Abstract
Abstract. A single large glacier can contain tens of millions of times the mass of a small glacier. Nevertheless, very small glaciers (with area ≤1 km2) are so numerous that their contribution to the world's total ice volume is significant and may be a notable source of error if excluded. With current glacier inventories, total global volume errors on the order of 10% are possible. However, to reduce errors to below 1% requires the inclusion of glaciers that are smaller than those recorded in most inventories. At the global scale, 1% accuracy requires a list of all glaciers and ice caps (GIC, exclusive of the ice sheets) larger than 1 km2, and for regional estimates requires a complete list of all glaciers down to the smallest possible size. For this reason, sea-level rise estimates and other total mass and total volume analyses should not omit the world's smallest glaciers. In particular, upscaling GIC inventories has been common practice in sea level estimates, but downscaling may also be necessary to include the smallest glaciers.
Highlights
The world’s largest glaciers dwarf the world’s smallest glaciers by five or more orders of magnitude, and one large glacier can contain up to 10 million times more ice mass than the smallest glacier. Such an overwhelming ratio suggests that a few of the world’s largest glaciers contain the bulk of the world’s ice mass, it is reasonable to ask if the rest of the glaciers are so numerous that they contain as much or more total ice
It is entirely possible that the smallest glaciers’ sea-level contribution could be underestimated, in large part because of practical reasons which make a catalog of the smallest glaciers expensive, time consuming, and error prone due to difficulties in separating small glaciers from snow patches (Bolch et al, 2010)
For glaciers and ice caps (GIC), the most recent and complete calculation found a total volume of 0.60 ± 0.07 m sea level equivalent, but by necessity this estimate must be scaled up from incomplete inventories (Radicand Hock, 2010)
Summary
The world’s largest glaciers dwarf the world’s smallest glaciers by five or more orders of magnitude, and one large glacier (circa 104 km2) can contain up to 10 million times more ice mass than the smallest glacier (circa 10−1 km). It is entirely possible that the smallest glaciers’ sea-level contribution could be underestimated, in large part because of practical reasons which make a catalog of the smallest glaciers expensive, time consuming, and error prone due to difficulties in separating small glaciers from snow patches (Bolch et al, 2010). As an inventory’s size threshold is lowered, relative errors may rise, but with the smallest glaciers rapidly melting and possibly disappearing over the few decades (Mernild et al, 2011; Radicand Hock, 2011), the potentially rapid sea-level contribution of these smallest glaciers should be considered, or systematic errors due to their exclusion should be estimated. For glaciers and ice caps (GIC), the most recent and complete calculation found a total volume of 0.60 ± 0.07 m sea level equivalent, but by necessity this estimate must be scaled up from incomplete inventories (Radicand Hock, 2010). The following shows that 1 % and sometimes even 10 % errors in the total volume necessitate inventories with surprisingly small ice masses, in some cases pushing the semantic boundary between glaciers and snow patches
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