Saturday, September 08, 2007

Climate controversies circa 1874 Royal Society NZ


You will find at page 391 of the Transactions for 1873, a short notice of a discussion on Solar and Terrestrial Radiation, introduced by Mr. C. R. Marten, who explained that the black bulb thermometer in Southland frequently ranged as high as 170°, being 30° higher than in Sydney, and much higher than it has ever reached in the North Island.

As some doubts are implied in the printed report of the correctness of the readings, I wish to state that Mr. Marten is not only an enthusiast in meteorological pursuits, but a most painstaking observer, with whom my duties as first Director of Meteorological Stations in New Zealand brought me in very pleasing communication. As this is a subject on which I formerly took much trouble, and may claim-for myself the merit of having established all the principal Meteorological Stations in New Zealand, and as it was a great comfort to have the co-operation of Mr. Marten, I am anxious to explain why I believe the observations referred to are correct. Of course we all know how difficult it is to prevent “cooking” of observations. In looking over my correspondence with a distinguished savant who had a great deal to do with getting up meteorology in India, he notices how discouraging it was to work at the results of people who had no training in the use of instruments. The stupidity of some observers is impregnable. An intelligent, well-educated man supplied him a long series of wet-bulb observations obtained by holding a thermometer under water and reading off—the bulb was wet, what more could be wanted! You will understand, then, the comfort, in starting a number of Meteorological Stations, of having a Member of the Meteorological Society of England for a coadjutor.

Water Vapor and Greenhouse observations

The calorific rays of the sun pass through- air devoid of aqueous vapour with no appreciable loss; but if water in the form of invisible vapour be present, the air is not perfectly transparent to those rays, and offers, I believe, a slight obstruction to their passage. It is almost opaque to radiant heat from the surface of the ground. Transparency to heat and light is witnessed in the passage of the sun's rays through the glass windows of our dwellings. The heat in a close room into which the sun shines may be overpowering, while the glass, through which the whole of the heat has passed, remains cold. The greater the proportion of aqueous vapour the more solar heat is absorbed in its transit through the atmosphere. Now, the quantity of vapour in the air depends mainly on temperature. In the colder regions of the south, although the air may be saturated with vapour, the relative proportion of vapour to air is much less than in tropical climates;

Californian Tree huggers

I find that in California they are already alarmed at the rapid destruction of their forests, containing the largest and finest trees in the world. It is estimated that one-third of all the available timber has been consumed, and that the whole of the available timber will be consumed in twenty years. One of the worst features of the settlement of new countries is the reckless way in which the timber is destroyed. Not only is the practice condemned in severe terms by thoughtful men in California, but the opinion must be gaining ground that the State should interfere. The only remedy seems to them to be for the Legislature to take up the matter, and by proper laws to provide not only for the preservation of the forests, but for the planting of trees pari passu with the settlement of the country.

Greenland Glaciers

Professor Phillips, at a late meeting of the British Association, remarked that one is almost frozen to silence in presence of the vast sheets of ice which some of his friends, followers of Agassiz, believe themselves to have traced over the mountains and vales of a great part of the United Kingdom. He refuses to accept the proposition that these “ice-rubbers” plough out the valleys and lakes, until we possess more knowledge than has yet been attained regarding the resistance offered by ice to a-crushing force, seeing that under a column of its own substance 1000 feet high it would not retain its solidity.

I have alluded to Phillips' opinion, because I see in Geikie's late work that reference is made to the fact that from the foot of glaciers in Greenland streams of water issue and unite to form considerable rivers, one of which, after a course of forty miles, enters the sea with a mouth nearly three-quarters of a mile in breadth—the water flowing freely at a time when the outside sea was thickly covered with ice.

This flow of water, Geikie thinks, probably circulates to some extent below every glacier, and he accounts for it by the liquefaction of ice from the warmth of the underlying soil. I am sure you will find a more natural solution of this flow of water from glaciers—estimated not less than 3000 feet thick—in the suggestion first made by Professor James Thomson, and subsequently proved by his brother, Professor W. Thomson, that the freezing point of water is lowered by the effect of pressure 0.23° Fahr., or about a quarter of a degree for each additional atmosphere of pressure. Now, a sheet of ice 3000 feet thick is equal to a pressure of eighty-three atmospheres, at which pressure it would require a temperature of 19° below freezing point to retain the form of ice. In the state of running water below the glacier, it might readily, as Geikie states, absorb heat from the underlying soil sufficient to retain its liquid form, as the overlying weight gradually lessened at the edge of the glacier. In this, too, we have a safe assurance that these enormous thicknesses of glaciers can exist only where there is scarcely any or no inclination of the land to the sea board, and that no sheets of ice of such enormous thickness could possibly exist on the sides of mountains, as they would have between them and the mountain side a stratum of water; and, to use a common expression, would come down “ on the run.”

Climate glaciations European or global

Captain Hutton admits that the glaciers of the South Island have been at some former time of much larger dimensions than they are at present, and that there may have been a glacial epoch in the southern hemisphere. But he does not admit that such an epoch bears any relation to, or was contemporaneous with, that of Europe. He would refer it, if it ever existed at all, to a period long antecedent. At the same time he guards himself by stating that we have no proof of a change of climate;

Greenland warmer climate

In latitudes so high as those of Greenland, no hypothesis, based on an assumed elevation or depression of land, will account for the warm climate which must have existed in Greenland in times remotely ancient. We might look to changes in the great luminary whose rays vivify either directly or indirectly all growth on earth.

Professor Heer has concluded from his examination of the fossil flora that the temperature of Greenland was about 30° higher than it is now. You will find from Professor Heer's “Contributions to the Fossil Flora of North Greenland” much wonderfully calculated to revolutionize our notions of the climate of the north of Europe. In the deposits of the outskirting land under the great ice-field which now obliterates all indications of hill and valley were found “thirty different kinds of cone-bearing trees, including species allied to the gigantic Wellingtonia, at present growing in California, with other trees, such as beeches, oaks, planes, poplars, maples, walnuts, limes, a magnolia, hazel, blackthorn, holly, logwood, and hawthorn. These were represented not merely by leaves, which occurred, however, in vast profusion, but by fossil flowers and fruits, including even cones of the magnolia, thus proving,” says a writer in the “ Popular Review,” “that they did not maintain a precarious existence, but ripened their fruits. Vines twined round their trunks—beneath them grew ferns having broad fronds, and with them were mingled several evergreen shrubs.”

Transactions of the Royal society of NZ Volume 7, 1874


Post a Comment

<< Home

Web Counters