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The sun, sovereign ruler with chilling power: An assessment of the potential impact of solar activity on future climate

G. Windelius, in collaboration with P. Tucker

Göran Windelius is an interdisciplinary researcher based in Hagfors, Sweden.
Peter Tucker is an independent illustrator and editor based in Stockholm.

The author presents a provocative opposing view to the global warming hypothesis, and predicts that changes in solar activity are about to result in a period characterized by significantly cooler climate, accompanied by increased seismic and volcanic activity.

A substantial number of meteorologists (most of them schooled in atmospheric chemistry) believe that the earth's climate will soon be subjected to a powerful warming impulse - that is, if humans continue to burn fossil fuels and cut down tropical forests at the present rate. A rise in global temperature of 2.5°-4.5°C within the next 50 years has been forecast, bringing with it the melting of the polar ice-caps and a rise in sea-level. This would deal a severe blow to modern civilization, drowning many urban centres and huge tracts of productive farmland in coastal areas all over the world. The global warming hypothesis, however, is marred by a number of scientific weaknesses. Before science can make reasonable assumptions about the future climate, it must first have a reasonably clear understanding of the primary forcing factors responsible for climate change.

This is not easy. Primary forcing factors tend to get lost against the background of more obvious secondary, reactive factors, of which the action of greenhouse gases in the atmosphere may well prove to be one. Earlier as well as current research in fields other than atmospheric chemistry gives ample reason for supposing other natural mechanisms to be more important for changes in climate than the greenhouse effect - even when the latter is reinforced by human action.

We obviously cannot directly test experimental findings on the climate system itself. We can only test our assumptions in artificial simulations under laboratory conditions, for example in the General Circulation Models of the atmosphere. To be credible, these simulations must take proper account of numerous feedback systems, both positive and negative. An example of the latter is the cooling effect of increased cloud cover, which may well exceed any greenhouse warming imposed on the atmosphere by the concomitant increase in water vapour.

Such negative feedback may be more important than we imagine. For example, ice-bore samples from the Antarctic ice-sheet (Vostok) show that, at least during the past 160000 years, periods characterized by rising temperature and high levels of carbon dioxide (CO2) in the atmosphere were invariably accompanied by an expansion of the polar ice-sheet. In these cases, CO2 obviously cannot have been a primary forcing factor.

To explain CO2 changes in the atmosphere as an indirect result (rather than as a cause) of variations in air temperature is not difficult. Reduced plant cover during a cooling of the climate would certainly weaken a major mechanism of CO2 absorption. Further, cooling conditions would lead to a massive extinction of many microorganisms in the soil, thereby reducing CO2 emissions.

At the same time, falling temperatures could be expected to lead to large increases in the amount of CO2 absorbed by the oceans. This would be due partly to the increased solubility of CO2 in cooler water, and partly to the increased wave action associated with cooler conditions, which would in turn increase the absorptive area of ocean surfaces.

Thus, it is possible that current calculations misjudge the tendency to global warming by a factor of 10-20, both by overestimating the climate-forcing capacities of the greenhouse gases and by underestimating the importance of negative feedback that might drive the climate system in the opposite direction. In this context, it should be emphasized that invalidation of the greenhouse warming hypothesis gives no carte blanche for continued over-exploitation of tropical forests.

Are there any grounds for supposing that the earth may soon be subjected to a powerful cooling impulse? I believe there are, and that this "cold shock" will probably obliterate any warming that might be attributable to an enhanced greenhouse effect.

The cyclic nature of climate change

First of all, it is certain that the basic processes driving the solar system are cyclic in nature. The planets and other celestial bodies all follow orbital paths and all rotate around their respective axes; these astronomical factors govern the cyclic recurrence of ice ages. In shorter-term fluctuations, the earth's climate has continuously alternated between warm and cold periods at regular intervals. The intrinsic pattern of past fluctuations in climate and the present state of global temperatures give every reason to expect the advent of another so-called mini ice age similar to that which occurred during the seventeenth century. The real question is when this will occur, and how deep the plunge in temperature will be.

To understand when, it is necessary to understand why. Why should the climate fluctuate in this particular manner? What cyclically variable mechanism or mechanisms could be responsible for the constant changes in temperature and weather conditions that we know have occurred during the past 12000 years?

The solar factor in climate change

One obvious suspect is, of course, the sun. This central body is certainly a fundamental force in the climate system, and its energy processes are known to be variable. Solar electromagnetic activity varies in a cyclic pattern that finds its clearest expression in the roughly 11-year sunspot cycles.

In examining the pattern of sunspot activity since 1700 (see Fig. 1) it is clear that hyperactive cycles are soon followed by hypoactive ones. The strong cycles between 1770 and 1800 were followed by three weak cycles between 1800 and 1830. Similarly, the strong cycles between 1830 and 1870 were followed by weak cycles from 1880 to 1910. According to available records, the climate in the Northern Hemisphere reacted consistently throughout this period, alternating episodes of warmer and cooler conditions closely following the variations in sunspot activity.

The authors predict a period of global cooling

The sun is capable of far more drastic reductions in its level of activity than have occurred during the past 200 years. Sunspots totally failed to appear throughout a period of 70-80 years in the seventeenth century. This weakening of solar activity exactly coincided with the "mini ice age" of the latter half of the seventeenth century when forest growth in highland areas was severely curtailed, and agriculture suffered a series of disastrous harvests, resulting in decades of hardship and social unrest in Europe.

FIGURE 1: Annual mean number of sunspots, 1700-1990

That the sun's output of heat and light radiation varies with changes in solar electromagnetic activity is borne out from satellite measurements made during the Solar Maximum Mission of the 1980s. Therefore, it can be concluded with some certainty that the suppression of solar activity was mainly responsible for the shift to cooler conditions during the seventeenth century, and doubtless also for the previous cooling during the fourteenth century. Although there are no reliable records of sunspot observations for the earlier ''mini ice age'', measurements by dendrologists of fourteenth century isotopes in tree rings clearly indicate a similar reduction in solar electromagnetic activity.

On these grounds, considerable concern should be attached to the fact that the sun has registered five over-active cycles since 1940. The latest cycle, which probably culminated in 1989, registered an exceptional peak well above 200 in annual mean, more than twice the average peak level for the entire period observed since the seventeenth century (a factor that no doubt has contributed significantly to the extraordinarily warm weather conditions experienced in northern latitudes during the past 18 months). On the basis of previous patterns, one would expect the present sequence of strong cycles to be succeeded by a sequence of weaker ones, accompanied by a cooling of the global climate. If we examine the mechanisms lying behind sunspot activity, some indications of the likely course of events during the next few years become apparent.

The importance of solar oscillation

It is now well established that, rather than remaining in a fixed position, the sun moves, tracing an oscillating path through space around the centre of mass of the solar system. Isaac Newton was the first to provide a theoretical explanation for this phenomenon (Principia mathematica, 1687). Much later, in 1965, RD. Jose at the US National Aeronautics and Space Administration (NASA) elaborated the planetary equations that make it possible to exactly reproduce solar motion in space and time. Although not fully appreciated by the scientific community in general, it is now common knowledge among astronomers that the path of the solar centre through the galaxy takes the form of a spiral which can be accurately plotted by computers.

It is important to understand that the pattern of solar oscillation is determined by the movement of the planets - particularly of the two largest and most massive, Jupiter and Saturn. The sun shifts its position in relation to the centre of mass of the solar system in response to the constantly changing strength and alignment of the common planetary vector, thus continually maintaining the stability and balance of the system as a whole (see Fig. 2).

It is therefore not surprising to find that the period of Jupiter/Saturn conjugations and oppositions - 9.93 years - closely coincides with the median interval of the solar sunspot cycle: ten years. That the average length of the cycle over the past 300 years is just under 11 years can be explained by changes in the degree of reinforcement contributed by the next two largest planets, Uranus and Neptune. In other words, the rhythm of the sunspot cycle is essentially governed by solar orbital motion, and ultimately by the movement of the planets.

How can this be so? As pointed out originally by T. Landscheidt in 1981, it is probable that the sun's orbital motion produces long-term changes in the flow of convection currents beneath the solar surface - the ''dynamo" of the solar field (see Fig. 3). Changes in this vital component of the solar process could be expected to affect levels of solar radiation, while leaving an imprint on the solar cycle, in regard both to the intensity of sunspot activity and to the patterns of polarity change that determine the magnetic character of sunspots.

Recent findings provide substantial support for this explanatory model. A team of climatologists from Massachusetts Institute of Technology (Newell et al., 1989) have demonstrated that fluctuations in marine air temperatures at night between 1855 and 1985 followed a clearly defined 21.8-year cycle, i.e. close to the double sunspot cycle (2 x 11 years). Perhaps even more revealing, the rhythm of temperature change follows, with a time-lag of never more than 1-3 years, the phases underlying changes in solar momentum.

FIGURE 2: Schematic representation of the effect of the planets on solar oscillation

This coincidence suggests rather conclusively that solar motion must now be regarded as a primary factor in climate change on earth. On the basis of unmistakable correlations that have been shown between multidecade-long climate trends in the past and changes in overall levels of solar activity (Eddy, 1975), up to 8085 percent of climate variations on earth during the past few thousand years would seem to be governed by the sun (alternately warming and cooling the climate over periods of roughly 70-90 years). Of the remainder, volcanic activity would seem to be responsible for some 10-15 percent (cooling the climate over periods of 10-20 years, i.e. when volcanic "surges" occur). while greenhouse gases are probably responsible only for a maximum of 5 percent of climate variation (either warming or cooling the climate the direction is hard to determine with certainty).

The case of the anomalous solar passage

More important for present concerns, however, is that on rare occasions, the sun makes particularly disturbing passages past the centre of mass of the solar system in which an exceptional arrangement of the planetary vector forces the solar centre to pass on the "wrong" (Jupiter) side during a Jupiter/Saturn opposition.

Although only two anomalous passages have occurred within recent historical record, one in 1632 and one in 1811, enough is known about events in conjunction with earlier, similar passages to conclude that this type of passage is particularly critical from a seismic/volcanic point of view. The box summarizes some of the more dramatic repercussions of the 1632 and 1811 passages. It should be emphasized that nothing comparable to these two sudden bursts of seismic and volcanic activity occurred during the period between the two anomalous passages.

FIGURE 3: The fluid, rotating and oscillating sun

This apparent relationship between extreme phases in solar motions and exceptional volcanism can be explained by reference to the more or less accentuated disturbances to the spin rates of both the sun and the planets that appear in conjunction with anomalous solar passages (Eddy et al., 1977; Landscheidt, 1988). In the case of the sun, these changes in spin rate are caused by the peculiar stress of the passage, in the case of the planets, caused by orbital perturbations forced by the need to restore the balance of momentum in the system as a whole.

Disturbances to the spin rates of the planets are likely to have direct effects on their surface. In the case of the earth, variations in the rate of rotation - causing minute but significant changes in the length of day - increase tensions in the lithosphere (the earth's outer crust), followed invariably by a considerable rise in seismic and volcanic activity. Such events can also be shown to coincide with shifts in the strength and direction of ocean currents and increased turbulence in the atmosphere, often giving rise to exceptional hurricane activity.

The 1990 anomalous passage

These observations would be of academic interest only were it not for the fact that, as of the writing of this article in March 1990, the sun was half-way through an anomalous passage. Not until December 1990 will the solar path return to a more normal course. The natural catastrophes that occurred on earlier, similar occasions should provide food for thought. What can we expect this time? Have there been any indications during the past few months of similar kinds of disturbance within the solar system?

Repercussions of the anomalous solar passages of 1632 and 1811


Large volcanic eruptions:

Etna (Italy): five eruptions - 1630-40; Vesuvius (Italy): exceptional outbreak after 600 years of dormancy - 1631; Öraefajökull (Iceland): more than 10 km of debris 1632; Hekla (Iceland): incessant eruptions from May to September 1636; Gamkunoro (Indonesia) - 1637; Raung (Java, Indonesia): death toll 3000 - 1638; Kamagatake (Japan): death toll 700-1640.

Large earthquakes:

Tokyo: totally destroyed- 1633; Kongsberg (Norway): an entire mine system destroyed not far from Oslo - 1633.

Large storms:

Not documented but probable.


Large volcanic eruptions:

Soufrière (St Lucia) - 1812; Awu (Indonesia): death toll 953 - 1812; Mayón (Philippines): death toll 300 - 1814; Tambora (Indonesia): largest eruption in historical times - 100-150 km debris deposit, death toll 56 000- 1815; Kawah Idjen (Indonesia): death toll 2 000 - 1817; Eyjafjallajokull (Iceland) - 1820; Galunggung (Indonesia): death toll 4 011 1822; Vesuvius (Italy) 1822.

Large earthquakes:

Three megaquakes (8.5-9.0 Richter) in New Madrid region, United States, affecting 20 percent of US land area - 1811-1812); three large quakes (c. 8 Richter) in California 1812; one megaquake in Caracas, Venezuela, totally destroying the city 1812.

Large storms:

Exceptional hurricane in July 1811 over North Sea, sinking hundreds of merchant ships and drowning thousands of sailors.

The unusually high number of earthquakes reported during the past 12 months certainly seems to indicate that there are unusual forces at work in the earth system, although the critical period will be from October 1990 through the end of 1991. More ominously, remarkable changes have been observed on the surface of Jupiter. The famous red spot (presumed to be an enormous, cyclonic weather phenomenon) has shifted its position. This implies a change in the spin rate of the planet by about 1.5 seconds a revolution. To give an idea of the magnitude of this change and the energies involved, changes in the spin rate of the Earth are not generally more than a few milliseconds a revolution, yet these can give rise to considerable reactions at the surface of the planet. It would not be surprising if the Earth were also to experience rotational changes.

The 1990 solar passage may, however, initiate more long-lasting and distressing effects on the earth than isolated storms and earthquakes. It is the effect of the sun itself that is of most concern. The coincidence of an exceptional sunspot maximum with an anomalous passage implies extraordinary reactions. To understand why, it is necessary to look more closely at conditions during the two previous anomalous passages.

The particularly stressed state of the sun during the 1632 passage may well have been responsible for the disappearance of sunspots after 1640. The anomalous passage caught the sun in the middle of the strongly rising sunspot cycle which culminated in 1634-35 and waned in approximately 1638-39. It can be surmised that the shock of the passage disrupted the electromagnetic processes of the sun, leading to a drastic reduction in solar activity, a dearth of sunspots over subsequent cycles, and the cooler climate on earth during the latter half of the seventeenth century.

No comparably drastic cooling of the climate occurred in conjunction with the 1811 passage, but this serves to confirm rather than disprove the validity of the mechanism proposed above. In 1811, solar activity was at a particularly low ebb, zero sunspots were observed for that year. The disturbances to the solar spin rate initiated by the passage therefore did not have the same profound and long-lasting effects on the sun's electromagnetic activity, and only resulted in a minor suppression of the subsequent sunspot maximum in 1816-17.

On the other hand, the rotational disturbances forced on the earth in 1811 appear to have had a pronounced effect on atmospheric circulation. Changes in the earth's spin rate were probably also responsible for the violent seismic reaction during the years immediately after the anomalous passage.

The volcanic reaction was no less marked, although spread over the entire subsequent decade. The constant surges of volcanic dust in the atmosphere presumably contributed to the general suppression of temperatures recorded between 1810 and 1830; certainly the enormous eruption of Tambora in 1815 caused a sharp drop in temperatures in the Northern Hemisphere in 1816 - the "year without a summer" resulting in widespread starvation and hardship on both sides of the Atlantic.

What of the future?

On the basis of this analysis, and of more elaborate studies that it is not possible to present within the framework of this article, there are sound reasons for expecting the 1990 solar passage to be followed by a repetition of the same kind of developments that occurred in conjunction with the passages of 1632 and 1811. On the one hand, we should be prepared for a number of particularly violent earthquakes (8-9 Richter) in various parts of the world during 1990-91. With perhaps a few years' delay, we should also expect a series of impressive volcanic eruptions.

On the other hand, really cold temperatures can be expected as early as the mid-1990s, partly owing to increased volcanism, but mostly because of a pronounced reduction in solar activity, followed by visible confirmation in a dearth of sunspots at the time of the next predicted sunspot maximum around the year 2000. Thereafter, it would not be surprising if sunspots completely ceased to materialize over several decades - as between the years 1640 and 1715.

Other researchers have made similar predictions during the past few years. For example:

Dr Iben Browning is one of the most respected climatologists in the nation. His predictions are based to a large extent on the timing of peak tidal forces. Browning's record on climate has been outstanding. He states that the world is now entering a 90-year cycle of cold weather (directly opposite to what most climatologists believe). Browning says the weather in the northern hemisphere will get irregularly colder until around 2010 - then stay cold until around 2070... If the future resembles the past, says Browning, look for hard times during that period. (US Finances, 8 January 1990)

A word to the forester

From the perspective of the forester, whether operating in tropical, temperate or marginal highland zones, this prospect should give cause for concern. Turbulence in the atmosphere during the transition to colder conditions can be expected to lead to severe storm damage in forests during the coming decade. The experience of Nicaragua in October 1988, when enormous tracts of that nation's most valuable forest land were decimated by hurricane Joan, is likely to be repeated in many parts of the tropical world. The same problems will be faced in more temperate zones wherever established weather patterns provide a potential for hurricane activity. Northwestern Europe, for instance - the United Kingdom in particular can expect an increase in the frequency and intensity of storms running in from the North Atlantic over and above that experienced during 1989-90. Judging from the investigations of climate historian H. H. Lamb into conditions during the seventeenth century, wind speeds could reach gust strengths of 80- 100 m/sec.

In addition to the effects of high winds, forests would be subject to the consequences of rapidly falling temperatures - e.g. premature tree death and regeneration problems. Marginal highland forests in all parts of the world are particularly vulnerable in this respect, giving this type of forest a new importance in forestry concerns.

Many other areas of society would also be affected by a temperature recession. Agriculture in particular would be hard hit, suffering from persistent drought in some areas, torrential rains, snow and frost in others. These latter effects would be keenly felt at higher latitudes of both hemispheres, where the drop in temperature would be most pronounced. Above 60°N, this might mean a reduction in the mean average by 1.5°-2.5°C, implying a temporary but considerable shift in climatic zones, and a redistribution of the geographical limits imposed on all types of plant life, natural and cultivated. In these marginal zones, massive investment in large-scale controlled climate cultivation would therefore be in order- a "greenhouse effect" of another and more fruitful kind.

Increased volcanic activity, with widespread damage to forests, could result from the anomalous solar passage

At this stage, more detailed predictions are impossible to make, since the current fascination of climatology with the global warming hypothesis has redirected resources away from cold climate studies. A relatively detailed picture of probable developments at a broad regional level during a global warming is in the process of construction, but little work has been done on the equivalent scenario for cooler conditions. This is a serious omission. Without research into the regional consequences of a cooling climate, and without research directed toward solving the problems that would arise under such conditions, it will be difficult to prepare even the most provisional of contingency plans for the forestry sector, or indeed for any other, similarly vital sector of society.


Eddy, J. A. 1975. The Maunder minimum. Science, 192(4245): 1189-1202.

Eddy, J. A., Gillman, P.A. & Trotter, D. E. 1977. Anomalous solar rotation during the seventeenth century. Science. 198(XX): X34.

Landscheidt, T. 1981. Swinging sun, 79-year cycle and climatic change. J. Interdisc. Cycle Res., 12: 3-19.

Landscheidt, T. 1988. Solar rotation, impulses of torque in the sun's motion, and climatic variations. Climatic Change. 12: 265-295.

Newell, N.E. et al. 1989. Global marine temperature variation and the solar magnetic cycle. Geophys. Res. Lett., 16: 311-314.

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