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There seems to be a scientific consensus that glaciers are melting.

For instance:

  • Buzzle (Non-peer reviewed web-article):

    The last century has been a problem for glaciers across the globe. They are melting, but at an alarming rate. Fresh snow that replaces the melting ice is not able to maintain the size of almost any glacier worldwide. One of the main causes for this is thought to be 'global warming'. As the average global temperature keeps on increasing, ice from glaciers keep melting faster.

  • Wikipedia on Retreat of glaciers since 1850

    Since 1980, a significant global warming has led to glacier retreat becoming increasingly rapid and ubiquitous, so much so that some glaciers have disappeared altogether, and the existence of a great number of the remaining glaciers of the world is threatened.)

  • Science Daily Blog

    ASU geologist Rick Wessels is part of an international team of scientists studying the climate of the entire earth over several years with the Global Land Ice Measurement from Space (GLIMS) project. The team, led by United States Geological Survey (USGS) scientist Hugh Kieffer, is monitoring climate change by tracking the melting of glaciers across the earth. The global scale combined with a long study period will give the scientists the broad perspective needed to determine whether worldwide changes in climate are actually taking place. But in only seven months of monitoring, Wessels has already seen melting in glaciers all over Earth, which provides some solid evidence -- or liquid evidence -- for global warming.

However, some glaciers are growing:

  • The Telegraph

    Glaciers in parts of the greater Himalayas are growing despite the worldwide trend of ice melting due to warmer temperatures, a study has found.

The site Ice Age Now lists many more.

  1. Do these finds show that glaciers are, overall, not shrinking?
  2. Do these expanding glaciers show that there has not been any global warming?
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    There are several separate questions here. Let's whittle it down to one. Which of these do you want answered, and we can focus the question appropriately (including providing links to the claims): (1) Are glaciers melting? (2) Are glaciers melting due to the greenhouse effect? (3) Is the rise in global temperature due to global warming? (this is a tautology, isn't it?) (4) do climate models predict more than negligible global warming now?
    – Oddthinking ♦
    Commented Apr 24, 2012 at 2:03
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    Bizorke: You say 1 is known, but the only answer claims it isn't. You say 3 isn't a tautology, but the other comment suggests it is. You say 2 and 4 are the same, when to me it clearly isn't. Rather than re-open a question that is clearly able to be misinterpreted, how about we fix it first?
    – Oddthinking ♦
    Commented Apr 24, 2012 at 2:56
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    Note that some glaciers are growing because of climate change. For example, a warmer Australian continent and Tasman Sea dump more precipitation over New Zealand's west coast, making the Fox Glacier a very rapidly advancing glacier.
    – Lagerbaer
    Commented Apr 24, 2012 at 4:18
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    @Lagerbaer That's fine, but not all "climate change" is "global warming". Has the "warmer Australian continent and Tasman Sea" been conclusively linked to global warming?
    – JSideris
    Commented Apr 24, 2012 at 4:24
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    I don't know. I just wanted to caution you that sometimes results (glaciers melting or growing) can be the opposite of what one would expect.
    – Lagerbaer
    Commented Apr 24, 2012 at 4:26

1 Answer 1

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Summary

Do these finds show that glaciers are, overall, not shrinking?

No. The estimated rate of change in the mass of glaciers in the Himalayas is 3+/-6 Gt/year. (1 Gt = 109 tonnes = 1012 kg.) Given this level of uncertainty, it is not certain that they are growing. The global rate of mass lost from glaciers overall is closer to -500±100 Gt/y (from Jacob et al 2012), which is much greater in magnitude than the changes observed in the Himalayas.

Do these expanding glaciers show that there has not been any global warming?

No. Global warming is observed directly as the increase in surface temperature over time (e.g. see Is the world warmer now than during the Medieval Warm Period?). The effects of global warming, including melting glaciers, do not affect conclusions whether or not the warming is actually occurring. But the global declines in ice mass are consistent with what is expected to occur in a warming world.

Background

Glaciers lose mass through melting, ablation, and calving. In the popular press, the term "melting" is used to account for all three. Thus, saying that the glaciers are 'melting' is used as a way of saying that the amount of ice in the world - the size of the cryosphere - is decreasing.

The mass of a glacier is dynamic - it changes through time: mass is lost to melting etc. and mass is gained through precipitation of ice and snow. A nice overview of glacial dynamics is provided by the IPCC (IPCC 2007 section 4.5.1).

Evidence

In section 4.5.2, The IPCC concludes that the global mass of glaciers is decreasing. According to a recent estimate that is based on satellite measurements of changes in the earth's gravitational field, the cryosphere is losing ~500±100 Gt / year of water per year (Jacob et al 2012).

Although not every single glacier is decreasing in size, the overall trend is decreasing. Jacob et al provide a nice synthesis of the variability among different parts of the cryosphere, as shown in the figure and table below.

enter image description here

enter image description here

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  • From the main diagram: "Time series are shifted for legibility." I don't understand. Can anyone explain?
    – Oddthinking ♦
    Commented Apr 26, 2012 at 9:25
  • @Oddthinking - typically, one would find such data for such a diverse set of regions that varies in sampling rates and sample times. Thus, perhaps they found data for one region with a monthly sampling rate, a yearly rate at another. In any event, interpolations were probably done to make all the data conform neatly.
    – user3344
    Commented Apr 26, 2012 at 10:28
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    @Oddthinking Could it mean just that the graphs are shown mixed overlapping in the "same" graph, with y-axis being only meaningful within a single graph, instead of having a separate graph for each data set?
    – Ilari Kajaste
    Commented Apr 26, 2012 at 10:37
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    @ilari that is correct. The lines were shifted vertically, with a dark line at the long term mean for each series
    – David LeBauer
    Commented Apr 26, 2012 at 12:21
  • @woodchips the plot is all made from a single data set, so sampling rates were consistent.
    – David LeBauer
    Commented Apr 26, 2012 at 12:24

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