By Will Alexander
VULNERABILITY to nature is, unfortunately, characteristic of life for most Africans. Millions of people live in conditions of poverty, malnutrition and
disease, and are vulnerable to natural disasters and weather-related events like floods and droughts.
At the UN’s global warming conference this week in Nairobi, activists and government agencies were touting these problems as evidence that the continent is already experiencing the devastating effects of global warming.
The Intergovernmental Panel on Climate Change predicts that water will be drastically affected by the earth’s rising temperatures, especially through a decline in rainfall in the African subcontinent. This, it is alleged, will cause more droughts and damaging floods, resulting in threats to water supplies, harming agriculture, human health and the natural environment.
Yet current predictions of adverse effects of global warming on water supplies, floods and droughts on the African continent are completely unfounded, both in theory and measurement.
Alarmists have been quick to uphold regional variations in rainfall as evidence of global warming — but no evidence supports this claim. More broadly, they have assumed that all climatic change is undesirable. In fact, an increase in the magnitude and frequency of heavy rains would be beneficial over most of Africa.
South Africa is the ideal sub-continental region to observe climatic signals related to global warming and water. The eastern part has a high rainfall, while the west is an arid desert. The south receives rain in the winter, while the north receives it in the summer. The average annual rainfall for the whole region is 500mm, compared to a world average of more than 850mm.
Studying the South African data, we find that the mean annual precipitation over almost the whole of South Africa has progressively increased by at least 9% during the 78-year period of record with a high degree of assurance. The 19 districts that constitute the southern and Western Cape benefited from a 17% (57mm) increase in rainfall from 1950 to 1992. Obviously, in a region like South Africa that suffers from water stress, such change is desirable.
Although the 1990s were reported to be the warmest decade of the past millennium, this was not reflected in an unusual increase in the numbers and magnitudes of exceptional hydrological events in South Africa. More recently, the 2005 global temperatures were proclaimed to be higher than any in the recent geological past.
Yet again, no exceptional rainfalls, river flows, floods or droughts occurred during the year. Any additional global warming will further increase the annual rainfall over South Africa. The possibility that it will decrease the rainfall in the foreseeable future is remote and without scientific merit.
Meanwhile, neither South African climatologists nor their overseas counterparts have produced evidence that links increased CO2 emissions to South African rainfall patterns. The increases discussed above were already occurring early in early parts of the 20th century — well before post-WWII increases in industrial activity and carbon dioxide emissions.
While the causal linkage between variations in solar activity and global climate can be debated, the parallel increases in sunspot numbers, surface air temperature, open water surface evaporation and rainfall during the last century are incontestable. Records show a significant 21-year periodicity in the South African annual rainfall and river flow records that is synchronous with solar activity.
It is water, not temperature, which determines the habitability of our planet. Furthermore, temperature is a measurement — not a property.
Temperature does not feature in hydrological analyses: their principal variables are rainfall, river flow and open water surface evaporation. Their relative values vary greatly from region to region in South Africa.
Moreover, it is the consequences — such as changes in rainfall and river flow — that are important, not changes in the atmospheric and oceanic processes that produce them. Proof of global warming is not proof of the postulated undesirable consequences.
In recent years, high losses of life and damage to property in South Africa and elsewhere in the world were primarily the consequence of rising populations and not enough space, so people moved to flood-prone areas. The floods were worsened by socio-economic conditions — not increases in flood magnitude or frequency. This is similarly the case with droughts.
Recently some scientists have repeated their predictions that global warming will degrade the natural environment, based on the assumption that future climate will be warmer and drier. This alarmist view suffers from two fundamental errors.
First, rainfall is increasing — not decreasing. Second, the predicted increases in temperature are no more than the temperature increase between dawn and midday, to which South Africa’s vegetation is well adapted. It is thus unlikely that large swathes of natural vegetation will be destroyed.
Sadly, many claims about how global warming will affect Africa are not backed up by scientific evidence — and those who make them appear to be indifferent to the needs of much of humanity. Environmental doomsayers and alarmist scientists have effectively stifled the debate over climate change — with serious implications for other issues.
For instance, South Africa is rapidly approaching the limit of its available water resources. The only large-scale, viable alternative is energy-consuming seawater desalination.
The most economical source of this energy is from coal-fired power stations near the site. If this is not possible because it will increase greenhouse gas emissions, the inevitable consequence will be that South Africa’s future development will be increasingly constrained by lack of water supplies.
If the present alarmism continues, Africans will be the first casualties of the war on global warming.
* Will Alexander is professor emeritus in the Department of Civil and Biosystems Engineering, University of Pretoria, South Africa.