Cloud seeding, flooding and communicable diseases


FOLLOWING the Southern Africa Regional Climate Outlook Forum (SARCOF), the local annual regional forum of the Meteorological Services Department of Zimbabwe (MSD) convenes a National Climate Outlook Forum (NACOF) where the seasonal weather forecast for the upcoming rainfall season is presented to interested national stakeholders.
Using statistical, other climate prediction schemes and expert interpretation, the climate scientists determined likelihoods of above-normal, normal and below-normal rainfall for each area; taking into account oceanic (sea surface temperatures) and atmospheric factors that influence our climate over the SADC region, in particular the El Niño-Southern Oscillation (ENSO).
The ENSO phenomenon is the interaction of anomalous sea surface temperatures and atmospheric pressure over the Eastern Tropical Pacific Ocean (Peru and Ecuador) and affects climatic patterns around the globe.
The term ENSO refers both to El-Niño and La-Niña phenomena and the Southern Oscillation. On average El Niño and La Niña events occur once every four to seven years in an alternating sequence.
El Niño explains the warming of the Eastern Tropical Pacific Ocean while La-Nina explains the cooling of the same region. In the case of Zimbabwe, a rainfall season that follows an El Niño has a high probability of being dry while a season that follows a La Nina event is very likely to be wet.
A ‘neutral’ ENSO event is when it is neither cooler nor warmer than normal over the Eastern Tropical Pacific Ocean.
The neutral phase is the current ENSO status over Zimbabwe which is forecast to remain throughout the 2017/2018 rainfall season, which climatologically, a rainfall season associated with the neutral phase of ENSO can potentially go either below or above normal.
Furthermore, a quick survey of views of experts in the indigenous knowledge systems also showed the same trend for the country as the scientific projections.
The need for cloud seeding is annually premised on the need for the intensification of precipitation country-wide and to augment the availability of water for agriculture and other different socio-economic purposes.
In 2016, as the dry spell persisted, like Sonny Perdue, the Governor of Georgia, in the US, the Government of Zimbabwe organised traditional and religious rites in a desperate bid to conjure the much-needed evasive rains.
This year, the new Government dispensation generously made provision for US$500 000 and two new planes to carry out cloud seeding exercises throughout the country so as to ensure adequate rainfall for the Command Agricultural Programme.
But what is cloud seeding?
Is cloud seeding a health risk?
What chemicals are involved in cloud seeding?
How frequently should we be using cloud seeding technology and where?
Is it safe for human, animal and plant populations?
What about our water?
All these are very good questions to be asking.
In Queensland, Australia, as of 2015, a waterborne brain-eating parasite has claimed the lives of three children aged eight, five and one years.
Known as naegleria fowleri and first identified in South Australia in the 1960s, it has since caused 300 known deaths worldwide, mostly youth and children, with 25 deaths recorded in Australia.
The waterborne parasite is said to thrive in water temperatures above 25 degrees Celsius and has been discovered in lakes, creeks, dams, boreholes and rain water tanks across Australia.
However, authorities in the country stress infection from naegleria fowleri cannot occur from drinking, cooking or washing clothes in the water.
The danger arises when contaminated water enters the nose, into the brain through the top of the nasal passage, which is usually under-developed in children.
According to a specialist public health physician: “…It causes catastrophic meningitis encephalitis and by the time these kids are diagnosed the treatments are usually ineffective.”
Where did it come from – could it be a result of climate warming or cloud seeding?
During cloud seeding, a chemical compound known as silver iodide is introduced into suitable clouds, where updraft or upward-moving air currents diffuse the hydroscopic silver iodide into the passing clouds, whereupon the silver iodide and water vapour immediately condense on the microscopic particles as ice crystals.
The ice crystals grow ever-larger until they become large enough to overcome the forces of uplift in the cloud and fall to earth as rain – simple enough.
Is cloud seeding harmful?
The pros and cons are numerous.
Some claim the harmful effects of silver iodide to be insidious; others contend the concentration of iodide in iodised salt used on food to be far in excess of the concentration found in rainwater from a seeded cloud. Whilst iodine is known to be an effective treatment for goitres, there are those who think that silver iodide is good for the heart.
When interested parties study the efficacy and consequences of cloud seeding, they tend to be biased towards cloud seeding, believing silver iodide enhances precipitation without negative consequences.
Growing evidence, however, shows it also yields harmful consequences. Some of these consequences include flooding, tornadoes (in some countries), subdual of rain and silver iodide toxicity. 
It has been found to be highly toxic to fish, livestock and humans.  
Numerous medical articles reveal that humans absorb silver iodide through the lungs, nose, skin and gastro intestinal tract where mild toxicity can cause irritation, renal and pulmonary lesions as well as mild argyria — blue or black discoloration of the skin.
Severe toxicity from elevated silver concentrations that occur in the vicinities of sewage outfalls, electroplating plants, mine waste sites, and silver iodide-seeded areas can result in hemorrhagic gastroenteritis, shock, enlarged heart, severe argyria, and death by respiratory depression.
The result of cloud seeding with silver iodide and runoff also have adverse effects on water, soil, flora and fauna. It leaches into groundwater, streams, soil and the root systems of plants. 
Floods, can potentially increase the transmission of diseases, including the communicable water-borne diseases, such as typhoid fever, cholera, leptospirosis and hepatitis A; and vector-borne diseases such as malaria, dengue fever, yellow fever and West Nile fever in humans and theileriosis in cattle, as has been experienced in Zimbabwe recently.
Though flooding may initially flush out mosquito breeding, when the waters recede, the mosquitos and malaria return. The lag time is usually around six to eight weeks before the onset of a malaria epidemic.
Malaria epidemics in the wake of flooding are a well-known phenomenon in malaria-prone areas worldwide.
For instance, flooding on the Dominican Republic in 2004 led to malaria outbreaks.
Periodic flooding, linked to El Nino-Southern Oscillation (ENSO), is also associated with malaria epidemics in the dry coastal region of Northern Peru and with the resurgence of dengue in the past 10 years throughout the American continent.
Heavy rains and flooding, in Europe has witnessed a resurgence of West Nile fever — with outbreaks in Romania in 1996-97, in the Czech Republic in 1997 and Italy in 1998.
Water-borne diseases associated with flooding usually risk outbreaks of infection where there is significant population displacement and/or where water sources are compromised, resulting in the contamination of drinking-water facilities such as the cyclone and flooding in Mauritius in 1980 that led to an outbreak of typhoid fever.
There is also an increased risk of contracting infection of water-borne diseases through direct contact with polluted waters such as wound infections, dermatitis, conjunctivitis, as well as ear, nose and throat infections, though they are not epidemic-prone.
Floods indirectly lead to increases of vector-borne diseases through the expansion in the number and range of vector habitats.
Standing water caused by heavy rainfall or overflow of rivers can act as breeding sites for parasites and therefore enhance the potential for exposure of the disaster-affected population and livestock to infections.
Under the guidelines of the Clean Water Act by the American Environment Protection Agency (EPA), silver iodide is considered a hazardous substance, a priority pollutant and as a toxic pollutant.
The Office of Environment, Health and Safety, UC Berkeley, US, rates silver iodide as a Class C, non-soluble, inorganic, hazardous chemical that pollutes water and soil.
Where should we stand – cloud seed or no rain.
The obvious detrimental effects of no rain would mean no gain — losses to everyone.
For farmers and cattle ranchers, no rain would include poorer crop harvest, lack of grazing vegetation for livestock in addition to loss of hunting lease income due to wildlife reduction, not including the national economic loss.
The choice is ours!
Dr. Tony Monda holds a PhD. in Art Theory and Philosophy and a DBA (Doctorate in Business Administration) and post-colonial heritage studies. He is a writer, lecturer, musician, art critic, practicing artist and corporate image consultant. He is also a specialist art consultant, post-colonial scholar, Zimbabwean socio-economic analyst and researcher. E-mail:


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