Principal Sources of Proxy Data On Earth's Climate System
Proxy Data
Historical Data
Geological Data
Glaciological Data
Biological Data

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Proxy Data

The following discussion of historical, geological, glaciological, and biological sources of paleoclimatic data is derived from Table 1.1 and associated text in Bradley (1985) (pp. 4 - 6).

Key aspects of a proxy data source are the minimum sampling interval and date resolution, as these determine the degree of detail that can be extracted from the record. Ice cores and tree rings provide annual and seasonal resolution of climate events on time scales of 10¹ to 10³ years. On longer time scales of 10⁵ to 10⁶ years, cores of ocean sediments provide the best records, though the resolution is around 10³ years, increasing to around 10⁴ years around 1M YBP.

Also important is the sensitivity of the data source to abrupt changes in climate. Pollen tends to be relatively insensitive to abrupt climate change as plants may take many years to adjust. On the other hand, many insect populations are very temperature-sensitive.

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Historical Data

Written records of environmental indicators (parameteorological phenomena) - diaries, ships' logs

Phenological records

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Geological Data
Marine Sediments

Organic sediments (planktonic and benthic fossils):
Oxygen isotopic composition

Faunal and floral abundance

Morphological variations

Inorganic sediments
Mineralogical composition and surface texture

Accumulation rates, and distribution of dust and ice-rafted debris

Geochemistry

Terrestrial

Glacial deposits and features of glacial erosion

Periglacial features

Glacio-eustatic features (shorelines)

Aeolian deposits (loess and sand dunes)

Lacustrine deposits and erosional features (lacustrine sediments and shorelines)

Pedological features (relict soils)

Speleothems (age and stable isotope composition)

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Glaciological Data - Ice Cores
Oxygen isotopes

Physical properties

Trace element and microparticle (dust) concentrations

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Biological Data
Tree rings (width, density, stable isotope composition)

Pollen (type, relative abundance, and/or absolute concentration)

Plant macrofossils (age and distribution)

Insects (type and assemblage abundance)

Modern population distributions (refuges and relic populations of plants and animals)