Comprehensive Study: Glacier Melt Estimates In Tropics Of South America OVERSTATED BY 10 TIMES!

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Geographers from FAU investigating glaciers in South America in more detail than ever

If you compare historical photos of glaciers with those taken more recently, you can see that where there was formerly ice there is now very often nothing but rock. Geographers, however, are less interested in the area covered by a glacier, and more interested in its mass. Researchers from FAU have now investigated all glacial areas in South America in more detail than ever before, from the tropical areas of Venezuela to the subpolar regions of Tierra del Fuego.

Their two major findings are that the highest rate of mass loss is in the Patagonian ice sheet, and that the glaciers in the tropics have lost considerably less mass than previously projected, although this is not the good news which it might appear at first sight. The researchers’ findings have been published in the journal Nature Climate Change.*

Surveying glaciers is nothing new. There are two methods which are used particularly often. In the first method, researchers take several measurements directly at a glacier and project the results for entire regions. This is particularly problematic when it comes to large glacial areas such as the large ice fields in Patagonia, as barely any in situ measurements are available for these areas.

The other option is to take gravimetric measurements using satellites. Scientists base their measurements on the fact that gravity on Earth changes depending not only on the location but also over time. It is influenced by aspects such as the composition of the Earth’s surface, mountain ranges, movements in the core, plate movements – and, of interest for our context, when glaciers lose mass. One disadvantage of this method is that when only small areas are covered by glaciers, as is the case in the South American tropics, the satellite only receives a weak signal and the measurement is significantly less accurate.

One method for measuring all glaciers

Geographers from FAU specialising in both climatology and remote sensing and spatial information, led by Prof. Dr. Matthias Braun and Dr. Tobias Sauter, also used satellite data for surveying South American glaciers, but they focused on calculating elevation levels instead of basing their results on gravimetric measurements. Two radar satellites from the German Aerospace Center (DLR) have been orbiting the Earth since 2010. The aim of the TanDEM-X-mission was to obtain a three dimensional image of the Earth, which is not only of a consistent quality but also more accurate than anything that has gone before.

Differences in elevation were recorded down to the last metre. The researchers from FAU used data collected between 2011 and 2015 and compared them with measurements from the Shuttle Radar Topography Mission of 2000. Using a complex method which involved making various corrections and calculating possible error margins, they compared the data to calculate the changes in elevation in the glacial regions of South America, thus obtaining an accurate picture of the changes in glacial mass.

Their method was unusual in that they were able to use one uniform method to record all glacial areas in the region. In addition, the method even provided accurate data for individual glaciers. Comparing the measurements from both space missions allowed the researchers to gain detailed insights into the situation throughout South America. For the first time, researchers succeeded in analysing the large Patagonian ice fields separately from the surrounding, smaller glaciers.

Entire glaciers have vanished

The greatest loss of mass, both relatively and in comparison to the other South American glaciers, was found in both inland ice fields in Patagonia, two regions with an area of approximately 18,000 square kilometres, roughly equivalent to the Rhineland-Palatinate region in Germany.

Slower rate of mass loss in tropics

The second important fact revealed by the research is that the mass of glaciers in the tropical regions of South America – in Venezuela, Columbia, Ecuador, Peru and Bolivia – is changing at a considerably slower rate than previously supposed. Projections to date calculated that the 2900 glaciers there were losing approximately 6 gigatonnes of mass per year. The geographers from FAU have discovered, however, that they are only losing 0.55 gigatonnes per year, approximately 10 percent of the estimates to date.

This result is important, as glaciers are an important source of water in the dry period: when no rain falls and the temperatures reach their highest level, glacier melt water is used as drinking water, for irrigation and hydro power. People in these regions therefore have to know to what extent the glaciers are changing, and need quantitative data not only with respect to area but also in terms of their volume and mass.

In some areas such as the Central Andes in Chile and Argentina or the Cordillera Real in Bolivia, experts are even of the opinion that the maximum amount of water available from glacial melt has already been exceeded. This is an indication that glaciers are irrevocably on the retreat and will vanish entirely in the foreseeable future. In future, these areas will have less water available during the dry season.

The survey, however, also revealed that some areas have hardly experienced any change at all, such as the Andes in northern Chile and Argentina as well as in southern Bolivia at the latitude of the Atacama desert.

The researchers from Erlangen now hope that their study will be included in the next report of the Intergovernmental Panel on Climate Change (IPCC). After all, melted glacier ice is contributing to the rise in sea levels and the huge ice fields in Patagonia are particularly relevant. Glaciers are also used as an indicator for climate change in other respects as well.

The geographers from FAU now want to extend their analyses to cover other regions and investigate how the situation develops over a longer period of time. At present, the global terrain model from the TanDEM-X mission is currently being updated. Researchers hope to be able to benefit from these data in future. They are also relying on further national missions which are in the pipeline such as the Tandem-L satellites, which would make it possible for such measurements to be repeated more frequently.

* https://doi.org/10.1038/s41558-018-0375-7

Further information:

Prof. Dr. Matthias Braun
Phone + 49 9131 85-22015
matthias.h.braun@fau.de

=========================================================
Hat-tip: Die kalte Sonne.

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11 responses to “Comprehensive Study: Glacier Melt Estimates In Tropics Of South America OVERSTATED BY 10 TIMES!”

  1. tom0mason

    Indeed glaciers melt or gain mass depending on the LOCAL climate conditions.

    Climate is LOCAL and not global as the cAGW nitwits would have everyone believe.

    1. SebastianH

      The change is affecting climate(s) globally. Heat content is a global variable and increasing heat content means there ought to be global changes. Of course all the additional heat could accumulate in just one tiny region and everything else stays the same, but that is clearly not what we can observe 😉

      https://www.nodc.noaa.gov/OC5/3M_HEAT_CONTENT/basin_data.html (heat content increase in every basin and both hemispheres)

      1. Kenneth Richard

        The change is affecting climate(s) globally. Heat content is a global variable and increasing heat content means there ought to be global changes.

        Many regions of the world, both land and ocean, have been undergoing cooling during the last few decades. While the cooling regions didn’t quite off-set the regions where there has been warming, leading to a slight net heating effect, the lack of pervasive warming, especially the widespread cooling in the abyssal oceans, suggest that the model-based “there ought to be global changes” expectation has not been realized.

        1. tom0mason

          Thank-you Kenneth Richard,
          “Many regions of the world, both land and ocean, have been undergoing cooling during the last few decades.”

          And so in areas where there are glaciers the will either decrease or increase in volume depending on the local conditions. So some South American glacier (as shown by this paper) have declined in volume slightly, others hardly at all.
          What it does show is that UN-IPCC’s assertions of how any Climate Change™ will affect a particular place is willfully wrong.

      2. tom0mason

        Yes SebastianH I understand your view, tainted by the modeled version of our planet with all that unnecessary temperature homogenization, with over averaged parameters filtering removing the chaotic signal that can not be analyzed (even though it holds the key to why/when our climate flips between cool and warm periods), and having to make hundreds of ensemble variant outputs because there is no real conclusive result from all that modeling.

        I know it will come as a bitter pill to you when you realize I’m quite correct in saying that climate is LOCAL and not global as the cAGW nitwits would have everyone believe.

        Enjoy the rest of your day but please try to stop trolling me with your unsubstantiated opinions and half truths. 🙂

  2. Frank Lansner

    Dear Pierre and Kenneth, just needed to say that you have the best climate internet site in the world. Thats just the facts. Well done.

  3. sasquatch

    A simple experiment by accident was the airplanes left on the Greenland ice sheet.

    Just fly airplanes to different elevations on top of the glaciers in Patagonia, leave them, then after fifty years, find out where they have moved to and at what depth in the glacier to where they sunk.

    I suppose there are better markers out there, but airplanes would tell the story.

  4. R2Dtoo

    Confiscate all the private jets from the next Davos meeting and fly them to the glaciers. Solve two problems! Capital idea ole chap.

    1. Yonason

      👍👍👍👍👍

  5. tom0mason

    It appears about right that glaciers high on mountain peaks would reduce in the run-up to the solar peaked that happened in the late 1990s early 2000s.
    NASA shows some of this in their cloud observations at https://isccp.giss.nasa.gov/analysis/climanal1.html , where the first image shows the reducing cloud cover during the late 1990s to early 2000.

    Also at Clive Best’s blog, Ken Gregory P.Eng. does a creditable analysis of changes in global humidity (http://clivebest.com/blog/?p=4730 ).
    And don’t we all like his swipe at the models with this —

    In contrast, climate models all show RH staying constant, implying that specific humidity is forecast to increase with warming. So climate models show positive feedback and rising specific humidity with warming in the upper troposphere, but the data shows falling specific humidity and negative feedback.

  6. Yonason

    “…but the data shows falling specific humidity and negative feedback.”

    So, the data’s wrong then? Who knew! //sarc//

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