What is climate change and how can we know if the climate of a place has changed?
My friend Brian amused us with a tale that sounded like it had come straight from the ancient times of hunter gatherer communities. During one of his travels up country, he witnessed some old men slaughtering a goat in preparation for a party that was to take place later in the day when one of his brothers was expected to arrive home to introduce his girlfriend.
“After the carcass had been skinned, one of the men cut open the stomach, exposing the contents of the goat’s last meal. He then invited another old man to examine the semi-digested stuff. This process took nearly half an hour,” Brian narrated, making all of us laugh at what he had just described.
On inquiring why such a ritual was necessary, Brian was informed that the old man examining the contents of the goat’s stomach could determine whether rains would be falling soon or if the community should brace for an extended drought, just by looking at what the goat had eaten.
We later learnt that the contents of the goat’s stomach were a very accurate source of climate information. The proportion of different types of grass, twigs, leaves, berries or grains in the diet of livestock at certain times of the year provides the clues that traditional weather forecasters use to learn whether subsequent seasonal periods would be rainy or dry.
Fortunately, such “experts” still exist in our friend’s village and the information they provide helps their communities to prepare themselves for either drought or rains.
We realised that the story our friend had just narrated is something that might be useful for many people who have recently been hearing about climate change. What is climate change? We had all heard about it, but none of us had really understood what it is.
Fortunately, Chris, who studies climatology at the university was with us. He told us that climate change is a permanent change shown by the increase or decrease of the average of one of the measures used to describe weather particularly temperature and rainfall for a period of at least 30 years. For it to be regarded as climate change, the change in temperature, rainfall or any other indicator of weather, must have been measured for that long. We asked Chris to explain further because we were all confused and this is what he had to say.
“Temperature can change several times in one day, the morning might be cool and the afternoon hot, while some years have more rain than others in the same village. This does not mean that the climate of the village has changed,” Chris told us. According to him, such short-term changes in weather conditions are referred to climate variability as long as they occur over a period of less than 30 years.
However, if we take the average annual temperature or rainfall of the village for the past 60 years and compare the averages for the previous 30 years say, 1920 – 1950 and next 30 years (1950 – 1980), we can tell if the climate of the village has changed or not. If the difference between the two averages is one degree centigrade and the period 1920 – 1950 was cooler on average than 1950 – 1980, then we can conclude that the climate of the village had become warmer and had therefore had actually changed.
From what Chris had told us, we understood that it is very difficult to say for sure if the climate of a place has changed without having the weather records for at least 60 years.
We all realised how important it is for the national and county governments to keep accurate weather records. It also occurred to us that they can also learn some of the techniques from the elders who predict weather in Brian’s village.