Studies of past climates must begin
with an understanding of the types of proxy data available and the methods used
in their analysis. One must be aware of the difficulties associated with each
method used and of the assumptions each entails. With such a background, it may
then be possible to synthesize different lines of evidence into a comprehensive
picture of former climatic fluctuations, and to test hypotheses about the
causes of climatic change.
Major types of proxy data available
is given below; (Bradley. R.S., 1991)
1.1.
Glaciological (Ice cores):
A.
geochemistry
(major ions and isotopes of oxygen and hydrogen)
B.
gas
content in air bubbles
C.
trace
element and micro particle concentrations
D.
physical
properties (e.g., ice fabric)
1.2.
Geological:
A.
Marine
(ocean sediment cores)
(i) Biogenic sediments (planktonic and benthic
fossils)
(a) Oxygen isotopic composition
(b) Faunal and floral abundance
(c) Morphological variations
(d) Alkenones (from diatoms)
(ii) Inorganic sediments
(a) Terrestrial (Aeolian) dust and ice-rafted debris
(b) Clay mineralogy
B.
Terrestrial
(a) Glacial deposits and features of glacial erosion
(b) Periglacial features
(c) Shorelines (Eustatic and glacio-eustatic features)
(d) Aeolian deposits (loess and sand dunes)
(e) Lacustrine sediments, and erosional features (shorelines)
(f) Pedological features (relict soils)
(g) Speleothems (age and stable isotope composition)
1.3.
Biological:
A.
Tree rings
(width, density, stable isotope composition)
B.
Pollen
(type, relative abundance, and/or absolute concentration)
C.
Plant
macrofossils (age and distribution)
D.
Insects
(assemblage characteristics)
E.
Corals
(geochemistry)
F.
Diatoms,
ostracods, and other biota in lake sediments (assemblages, abundance, and/or
geochemistry)
G.
Modern
population distribution (refugia and relict populations of plants and animals)
1.4.
Historical
A.
Written
records of environmental indicators (para-meteorological phenomena)
B.
Phenological
records
Reference:
1. Bradley, R.S. and Eddy, J.A. (1991). Records of
past global changes. In: Global Changes of the Past (R.S. Bradley, ed.).
Boulder: University Corporation for Atmospheric Research, pg. 5-9.
