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Himalayan glaciers: how the IPCC erred and what the science says

What the science says...

Select a level... Basic Intermediate

The IPCC error on the 2035 prediction was unfortunate and it's important that such mistakes are avoided in future publications through more rigorous review. But the central message of the IPCC AR4, is confirmed by the peer reviewed literature. The Himalayan glaciers are of vital importance, providing drinking water to half a billion people. Satellites and on-site measurements are observing that Himalayan glaciers are disappearing at an accelerating rate.

Climate Myth...

IPCC were wrong about Himalayan glaciers


"In 1999 New Scientist reported a comment by the leading Indian glaciologist Syed Hasnain, who said in an email interview with this author that all the glaciers in the central and eastern Himalayas could disappear by 2035.


Hasnain, of Jawaharlal Nehru University in Delhi, who was then chairman of the International Commission on Snow and Ice's working group on Himalayan glaciology, has never repeated the prediction in a peer-reviewed journal. He now says the comment was "speculative".


Despite the 10-year-old New Scientist report being the only source, the claim found its way into the IPCC fourth assessment report published in 2007. Moreover the claim was extrapolated to include all glaciers in the Himalayas." (Fred Pearce)


This is not the first inaccuracy to be found in the IPCC Fourth Assessment Report - there have been several papers demonstrating where IPCC predictions have underestimated the climate response to CO2 emissions. However, this time the climate response has been overestimated. Specifically, the IPCC AR4 predicted the Himalayan glaciers would disappear by 2035 which is decidedly not the case. What's the significance of this error? To determine this, let's look at how it happened and the broader context.

The error occurs in Section 10.6.2: The Himalayan glaciers of the IPCC Fourth Assessment Report:

"Glaciers in the Himalaya are receding faster than in any other part of the world and, if the present rate continues, the likelihood of them disappearing by the year 2035 and perhaps sooner is very high if the Earth keeps warming at the current rate. Its total area will likely shrink from the present 500,000 to 100,000 km2 by the year 2035 (WWF, 2005)."

The source for this information was "An Overview of Glaciers, Glacier Retreat, and Subsequent Impacts in Nepal, India and China", a 2005 report by the World Wildlife Fund. The WWF report was not peer reviewed. On Page 25, we find:

"In 1999, a report by the Working Group on Himalayan Glaciology (WGHG) of the International Commission for Snow and Ice (ICSI) stated: “glaciers in the Himalayas are receding faster than in any other part of the world and, if the present rate continues, the livelihood of them disappearing by the year 2035 is very high”. Direct observation of a select few snout positions out of the thousands of Himalayan glaciers indicate that they have been in a general state of decline over, at least, the past 150 years. The prediction that “glaciers in the region will vanish within 40 years as a result of global warming” and that the flow of Himalayan rivers will “eventually diminish, resulting in widespread water shortages” (New Scientist 1999; 1999, 2003) is equally disturbing."

The WWF sourced their information from a 1999 news item in New Scientist. Again this was not peer reviewed (New Scientist is a popular science magazine). The article was based on an interview with Indian scientist Syed Hasnain, chair of the Working Group on Himalayan Glaciology, who speculated that Himalayan glaciers might disappear by 2035. This speculation was not supported by any formal research.

Unfortunately, the error was not spotted in the review process. This may be because it was buried deep in the Working Group II section (which focuses on Impacts, Adaptation and Vulnerability with a regional emphasis). It was not one of the key features included in the Technical Summary, the Summary for Policymakers or the Synthesis Report. The 2035 prediction was not included in the Working Group I section (focusing on the Physical Science with more of a global emphasis) which was solidly based on peer reviewed research.

The moral of the story seems clear - stick to the peer reviewed scientific literature. This is not to say peer review is infallible. But as a source for climate science, there is no higher standard than rigorous research based on empirical data, conducted by scientific experts and reviewed by other experts in the field.

This leads to an important question: what does the peer reviewed science say about Himalayan glaciers? The ice mass over the Himalayas is the third-largest on earth, after the Arctic/Greenland and Antarctic regions (Barnett et al. 2005). There are approximately 15,000 glaciers in the Himalayas. Each summer, these glaciers release meltwater into the Indus, Ganges, and Brahmaputra Rivers. Approximately 500 million people depend upon water from these three rivers (Kehrwald et al. 2008). In China, 23% of the population lives in the western regions, where glacial melt is the principal water source during dry season (Barnett et al. 2005).

On-site measurement of glacier terminus position and ice core records have found many glaciers on the south slope of the central Himalaya have been retreating at an accelerating rate (Ren et al. 2006). Similarly, ice cores amd accumulation stakes on the Naimona'nyi Glacier have observed it's losing mass, a surprising result due to its high altitude (it is now the highest glacier in the world losing mass) (Kehrwald et al. 2008).

While on-site measurements cover only a small range of the Himalayas, broader coverage is achieved through remote sensing satellites and Geographic Information System methods. They've found that over 80% of glaciers in western China have retreated in the past 50 years, losing 4.5% of their combined areal coverage (Ding et al. 2006). This retreat is accelerating across much of the Tibetan plateau (Yao et al. 2007).

The IPCC error on the 2035 prediction was unfortunate and it's important that such mistakes are avoided in future publications through more rigorous review. But the central message of the Synthesis Report, the concluding document of the IPCC AR4, is confirmed by the peer reviewed literature. The Himalayan glaciers are of vital importance to half a billion people. Most of this crucial resource is disappearing at an accelerating rate.

Last updated on 9 July 2010 by John Cook. View Archives

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Further reading

IPCC statement on the melting of Himalayan glaciers

A comprehensive review of the whole incident is presented in the Yale Forum's Anatomy of IPCC’s Mistake on Himalayan Glaciers and Year 2035


Comments 1 to 11:

  1. I am afraid both the current versions of "Basic" and "Intermediate" need some revision. I think that the issue of the Himalayas proper and the issue of the central Asian highlands including the Himalayas should be distinguished. I have made some comments on the blog article of "Himalayan Glaciers, Wrong Date, Right Message. I am tempted to write clarification myself, but, regrettably, I cannot promise it. At least, Kehrwald et al. (2008) should not be used as a reference for the issue of population who depend on glaciers. Kehrwald et al. just quoted from IPCC AR4 WG2 (including the errorneous "prediction") and Barnett et al. (2005) about that. Kehrwald's paper seems to be a good reference about the mass balance of certain glaciers they studied. Also, the word "IPPC" in the title should be "IPCC".
  2. I'm glad to see, at least in the Intermediate version, that WG1 and WG2 are differentiated. There exist those that would invalidate all of WG1 on the basis of, effectively, a typo in WG2. The Yooper
  3. This says they are not retreating because of climate-change.
  4. From the Telegraph report : Their report, published in the journal Nature Geoscience, found the key factor affecting their advance or retreat is the amount of debris – rocks and mud – strewn on their surface, not the general nature of climate change. Glaciers surrounded by high mountains and covered with more than two centimetres of debris are protected from melting. Debris-covered glaciers are common in the rugged central Himalaya, but they are almost absent in subdued landscapes on the Tibetan Plateau, where retreat rates are higher. From the report itself : More than 65% of the monsoon-influenced glaciers that we observed are retreating, but heavily debris-covered glaciers with stagnant low-gradient terminus regions typically have stable fronts. Our study shows that there is no uniform response of Himalayan glaciers to climate change and highlights the importance of debris cover for understanding glacier retreat, an effect that has so far been neglected in predictions of future water availability,or global sea level. Interesting contribution which provides more detail. Hardly "they are not retreating because of climate-change" !
  5. Its black carbon deposited by pollution that plays the major role in the melting. The article does imply that the greenhouse effect does play a role but the majority of the melting is caused by black carbon deposits.

    [DB] Apart from Sphaerica's fine response, you may wish to read up a bit on Himalayan Glaciers.  Your NASA reference dates from 2009.  Glaciologist Mauri Pelto has a list of blog posts on glaciers worldwide here.  The Himalayan posts are all 2009-2011.  Mauri indicates that fresh snowfall on the glaciers tends to blunt the impacts of black soot on the glaciers (due to their altitude, they retain much of the fresh snow year-round in their accumulation zones).

    Despite this, many such as the Gangotri Glacier have receded heavily over the past century:


  6. 5, Roh234, Wrong. From the article you linked (emphasis mine):
    "Tibet's glaciers are retreating at an alarming rate," said James Hansen, coauthor of the study and director of NASA’s Goddard Institute for Space Studies (GISS) in New York City. "Black soot is probably responsible for as much as half of the glacial melt, and greenhouse gases are responsible for the rest."
    That says black soot gets up to but not more than half. This does not equal "the major role" and may in fact be at best equal to (but probably secondary to) greenhouse gases. The concluding line?
    "Reduced black soot emissions, in addition to reduced greenhouse gases, may be required to avoid demise of Himalayan glaciers and retain the benefits of glaciers for seasonal fresh water supplies," Hansen said.
    Which means the problem is even worse, because we now have two problems to fix instead of only one.
  7. Of course, black carbon and CO2 are often from same source. You might also note that black carbon has much lesser role on other ice melts (distance from asia). Also note that effect of black carbon is short-lived while CO2 is very much longer.
  8. You might also like to look at its soot if you are interested in the science rather than repeating skeptic talking points.
  9. Yeah, I always love the 'no it is soot' argument.... even if it were true, the solution would be exactly the same: transition away from the coal power plants which are the primary source of increasing atmospheric CO2 AND soot. Somehow 'skeptics' never seem to make that connection.
  10. @9, isn't the point that 'soot' can be scrubbed whereas CO2 cannot be scrubbed!??!

  11. Just wanting to point out the link under "Many of the Himalayan Glaciers are retreating" in the 2nd from last paragraph no longer goes anywhere.

    I'm not sure if this was due to a recent webpage change at USGS.

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