IN 1590, severe storms nearly capsized the ship of King James I as he returned from Scandinavia with his new bride, Anne of Denmark. Meanwhile, in Tranent, near North Berwick, the wealthy master of a poor servant girl, Geilie Duncan, thought that the girl's ability to help the sick was more akin to witchcraft.
The suspicious landowner subjected his servant to severe torture until she confessed not only to being a witch, but also to conspiring with a North Berwick coven to kill King James.
The 200 "Witches of North Berwick" were charged with using witch
craft to create the storm that delayed James' return with his young bride. Many of the "witches" were tortured and later killed.
Scholars now think that there may not even have been a coven in North Berwick, let alone one with the express aim of cooking up a storm. Certainly, scientists today would not believe that dancing to an Irish harp, exhuming graves and throwing a dead cat into the sea would conjure up a meteorological maelstrom.
But with the elements running amok in the past month, some of us may be wondering whether there are more scientific ways of modifying the weather.
Could, it might be supposed, weather modification have prevented the drought that led to the wildfires that recently ravaged south Australia, or the storms that recently deluged the south of England?
There are many areas in the world that are at the mercy of the weather. Droughts, with resultant crop failure, are commonplace in Africa. But although images of hungry people are shocking, adverse weather events often seem quite far removed from people in more temperate climes.
However, the extraordinary events of the past month, in which the more privileged have experienced the vagaries of the elements, will surely provoke questions of "can we?" and perhaps more aptly "should we?" modify the weather.
The control of meteorological conditions has long fascinated humans, but things have moved on from rain-making rituals and, unlike the North Berwick Witches, modern scientists may actually be able to do something about it.
The most common method of modification is to influence rainfall patterns. Clouds are fickle beasts, they float over dry areas, refusing to part company with their water, only to arrive at airports and drop their cargo as hail that delays flights.
Cloud seeding is a technique used by scientists to modify rainfall. Water needs to form heavy droplets to fall to the surface, but water vapour in some clouds is too light to fall. The technique sees planes inject chemicals such as silver iodide and dry ice (carbon dioxide) into clouds to encourage ice crystals to form.
These are heavy enough to fall and in their transit to earth the crystals are warmed, melt and fall as rain.
This is good in theory – we can seed clouds over deserts and also before the rain reaches areas where it will be particularly destructive – but does the technique work, and what are the long-term effects of this strategy?
Whether cloud seeding actually works is controversial; while it is known that the system does increase the amount of ice in clouds, it is difficult to ascertain whether this actually results in the alteration of rainfall patterns.
Unfortunately, there is no parallel world in which scientists can determine what would have happened if the cloud had not been seeded.
It is impossible to perform controlled experiments where clouds of the same composition and temperature, in identical environmental conditions located in the same area are compared, therefore much research has been based on computer simulations, which may not be applicable to the real world.
Associate Professor Steven Siems of Monash University in Victoria, Australia, has results from a real-life study of the effects of more than four decades of cloud seeding in Tasmania.
He compared monthly rainfall figures from an area that had been seeded with figures from surrounding non-seeded areas and found the process may have increased rainfall by 5 per cent each month (he states that this is a conservative estimate).
However, Prof Siems cautions: "There could be other explanations for the increased rainfall – although we suspect that cloud seeding is a significant contributor."
The other issue is the matter of the actual quantity of increased rainfall; in terms of volume, this equates to 5 extra litres per square kilometre per month. If we relate these statistics to Scotland, would a 5 per cent increase in rainfall make a difference to the already drenched climate?
It is difficult to say; Scotland had more than 1,400mm of rainfall last year, so as a simple calculation, an additional 5 per cent would increase this by approximately 70mm. Conversely, Ethiopia's annual rainfall can be as low as 450mm – would an extra 5 per cent (22mm) be enough to stop its crops from failing?
Even if cloud seeding proves successful, what are its adverse effects? There are very few studies in this area. We know that some of the chemicals used are toxic to fish, but the concentrations released by seeding are unlikely to be harmful.
There are, however, other possible as yet unstudied or unreported problems, such as the collateral damage to areas in which weather patterns have been modified due to distant cloud seeding efforts.
Also unstudied are the climate-related carbon dioxide pollution effects of flying aircraft to inject chemicals into clouds. It would be ironic if the extra carbon dioxide released were to ultimately enhance drought in areas where cloud seeding is being carried out.
So, although the use of cloud seeding has gained in popularity so much that Beijing reputedly used it during the Olympics, caution should be applied before we consider it a panacea for all our rainfall problems.
It may be that, like the Witches of North Berwick, even modern scientists cannot alter the weather.
