Climate change - there is no need for concern
Going against the flow
A scientist has gone against the flow of global opinion on the detrimental
effects of climate change. He argues that the beneficial consequences of increased global warming will be
greater than the adverse effects. Prof Alexander explains his view on climate change below. Science in Africa
invites contributions on this important discussion.
Prof WJR Alexander
There is no evidence to support the view that climate change could cause
appreciable environmental damage or increase the frequency and magnitude of
floods and droughts in South Africa within the foreseeable future. On the
contrary, the beneficial consequences of increased global warming will be
greater than the adverse effects.
In the 1940s DF Kokot, a civil engineer in the then Department of Irrigation
undertook a comprehensive study to determine whether or not there had been
recent climatic changes that could have had an effect on rainfall and river
flow. The results of his study were published in 1948 in a 160-page Irrigation
Department memoir titled An investigation into evidence bearing on recent
climatic changes over southern Africa. It contained 418 references, including
reports by early travellers and missionaries.
He discounted many of the theories that had been advanced for climate changes.
He noted for example, that an elaborate theory had been built up to connect
known climatic changes with assumed changes in the percentage of carbon dioxide
present in the atmosphere, but he remained sceptical.
His final conclusion was: The rainfall record is too short to be of much
value in disclosing rainfall trends. It shows, however, that if we take South
Africa as a whole there is little evidence of any change. Whilst rainfall in
some areas seems to have diminished, in others it appears to have increased.
Today, more than 50 years later his conclusions remain valid. There is still no
concrete evidence of large-scale adverse effects of climate change on the
environment in South Africa. This observation on its own, is sufficient to
demonstrate that future adverse changes are unlikely.
Nevertheless, within the last three decades South African and international
climatologists have become increasingly concerned about the possible damaging
effects of global warming on the environment. More researchers have spent more
money on climate change research than in any other research activity. Dire
predictions have been made over the years but few have been fulfilled. The
emphasis has now shifted from changes in the average conditions to changes in
the extreme conditions, which are even more difficult to demonstrate - or to
refute. Both the USA and Russia have refused to ratify the Kyoto Protocol, which
requires signatories to take action to control greenhouse gas emissions.
Practitioners who would have to implement any measures to counter the
undesirable effects, are waiting for solid evidence of changes taking place
before reacting to them. A stalemate position has been reached.
However, the issue is too important to ignore. Climate change predictions
will continue to have no practical meaning until such time as credible numerical
linkages have been established between climatic processes and
hydrometeorological responses on a catchment scale. The systems are far too
complex to permit the establishment of these relationships theoretically.
There is a way out of this difficulty that has not yet been attempted by
South African researchers. It is generally agreed that global warming has been
present for many decades and is increasing. If this is so, then the signals
should be present in long hydrological and meteorological records.
This is a time series analysis problem, but there are differences of opinion
relating to the appropriate statistical methodology. The basic reason for the
difficulty is that the signals are not always regular and are often very faint.
Those who denigrate graphical methods as being 'subjective' are unable to detect
the changes by direct mathematical analysis, and then assume that they are not
there. Efficient time series analysis therefore has to be carried out in two
stages - the graphical analyses to determine the presence or absence of the
characteristics, and mathematical analyses to determine their strengths and
relationships.
With this objective and methodology in mind, I assembled the largest and most
comprehensive set of meteorological and hydrological data yet analysed in South
Africa. It consisted of a total of 11 804 years of data from 183 gauged sites
and eight processes: open-water surface evaporation, concurrent rainfall, areal
rainfall, dam inflow, river flow, flood peak maxima, ground water levels, and
the southern oscillation index.
A surprising result, in that it had not previously been reported by others,
was that the mean annual rainfall over South Africa has increased steadily from
497 mm at the beginning of the record in 1921 through to 543 mm at the end of
the record in 1999. This is a substantial increase and is in close agreement
with the 10% increase reported for the USA since 1910. There were corresponding
increases in river flow, open-water surface evaporation and ground water levels.
As open water surface evaporation is a function of solar radiation, air
temperature and wind, all at water surface, this identifies global warming as
the probable cause of the increases in evaporation, and consequently rainfall,
river flow and groundwater levels as well. There were no indications of
increases in the severity and magnitude of droughts and floods.
The conclusion must be that additional global warming will have a greater
beneficial effect than detrimental effect on the natural environment. This is
directly contrary to current views by South African climatologists and
environmental scientists.
It is unlikely that any other data sets or calculation methods will lead to
different conclusions.
Data
All the data used in the analyses were from the official databases operated
by the Department of Water Affairs and Forestry, and the South African Weather
Service. The data were not smoothed, filtered or otherwise manipulated before or
during the analyses.
Confirmation
1. The general view of climatologists is that global warming has been present
for many decades and is increasing.
2. There is also a general, but not unanimous view that global warming increases
rainfall.
3. My studies based on the largest database yet assembled in South Africa,
demonstrated that open water surface evaporation is increasing. This is
consistent with an increase in air temperature attributable to global warming.
4. My studies also demonstrated that the rainfall, river flow and groundwater
levels are increasing. This is consistent with reported increases in rainfall
associated with global warming.
5. There was no discernable evidence of increases in floods and droughts.
However, this is inconclusive due to the large natural variability of these
phenomena. It does indicate, however, that if such increases are present, they
will not have any practical significance.
6. Most importantly, there is no credible evidence of large scale increasing
damage to the environment that can be attributed to global warming. This is
despite the claims of many climatologists and environmental scientists that
global warming will cause environmental damage.
7. The general conclusion, therefore, is that global warming has not caused any
environmental damage in South Africa in the past, and that future increases in
global warming are more likely to be beneficial than damaging.
It is appreciated that these conclusions are contrary to widely held beliefs as
expressed in research activities, funding and reports to government departments
and other institutions. Nevertheless the analyses and conclusions are soundly
based. The results are from different processes at different sites hundreds of
kilometres apart and located in different climatic regions. The conclusions are
also consistent with international studies that show concurrent increases in
rainfall with global warming.
I have presented the methodology and conclusions at three conferences and
discussion groups, and have had extensive email correspondence with professional
colleagues and others during the past year. Although there are some differences
of opinion, to date nobody has challenged my conclusions when using the same
data set, nor, as far as I am aware, has anybody in South Africa undertaken
similar or parallel studies on this subject. General interest articles have
already been published and formal papers containing details of the study are in
the pipeline.
More Information:
WJR Alexander is Professor Emeritus, Department of Civil and Biosystems
Engineering, University of Pretoria. Email: alexwjr@iafrica.com
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