CLIMATE, HISTORY AND THE MODERN WORLD

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Re: CLIMATE, HISTORY AND THE MODERN WORLD

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WORLD TEMPERATURE

An assessment of the changes in overall world temperature over a hundred years past has been shown in fig. 91.

Whatever reservations one must have about our ability to gauge the global temperature average to the degree of accuracy necessary to identify the changes, there is no doubt that the main features of fig. 91 are essentially right as regards the land areas, especially the five-or ten-year means indicated by the northern hemisphere curve.

Other details known show that the recent cooling of the Arctic has been broadly matched by a warming in the Antarctic and in the sub-Antarctic ocean zone, which in one sector extends far enough north to embrace New Zealand.


The changes in high latitudes north and south are several times greater than elsewhere and so we can be surer of them and detect them more easily.

But it is clear that over the rest of the world there has been some net cooling since the warmest decades of the century.

In Europe the peak years, and the most summer warmth and sunshine, were between 1933 and 1952.

The change back to a cooler climate generally took place between about 1950–3 and the late 1960s; up to the end of the 1970s or later, there was no significant change.

Some studies have suggested that the increased warmth of our cities; with their well-drained, paved surfaces and extravagant heating of buildings, which has made urban observation sites commonly 1.0–2.0 °C (up to 3.5–4.0 °F) warmer (in the averages for the whole year) than the surrounding countryside, enters into enough of the temperature statistics to account for most of the difference between the apparent overall world averages for the 1960s and 1970s and the level of the late nineteenth century.


Even some towns with only 50,000–100,000 inhabitants now show this ‘urbanization effect’ and are liable to be overall 0.5–0.7°C warmer than the open country.

On still, cold winter nights and hot summer afternoons, when the sky is clear, the temperature drop between inner city sites and the country outside is usually much greater and may exceed 5°C.

The twentieth-century warming was not entirely a fiction due to urbanization of the observation sites, however, for it affected Valentia Obervatory in southwest Ireland on the edge of the Atlantic and is impressively shown by the world’s glaciers.


The temperature changes since 1950, small as they look in terms of averages, have affected the length of the growing season.

In England many farmers and gardeners are familiar with the turn to colder springs.

Between 1938 and 1953 all but two of the sixteen years had warm springs, warmer than the 1920–60 average.

Since 1962 up to 1980 only one spring has been up to that average level, and in the sixteen years 1965–80 none at all.


The warmest spring (March to May) in the earlier group was 1943 with an average temperature in central England of 10.5° C (51.0°F), the coldest in the later group 1978 with 6.3°C (43.0°F).

At the same time there have been some runs of notably warm autumns; only two were below the 1920–60 average in the decade 1945–54 and there were three or four warm autumns in a row in the later parts of each decade between 1950 and 1979, while 1969 produced the warmest October (average 13°C, or about 55°F) in the 320-year record for central England.

But warm autumns in England in the past as in Switzerland (see figs. 28 and 76) seem rather to have presaged some of the more notable drops in the annual temperature curve.

The net effect of these changes in England has been that the growing seasons (defined by the duration of temperatures above 6°C) have been on average about nine to ten days shorter since the mid-1950s than in the previous warmer decades, and the mean date of onset of spring (similarly defined) at Oxford has changed from 4 March between 1920 and 1950 to about 20 March between 1963 and 1980.


Other effects of the temperature changes since 1950 which have been reported include a notable delay (and an increased year-to-year variability) in the arrival of the first summer day with maximum temperature 25°C (77°F) or above in the Netherlands: in each decade from 1910 to 1949 the average was between 9 and 17 May, in the 1950s and 1960s 22 May and in the 1970s 3 June.

On the other hand, the wheat growers on the Canadian prairies have been troubled in the 1970s by earlier arrival of the first frosts of autumn in September.

And despite all the variations of autumn and winter temperature in Europe, the first snowfalls in autumn have on average come earlier and the last snowfalls in spring have come later in the 1960s and 1970s.


Temperature changes in and near the tropics are harder to establish than in northern latitudes because of the great extent of ocean and because they are often smaller (though not where changes in the upwelling of cold water in the oceans are involved).

The 1970s seem to have been cooler on overall average than the previous thirty to fifty years by about 0.3°C between latitudes 20 and 40°N and by up to 0.5°C (about 1° between the equator and 15°S, presumably indicating greater cloudiness in those zones.

A smaller increase of temperature seems to be indicated around 15°N and 30–40°S, suggesting reduced cloud amounts there.

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Re: CLIMATE, HISTORY AND THE MODERN WORLD

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EFFECTS ON RAINFALL

It is only in recent years that attempts have been made at mapping the world distribution of rainfall — or, strictly, the total downput of rain and snow expressed as equivalent rainfall — in different periods for comparison.

Fig. 98 shows the results of comparing the distribution by latitude in various runs of years since 1950 (from provisional surveys of a few hundred observation points) in terms of the change from the 1931–60 average.

What is most apparent here is that the equatorial rains have been concentrated nearer the equator than in the earlier decades of the century.

This is the counterpart of the rainfall deficiency in latitudes near 15°N, which has been seen in its most serious form in the prolonged drought in the Sahel-Ethiopia zone of Africa, and between 20 and 30° S where Rhodesia/Zimbabwe and parts of South Africa have at times been seriously affected.


Bryson has shown how the northernmost limit of the monsoon rains in Africa near the southern fringe of the Sahara progressively retreated from near 22°N in 1952–8 to about 19°N by 1972.

Fig. 99 illustrates the history of the rainfall at five places in west Africa between 12 and 14°N on the fringe of the Sahel with records from the beginning of the century, showing the apparently continuing decline from the years of maximum rainfall between about 1915 and 1960.

There is some suggestion from the best-fitting smooth (sine) curve shown that the variation may be an aspect of a two hundred year oscillation.

In the late 1970s it has come to appear that the equatorial rain belt over Africa has become further restricted so that even its yield near the equator has declined; but this may be part of another (possibly much shorter-term) process, since in just the same years rainfall near the equator on the opposite side of the globe (Indonesia, western and central Pacific island groups) seems rather to have become more abundant.


Along with the more limited seasonal movement of the equatorial rain system and the increased variability associated with meridional wind flow patterns in middle latitudes, the average rainfall over northern India has declined and the southwest monsoon has become less reliable in recent years, as may be seen in fig. 100.

The same applies to some extent also to the monsoon in East Asia: M.Tanaka has found that the large-scale rainfall patterns over the whole region show a linkage with the position and westward extent of the North Pacific anticyclone, so that the rice yields over the whole monsoon region of Asia have some tendency to suffer simultaneous variations.

It was Bangladesh, India, Burma and Korea that were found to experience the greatest variations of rice yield due to climatic fluctuations.

The total yield of the summer monsoon over India in 1965 and again in 1972 was reported to be less than in any year since 1918, ranking with that year and the worst years of the later nineteenth century (1848, 1855, 1877 and 1899).

Other recent years, such as 1975, have produced very high rainfall and disastrous flooding on the river plains of northern India.

In the same sector of the globe the variability in middle latitudes has produced some great droughts that have interfered with grain production in Soviet central Asia.

The overall average rainfall also seems to have declined there, though not to the levels which prevailed for some decades in the middle of the last century (fig. 101).

In 1972, from May to September, a huge area of the Soviet Union covering most of European Russia and stretching into central Asia had under half the usual rainfall, and in most of that area the totals were under a quarter of the expected amount.

With the average temperature of the summer up to 3.7°C above the long-term averages for this century, the great drought ruined the crops, caused extensive forest fires and even set the dried-up peat-bogs on fire.

This was a year when the Soviet Union was apparently obliged to make massive wheat purchases in the West.

But, as it also coincided with monsoon failures in India and west Africa, the food shortage was more widespread and had serious effects on world trade.

The same summer of 1972 in the neighbouring sector embracing central and western Europe produced temperatures 1°C or more below the usual level and, though dry in the British Isles, it gave over twice the usual rainfall in parts of Italy and the Balkans.

The whole eastern half of North America was also cooler and generally wetter than usual.

Western Europe and North America, both east and west of the Rockies, experienced in their turn great droughts and flooding in different years in the same decade.

In 1973 the Great Lakes of North America and the Mississippi River were at their highest levels since 1844.


TO BE CONTINUED ...
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Re: CLIMATE, HISTORY AND THE MODERN WORLD

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EFFECTS ON GLACIERS, ICE-SHEETS AND SEA LEVEL

The cooling of the general run of European summers since 1953, albeit with the year-to-year variations stressed in this chapter, has had another consequence which marks out the change of climatic tendency since the middle of the century.

The long retreat of the glaciers in the Alps first slowed down; then in 1965 some, mostly small, glaciers which were evidently nearly in equilibrium showed advances; and since 1972 in some regions, 1975 in others, in most years the majority of the glaciers, including the big ones, in Italy, Austria and Switzerland have been advancing.


Also in west and north Norway these years have produced the first general advance of the glaciers for many decades past.

Similarly, in North America the earlier twentieth century predominance of glacier retreat has been followed by advances in some areas, in the Cascades Range in the northwest of the United States from as early as the 1950s.

And on (the large) Baffin Island in northeast Canada, in the central part of which 70 per cent of the highland region seems to have been covered by ‘permanent’ ice and snow between two hundred and four hundred years ago and where this had been reduced to 2 per cent by 1960, the ‘permanent’ snow beds have been increasing again since and incipient new glaciers have been found.

This has been brought about by a lowering of the summer freezing level by nearly 300 m (1000 ft) in the later years.

With the melting back of glaciers all over the world from their maximum Little Ice Age positions, most of the retreat taking place in the earlier part of the present century, one should expect that the general world sea level was rising (although the biggest element in deciding this question could be the state of balance between nourishment and wastage of the great mass of the land-based ice-sheet covering Antarctica).

In fact, sea level does seem to have been rising, although unfortunately our longest tide-gauge records are from the North Sea basin where a great part of the changes measured may have to be attributed to the warping of the Earth’s crust in that region.

The earliest of these records, a gauge installed at Amsterdam in 1682, points to a rise of the sea level in that locality by about 18 cm up to 1930.

The rise in the region of the mouth of the Elbe seems to have been as much as 37 cm between 1825 and the 1970s.

From 1830 onwards gauge measurements were made at an increasing number of places, becoming ultimately a more or less world-wide network.

It is clear that the main rise, amounting in the region of the British Isles to 15–20 cm, took place between about 1895 and 1960.

(Some places, e.g. on the continental shore of the North Sea, reported a slowing of the rise towards 1960.)

These observations show such good conformity with the time of general warming and most rapid retreat of the glaciers in temperate and higher northern latitudes that it suggests this as the main cause.

Since about 1960 this trend also seems to have ceased.

At least for the time being a levelling off of the sea level curves is reported — though there are still, and seem to be always, some irregularities around the southern North Sea — and it has been suggested that the beginnings of a reversal may be detected in the 1970s.


At the time of writing (1981), it is too early to be sure of any such favourable trend, far less to predict its continuance, which demands a climatic forecast.

And while the general sea level remains 20–40 cm higher than it was at various times in the last century, this increases the danger of storm surges leading to sea floods.

TO BE CONTINUED ...
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Re: CLIMATE, HISTORY AND THE MODERN WORLD

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MONITORING THE DEVELOPMENT OF WORLD CLIMATE

As we find ourselves driven towards the question of prediction of future climate, it is important to consider how we can most effectively and economically keep a watch on the basic tendency of the climate.

In this chapter, as throughout the book, we have treated any change in the overall average temperature level as the most fundamental index of the state of world climate.

Through any resulting change in the gradient of temperature between high and low latitudes, and the location of the main part of this gradient, this affects the strength and patterns of the wind circulation — and thereby the transport of heat poleward and the more detailed distribution of prevailing warm and cold, wet and dry, calm and stormy weather.


We have seen that the changes produce much bigger changes of temperature level in high latitudes than elsewhere, not necessarily of the same sign in the Arctic and Antarctic (although the main ice age to interglacial variations seem to have been roughly contemporaneous in both).

It is in the Arctic that the variations, at least in historical time, judged by observations in its Atlantic and European fringe, seem to be in the same direction as those prevailing over the rest of the Earth.

There have been some significant temperature variations in other latitudes, including the tropics, although in more complex regional or localized patterns related to the wind and ocean circulations.

Changes in raininess can be both strong and localized where changes in the frequency of winds blowing towards one or the other side of a mountain range (and even smaller hills) are involved.

Thus in the 1960s and 1970s, with the decline of the North Atlantic westerlies in latitudes between 45 and 60°N, rainfall has decreased by a few per cent in western Europe and has decreased more on the western than on the eastern side of the British Isles.

In the northeastern segment of North America from New England to Labrador there have been net increases.

In the corresponding sector of northeast Asia, in the Soviet Far East and around the Okhotsk Sea and Kamchatka, the increases have in some areas exceeded 20 per cent, presumably registering an increase of the rain and snow-bearing easterly winds from the Pacific and less frequent winds from the west.


Around the fringe of the Arctic Ocean the coasts exposed to rain and snowfall with onshore winds associated with the increased cyclonic activity in the highest northern latitudes have had increases of up to 20–50 per cent in the total down-put in the 1960s and 1970s compared with the previous three decades.

We have also noted significant changes of rainfall at the fringes of the desert zone in low latitudes.

Thus, our simplest indicators of the state of world climate seem likely to be found in the temperatures prevailing in high latitudes, particularly in the Arctic (the strong variations with time offer a strong ‘signal’, but the big variations from year to year in any individual area in the Arctic, associated with shifts of position of the coldest conditions which develop wherever little disturbance happens to be felt from other latitudes, may however cause confusion); some indicator of the overall character of the wind circulation in middle latitudes, such as the frequency of the westerlies over the British Isles or the frequency of blocking; the temperatures in low latitudes (if we can sense the rather small net variations with sufficient accuracy).

It is possible that the overall rainfall in the inner tropical zone or the yield (and latitude range in Africa) of the monsoons, as well as the down-put of snow and rain in the highest latitudes, may also serve as indicators of the energy of the global wind circulation.

We have noticed in this chapter the fairly quick response of the Arctic sea ice to the fall of temperature from the 1950 level, just as it had retreated quickly in the earlier twentieth-century warming (see figs. 96 and 97).

It has, in fact, long been supposed by investigators that the variations of the Arctic ice could be used as an index of world climate (even though there may be danger in the fact that the only long data series are for the Iceland and Greenland sectors, which may not at all times be representative of the whole Arctic).


We must also notice the generally parallel course of the frequency of the middle latitudes westerlies as indicated by that of westerly wind situations in the British Isles (fig. 17, p. 53) with the course of world temperature since 1870–80 (fig. 91a).

If we may safely use the data from the limited period of history for which instrument observations and numerical assessments of the ice exist, then we do find some warrant for using this and a few other items as a world index, as table 4 shows.

In discussing our list of possibly simple indicators of the state of world climate in these pages, and the associations between them, we have touched on items which are clearly among the things which it would also be most desirable on directly economic and social grounds to be able to forecast.

In the remaining chapters of this book we must review the range of impacts of climatic developments on human affairs both now and in past history.

And we must survey the possibilities of forecasting the future tendencies of the climate, including any side-effects of man's activities which might affect the trend.

We must also consider the application of climatic knowledge to how else we may best plan our affairs to allow for the impact of climate and its future development.

TO BE CONTINUED ...
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Re: CLIMATE, HISTORY AND THE MODERN WORLD

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15 THE IMPACT OF CLIMATIC DEVELOPMENTS ON HUMAN AFFAIRS AND HUMAN HISTORY

GENERAL INTRODUCTION


In our survey of human history against the background of what is so far known of the past record of climate, we have remarked only on some of the most obvious or interesting hints of relationships between the two.

If we wish to assess the impact of climatic shifts and changes upon human history, or on human affairs today, we must first recognize the many different ways in which an impact may occur.

Second, we must be prepared to treat as separate issues the case of peoples directly hit by a climatic event and the more difficult problem of tracing the influence of a climatic event upon societies which were, or are, only indirectly affected or affected much less severely by it.

This is also a matter of recognizing that there are situations in which some development of the climate may completely bar certain previously accustomed human activities; in many other situations there is no compulsion, the influence of the climatic event or trend is only a matter of degree, of increasing pressure or difficulty of some operation, leaving the human societies concerned a wide choice.


In these cases, their reactions will be decided in large part by other pressures or opportunities.

And the weaker, or the more remote the origin of, the climatic stress, the more difficult it must be to trace the working of its effects upon society and the economy.

It may be useful to think of the cases of direct impact as ‘first order effects’ of climatic fluctuation or change and the more indirect impacts as second, third or fourth order effects according to the number of links in the chain by which the impact is transmitted.

Third, we must distinguish between the effects of short-term climatic or weather stresses and those of long-term changes, whether gradual or abrupt.

Since there is no difference in general nature between the climatic (or meteorological) events which impose stresses on settled ways of life today and those which did so in the past, the impact on history and the difficulties for human society now or in the future can usefully be considered in the same chapter.

Such differences as there are depend on the shield provided by modern technology and our increasing knowledge and ability to adapt our ways or take suitable precautions.

But there is reason to ask whether, and in what ways, our vulnerability to climatic events may now be increasing again.

If we analyse the climatic stresses, in origin they are of course physical — a matter of the freezing up or evaporation of waters, of wind stresses, of rainfall and flood levels, or the energy and power of storm waves and tide, and so on.

Both physical effects and direct biological consequences come in with consideration of changes in the accumulated warmth of the growing season or the occurrence of prohibitively high or low temperatures inimical to the life of human beings, animals or disease organisms, as also with some of the effects of rainfall, flood levels, drought, and so on.

But many significant results may come about through economic and even psychological effects on societies.

In some cases it may not be so much the climatic event itself as how it is interpreted, and what it is thought at the time to portend, that influences human action.

Some combinations of the physical variables produce effects on the environment and on man-made structures which have to be considered.

For instance, as Professor Flohn has pointed out, variations of rainfall commonly result in much bigger percentage variations in soil moisture, run-off and river flow because of the reduced evaporation in heavily clouded, rainy weather.

The effects of rain and snow driven by strong winds are also different — in respect of penetrating walls and loading roofs - from those of similar falls in calmer weather.

With temperatures below the freezing point of sea water (about −2°C), any wind strong enough to produce spray may have a lethal effect on ships by the accumulation of frozen spray on the upper-works and rigging, causing the vessel to capsize: there have been many disasters of this kind on the Arctic fishing grounds.

And as is well known to dwellers on the plains and prairies of North America and from the experience of polar expeditions, strong winds greatly increase the physiological effects of low temperatures.

Put simply: in the Antarctic — as on mountain heights and in frozen landscapes in winter elsewhere — it is the wind (or really the combined effect of wind and low temperature) that is the killer.

A 30-knot wind with a temperature of −5°C has about the same cooling power as temperatures approaching −30°C with little wind.

The range of ambient temperatures within which the human body is comfortable is also much affected by the humidity of the air, because the body’s cooling mechanism depends on sweating.

Studies on twentieth-century white European populations have indicated that in still air and out of the sun the average upper limit of ‘comfortable’ temperatures is about 22°C (72°F) for 100 per cent relative humidity, rising to 27°C when the relative humidity is 66 per cent and 38–39°C (102°F) with very dry air.

The upper limit of what is ‘just bearable’ appears to go from 38°C (100°F) with 100 per cent relative humidity to about 56°C (over 130°F) in very dry air.

Since humidities over 90 per cent are found to induce feelings of lethargy whatever the temperature, and cause temperatures below about 7°C (45°F) to be felt as ‘raw’, the range of temperatures which are comfortable is narrower the higher the humidity.

A full consideration of the influence of climatic conditions on comfort and the ability to work would have to include the effects of exposure to solar radiation as well.

Considerations such as these have been thought to have to do with differences in the energy of nations.

Similar studies might throw light on differences in the energy, ability to acclimatize, and tolerances of different human racial types, if such exist.

The comfort and well-being of animals is determined by the same elements of the climate, though the thresholds differ for different species.

There is a like need for knowledge and understanding of the climatic tolerance ranges for different food crops as well as the optimum conditions for each.

No less important are the climatic conditions which favour, and the limiting conditions for, various pests, diseases and disease-carriers.

We may list the main ways in and through which climatic fluctuations and changes impinge on human affairs, as follows:

1 Water supply, particularly affecting ground-water levels and soil moisture, well levels, river levels, lake levels, also glaciers and, of course, the availability of water for water-power (from mills to hydroelectricity).

2 Temperatures prevailing and their direct effects on human and animal comfort, and hence on fuel demand, and on crop growth.

3 Sunshine, humidity and cloudiness and their effects on health and growth, also the potential of solar power.

4 Windiness and its effects in either damaging structures or the availability of wind and wave power.

The effects on evaporation, and hence on vegetation and crops, and on the breeding conditions for insects and bacteria may also be important.

The specific fields in which the impacts are felt can be summarized as:

1 Agriculture and horticulture, including fruit and vine cultivation.

2 Forestry.

3 Insects (e.g. locusts) and other pests, blights, mildews, and their control.

4 Plant, animal and human health and diseases.

5 Weather-sensitive manufacturing and construction industries (textiles, civil engineering, etc.).

6 Trade (national and international trade and planning, quotas and their fulfilment, planning of the locations of agricultural cropping and industrial concentrations and emergency back-up measures) and effects on prices.

7 Travel and communications (opening and closing of mountain passes, of ways across deserts and marshlands, and of routes across seas threatened by storms or ice), costs of highway clearing and maintenance, of telegraph and cable lines, electricity lines, oil and gas pipelines, etc., and in some regions of ice-breaking.

8 Tourism (summer and winter sports, arrangements for travel and cruises, health resorts, and the costs of investment in equipment and maintenance).

9 Disasters and difficulties caused by avalanches, glacier surges, mud-flows, landslides, rock-falls, floods or parched ground, subsidence and frost-heave, exceptional snowfalls, violent windstorms, etc.

Disasters to wildlife (fauna and flora) may also be of economic importance (as when the walnut trees of Europe were so devastated by the great winter of 1708–9 that the crisis in the furniture industry caused France to ban the export of walnut for twelve years, and importation was begun in Europe first of black walnut from America and later of mahogany in the ships of the East India Company).

10 Coastal flooding and erosion, sand and gravel movements, silting of estuaries and harbours, associated with either sea storm surges or longer-term changes of sea level.

11 Arrangements for, and costs of, insurance and safeguards (insurance industry, storage and stockpiles of food and water, irrigation, building of coastal defences, climate monitoring and research).

12 Arrangements for, and costs of, relief measures and resettlement of refugees, settlement of disputes and containment of riots, and threats of revolutions and wars.

TO BE CONTINUED ...
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Re: CLIMATE, HISTORY AND THE MODERN WORLD

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IMPACTS OF THE FIRST ORDER

In our survey of the past we can notice a number of cases where climate exercised a compulsion on human affairs.

The great rise of world sea level progressing over thousands of years, which followed the ending of the last ice age and submerged formerly inhabited lowlands and coastal plains, is one example.

The later drying up of the north African, Arabian, north-west Indian and central Asian deserts ended the human activities and cultures there and must have caused at first famines and ultimately a like shift of populations.


It has even been suggested that the refugees may have provided the source of slave labour that made the highly organized river-valley civilizations possible.

Other examples of climatic compulsion are provided by the loss of access to the high-level mines in the Alps about 800 BC and again in the later Middle Ages; the flooding of the prehistoric lake villages in central Europe at various earlier times and also around 800 BC; and probably the variations of moisture and forest growth in the valley of Mexico and Yucatan, as well as in Cambodia and elsewhere in southeast Asia.

We have noticed the climatic developments which seem likely to have caused the abandonment of the old caravan route of trade between China and the Roman empire, the Great Silk Road through central Asia, and the cities along it; and those which cut off and doomed the Old Norse colony in Greenland and caused the late medieval depopulation of the uplands in central and northern Norway, the abandonment of tillage in many other parts of Europe, and the retreat of the northern limit of vine cultivation.

In these last-named cases it may be held that we have entered a ‘grey area’, where other causes for the change can be alleged.

It is often said that the demise of the medieval vineyards in England and northern Germany and elsewhere was due to economic causes and most particularly that good wine could at last be transported from Bordeaux and southern France; and this is continually repeated as the ‘obvious explanation’, a matter which can be readily understood by the ordinary man.

But from analysis of the data it seems undeniable that climate tipped the economic balance.

The purely economic explanation does not square with the fact that in the twelfth and thirteenth centuries, when these French wine districts were under English rule, diplomatic pressure was exerted to try to get the king to suppress the English vineyards.

It seems more likely that the Bordeaux trade gained and the terms of trade changed when the English vineyards increasingly failed to produce an acceptable harvest in the fourteenth and fifteenth centuries.

Indeed the failure of at least one of the English vineyards, at Ely, seems to be fairly well documented to the bitter end in 1469.

Long before that, it is recorded in 1341 that there was still much land uncultivated all over England which had been cultivated before the disastrous summers, and the severe death roll from starvation, in the decade around 1315.

Suspicions of a more far-reaching influence of climate on history have inevitably been aroused by the apparent correspondence between the high points of cultural achievement in northern Europe in the Bronze Age (particularly in the development of sea-going trade), in late Roman times, and the high Middle Ages, and the crests of the temperature curve.

There is suggestive further detail too in the coincidences of decline and unrest with a number of the known climatic shocks, particularly around 800 BC in central Europe and more widely in the fifth, sixth, fourteenth, fifteenth and seventeenth centuries AD.

In one decade, the 1430s, characterized by a majority of severe winters in much of Europe (and evidently remarkable frequency of ‘blocking’ in the atmospheric circulation), the summers setting examples of both extremes of temperature and rainfall, we find the Scottish Highlands and Bohemia in civil turmoil, the capital of Scotland moved south for greater security to Edinburgh, a particularly savage phase of the Hundred Years War between England and France, and the collapse of a period of Chinese expansion on land and sea under the Ming dynasty because of internal troubles.

And, as we have seen in the last chapter, over the time between the late thirteenth century and the fifteenth, the cultural (and in some senses the political) capital of northern Europe moved south in successive stages from Trondheim to Bergen to Oslo and thence to Copenhagen.

Finally, in 1536 Norway ceased to exist as a separate country.

Iceland was also subjected to more and more absolute rule from Copenhagen.

In 1707 a like move ended the independence of Scotland, which was absorbed in the United Kingdom and ruled from London.

At each stage in these developments other, non-climatic causes can usually be alleged, and climatic stress was seldom mentioned as the reason for decisions taken by the people at the time, except in relation to events in Iceland and Greenland or near the glaciers of Europe and in cases of harvest failure.

And if we look at the history of the Far East, the time of drought around AD 300 in central Asia coincided with conflict there leading to the destruction of the
Tsin dynasty in northern China by invading nomads.

Refugees poured into south China and contributed to the cultural development there, while others fleeing to Korea and western Japan figure prominently in the peopling of those countries.

Something like this history was repeated with the Manchu invasion of China, ending the Ming dynasty in 1662 in the midst of one of the severest parts of the Little Ice Age period.

If there is any reality in the web of climatic influence appearing to show this much control over history, it is certainly not simple in its working and comes to light only as the net outcome, the statistical result of an enormous diversity of movements, choices and activities.

TO BE CONTINUED ...
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Re: CLIMATE, HISTORY AND THE MODERN WORLD

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MORE COMPLEX CONSEQUENCES

There is not much difficulty in finding cases of contrary effects and opposite movements.

Clearly, Denmark and England gained from the decline of their northern neighbours under the difficulties and disasters with which they were beset in the advancing Little Ice Age between 1300 and 1700.


And thanks to the mortality experienced in those countries as well as almost all of Europe in the famines and epidemics of the second decade of the fourteenth century, and in the Black Death and subsequent plague epidemics which followed, the surviving population of Europe seems possibly to have been better nourished in the later fourteenth century than in the seventeenth and eighteenth centuries.

Thus Slicher van Bath cites the quantities of meat, fat, bread, etc, and estimated total protein served in a fourteenth-century hospital in Nuremberg, totalling about 3400 calories per diem, compared with that in a hospital in Munich four hundred years later, totalling an estimated 1900 calories per diem.

Shifts of the northern Atlantic codfish stocks in the fifteenth century are thought to have encouraged the exploration by English, French and Portuguese fishermen of new areas of the ocean, until at some apparently unrecorded date in the middle or late 1400s they began fishing on the Newfoundland Banks.

And in the early part of the next century the abandonment of the Baltic by the herring caused the North Sea fisheries to spring into importance, giving a great boost to English and Dutch seafaring activities.

Holland became very prosperous by the early seventeenth century, though the later part of that century saw some decline also there owing to troubles from the great storms and sea floods which broke the dykes and with disruption of the fisheries and on the farms.

Already long before, in the decline of the Old Norse colony in Greenland, the fading out of the hunting along the northern reaches of the west coast near Disko Bay seems to have led to an outburst of renewed foraging farther afield, at first in 1267 north and west into Baffin Bay and as late as 1347 west to Markland (Labrador).


And it seems that the furthest explorations achieved in the history of the colony were made at that late stage.

Other examples of curious and complex phasing of population movements during the development of the Little Ice Age can be found in Scandinavia itself.

While farms were being abandoned in the fifteenth and sixteenth centuries in north Norway, the fisheries along the coast were being increasingly developed and population was increasing there; in part this is thought to have represented an influx of different people spreading northward from the coastal fishing settlements farther south.

At the same time, while even in England and central (and parts of southern) Europe farms and villages on the uplands and elsewhere were being abandoned, settlement was still advancing in places in northern Sweden and Finland.

This may have been, in part, because population had always been so sparse there that even many favourable localities had never been occupied.

But the evidence of tree rings in Lapland, in fact, indicates a predominance of good years for growth there right on until 1580 or almost 1600.

There is similar evidence from Alaska and the Yukon.

Taken together, this is meteorologically suggestive of blocking anticyclones commonly giving warm sunshine over those areas, while the northerly and easterly winds on their eastern and southern sides carried Arctic air into Russia and central Europe and similarly into central and eastern North America.


In the late sixteenth century, however, there was some migration of Finns into central Sweden and Norway and towards the Atlantic coast farther north.

And in the more widespread and well-documented cold regime in the seventeenth century, particularly towards the end of that century, the tide of settlement went into retreat over the whole of northern Scandinavia and Finland.

Thus, while we reasonably look for the most direct effects of climate on human history — and on human affairs in any age — among peoples living at the poleward or hot desert margin, there is no lack of complex and contrary movements and activities in the regions from which we have drawn examples.


One of the most remarkable responses to the climatic stress of the climax of the Little Ice Age is reported in southern Norway all around the coast between Trondheim and Oslofjord.

In the late seventeenth century, when the harvests were poor and the grain sometimes failed to ripen on the farms even in the most favoured areas along the southeast coast, as mentioned briefly in chapter 12, the farmers took to trading abroad the timber on their land, notably to England, and those near enough to the coast built their own ships to carry it in.

Those, particularly in the south, who had oak were in the best position.

This seems to have been the beginning of what became two of Norway’s greatest industries, the timber trade and her merchant fleet which by our own century was one of the biggest in the world.

And so it came about that the years 1680–1709, which seem clearly to embrace the bitterest period of the climate in northern Europe, are described as ‘the first great period of Norwegian shipping’.

Of course, those were also times when the great powers farther south in Europe were at war: the war boosted the trade in timber, and together with the activities of pirates it encouraged those not involved to protect themselves in an armed neutrality.

A report on Stavanger briefly indicates the situation at an early stage in this development: ‘despite the town’s miserable condition in 1685, it managed to keep one defence ship with 25 pieces’.

In some years in the 1690s the death rate greatly exceeded the birth rate, and there was a net fall of the population of the town from 1685 to 1701.

The numbers and sizes of the ships kept at nearly every port along the coast increased greatly in the next twenty-five years.

The numbers were swollen by incoming Dutchmen, who took Danish-Norwegian nationality in order to sail under the ‘flag of convenience’ of a neutral country and who then stayed on to become big shipowners in Norway.

(The Dutchmen came especially to Bergen, where there was some involvement in the whaling up to Spitsbergen though not on the scale of the operations from the Dutch and German ports.)

In Sweden it is recorded that Dutch shipwrights in the seventeenth century took a leading part in shipbuilding and contributed significantly to the strength of the Swedish navy.

At the same time as these developments were going on in Scandinavia, in Iceland the reaction to the climate stresses of the seventeenth century was very different.

According to the Icelandic historian Gisli Gunnarsson, the strength of the landowners’ position in what was very much a feudal society enabled them to oppose in several effective ways the drift of labour from the farming areas, where difficulties were increasing, to take up fishing on the coast.


This opposition is documented in the records of the courts.

All sections of Iceland society — in its depressed and fossilized state at that time — seem to have been against technical innovation.

Only open-decked boats were used.

And this was compounded by crippling restrictions, permitting no more than one hook on a line and forbidding the use of worms as bait.

It is clear that the difficulties were always greatest in the north and east of Iceland, where the polar water from the East Greenland Current is liable even now to come in along the coast; but in the worst phase, between 1685 and 1704, not only the hay harvests but also the cod fishery were poor, or failed completely, even in the southwest of the island.

In the late eighteenth century, when the government in Copenhagen was trying to stimulate recovery in Iceland by encouraging fishing and seamanship with the introduction of decked sailing vessels and more hooks on the lines, it had a long struggle against general opposition to any change.

Over the whole Little Ice Age period the population of Iceland was falling.

At its peak in the eleventh to thirteenth centuries it can be estimated from tax records at between seventy and eighty thousand.

At the first census in 1703 it was 50,358, but was reduced four years later by about a third in a smallpox epidemic.

It rose in the warm years in and around the 1730s to about 48,000 by 1755 and again in the 1770s to 49,863, after a dip in the severe years in between.

But the severe seasons which followed, and the volcanic effluents which poisoned the pastures and the cattle, reduced the population again to its lowest, about 38,000, in 1784–6.

Once again we see a historical development which runs fairly closely parallel to the temperature curve, even though the apparent link operates in various ways, through undernourishment and starvation, through illness and emigration.

Resistance to change is, of course, familiar enough in other parts of the world.

As if to parallel and explain the seventeenth-century Iceland situation by a
current anxiety in the modern world, the 1980 Report of the Brandt Commission stresses that human energy and ability to innovate depend on adequate nourishment and good health; yet most people in today's poverty belts suffer from long-standing malnutrition and parasitic diseases, and for that reason cannot help themselves unaided to set up a new economy that might better withstand the pressures of overpopulation and the harsh climates of Africa and south Asia.

We have noted (p. 245) the slow progress in Europe in adoption of the potato.

In the moist climate of Ireland it was so much more reliable than either wheat or even oats that it was soon taken on — already in the seventeenth century — as the ‘bulwark against famine’ and gradually eliminated grain growing over wide areas.

But in France it became regarded as suspect because of its botanical family relationship to the native belladonna (deadly nightshade).

Some other crops from the New World, such as string beans, were taken on readily enough in southern Europe; and John Locke after travelling in France in the 1670s recommended putting leaves of kidney beans under your pillow, or in other convenient places about your bed, to concentrate the bed bugs and save yourself from being bitten.

But maize was not liked and its progress seems to have been delayed partly for that reason and partly because of the cool summers of the Little Ice Age.

We have taken our examples of the more complex involvement of climate in human decisions in the past mostly from those parts of Europe which were particularly vulnerable to climatic change and for which we have good information.

If we are to attain a fuller understanding of the lessons for our own day and for the future, we must proceed to more specific detail of how the climate works upon food production and health.

Among the indirect and subtler influences are, of course, many that can hardly be measured, such as the effects upon art (p. 233) and architecture.

Was it, for instance, just a coincidence that the widespread introduction of glass into windows in the houses of Europe coincided with the late sixteenth and seventeenth-century privations of the Little Ice Age?

Instances are also not hard to find of influence upon fashions in dress, particularly as regards warmth — often adjustments to an event that has already taken place and which therefore may or may not be repeated.

Among the subtler influences, one may perhaps detect the optimism engendered in Europe by the glorious summers of 1718 and 1719, the warmth of the 1730s, and more good summers in 1759 and around 1778–80, in the writings and perhaps in the music of the time.

The psychological effect must have been particularly strong on those who had lived through the 1690s.


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Re: CLIMATE, HISTORY AND THE MODERN WORLD

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EFFECTS ON GRAIN HARVESTS

We have seen how in the late Middle Ages wheat cultivation was given up in Norway and in much of Scotland.

In Iceland, and on difficult land in many other areas of Europe, grain cultivation was given up altogether for a long time.

Elsewhere oats or barley were kept on (in one or two places in Iceland until the sixteenth century and in Scotland and Norway throughout), and rye was brought
in or increased.

Sooner or later in the progress of the climatic recovery after 1700 these changes were reversed, except that in many areas rye had won a permanent place.

What do we know about these crops’ requirements that might explain the linkages which we must suppose to exist in these parallel histories?

M.L. Parry has shown how the matter may be investigated.

Grain crops, like any other plant, have certain requirements as regards overall warmth, moisture, sunshine and not too much wind in the growing season, if they are to come to fruition.

Parry considered in some detail the case of oats, which were the major grain crop at the upland limit of cultivation in Scotland over many centuries past and were important also in Iceland and north Norway.

The varieties grown were changed in the nineteenth century, the older varieties being shorter in the stalk and less liable to shaking, but there is no evidence to suggest that their warmth requirement was any less, or their tolerance of wetness any greater, than the modern varieties.

The differences were probably slight but such as to make the modern oats somewhat hardier on the high farms except in regard to wind speed.

Comparison with climatic atlas data for the Lammermuir Hills in southeast Scotland showed that the upper limit of oats cultivation in 1860, at about 320 m above sea level, corresponded closely with the 4.4 m/sec mean wind speed line.

Mean wind speed increased about 1 m/sec for every 80 m increase of height above the 200 m level.

Changes of solar radiation with height appeared too slight to be a limiting factor: the increased intensity of the radiation at the higher elevations is slightly more than offset by reduced duration owing to hill fog, the net reduction being only of the order of 5 per cent on the upper levels of these hills.

Soil moisture increases rapidly with height and for this reason oats, which are intolerant of water-logging, have an absolute limit at 425 m above sea level on the hills of southeast Scotland in the present climate.

The temperature requirement generally limits the possibility of growing the crop at well below that level; moisture may, however, also contribute to failure of the crop at still lower levels in some years.

Parry proceeded to examine the moisture and temperature involvement more closely.

There is liable to be a spell in early summer, even on the heights and near the northern limit of cultivation, when the potential transpiration of moisture through the stems and leaves of the plants exceeds the rainfall and leads to drying of the soil.

What is liable to damage crops on the heights is the water surplus produced in the later part of the summer, when the crop is ripening and the rainfall exceeds the potential for evaporating transpiration (a quantity known as the ‘potential evapotranspiration).

The wetness of a summer on the heights can usefully be measured, according to Parry, by the difference between the water surplus at the end of August and the greatest potential water deficit which occurred earlier in the summer.

Study of present-day oat cultivation in the hill country of southern Scotland established that the limiting conditions corresponded to an average value of 60 mm of water for this difference, and a mean wind speed of 6.2 m/sec, while the minimum accumulated warmth requirement for the growing season was about 1050 day-degrees C above the 4.4°C threshold of growth.

For commercially viable cropping the critical figures could be taken as 20 mm accumulated water surplus, 5 m/sec mean wind speed and 1200 day-degrees C.

The zone with conditions normally between these two sets of criteria can properly be described as marginal land.

Wind speed and humidity records are too short to provide the relevant figures on greatest potential water deficit and later water surplus for summers in past centuries to compare with the harvest records; but the accumulated summer warmth can be calculated for summers in Scotland in the late eighteenth and nineteenth centuries and can be estimated for earlier times.

This is not such a serious restriction as it might seem because there is a strong correlation between warmth and the dryness of the summers.

Parry therefore went on to consider the probable frequency of failures of the oat harvest in earlier centuries by reference to the temperature changes known or derived for central England (fig. 30 in this book, p. 84).

Total failures of the oats may have been rare where the crop was grown for consumption by the family on the farm.

There are cases recorded where the crop was reaped in December and even January, though in a poor state, liable to be mildewed or sprouted in the ear and much of it lost by windshaking.

Such were the dreaded ‘green years’ when the crops failed to ripen.

And in such cases recourse would be had to eating some of the seed reserves from the previous year.

A sequence of such harvests, as in several reported runs of two or three bad years in Scotland (e.g. in 1740–2, and 1781 and 1782, let alone the seven years out of eight between 1693 and 1700, when in the upland districts overall perhaps a third of the population died), would soon produce famine and tend to put some farms out of business.

After establishing the accumulated warmth figures for some historic summers, such as 1782, 1799, 1816, when the harvest was not got in until the end of November or later on the hill farms in southeast Scotland, Parry was able to calculate the probable frequency of such summers at various times in the past by assuming the changes of mean temperature level to have been the same as those affecting central England and taking the variability (standard deviation) as constant.

The calculations produced the curves seen in fig. 102.

The curves show the most probable intervals between harvest failures in a single year or between failures two years in succession on these assumptions, when and wherever the longer-term average summer warmth gives the accumulations of day degrees above the 4.4°C datum specified.

With the temperatures prevailing in recent times the average accumulation can be taken as about 1150 day-degrees at 300 m above sea level in the area investigated, for which the graph indicates an average expectation of a harvest failure about one year in seven.

With the temperatures derived for the thirteenth century, giving an average of 1200 or more day-degrees at the same height, this expectation might be reduced to one year in about twenty.

But with the climate as it was in the second half of the seventeenth century, the average would be about 975 day-degrees and harvests likely to fail two years running once in about four years.

Clearly agriculture could not then be sustained at the 300 m level.

Crude as the assumptions are on which these calculations are based, they give a firm enough glimpse of the compulsion to abandon the upper areas of former cultivation under such circumstances.

An attempted similar use of the available rainfall estimates indicated no significant changes in the historical course of the apparent upper limit of possible oat cultivation.

A temperature curve resembling fig. 30 in this book, but with the values reduced by the difference between central England and the southern uplands of Scotland and converted to average yearly accumulations of day-degrees above the 4.4° datum, which we take to represent zero growth, should give us a history of the frequency of harvest failures.

This is the message of fig. 103, which Dr. Parry has kindly allowed me to reproduce from his book.

It indicates the dates at which a farm which is now near the limit of cultivation at about 320 m was (a) no longer marginal around AD 1200, when the limit was more than 400 m above sea level, and (b) when it encountered increasing difficulty and presumably became no longer viable from around AD 1400 till the nineteenth century.

Parry was able on this basis to map the probable cultivation limit at various stages of the climatic cooling between AD 1300 and about 1700 and of the subsequent warming, mainly since 1900.

As it was also possible to map the former settlements abandoned at various dates — fifteen of them before 1600 and twelve more between 1600 and 1750 — in the Lammermuir Hills study area, and compare these maps with Parry’s theoretical limits, the thesis can be regarded as having been vindicated by test.

Barley also is one of the most important crops in most parts of northern Europe.

Studies in the 1970s of its responses to weather have indicated that in eastern England it does best in cool years.

High yield was found to be favoured by lower than average temperatures and dryness in spring, items tending to produce slow progress at that stage.

In the next stages high rainfall was beneficial, but the strongest relationships were between high yield and Julys that were cooler, duller and more humid than average.

In Scotland, where barley is now grown mainly in the broad eastern lowlands, over about the same years it was found that the average yield in tonnes/hectare was about 20 per cent higher than in England and was less variable from year to year.

Evidently this is the climate that suits the crop; significant sensitivity to year-to-year weather differences was indicated only by the positive response to the sunniest years in the growing season, particularly in June and July, in Scotland.

In the grain growing areas on the extensive low ground of eastern England, anxiety is nowadays more often caused by drought in the growing season, although waterlogging in wet autumns can hinder, or perhaps even prevent, the autumn sowing of grains just as it does the lifting (especially with modern heavy machinery) of root crops.

A history of the soil moisture deficit built up over the four months of the growing season from May to August in southeast England has been reconstructed from the long series of temperature and rainfall data for London (Kew).

The result, illustrated in fig. 104, reveals the periods of greater moisture — enough to produce troubles with the grain harvest in parts of the region — in the 1760s-early 1770s and before 1740, as well as in the period 1810 to the 1830s and the 1870s and 1880s.

But the most notable feature is the increased frequency of droughts in the warmer years of the present century, to some extent paralleled two hundred years earlier in the 1740s.

Indeed, it is reasonable to consider whether the difference apparent between recent times and the eighteenth-century incidence of drought could largely be explained by the growth of London and the now pronounced urban effect on the temperatures measured at Kew (now on average about 2°C above those observed in the surrounding country).


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Re: CLIMATE, HISTORY AND THE MODERN WORLD

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DETAILS FROM SWITZERLAND IN THE EIGHTEENTH CENTURY

The history of the renewed deterioration of the climate in the latter half of the eighteenth century in Switzerland and its effects on agriculture has been closely studied by the Swiss historian, Christian Pfister, with the aid of daily meteorological observations and the agricultural and economic reports collected at the time by the then newly established Economic Society of Bern (Ökonomische und Gemeinnützige Gesellschaft des Kantons Bern).

There were short runs of warm years between 1759 and 1763 and between 1778 and 1784, but in the colder periods outside those dates some of the severest conditions of the Little Ice Age occurred.


After 1764 the summers were generally cold and rainy in the Swiss lowlands and there were up to twenty-four days of new snowfall between mid-May and mid-September on the heights between 1500 and 2300 m.

Those summers were too short to clear the snows that had accumulated on the upper Alpine pastures, an experience to some extent repeated after a long respite in 1978.

In 1770 the Stockhornkette chain at 2000 m remained snow-covered all summer, and 1771 was little better.

Similar years are known to have occurred around 1713, 1740, 1792–5 and especially from 1812 to 1817.

Several of the winters were longer and delayed the coming of spring even on the lowlands until later than has occurred in the present century.

In the worst years the harvest was not brought in until after the long, snowy winters and the seed was found to have rotted under the snow cover, probably due to the parasite Fusarium nivale (see p. 216).


The total harvest of bread grains and the yield of the tithes in the cantons of Bern, Vaud and Emmental fell by a quarter to a third in 1769–70, and the price of bread grains more than doubled in 1771.

The prices of hay and animal products — beef, butter and cheese — were similarly affected.

A 40–60 per cent drop in the yield of the tithes in 1785 betokens another very bad year after the exceptionally long winter of 1784–5 and a spring and summer that were wet except in the extreme west of the country.

Grain prices reached another sharp peak in 1789 and again doubled in 1795, when animal products were also affected after another severe winter followed by great wetness, but the situation was eased by the potato harvest.

Prices continued abnormally high in 1796.

These were the worst years in the forty-year series of data for Switzerland tabulated by Pfister.

Although the long-term average levels of the tithes and the harvest yields showed a minimum centred about the 1770s, and the glaciers were advancing, the other years were by no means so bad.

Thus the yield of the tithes in the sampled areas was about 10 per cent above the smoothed average in 1786 and 1787 before another sharp drop (10–30 per cent deficiency) in 1788 and 1789.

It can, of course, be argued that neither Iceland nor Norway nor the uplands of central Europe, let alone Scotland, provides a meaningful test of the effects of climatic vagaries on the wider community of Europe.

But the effects of the severe winters of 1784–5 and 1788–9 seem to have been harsher in France than in Switzerland, perhaps because of the summer droughts in 1785 and 1788, and we have seen in chapter 13 how the consequential rise in the price of bread may have played a part in the French Revolution.

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Re: CLIMATE, HISTORY AND THE MODERN WORLD

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THE TIME AROUND 1816

The anomalous weather of the years 1812–17, which accompanied the exceptional outburst of volcanic activity in those years with tremendous injections of matter into the stratosphere, reached its climax in 1816, as described in chapter 13.

In the summer of that year the usual sub-Arctic cyclonic activity, with its rainfall and storms, was concentrated in a belt from near Newfoundland crossing England into the southern Baltic.

In central England the average temperature of the summer three months (June–August) 1816 was 13.4 °C (56.0 °F), almost as low as the coldest years in the Little Ice Age period (13.2 °C in 1695, 13.1 °C in 1725) and a figure bettered by many a September and one or two Mays.

The overall climate, but especially the summers, averaged almost 1°C colder in England in that decade and again between about 1835 and the late 1840s (also associated with volcanic dust loading of the stratosphere) than in the preceding and following decades.

Severe cold and harvest difficulties were reported from many other regions, especially in Europe and the northern United States in 1816 and Japan in 1836.


The monsoons were disturbed in India (see p. 248).

Can it really be unconnected that ‘the years 1812–17 introduced three decades of economic pause punctuated by recurring crises, distress, social upheaval, international migration, political rebellion and pandemic disease?

The writer of those words does not think so.

He goes on:

Those who account for this period by citing the nettlesome decades of early industrialization should recall that these phenomena were not limited to western Europe.

Although the numerous crises, popular disturbances, and rebellions between 1812 and 1848 are well known, the epidemiology of these decades is not…the meteorological patterns of 1816 induced the first modern pandemic of cholera which began in Bengal in 1816–17.

The most extensive typhus epidemic in European history struck in two waves, an earlier one in 1813–15, and a more severe contagion in 1816–19…an epidemic of plague raged in the Balkans, along the Adriatic coast, and in the lands of the southern Mediterranean, during the last half of this decade.


He adds that the connection between typhus or cholera and cold, wet vegetative seasons is now well understood, but the ecological conditions which favour plague are not and the plague outbreak may well not have been so directly attributable to the weather.

Any direct connection with the Napoleonic war which ended in 1815 is at least equally unlikely, since, for instance, in the Swiss records studied by Pfister in the parish of Alpenzell there was a 50 per cent reduction in the birth rate which culminated sharply in 1819.

And it was from about 1818 to 1855 that the Alpine glaciers showed perhaps their most continuous advance.

The effect of these years on the price of rye in Germany is marked by the sharp peak in 1816 and 1817 seen in fig. 33b (p. 88) and is probably the main contributor to the great peak of the wheat prices in the parts of Europe covered by fig. 33a, even though many of the war years were included in the same twenty-five-year mean.

J.D. Post has described these years as the last great subsistence crisis in the western world.

The effects were already mitigated, however, in all those areas, notably Ireland, where potatoes were already grown.

In England the practice of irrigation, which had been begun on the farms in the pursuit of agricultural improvements in the eighteenth century and was no doubt given an impetus by the dry years in the 1740s and 1750s, seems to have been given up in the cooler, wetter summers of the nineteenth century, particularly from the second decade onwards.

Spring was also more frequently wet than before.

Similarly in the Far East the double rice cropping regime which had been adopted in the lower Yangtze valley in the eighteenth century — giving its greatest yield of 7.6 tonnes/hectare in 1718, which was a warm year there as in Europe, and an average of 6.2 tonnes/hectare — failed in the early nineteenth century owing to the climate turning cold.

In Japan this was perhaps the coldest part of the Little Ice Age with great famines caused by harvest failures and shortfalls in the cold summers of 1782–7, 1833–9 and 1866–9 produced by cold northeast winds and excessive rains.


(At least the first two of these groups of years were characterized by exceptional loading of the stratosphere with volcanic matter after very great eruptions.)

Much of the rice crop never ripened, and the poor were driven to gather nuts and roots for food and to eat dogs and cats.

And as in Europe in the famines of the late Middle Ages there were some reports of cannibalism.

The population of districts in northern Japan fell by about 10 per cent partly due to deaths and partly through vagrancy.


Also, as in Iceland in the seventeenth century, it appears that feudalism and the imposed isolation from contacts with the outside world aggravated the disaster and told against any adjustment and innovation which might have improved the situation either in the short or longer term.

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