Dating glacier layers

Ice core records have allowed well dated reconstructions of past temperatures over hundreds of thousands of years.

Stable water isotopes, such as deutrium (d D), have a known relationship with temperature and therefore have been used to infer past temperatures.

Even in cores where the yearly snowfall produces thick layers, the nature of glacier flow stretches and thins layers as they get buried deeper.

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Where layer-counting is not possible, dating generally relies upon mathematical models of ice flow.

Another useful technique is to identify events which are seen in other types of climate records, such as historical, tree ring and sedimentary records.

In fact the clearest dating is obtained when several seasonal signals are examined and compared.

Many cores however come from regions where the yearly snowfall accumulation is too small for the annual layers to be distinguished, and other methods of dating must be used.

Comparison between ice core temperature reconstructions and ice core trends are consistent with the nature of greenhouse gases (GHGs); the higher the concentration of GHGs in the atmosphere the greater the amount of heat that can be “trapped” in the atmosphere.

It is important to note, that the similar trends in Atmospheric circulation patterns are a fundamental component of the climate as they transport heat, moisture, gases, and aerosols (e.g.

This is a result of the high snowfall rate on Law Dome, which leaves a thick layer of snow every year.

The disadvantage is that, especially with an icecap only 1200 m thick, the record does not extend as far back in time as some other ice cores.

) can be used to identify input from volcanic sources.

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