The following is my translation of an article called: Klimawechsel, Eine Sommerbetrachtung von Wilhelm Bölsche. It appeared in a German popular science magazine, Kosmos Handweiser für Naturfreunde 1913, Heft 8, Seiten 281-282.
The original article is presented with no paragraphs whatsoever, and no indication as to where they should be. That results in unnecessary eyestrain and so, for reasons of health and safety, I'm introducing some according to my own judgement. It should also be kept in mind that some of the information, especially with regards to lengths of time, is seriously out of date. I'm not aware of any previous translation.
Trevor Dykes.

Climate change, a summer observation by Wilhelm Bölsche
"For as long as the Earth endures frost and heat, summer and winter will be ceaseless..." So can be read. But, in reality, we do not have it as straightforward as that as, despite the assumption, the climate changes. We all have an idealized perception of the joys of the seasons in our maturity; and it reaches back to our school days; when the winter was properly cold, with ice skating and snowmen for months on end, the light blue of the spring above catkins and lavender, the summer was hot and the autumn golden. The actual practice, however, gives the lie to the idealized picture. We sit in the open air in summer beneath umbrellas and freeze, our poor, short human lifespan will be cheated of this or that real spring, the winter is a miss-birth with a pair of hopeless attempts at frost quickly followed by thaw: We already have enough great burdens which people must bear with brave fortitude; but no minor, incessant annoyance exists with such enduring power to plague us through all our days that can match the imponderable devilish moods of the weather, and nothing else has been so universally cursed by honest souls for as long as our culture has existed.

And now we receive the disturbing news from geology of the adventures our climate experienced earlier. It was so warm in Germany during the time of the Tertiary, that there were extensive forests of palms housing apes and parrots. In contrast, we had polar moss tundra during the Ice Age, with reindeer and Greenland Musk oxen, and the whole of North Germany was under the ice of glaciers. Since those geological things began to be something like common knowledge, it can be heard during cold summers that a new period of ice is obviously commencing and, during warm winters, that the paradise of Tertiary time is about to return.

There is at least something heroic in this. As we sit below our summer umbrella, we can dream that it is our generation that can at least experience the entire great change as contemporaries, and not simply be pointlessly plagued by the small gnats. But, unfortunately, this blessing is not of much importance. Such change happens partly in a ginormous and partly in a Lilliputian scale of time. On the one hand we think, should three summers be cool or three winters warm, that these may already be obvious signs of a dramatic change, that an increase or a decrease in temperature is altering the climate from that which we knew when young, to say nothing of that known by our ancestors. In truth, however, these are just small variations with little significance. Since years, our climate has experienced certain periodic swings of warmer or cooler, drier or wetter, and these can last thirty and a few years. The causes are still in the dark. One has attempted to explain them in terms of sun spots (which do seem to influence our earthly magnetism with genuine regularity), but there is not yet any guarantee of this. In any case, history records similar fluctuations and, since the days of old Homer, generations of people have been equally annoyed by the fickle weather, but none have yet been witnesses of a really great climatic change.

On the other hand, most of us do not really appreciate sharply enough the enormous timescales involved with profound geological changes. Our immediate cultural history, dating from the oldest Babylonian sources up until today, amounts to ten thousand years at most. This figure could sensibly be multiplied by three to reach the end of the Diluvian period; and that time already lay beyond the Ice Age. The Diluvian period, during which the climatic temperature sometimes sank a number of degrees below the average, only to later rise again, lasted for, at the very least, one hundred and fifty thousand years. And beyond that lay the Tertiary period, the oldest parts of which are marked by a flora of palms extending to the Baltic Sea, lasted for something like four million years. Those are the spans of time involved in genuine geological climatic changes of increase or decrease. And the experience of change known from one or two human lifetimes have little to say about this. It is as if, on each day, a small drop of red colour were to fall into a large pond, the change would advance so slowly as to be imperceptible; only time would allow it very, very slowly to come to power. Our mountain chains, the Alps, Cordilleras, Himalayas, first arose in the Tertiary age. Since then, they have already been weathered into ruins. Similarly large mountains, from earlier geological ages, have already been eroded right down to their bases. The slowly rummaging waves have broken down whole continents, and carried the dust away. Climate change occurs across such spans of time. Even the greatest ten thousand years of human culture cannot be measured against this!

As a result, it remains scientifically valid that, in the future as well but only perceptibly across the appropriate scale of geological time, climate change must happen and will happen. Not yet or within our pathetically minor weather fluctuations, but something decisive may occur across the next hundreds of thousands of years, whether it be a new Ice Age or a new period of Tertiary warmth. And there are geological analogues which allow this to be said with a good degree of probability. And one aspect of this is already valuable today. It was long believed that the laws governing climate change on our Earth could be found by a very straightforward formula. Once, the Earth was hot but it has since become progressively cooler; the coal forests of the Carboniferous seemed to fit in with this, then the ghoulish reptiles, and a still universally tropical Tertiary age; and then followed the Ice
Age; and, if today, it is somewhat milder, then this could simply be a short interval; a new, terrible time of eternal ice will follow. Today, this view is out of date.

In the recognisable history of the Earth that we can see, since the existence of continents and sea, since the origin of biological life, we do not find this constant decrease but rather, we recognise an interchange between warmer and colder periods, between drier and damper earthly epochs, and these spread across the incomprehensible time span of about a hundred million years. Already, in the very first Algonkian epoch of the Cambrian age (Additional note: The Algonkian is now recognised as being the end of the Precambrian.), we find traces of glaciers. Then follows a long warm period of deserts. In the Carboniferous age came an obvious time of dampness which culminated, during the Permian period (many millions of years before us at the beginning of the age of the great reptiles), with a very remarkable ice age that left the region of today's Indian Ocean covered with glaciers, and with wintry, frosted coasts. But then the climate improved again, dragon-like reptiles could sun themselves on coral reefs above which waved beautiful fronds of tropical palms. This warm period persisted into the Tertiary. And then came the endless stretches of time of the great Diluvian climatic crash. Since then, the climate has been somewhat warmer and generally drier.

Should these ups and downs over the eons have any kind of prophetic energy, then it would say that, in the course of a monstrous chain of years, there will again be tropically hot conditions in our area. There is absolutely nothing to indicate a ceaseless cooling will put an end to these changes. Then the warmth of the surface of our Earth has come, since countless years, not from below but from above, from the Sun. Only changes to the rays of the Sun could be decisive. As Arrhenius and Frech maintain, a periodic increase or decrease in the concentration of carbon dioxide and steam in our atmosphere, which sometimes magnify and at other times deflect the warmth of the Sun, could keep this geological fluctuation of warmer and colder conditions going. The causes of periodic increases in concentrations of carbon dioxide are sought in volcanism; the end of volcanism in a distant future cannot be envisaged. We also see no signs showing the energy of the Sun is decreasing towards a final end; on the contrary: all physicists exhaust themselves with theories explaining why the heat will always continue despite its notoriously enormous consumption of energy. And whoever, in line with a long held opinion, believes that the ice ages are connected with changes to the axis of the Earth resulting from changes in polarity must accept, in view of the ice ages from earlier geological periods, that such alterations to the axis are a periodic occurrence that comes and goes and goes and comes, and there is no reason why it will not continue to do so in the future. It should be said though, that of all theories about the causes of ice ages, those concerned with polarity changes are by far the worst, when it comes to being in line with the actual facts. One can shove the poles in one's mind where one will, but it will never provide a satisfactory explanation for phenomena such as the Diluvian ice masses. We always return back to the simplest conclusion, that the Earth was much as it is today, but the global climate sank by a couple of degrees, and ice took advantage of opportunities provided by latitude, land distribution and mountains for purely geographical reasons and, locally, the snow line came lower down and allowed large glaciers to form. But finally, all this is a matter of theory. We do not need to make any of it worry us.

An index of more of my translations of old Kosmos articles can be found at:

Kosmos Translations Archive

A number of Mesozoic (and post-Mesozoic) location summaries can be found at Localities.