ICE OR WATER

Another appeal to induction from the scholastic methods of modern geology

Dedicated to the right honourable A. J. Balfour M.P., D.C.L., LL.D., F.R.S.

Some notes and caveats

The book is supposed to be in 3 volumes (it says so on the front cover of vols I and II). However, the UL can't find any evidence of vol III ever existing. In the preface, reference is made to specific chapters in vols I and II, but not to vol III. Vol II terminates with "...ought to throw some light on the problem of finding a rational explanation of the so-called glacial phenomena of the temperate zones... to which I hope to turn in the next chapter". It would seem that he did not have time to do this.

Contents (vol I)

1. Astronomical theory of Ball. This theory (astro-only causes of an ice age) is "demolished" on the grounds that the changes in insolation calculated are too small to do very much. These grounds are probably fair enough (neglecting all feedbacks, which this chapter does). [Link here to further discussion of this]. Heavily reliant on arguments such as "no amount of disparity in the length of the seasons can create an ice age so long as precisely the same heat... reaches the earth in a year" (p24).
2. Theory of Croll. Notes (p39) that Stefans law (recently discovered, and apparently slowly replacing the earlier assumption of Newtonian (linear) cooling) would imply a reduction in the effect of increased insolation. This is true by probably trivial over the range of temperatures considered. (p59: notes that Croll in 1875 could not have known of Stefan 1879). Notes Tyndalls etc experiments showing importance of water vapour to absorption of heat radiation. Appears that Croll knew he needed feedbacks to get a significant temperature change.

   On p58 there is an interesting discussion (to those who have read Fourier 1827) on the temperature of space. Quoting Howorth paraphrasing Croll: "Pouillet and Herschel had calculated by different methods that the temperature of space is -239oF, or 222o higher than absolute zero. As the mean absolute temperature of the earth is about 521o, he accordingly concludes that the proportion of heat received from the stars is to that received from the sun as 222 to 299 [why not 222 to 521?]... Croll ...[says]... that the temperature of space is not far from absolute zero."

   On p67 we seem to meet the ice-albedo feedback for the first time: of the summits of the Alps, etc, Croll "very justly says, the greater part of the heat received there is reflected back into space", but apparently this will not do because "the air there is very dry and very transparent to heat". This seems to be invalid because it fails to split the radiation into solar (to which the atmos is largely transparent) and heat (largely absorbed, especially by moist air).

   It looks like Croll was arguing for alternation glaciation in opposed hemispheres [??Apparent contradiction: see below??]. Howorth attacks this idea, probably correctly since it isn't true.

   There are some attempts at analogies with Mars, which shows variable ice caps. Howorth (and Lowell) believe these are ice (not CO2, as now known(?)).

3. Various theories. Wallace (Croll plus geographic changes, eg breach of Isthmus of Panama; p93). Renoir etc (variations in solar output as deduced from changes in subspot number).
4. The answer of geology to the astronomical theory of an ice age
5. ...

Contents (vol II)

1. Some a priori Arguments against the great ice age. Starts off criticising the "epeirogenic" theory, which apparently suggested ice ages occurred because the affected regions were uplifted, which is easy to defeat. However, on p5 there is discussion of the evidence of fiords, which his opponents say shows former elevation of the land, and he dismisses (the fiords are clearly "simply transverse rifts caused by the elevation of the high lands where they occur"). Was it appreciated that sea level should be lower in glacial times? Howorth gives no hint of this.

   Then we have "transcendental glacial arguments". "When Croll and his followers talk and write about ice many miles thick as the instrument with which they would work, they never stop to inquire... the amount of ice which can be piled up in a heap without causing it to crush". [How thick did Croll think the ice should be? Ice *does* get 1-2 miles thick so Howorth is wrong here... and, as far as I can see this is typical of his work, he presents no counter-evidence, just says, effectively "well I can't imagine this so it must be wrong, guv".]

   Follows on with criticism of the interpretation of shropshire permian beds. [When exactly was the permian? Howorth takes it that the ice ages should have extended into the indefinite past; was this actually the way the theory was suggested?]

2. The biological evidence about the so-called ice age and the question of interglacial periods. "When Croll formulated the theory by which he made his great ice age extend over a whole cycle of years, from 240,000 BC to 80,000 BC, he urged that such an age necessarily included several minor periods involving alternations of climate, and hence he introduced the notion of interglacial periods. The notion does not seem to have occurred to geologists before...". [Odd. I thought that geologists believed in long interglacials with fairly short ice ages]. "Dr Croll says the glacial epoch may be considered as contemporaneous in both hemispheres, but the epoch consisted of a sucession of cold and warm periods, the cold periods of one hemisphere coinciding with the warm periods of the other".
3. The alleged southern frontier of the drift beds and the mistaken inferences based upon it
4. ...
5. The arctic regions in so-called glacial times. Howorth believed that Greenland and Antarctica were elevated rock covered in snow. He is definitely wrong in the case of Antarctica (where large portions of the bedrock are below sea level) and Greenland. Howorth doesn't believe that the polar regions are cold due to insolation: he argues that the heat of summer compensates for the cold of winter (this is bizarre: in volume I he has happily quoted tables of figures for insolations in various latitudes and so ought to be aware that the poles, on average, get less insolation through the year than the tropics). He quotes Peary saying "The term 'inland ice' suggests ... erroneous ideas. The surface is not ice, but a compacted snow." He appears to use this to bolster his claim that Greenland is rock overlaid with snow. Odd.