Environmental issues

I’m singing in the rain…

By Sériane Kenema

The first time, I heard about “man-made rain” I thought it was a joke. I was told by a friend in Beijing that the artificial rain was used to reduce the air pollution. Suspicious I decided to do my own research.


I quickly discovered that “man-made rain” is nothing new.  Discovered in July 1946 through a series of serendipitous events by two researchers from General Electric.

How it works?

Man-made rain is a weather modification process called “cloud-seeding”. In the ancient times, during periods of severe drought witches could be seen performing rain dances to bring back the rain. Today in the technology era, the new witches are the geo-engineers.


The most common chemicals used for cloud seeding include: silver iodide, potassium iodide, dry ice (solid carbon dioxide) and in some cases liquid propane, which expands into a gas, has also been used.


Cloud seeding can be done by ground generators, plane, or rocjet

 The effects from cloud seeding are almost instantaneous, it takes only minutes to see a visible increase in cloud size and precipitation levels.

China : World leader in cloud seeding

Through our courses we have learned about the success of Emperor Yu. As far back as 2150 BC he was made famous by his ability to control the Yellow River and stop the flood. Today China’s rulers face the opposite problem; water scarcity is threatening farms and industries.

In 1958, the cloud seeding technology was brought to the Middle Kingdom of China via Russia. In 2011, China spent $150 million on a single regional artificial rain program, for comparison the United State spends around $15 million per year. According to Reuters China’s Ministry of Finance aims to use the technology to create more than 60 billion cubic meters of additional rainfall annually by 2020.

With its horrendous air pollution and acute water shortage, China is a natural contender to be the world’s leading cloud seeder.

Global cloud seeding

China may have the most advanced technology when it comes to cloud-seeding, but it is far from the only nation with a water modification program. The World Meteorological Organization, lists over 52 countries who are trying to address large-scale shifts in temperature and precipitation brought about by climate change through similar programs, including 10 countries which started programs less than five years ago.

People across the globe are becoming increasingly more aware of the constraints that arid environments have on resources.

Apart from the environmental benefits associated with increased rainfall, there are economic opportunities for companies as well. In recent years, several commercial companies have grown offering weather modification services centered on cloud seeding. While some government operated, projects exist the most popular type of project involves coordination between the government and a private company, such as farms or hydropower stations. The largest such company, Weather Modification Incorporated, has operations worldwide and it claims prominently that its technology works.


  • Use in water scarce areas and those suffering from severe drought


 Due to the increase in rainfall conditions such as famine can be avoided. Many countries which are experiencing severe drought can utilize this technology to alleviate their problems. Last year, the drought-stricken Indian state of Maharashtra spent $4.5 million on cloud-seeding.

  • Economic improvement for Agriculture

In some cases, this technology has been effectively used to suppress undesirable forms of precipitation, such as hail storms, which can cause damage to crops and urban areas. Given better weather conditions farmers would have the ability to grow and sell more crops. This would result in an overall improved economy for the region.

  • Economic improvement for Tourism

Aside from agriculture, dry and arid places which were previously considered as inhospitable could be transformed into new desirable vacation spots.

Additionally, as part of the 2008 Summer Olympics opening ceremony in Beijing to keep the stadium dry, cloud seeding was used. The rockets were launched into the sky prior to the cumulus nimbus reached the Olympic City, preventing the disruption of the events. Cloud-seeding is also occasionally used by major ski resorts to induce snowfall.


  • Negative weather impacts

Cloud seeding is feared to ultimately change climate patterns even though it is also believed to regulate the weather. Some people argue that it would have rained anyway but in another location, the process leads to depriving other areas of precipitation.

  • Flooding

 It is doubtful in regions experiencing chronic water shortage that there is a system in place to deal with flooding. Hail and excessive snowfall are another risk to consider. During the winter of 2009, ice rockets were launched into the sky to induce rainfall during a four-month long drought, Beijing’s longest in 38 years. However, the temperatures dropped sharply and the precipitation fell as snow. The snowfall was heavier than expected leading to the closure of 12 main roads around Beijing.

  •  Health and Environmental impacts

Compared to other geo-engineering technologies, cloud-seeding is considered as a relatively environment friendly method. Still there is some concern about the uptake of elemental silver iodide in highly sensitive ecological conditions. Current research is showing that the silver generated by cloud seeding is fairly minimum (less 1%) of industry emissions into the atmosphere in many parts of the world, or even individual exposure from tooth fillings.

The long-term effects due to accumulation on the health of plants, animals (including humans), and the environment are not yet known. There are other processes, which require further research on their impacts and are worth investigating, such as shooting salt-and-mineral-filled bullets into the atmosphere.

Enhancing cloud seeding with biomimetics

Naturally occurring cloud seeding is called bioprecipitation. Bacteria present in some clouds have evolved to use rainfall as a means of dispersing themselves. The cloud forming and the rain are a key element of their bacterial life cycle. The most known bacterium species are the Pseudomonas syringae, which have proteins on their surface allowing water to freeze at temperatures around the melting point of ice (0 °C).

 So far, those bacteria have been used most frequently by ski resorts. Ski resorts dose their snowmaking machines with the bacteria, Pseudomonas syringae, which have been found to outperform artificial cloud-seeding chemicals, suggesting it might be able to be used as a rain-maker, one day in the not too distant future. However there is still much research that needs to be done to better understand the protein composition of these bacteria before we can expect to see them used to trigger rain.

Renewable energy in Scotland

By Joshua Wilkie

When I think back to what Scotland was like in my childhood, even before I started my undergrad in 2006, the change in the country is fascinating. When I was younger I was aware of a few hydroelectric dams and our two nuclear power stations, but other than that I – as most people do – had no clue where exactly my electricity was coming from. Since then both nuclear power stations have been decommissioned and strong opposition to any more being constructed, a carbon capture pilot at the country’s only coal fired power station was not renewed and no plans for any new large hydro-power schemes. How on earth do we manage to turn on the lights and keep our houses warm during our cold, dark winters?

I was driving home from England in the winter of 2012 – a journey I had made countless times in the past. I had recently bought my first car and it was the first time I had made the journey during daylight hours. As I admired the mountain scenery, I suddenly realised that, my country now had an abundance of wind turbines rising over the forested hillsides. Much of the hillsides within the central belt of the country – where most of Scotland’s 6 million people reside – are now a dynamic landscape of farmland, forestry and gleaming turbines.

Renewable energy now accounts for over 57.7% of Scotland’s electricity annually. The country is a green superpower: on top of the incessant winds, the country’s coastline (which is longer than that of Spain) possesses 25% of EU tidal reserves, and 10% of EU wave reserves. Our renewable projects are also not just restricted to large scale projects either; there are widespread small generation projects now underway such as micro-hydro installations in remote locations, wind-to-heat, and reclaiming heat and biomass from the world-famous whisky industry. So vast are these combined green energy reserves that their potential capacity (60GW or higher) almost exceeds Scotland’s current electricity production from all sources by a factor of six. The country has repeatedly exceeded the Scottish Government’s renewable energy targets – even the current ambitious goal of 100% of electricity from renewable sources by 2020 does not seem beyond reach. In fact, one very windy day this summer the country joined only a small handful of countries which have ever achieved 100%! Who would have thought our bad weather would be a blessing in disguise!


Scotland’s iconic coastline also offers extensive opportunities for thedeployment of wind, wave and tidal power

Of course, it isn’t as simple as throwing up a few thousand wind turbines – there are still environmental and ecological impacts to consider. Scotland also had to translate it’s success decarbonising it’s electricity supply into other areas such as transportation and heating systems (although such technical challenges are not beyond one of the most ingenious societies in human history). It’s also a country with a small population spread out over a relatively large area – would the same achievements be possible elsewhere? The greatest concern is the increasing conflict in energy policy between the Scottish Government in Edinburgh and the climate-sceptic British Government in London, as subsidies for renewables are being cut severely to promote nuclear power and shale gas fracking in England (both of which the Scottish parliament block using its control over planning permission within Scotland). This division is likely become increasingly profound in the new uncertainty of Britain’s relationship with the EU, which could impact UK environment legislation and renewable energy targets, which Scotland has no control over.

As a young person it is really encouraging to see that your government, society and culture values your future – as well as the futures of people beyond your borders. It is also positive to be included in making that future a reality; many students have opportunities to research and work towards achieving a sustainable future – I spent my Master’s year researching redox flow batteries which are a technology that could one day be used to store renewable electricity for those rare days when it is perhaps not so windy as we would like. It’s interesting to see the change too from 10 years agwhen most of my classmates aspired to work in the North Sea oil industry, when today many students look forward to working in renewable energy and sustainable development.

Yes, there is a still a long way to go, and many challenges along the way, but I’m still optimistic. The massive strides in progress Scotland has made towards a sustainable energy future is exciting and speaks volumes about how much our societies can achieve if we have the collective will and determination to address our problems.