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SA now experiencing half-year summers

12 October 2020 | Story Leonie Bolleurs | Photo Supplied

Although several international studies have used temperature metrics to statistically classify their seasonal divisions, a study in which Adriaan van der Walt was involved, would be the first known publication in a South African context using temperature as classification metric.

Gone are the days when we as South Africans would experience a three-month spring season, easing into summer, and then cooling off for three months before we hit winter.

Adriaan van der Walt, Lecturer in the Department of Geography at the University of the Free State (UFS), focuses his research on biometeorology (a specialist discipline exploring the role and climate change in physical and human environments) as well as climatology and geographic information systems.

He recently published an article: ‘Statistical classification of South African seasonal divisions on the basis of daily temperature data’ in the South African Journal of Science.

In this study, which Van der Walt undertook with Jennifer Fitchett, a colleague from the University of the Witwatersrand, data on daily maximum and minimum temperatures was collected from 35 meteorological stations of the South African Weather Service, covering the period between 1980 and 2015.

They went to great lengths to ensure that they had a complete set of data before presenting it to demonstrate seasonal brackets.

First for South Africa

Their statistical seasonal brackets indicate that South Africans now experience longer summers (from October to March), autumn in April and May, winter from June to August, and spring in September.

Although considerable work has been done using rainfall to determine seasonality in Southern Africa, Van der Walt believes that these methods did not work well as there are too many inconsistencies in this approach, as identified by Roffe et al. (2019, South African Geographical Journal). To make matters more complicated – as a semi-arid region, and with desert conditions along the west coast – some regions do not have enough rainfall to use as a classifier.

Temperature, on the other hand, worked well in this study. “Temperature, by contrast, is a continuous variable, and in Southern Africa has sufficient seasonal variation to allow for successful classification,” says Van der Walt.

He continues: “Although several international studies used temperature metrics to statistically classify their seasonal divisions, this study would be the first known publication in a South African context using temperature as classification metric.”

Van der Walt says what we understand as seasons largely relates to phenology – the appearance of blossoms in spring, the colouration and fall of leaves in autumn, and the migration of birds as a few examples. “These phenological shifts are more sensitive to temperature than other climatic variables.”

Seasonal brackets

According to Van der Walt, they believe that a clearly defined and communicated method should be used in defining seasons, rather than just assigning months to seasons.

“One of the most important arguments of our work is that one needs to critically consider breaks in seasons, rather than arbitrarily placing months into seasons, and so we welcome any alternate approaches,” he says.

A number of sectors apply the temperature-based division to their benefit. “For example, in the tourism sector it is becoming increasingly important to align advertising with the season most climatically suitable for tourism,” says Van der Walt.

Temperature-based division is also used to develop adaptive strategies to monitor seasonal changes in temperature under climate change. However, Van der Walt points out that each sector will have its own way of defining seasons. “Seasonal boundaries should nevertheless be clearly communicated with the logic behind them,” he says.

News Archive

Stem cell research and human cloning: legal and ethical focal points

2004-07-29

(Summary of the inaugural lecture of Prof Hennie Oosthuizen, from the Department of Criminal and Medical Law at the Faculty of Law of the University of the Free State.)

In the light of stem cell research, research on embryo’s and human cloning it will be fatal for legal advisors and researchers in South Africa to ignore the benefits that new bio-medical development, through research, contain for this country.

Legal advisors across the world have various views on stem cell research and human cloning. In the USA there is no legislation that regulates stem cell research but a number of States adopted legislation that approves stem cell research. The British Parlement gave permission for research on embryonic stem cells, but determined that it must be monitored closely and the European Union is of the opinion that it will open a door for race purification and commercial exploitation of human beings.

In South Africa the Bill on National Health makes provision for therapeutical and non therapeutical research. It also makes provision for therapeutical embryonical stem cell research on fetuses, which is not older than 14 days, as well as for therapeutical cloning under certain circumstances subject to the approval of the Minister. The Bill prohibits reproductive cloning.

Research on human embrio’s is a very controversial issue, here and in the rest of the world.

Researchers believe that the use of stem cell therapy could help to side-step the rejection of newly transplanted organs and tissue and if a bank for stem cell could be built, the shortage of organs for transplants would become something of the past. Stem cells could also be used for healing of Alzheimer’s, Parkinson’s and spinal injuries.

Sources from which stem cells are obtained could also lead to further ethical issues. Stem cells are harvested from mature human cells and embryonic stem cells. Another source to be utilised is to take egg cells from the ovaries of aborted fetuses. This will be morally unacceptable for those against abortions. Linking a financial incentive to that could become more of a controversial issue because the woman’s decision to abort could be influenced. The ideal would be to rather use human fetus tissue from spontaneous abortions or extra-uterine pregnancies than induced abortions.

The potential to obtain stem cells from the blood of the umbilical cord, bone-marrow and fetus tissue and for these cells to arrange themselves is known for quite some time. Blood from the umbilical cord contains many stem cells, which is the origin of the body’s immune and blood system. It is beneficial to bank the blood of a newborn baby’s umbilical cord. Through stem cell transplants the baby or another family member’s life could be saved from future illnesses such as anemia, leukemia and metabolic storing disabilities as well as certain generic immuno disabilities.

The possibility to withdraw stem cells from human embrio’s and to grow them is more useable because it has more treatment possibilities.

With the birth of Dolly the sheep, communities strongly expressed their concern about the possibility that a new cloning technique such as the replacement of the core of a cell will be used in human reproduction. Embryonic splitting and core replacement are two well known techniques that are associated with the cloning process.

I differentiate between reproductive cloning – to create a cloned human embryo with the aim to bring about a pregnancy of a child that is identical to another individual – and therapeutically cloning – to create a cloned human embryo for research purposes and for healing human illnesses.

Worldwide people are debating whether to proceed with therapeutical cloning. There are people for and against it. The biggest ethical objection against therapeutical cloning is the termination of the development of a potential human being.

Children born from cloning will differ from each other. Factors such as the uterus environment and the environment in which the child is growing up will play a role. Cloning create unique children that will grow up to be unique individuals, just like me and you that will develop into a person, just like you and me. If we understand this scientific fact, most arguments against human cloning will disappear.

Infertility can be treated through in vitro conception. This process does not work for everyone. For some cloning is a revolutionary treatment method because it is the only method that does not require patients to produce sperm and egg cells. The same arguments that were used against in vitro conception in the past are now being used against cloning. It is years later and in vitro cloning is generally applied and accepted by society. I am of the opinion that the same will happen with regard to human cloning.

There is an argument that cloning must be prohibited because it is unsafe. Distorted ideas in this regard were proven wrong. Are these distorted ideas justified to question the safety of cloning and the cloning process you may ask. The answer, according to me, is a definite no. Human cloning does have many advantages. That includes assistance with infertility, prevention of Down Syndrome and recovery from leukemia.

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