GLOBAL GLACIOLOGY
Here you will find three glaciological datasets at the global scale, on which the world's glacier ice interacts with the rest of the cryosphere and the hydrosphere to pose a number of problems for modern society.

Foremost among these problems is the water balance of the ocean. After the ocean, glaciers form the second largest reservoir of water on Earth, and exchanges of mass between the two imply changes in sea level - with potentially enormous socioeconomic consequences.

Nearly all of the frozen water is in the two ice sheets on Antarctica and Greenland, but these bodies require millennia to respond dynamically to the climatic forcing which brings about exchanges between the cryosphere and the ocean. (Recent evidence, however, suggests, that they can respond unnervingly rapidly to changes in indirect climatic forcing via the oceans.) Outside the ice sheets glacier ice is extremely restricted, covering about 0.7 Mm2 of the Earth's surface (511.0 Mm2), yet these other glaciers are all much more quick to respond, doing so on timescales of decades to centuries. This makes it vital to understand their state of health, quantified as the "mass balance". Glacier mass balance, however, is in phase with changes in the climate, so that the slow dynamic response of the largest glaciers is less relevant than one might think to social problems such as global warming.

 GGHYDRO field GLAC - Percentage extent of glacier ice
Percentage extent of glacier ice (GGHYDRO field GLAC)

GMBAL
Pentadal average global mass balance of small glaciers
Left: red squares - 5-year averages of direct measurements; blue circles - similar averages of geodetic measurements. Right: red squares - spatially-corrected global averages of direct measurements; dark blue circles, with grey confidence region - similar averages from a new combined direct and geodetic dataset.
 Mass balance measurements are expensive and difficult undertakings on objects which are mostly remote and inaccessible. The measurements are therefore few, and with present technology they are also inaccurate. This, however, makes them, and the information they contain, more rather than less important in the socioeconomic context. We have assembled a collection of published measurements of the annual mass balance of small glaciers which is as complete as possible. Click for more information on this collection, which is organized as the dataset GMBAL.

The graph summarizes the contents of GMBAL. The vertical scale is in sea-level equivalents: the negative of global average glacier mass balance, spread over the ocean surface and expressed as an equivalent depth. Geodetic measurements offer much better spatial coverage as well as the obvious improvement in historical reach. The close-up of recent decades (right), in which we have enough measurements to correct for their uneven geographical distribution, shows the importance of spatial correction: the corrected average for 2000-2005 is only 1.4 mm a-1 SLE as against the 1.7 and 2.0 mm a-1 SLE of the separate, uncorrected averages in the left panel.


GGHYDRO
The study of climate and of climatic change requires accurate knowledge of how the fluid in the atmosphere exchanges mass, energy and momentum with its bed: the land and water at the Earth's surface. Our dataset GGHYDRO is a contribution to this knowledge, with the hydrography of the land surface as its focus. It contains, among other things, a digital map of the cryosphere showing the global distribution of permafrost, glacier ice and sea ice. It also contains the only gridded estimates available at the global scale of the percentage extent of glacier ice. Click for more information on this dataset.

GGHYDRO field BAS2 - Smaller drainage basins
BAS2 - the Earth's land surface subdivided into about 150 drainage basins: an example of the non-glaciological content of GGHYDRO.


World Glacier Inventory - Extended Format (WGI-XF)
The World Glacier Inventory is an idea conceived in 1955, when it was decided that a complete global list of the world's glaciers should be prepared by the end of the International Geophysical Year in 1958. Fifty years on, it is clear that the time needed for the job was wildly underestimated. Scarcely one quarter of the extent of ice has been inventoried so far. A project at Trent University aims to revitalize the World Glacier Inventory by rescuing as much as possible of the many regional achievements to date, adding to the total number of inventoried glaciers, and presenting the ensemble of information in a unified, modern format. Click for more information on this project.

GGHYDRO field BAS2 - Smaller drainage basins
BAS2 - the Earth's land surface subdivided into about 150 drainage basins: an example of the non-glaciological content of GGHYDRO.