With religious zeal, people look for issues or events to blame on global warming, such as the recent high tides that washed away swathes of beach sand in Durban.
Newspapers trumpeted, “Durban hit by global warming.” The high tides in Durban are nothing new – I come from Durban and I recall watching them years ago.
I watched waves break over cars on the road and flood the lower Marine Parade area.
But now to another hype – Mount Kilimanjaro. There are those who loudly proclaim that the ice cap on Mount Kilimanjaro is melting due to global warming – but could this be true?
Counter voices say definitely not – there is another obvious and logical explanation. For starters, the Kilimanjaro ice cap has been receding for some 80 years now – probably longer – but nobody was measuring before that.
Before we go further, a bit of science is needed. Mount Kilimanjaro is the highest mountain in the world from bottom to top; of course, not the highest altitude – that is Everest. Kilimanjaro, unlike Everest, has a rather uniform conical shape.
Kilimanjaro is high enough to project up into the area where the top is always frozen. This is way above the weather. There are no clouds up there and it does not snow, so where does the ice come from?
It grows by deposition, just like the ice builds up in your fridge: wet air gets cold, freezes and then grows onto the existing ice.
During the day, the sun is always shining on the ice cap, which reflects most of the heat. However, some of the sunlight will melt a thin surface layer of ice. It is not hot air melting the ice, but direct sunlight.
It is also a scientific fact that there has been no measurable atmospheric warming in the region of Kilimanjaro. Satellites have been measuring the regional temperature since 1979 in the free troposphere between 1 000-m and 8 000-m altitude and they show no troposphere warming in that area. None.
So what is causing the ice cap to melt? The answer appears to be trees, or rather lack of them.
At the base of the mountain, which is a tropical-climate region, there is a major forest. But the forest used to be bigger, much bigger. What one also sees today are large coffee and banana plantations, where much of the natural forest used to be.
The bottom line is that, for the last century, the expanding population in the area has been cutting down trees for firewood and to convert the land to agriculture. Currently, a method called ‘fog stripping’ is used to collect water from the forest to route to the villages below. As the evening cools, water vapour condenses on the leaves of the trees in the forest and this water drips into containers that are routed to waterways. Much water just gets to the waterways itself.
Right now, 500-million tons of water a year is ‘fog-stripped’ to route to the villages and the agriculture down below the mountain. The Tanzanian government also has a major rice-growing project at the bottom of the mountain that has diverted most of the water supply of the village of Mwangania. The folk in the village complain that they have a water shortage.
Okay, so how does this affect the ice cap? The mechanism is that wet air from the forest moves up the mountainside; as the day’s warmth warms the air, hot air rises. This warm, wet air then hits the cold atmosphere at the top of the mountain and, as night falls, the water precipitates out of the air, freezes and adds to the ice cap, just as it does in your fridge.
If you open your fridge door very often, you have to defrost it often – every housewife knows that.
But, since the locals have cut down so many trees over the last century, there is much less wet air moving up the mountain than there used to be, so less ice forms at the top.
The government of Tanzania is now trying to protect the remaining forests in a project called the Pangani River Basin Management Project. However, people in the villages admit that when there is drought and they don’t harvest the required crops, they then illegally cut down trees and take the wood into town to sell as fuelwood.
Over the last century, human activity in the area has also led to many forest fires, which have wiped out large areas of trees. So there is just much less water moving up the mountain in the air convection currents than there used to be.
Former US Veep Al Gore is being totally simplistic in his movie by just saying that Mount Kilimanjaro’s loss of ice-cap volume is a sign of global warming. Most of Al’s movie exhibited the same absence of genuine science, and rather presented itself as part of an election campaign.