CLIMATIC IMPLICATIONS OF GLACIER RESEARCH’ 
By RICHARD FOSTER FLINT 
Yale University 
Glaciers as Climatic Indicators 
Nature and Causes of Changes in Glaciers. Recogni- 
tion of the relationship between changes in glaciers and 
changes in climate is older than the glacial theory as 
set forth by Agassiz. In 1821 Ignance Venetz [22], a 
Swiss civil engineer, announced an apparent correla- 
tion of fluctuations in Alpine glaciers with fluctuations 
of the regional snowline and of temperature. In land 
registers and other public records he found proof that 
these glaciers had been less extensive formerly than at 
the time of his investigation. Using glacier changes as a 
basis of inferences as to climatic changes, Venetz con- 
cluded that the average temperature fluctuates in an 
irregular manner, and that the abandoned end moraines 
of Alpine glaciers are very ancient and record earlier 
changes in climate. He even stated the opinion that the 
latest refrigeration had reached its climax, a statement 
that has proved to be remarkably true in the light of 
events since 1821. 
Some years later Agassiz [1, pp. 237-239] placed the 
evidence of glacier behavior against that of thermom- 
etry which, it had been asserted in 1834, indicated no 
change in the average temperature at the earth’s sur- 
face during historic time. In fact, Agassiz [1, p. 305] 
believed that the evidence of widespread former glacia- 
tion implied temperature changes of world-wide extent. 
Thus glaciers were acknowledged as climatic indi- 
cators as soon as they were first studied scientifically. 
Refined observations, however, did not begin until long 
afterward. In the later part of the nineteenth century 
contemporary changes in glaciers so placed as to be 
capable of systematic observation were compared with 
changes in temperature and snowfall, both annually 
and over periods of years. Only recently, however, has 
an apparent correlation been established between glacier 
behavior and climatic changes? affecting wide regions. 
Observed fluctuations of glaciers consist of changes 
in areal extent and thickness. Annual observations, 
begun in 1894, have been made on the positions of the 
termini of valley glaciers, notably in the Alps, western 
United States, western Canada, and Alaska (e.g., Field 
[7]). Some of the data obtained are detailed, and will 
increase in significance as the record lengthens. More 
recently changes in thickness—more difficult to de- 
1. Constructive reading of the manuscript by H. E. Lands- 
berg and W. O. Field, Jr., is acknowledged. 
2. The Climatological Commission of the International 
Meteorological Organization, meeting in Warsaw in 1935, dis- 
tinguished between climatic fluctuations (differences between 
two 30-year means) and climatic variations (differences of a 
larger order, not specifically defined by the Commission). As 
far as practicable, this usage is followed in the present paper. 
termine, but far greater in terms of volume—have been 
systematically recorded. 
Since 1894 the assembling and recording of observa- 
tions has been in the hands of capable committees. 
From 1894 to 1916 reports [19] were published by the 
International Committee on Glaciers of the Inter- 
national Geological Congress. From 1927 to date, re- 
ports have been published by the Commission Glacio- 
logique of the Union Internationale de Géodesie et 
Géophysique, with the American Geophysical Union’s 
Committee on Glaciers cooperating since 1931. 
The value of the records obtained, as far as climatic 
implications are concerned, does not lie in fluctuations 
from year to year, which reflect only short-term changes 
in precipitation and temperature, as well as the 
avalanching of snow and other local factors. It lies 
rather in the cumulative changes, both during periods 
of several decades and during much greater spans of 
time. During the last few decades such cumulative 
changes have been so great that they have been de- 
scribed as “catastrophic.” 
It has become clear that change of temperature af- 
fects a glacier in at least two ways. First and most 
obviously, it determines the amount of ablation that 
occurs. Also, however, it determines the proportion of 
the precipitation that occurs in solid form, thus directly 
affecting the nourishment of the glacier. Hence it is 
apparent that a rise in temperature operates to dimin- 
ish a glacier both through increased ablation and 
through decreased nourishment. 
It has been observed, further, that decreased thick- 
ness is ordinarily accompanied by shrinkage in area, 
and vice versa. However, this is not true universally. 
Examples of valley glaciers that lengthened while be- 
coming thinner were first noted very early [22, p. 15] 
and recently the Antarctic Ice Sheet, the world’s largest 
existing glacier, has been thought [6, p. 392] to be in- 
creasing in extent while thinning. Accordingly the most, 
refined observations take account of both thickness and 
area. 
It is known further that although nearly all the 
glaciers within a region may be shrinking, one or two 
may be expanding at the same time, and vice versa. The 
exceptions are commonly explained as delayed responses 
to the latest climatic change, influenced by variations 
in local factors such as the volumes, slopes, and alti- 
tudes of the glaciers and in the relief of the surfaces on 
which they lie. An example is the Taku Glacier in coas- 
tal Alaska. Despite a general shrinkage in that region 
during recent years, this glacier has been expanding. 
The most important qualitative-quantitative field 
study of glacier regimens ever undertaken is the work 
of Ahlmann [2] sustained throughout many years 
1019 
