precipitation trends, plus the specific weather behaviour on the Columbia Icefields area, all apply and I would not make too much of this.
Prev 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 Next
