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But this is not useful for understanding rates and magnitudes of change if we cannot put it into some kind of time-scale context.

Fortunately, we have many techniques at our disposal.

Radiocarbon dating is an essential part of the glacial geologists’ toolkit. One example of an application may be for a lake dammed by a moraine.

A radiocarbon age from the base of the sediment core gives a minimum age for moraine formation; the moraine must be older than the radiocarbon age.

Mapping landforms such as mega scale glacial lineations, drumlins, roche moutonnées and streamlined, striated bedrock helps glacial geologists to reconstruct these changing ice flow pathways and dynamic ice stream behaviour. Did the ice flow due to deformation of its bed, slipping, or deformation of the ice?

Looking in detail at the sediments laid down at the ice-bed interface allows glacial geologists to understand in detail the processes of past ice flow. By looking at sections of sediment under the microscope, we can infer detailed information about the processes of sediment deposition.

They can use equations that predict ice thickness by assuming a certain surface slope to reach a certain extent.

And they can use measurements of the Earth’s isostatic rebound to calculate the past volume of ice.

They hammer tubes into beds of sand and cover themselves, and the sand, in black bin liners. Why do we care how big or how thick past ice sheets were? This image shows the instrumental record of global average w:temperatures as compiled by the w: NASA’s w: Goddard Institute for Space Studies. We know that they are already contributing to sea level rise, but by how much? It is the role of palaeo ice sheet reconstruction, or palaeoglaciology, to answer these questions.

It’s pretty obvious that glaciers are shrinking and melting worldwide.

Examining past sea level rise in far-field locations, such as the Bahamas, gives us a record of changing global ice volume over long timescales.

Examining local sea level rise in near-field locations (where near-field means close to a present or former ice sheet) helps us understand rates of isostatic adjustment, and hence local ice volume.

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