Tuesday, May 6, 2014

Randolph Glacier Inventory (RGI): First globally complete glacier inventory

This image shows the Zhadang glacier south of lake Nam Tso on the nortern ridge of the Nyainqentanglha mountain range (Tibet). 

Credit: Tino Pieczonka (TU Dresden)

For the first time ever, we have a complete inventory of all the glaciers on Earth.

Now we know how many glaciers there are, where they are, and what their extents and volumes are.

The now available digital outlines allow for the first time reliable calculations of the glaciers' future development and hence their contributions to regional hydrology and global sea-level rise.

Thanks to the efforts of an international group of scientists, one of them is Tobias Bolch from Technische Universität Dresden, Germany, who have mapped all of the world's glaciers, glaciologists can now study with unprecedented accuracy the impacts of a changing climate on glaciers worldwide, and determine their total extent and volume on a glacier-by-glacier basis.

Nyainqentanglha mountain range
Overall, glaciers cover an area of about 730,000 km2 and have a volume of about 170,000 km3.

The scientists found nearly 200,000 of them, but they say that this is the least important result of the mapping exercise as the number constantly changes due to disappearing small and fragmenting larger glaciers.

More importantly, each glacier in the new inventory is represented by a computer-readable outline, making precise modelling of glacier–climate interactions much easier.

Graham Cogley
"This boost to the infrastructure means that people can now do research that they simply couldn't do properly before", said Graham Cogley of Trent University, one of the coordinators of the new Randolph Glacier Inventory (RGI), which is named after one of the group's meeting places in New Hampshire.

The now published article is presenting the RGI and first statistical analysis of the global glacier distribution.

The main stimulus for completing the inventory was the recently-published Fifth Assessment of the Intergovernmental Panel on Climate Change (IPCC). Several studies that relied on earlier versions of the RGI were essential sources for that assessment.

Tad Pfeffer
"I don't think anyone could have made meaningful progress on projecting glacier changes if the Randolph inventory had not been available", said the University of Colorado's Tad Pfeffer, lead author of the study just published in the Journal of Glaciology.

Like several of his co-authors, Tad Pfeffer was also involved in the IPCC assessment.

More information: Pfeffer, W.T., Arendt, A. A., Bliss, A., Bolch, T., Cogley, J. G., Gardner, A. S., Hagen, J.-O., Hock, R., Kaser, G., Kienholz, C., Miles, E. S., Moholdt, G., Mölg, N., Paul, F., Radic, V., Rastner, P., Raup, B. H., Rich, J., Sharp, M. J. and the Randolph Consortium: The Randolph Glacier Inventory (2014): a globally complete inventory of glaciers. Journal of Glaciology 60(221), DOI: 10.3189/2014JoG13J176

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