A Few Things Ill Considered

Glaciers have always grown and receded

Posted by coby on January 25, 2006
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This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.

Objection:

A few glaciers receding today is not proof of Global Warming, glaciers have grown and receded differently in many times and places.

Answer:

Firstly, it is more than “a few glaciers” that are receding, it is a pervasive, sustained and accelerating global trend.  The National Snow and Ice Data Centre (NSIDC) maintains a chart of global glacier mass balance, and for as far back as their data allows us to look, all but a few years have shown a loss in ice volume of subpolar and mountain glaciers.  Further, annual losses are increasing.

But no one claims that melting glaciers are proof of Global Warming. Proof is a mathematical concept. In climate science one needs to look at the balance of evidence and in that light, the above data is just one piece of evidence that is consistent with Global Warming.

So what do we find if we look to the other aspects of the cryosphere?.  It turns out what we find is lots more evidence that is indicative of world wide and sustained temperature increases:

And of course, this is all consistent with all the other evidence of warming that there is out there. Clearly we are dealing with much more than a few receding glaciers.

This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.

“Glaciers have always grown and receded” was first published here, where you can still find the original comment thread. This updated version is also posted on the Grist website, where additional comments can be found, though the author, Coby Beck, does not monitor or respond there.

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Comments

  1. #1 Matt
    January 31, 2009

    Glacier recession is a suggestion of warming (global? meh). It is not necessarily of a suggestion of anthropogenic warming.

  2. #2 Duh
    March 14, 2009

    Nice graph. Too bad you’re cheating. Why not show the full data? Back to the 1700s? Our current retreat is nothing new in the context of the past two hundred years or so. The trend simply continues. So much for the big bad humans doing it.

  3. #3 coby
    March 14, 2009

    Duh, why don’t you provide us with this misssing data, back to the 1700′s? Because it does not exist of course. There is not enough global coverage prior to the 60′s to construct such a graph.

  4. #4 RS
    March 24, 2009

    Coby, that was the point, you are drawing a massive conclusion from a tiny shred of data. Bad. Unless someone can show evidence that glaciers do not retreat without interference this is not evidence of anything.

    As for me I believe this planet experienced an ice age, and all those glaciers retreated. Man had nothing to do with it; the planet is better off for it. Also true that some small villages rely on melting glaciers for their precious water. Melting glaciers is therefore good. If they retreat a lot then some villages have to move. Oh, well, they must have done that before, so here goes again.

  5. #5 coby
    March 24, 2009

    RS, I believe what I said was it is consistent with all the other evidence of warming, so no I did not draw a massive conclusion from a tiny shred of data. Please provide the quote you had in mind.

    As for the retreating ice age, check this article. That retreat ended 10-8000 years ago.

  6. #6 RS
    March 24, 2009

    If you conclude that a tiny shred of evidence is consistent with anything I believe you must give significant weight to that shred.

    As for the 10-8000 years ago, what caused that? Seems like growth and retreat has been happening for a long time. And whatever it was that caused the retreat, aren’t we pleased?

  7. #7 coby
    March 24, 2009

    The last glacial period ended because of a combination of orbital forcing, CO2 rising and albedo changes as ice sheets shrank.

    Yes, it was fabulous news for me, my apartment might still have been under 2 km of ice.

  8. #8 John, Ft. Lauderdale
    July 28, 2009

    Coby you consistently miss the point that the sea level 18,000 years ago was 400 feet below where it is today! With no human input, the sea level came to its present level (but for about 2-3 feet) about 3000 years ago.

    In other words, the sea level is about where it was 30,000 years ago, before the last ice age. Earth cooled, with no human input, then it warmed with no human input.

    John

  9. #9 coby
    July 28, 2009

    Hi John,

    Please see this article:
    http://scienceblogs.com/illconsidered/2006/03/global-warming-is-nothing-new.php

    BTW, your chronology is a bit off. Going back from 18ky bp you have to get to about 120K yrs before sea levels were as high as today, actually about 4 to 6 metres higher, 30K yr bp it was still very cold!

  10. #10 dhogaza
    July 28, 2009

    In other words, the sea level is about where it was 30,000 years ago, before the last ice age. Earth cooled, with no human input, then it warmed with no human input.

    And, of course, before guns were invented, no one died of gunshot wounds, which proves that no one died from machine gun fire in WW I, WW II, Korea, Vietnam, Iraq I, Iraq II …

  11. #11 crakar14
    July 29, 2009

    Come on dhogaza, i can accept a little drift off topic but for christs sake that is just c@#p. If you cant think of anything intelligent to say then say nothing at all.

    Anyway guns were invented before the wars of conquest you mentioned above so people could have died from gunshot wounds.

    Looks like that “itchin for a fight” needs to be scratched again, consider it scratched ok.

  12. #12 coby
    July 29, 2009

    crakar, he is trying to make the point that just because X caused Y in the past does not prove that Z is not causing y now.

    I make that point a little clearer in this post:
    http://scienceblogs.com/illconsidered/2006/01/climate-is-always-changing.php

  13. #13 JackSprat
    January 22, 2010

    re: Recent measurements by NASA have found that Greenland’s massive ice sheet has been losing nearly 100 gigatons of ice annually in recent years.

    How long would it take for all the Greenland ice to melt at this rate? My “back of a fag packet” calc came out at approx 22,000 years. But I suspect that must be wrong. Anyone?

  14. #14 skip
    January 22, 2010

    I don’t know but is that even the issue?

    As I understand it the problem of Greenland’s ice retreat is not the prospect of it all being gone but a whole *lot* of it being gone and the resultant effects on sea levels and the positive feedback of less snow reflecting sunlight back to space. Also Greenland’s ice sheet retreat is a gauge of where we are. I mean, Jesus, its melting. Regardless of where we stand on the overall AGW hypothesis, does anyone dispute it?

  15. #15 JackSprat
    January 22, 2010

    Skip, thanks for your reply.

    I guess my question is “is there an issue”? 100 Gigatons sounds awfully impresive, however –

    100 Gigatons of ice melting is about 0.00452632% of the total Greenland ice sheet, which will put the sea levels up about 0.0003546 of a metre. (Someone please verify my figures).

    And the reduced reflectiveness of this small difference – does it amount to anything?

    BTW – I am agnostic regarding AGW, I’m just seeking answers to niggles I have. Thanks

  16. #16 GFW
    January 22, 2010

    Those numbers sound about right – for the recent melt rate. Changing units, that’s 0.35 mm/y. Current annual sea level rise is almost 10 times that (about 3mm/y) but more than half is from the expansion of warming water, the rest is from Greenland, Antarctica and other glaciers around the world.

    Here’s the trouble with 0.3 mm/y from Greenland. A mere decade ago it was basically 0. See http://www.skepticalscience.com/Why-is-Greenlands-ice-loss-accelerating.html (particularly the second graph). That’s an accelerating loss. It’s accelerating for probably two reasons: (1) It’s still getting warmer (2) Greenland is a hollow basin, ringed by mountain ranges, filled with ice. As the outlet glaciers retreat, the area exposed to warming ocean water increases, so the basal melt rate increases, with positive feedback.

    So, while I certainly can’t guarantee it, the mass loss rate of Greenland could double in another decade, double again in the decade after that, etc. until leveling off at a rate that would melt the whole thing in ~500 years. That would contribute over 1m/century. A slightly different accelerating dynamic is affecting the West Antarctic Ice Sheet. Taking all sources into account, we are likely looking at 1.4m sea level rise by 2100, with 2-3m/century for several centuries after that. That’s if we don’t get our act together on mitigation.

    1.4 meters is huge. It doesn’t seem that big if you live near a rocky shore, or don’t live near a shore at all, but the first 1 meter of sea level rise will wipe out half the agriculture in Bangladesh, and have similar effects on other low coastlines around the world. The population of Bangladesh is 160 million.

  17. #17 JackSprat
    January 23, 2010

    GFW – thanks for the comprehensive reply. I’ll checkout the link etc over the next few days.

  18. #18 gsp
    February 10, 2010

    You guys are so far scientifically over my head that it is impossible for me to participate in this conversation. But consider that most people are like me, stupid consumers. It might even be said from the contacts I have in daily life that most people are even below my abyssmal scientific comprehension level. We think about things like sports and fashion and entertainment and bills. The lame list goes on. But we vote, sometimes with disastrous results. Imagine trying to explain .0003546 meter sea level rise at a tea party meeting. The simple question I have is what I saw in an above headline. If it is so warm, why is it so damn cold, with record breaking snowfall in certain parts of the US right now. Nothing in the subsequent text answered the question, at least not on my level. And it seems to me that somebody MUST dumb down this conversation to communicate to the public. Right now I am freezing my tail in lower than normal temps in TX and worrying over the increase in my energy bill with my fixed income. I can only imagine what people in Baltimore are feeling. Also, how do you get disaster relief into an earthquake or tsunami affected area without producing large amounts of carbon exhaust?

  19. #19 coby
    March 2, 2010

    gsp, sorry for the long wait, but I have a bit of an answer for you here:
    http://scienceblogs.com/illconsidered/2010/03/a_chilling_effect_on_a_warming.php

  20. #20 Jeremy
    March 3, 2010

    gsp,

    As a former teacher I think I can make understand the missing connection between daily experience and largely intangible scientific theory. And I think analogy, at the risk of creating new misunderstandings, can clear things up very well.

    Without taking time to look up specific figures, here are two things I’m confident can be said about our world that bear some resemblance to the situation you’re describing:

    (1) The value of the stock market is on a long-term upward trend. This is regardless of the fact that there have been huge momentary dips and dives, like this most recent recession and the years-long Great Depression. Living in that moment, it’s easy to assume that now is different, that the long-term trend isn’t still heading up, but any economist will tell you this will all recover and go back to that gradual upward slope as it did after the Great Depression and every other market slump.

    (2) The population of the earth is on a long-term upward trend. There is at least one point in history when the population decreased markedly over a period of a few decades: The Plague. Living in this time it would be easy to assume that everyone was going to die and the world would end. But on the whole, since thousands of years ago, the population is still rising. The long-term trend is still upward.

    Regarding climate change, then: scientists almost completely agree that until this last decade there has been a decades-long warming trend. They largely agree that this recent leveling-off of the trend is just one of those dips and dives, and that it will soon continue upward. They largely agree that if it continues that way, it will eventually have a profound negative effect on our ecosystem, which would affect our own habitat, health, food supply, land use, economy, and practically every other element of our lives. And they *generally* agree, with confidence (but not certainty), that man’s activity has some measurable effect on this.

    Therefore, the best guess is that it’s worth our effort to take strong steps to lessen our contribution to the long-term warming trend.

    A cold day or even year in one city, state, or even the whole globe, is just a blip on the radar. Scientists believe the forces driving temperatures slowly upward are still at work.

    How’s that, gsp?

    Keywords that often get lost in the debate and the media’s coverage of it: “generally agree,” “not certain,” “believe.” The scientific facts and measurements may be (at least mostly) accurate, but the theory based around them is just a theory. There’s simply enough evidence to make *most* scientists *pretty* sure that it’s the right one.

  21. #21 kevin wareham
    November 8, 2010

    A few glaciers receding today is not proof of Global Warming, glaciers have grown and receded differently in many times and places.

    AND

    Glaciers have always grown and receded

    TWO different questions. i like the way you smoothly changed one question into the other. that should certainly fool THE STUPID people. well done coby. keep blurring the issues.

    SUN go HOT , planet GO hot.
    sun GO cold, PLANET go COLD.

    quick get me some graph paper and let me draw lines , then i can call it MATHEMATICAL SCIENTIFIC CERTAINTY…………………………. oh wait scientisits make up data and tell lies.

    University of East Anglia emails: the most contentious quotes …23 Nov 2009 … Here are a selection of quotes from the emails stolen from computers at the University of East Anglia. Many involve Phil Jones, head of the …
    http://www.telegraph.co.uk/…/globalwarming/…/University-of-East-Anglia-emails-the-most-contentious-quotes.html – Similar