Climate change- What the experts say

Monday, January 24, 2011

Pretoria- Floods in South Africa, Australia and Brazil have left death and destruction in their wake. Many have lost their lives and thousands have been displaced.

Many are questioning whether the extreme weather patterns that the country and some parts of the world have been experiencing are signs of climate change.

Scientists say while features of climate change are already starting to manifest, it is difficult to say scientifically that there is a direct relationship between the heavy floods and climate change.

Earlier, the Department of Cooperative Governance and Traditional Affairs reported that the floods have so far caused damage estimated at R356 million throughout the country.

Seventy people have been killed with the highest number recorded in KwaZulu-Natal at 40 and 21 in the Eastern Cape. 8 400 people have been displaced nationally. The Department of Water Affairs is monitoring dam levels and the rainfall impact on the flow of acid-mine drainage. The agriculture industry has also been hard hit by the incessant rains.

The Department of Social Development, business sector, civil society and faith based organisations have also formed a task team, which will primarily coordinate humanitarian assistance to people across the country. An amount of R145 million has been set aside to address people's needs. Currently, R5 million is being processed by the department to go to KwaZulu-Natal, while other provinces are still forwarding requests for assistance.

In Australia and Brazil, thousands more are trying to rebuild their lives and trying to pick up the pieces.

Emeritus Professor of Hydrology at the University of KwaZulu-Natal, Roland Schulze, says both South Africa and Australia are countries which are characterised by very severe floods on one hand and very severe droughts on the other and these two countries, in comparison to the rest of the world, are places with the most extreme climates.

Are these signals of climate change? Schulze says the big issue in climate change is not whether it is going to get wetter or dryer, the big issue for scientists, he explains, is that extremes are likely to become more extreme.

According to experts at the university, human-induced greenhouse gas emissions are increasing and with that, global temperatures are rising and rainfall patterns are changing.

They add that by 2050, the global population is expected to increase from 6.9 billion to 9.2 billion. Rainfall in the Western and Eastern Cape will decrease, while KwaZulu-Natal will gain rainfall with extreme events such as fire and flood.

"We've just had a very extreme winter in Europe; we've just had a very extreme drought for five consecutive years in Australia ending last year and now we have very extreme floods and many people start asking, are these signals of climate change? And the answer to that is that it may well be, but we cannot say that with certainty at this stage," he explains.

The reason why South Africa is currently experiencing these major floods, particularly in the northern parts of the country, explains Schulze, is due to tropical moist air moving south.

This, according to Schulze, is a summer phenomenon called an Inter-Tropical Convergence Zone (ITCZ). The name tropical, he says, is important because it indicates moist air and convergence means things are coming together.

"When we have strong tropical forest air movement like we've had in the past week or two that is when we experience sustained rainfalls," he says. "The issue here is not the amount of rain, but the sustained rain because what that means is that rain is falling on a catchment that is already wet and therefore, the water cannot infiltrate as quickly and therefore, we have major run-off."

Many of those affected by the floods, says Schulze, are people living below the 50 year flood line.

"A 50 year flood line is that level of water that occurs statistically only once in 50 years, but these people are living below that and so floods that are severe but not major, impact them hugely."

"There is no doubt among scientists that climate change is happening," he says. "We are measuring things like carbon monoxide concentration in the atmosphere, changes in high temperatures and changes in sea level. These are not speculations, these are observations. So the concept that climate change is happening is real," he adds.

Professor Coleen Vogel from the University of Witwatersrand says it is very difficult at this stage to say that there is a direct relationship between the major floods and climate change, but models are being worked on and the relationship is being investigated.

"I don't think anyone would say that there is a direct link, however, some initial work is beginning to indicate that as a result of what we are doing to the atmosphere that there might be a link with storms becoming more frequent with bigger intensity and greater magnitude."

"I think people have to be very careful in thinking that warming means warming everywhere and it means flooding everywhere because the system is very complicated. We are doing a lot of science on this and we saying the chances are quite high, but we need to do much more work," says Vogel.

Vogel adds that a study being conducted at the university that is looking at past rainfall patterns has picked up a hint that storms might be becoming stronger.

"The research is in its very early days and we have to do a lot more data assessment," says Vogel. "But it does seem to be showing a little hint that there is something happening in the system. Some parts of South Africa, the models seem to be showing, that the pattern of rainfall will stay much the same. The eastern parts will be wetter and the western parts dryer. Bu the models are hinting that the pattern might be more pronounced and possibly stronger," she adds.

Rudi Pretorius from the University of South Africa (Unisa) says extremes have always been a part of the earth's weather over millions of years and one must be very careful to attribute extremes like these to global warming. He says it is probably closer to claim a prominent role for La Nina or El Nino in these floods rather than global warming.

"A lot of factors can lead to flooding including changes in land use patterns and also changes in river channels by humans," he says. "One can argue that higher temperatures will lead to more evaporation and therefore more moisture in the air and therefore more rain, together with the effect of warming on weather phenomena in general."

"There is uncertainty about how fast and how much the temperature will increase. If fast and intense, the effect we will experience will obviously be more visible and more extreme," he explains.

On the issue of agriculture, Schulze has just completed major research on the potential impact of climate change on the agriculture sector. The project was funded by the Department of Agriculture, Forestry and Fisheries. The results of the study will be released soon. "We cover a whole lot of things from; background on climate change, different crops and adaptation potential."

Experts do believe that there will be difficulties in growing crops in periods of flooding and drought due to the effects of climate change. Certain sectors, such as the fruit industry, are highly dependent on optimal temperature and rainfall conditions - these crops may become more difficult to grow. Climate change could also lead to an increase in pests and diseases with severe impact on crops.

Adds Schulze: "Climate change is not a matter of doom and gloom, there are a lot of positives and what we need to do is identify where the positives are and not just concentrate on the negatives and create opportunities and not just threats."

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