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Climate change is a permanent deviation from the mean or the mean, whether it is hotter, cooler, wetter or drier.
It can also be defined as the changes that occur due to human activities, such as increased levels of greenhouse gases released into the atmosphere.
Climate variability, on the other hand, is a variation around the mean or the mean. It can happen in regular cycles over the years, or it can happen more randomly without any specific pattern.
It is also possible that climate change affects climate variability by increasing the frequency of extreme weather events.
Climate variability is responsible for most of the variations observed in the climate. Until recently, climate change has had a much smaller impact.
To some extent, climate variability can be managed by using climate statistics to determine the actual risks involved.
These statistics include average and extreme precipitation and temperature figures, duration and intensity of expected drought spells, likelihood of specific precipitation figures being exceeded, etc.
On the other hand, the effect of climate change is in no way quantifiable. However, its negative effects can be mitigated by factors such as climate adaptations, improved cultivation techniques and better genetics.
A good example is the maize yield trend in South Africa: 30 years ago the average yield was less than 2 t / ha; today it is nearly 5t / ha.
This change is not directly due to climate change or variability, but rather illustrates the response of farmers – where, for example, they plant improved cultivars.
The recent drought has also demonstrated climate variability; the perception was that it was worse than the droughts of the mid-1980s or even the 1990s, but if you look at the actual rainfall numbers, the droughts of the 1980s and 1990s were actually worse.
What is actually changing are the expectations of farmers and other users of natural resources. Farmers are now trying to get maximum yields, which not only increases input costs, but increases the risk of not making a profit in bad years.
Ecosystems change over time.
There is a perception that this is due to climate change; in most cases, however, it is caused by changes in human behavior or mismanagement of resources.
For example, flood damage is now more severe as many structures are being built in flood plains or rivers.
How to effectively manage climate variability
Climate variability is the main cause of changes in food production, both in South Africa and globally. In this regard, drought has been a factor for thousands of years.
In South Africa, climate variability has been responsible for periods of surplus
cereal production, as well as periods of low production during which cereals had to be imported.
This variability can be managed through sound agricultural decisions based on long-term planning that takes climate statistics into account. It is essential to have a long-term plan (more than five years) to manage the risk of adverse weather events.
One of the most effective ways to stabilize income and profitability over time is to diversify into non-farming activities. A simpler and more practical alternative is to be careful in managing risk.
High sowing densities of summer cereals can produce high yields, provided there is sufficient rainfall.
However, in years when rainfall is below average, high planting densities can lead to total crop failure.
A more conservative approach of reducing planting densities will still give good yields in good years, but will reduce the risk of total crop failure in years of low rainfall. The same is true for breeders who exceed the carrying capacity of their farms.
Rising temperatures
It is an established fact that global temperatures have risen by around 1 ° C on average over the past century. What we don’t know is whether this is a longer-term cycle or a permanent deviation from the mean.
The energy levels radiated by the sun are not constant, and historical data indicates that changes in these energy levels can impact temperatures on Earth.
In South Africa, the upward trend in minimum temperatures, in particular, may have implications for some agricultural industries. An example is the production of apples, which has a specific need for cold units in winter.
This is necessary to induce dormancy so that nutrient reserves can be built up for the next growing season. Warmer winters could therefore have a negative impact on production.
To adapt to changing climatic trends, breeders are now focusing on selecting crops that require fewer cold units for optimum production.
However, this could be risky, as these cultivars could break dormancy too early and suffer from a late cold snap.
A high requirement for cold units ensures that trees do not break dormancy until extremely low winter temperatures have passed.
It is very important to take into account both the negative and positive aspects of climate variability when planning for the future, as they can provide important information about production risks, such as frequency and intensity. droughts.
Since the compound effect of climate change on climate variability is difficult to quantify, it is more important to change a farmer’s risk profile.
Many farmers have unrealistic production expectations that can only be met in years of very good rainfall.
The opinions expressed in our weekly opinion piece do not necessarily reflect those of Farmer’s Weekly..
Johan van den Berg is the director crop insurance specialist in Santam and is based in Bloemfontein. For more information, write to him at [email protected].
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