Monday, 21 June 2010

Another look at the threats of Climate Change

Joachim Ezeji

Last week, the 5th World Water Forum held in Istanbul, Turkey. A total of 194 countries were in attendance to discuss the growing global world water crisis. Nigeria’s Minister of State for Water Resources Mrs. Felicia Njeze led a high power delegation to the forum to make valid contribution to the global process. One central issue that topped the agenda at the meeting was the menace of climate change and its threat to the world’s water resources.
For Africa, the meeting could not have come at a better time than this as South Africa raises campaign to host the next forum scheduled for 2012. But before the next forum is scheduled, and as the outcomes of the current forum is implemented, it becomes germane to once again look at climate models which have predicted that by 2050, Sub-Saharan Africa will be warmer by 050C to 20C and drier, with 10 percent less rainfall in the interior and with water loss exacerbated by higher evaporation rates.
It also predicts that there will be more extreme events such as drought and floods, and that seasonal patterns will shift hence threatening and undermining food production, water supplies, public health, and people’s livelihoods etc.
The UK NGO, OXFAM, also says that climate change is an "unprecedented" threat to food security, and in Africa has given rise erratic climates as new and dangerous extremes such as arid or semi-arid areas in northern, western, eastern and parts of southern Africa becoming drier, while equatorial Africa and other parts of southern Africa are getting wetter. Global warming means that that many dry areas are going to get drier and wet areas are going to get wetter.
People especially the poor would be caught between the devil of drought and the deep blue seas of floods. The greatest tragedy is the fact that Africa had played virtually no role in global warming; a problem that has been caused by economic activity of the rich, industrial countries.
The African continent is, on average, 0.5oC warmer than it was 100 years ago, but temperatures have risen much higher in some areas - such as a part of Kenya which has become 3.5oC hotter in the past 20 years. "Global warming is set to make many of the problems which Africa already deals with, much, much worse, "In the last year alone, 25 million people in Sub-Saharan Africa have faced food crisis.
However, since the mid-1970s, precipitation has declined by about 2.4+1.3% per decade in tropical rainforest Africa, this rate being stronger in West Africa (-4.2+1.2% per decade) and in north Congo (-3.2 +2.2% per decade).Overall, in the West Africa/north Congo tropical rainforest belt rainfall levels were 10% lower in the period 1968-1997 than in the period 1931-1960.
There has also been a moderate significant increase in dry-season intensity in Africa, as results from GCMs based on SRES scenarios project an increase in temperature, while projections in precipitation are less consistent. By the 2070-2099 periods, maximum warming is expected to occur in Northern and Southern Africa (up to 90C and 70C respectively), while, it is minimum in the oceanic regions (up to 4.80C in the tropical NE Atlantic and 3.60C in the Indian Ocean);
It has also been posited by experts that of the 19 countries around the world currently classified as water-stressed more occur in Africa than any other continent. In 1994, available freshwater resources in Africa were about 4,050km3 per year, representing about 9% of the world’s total, and about 5.7 thousand m3 per capita per year, against a global mean of 7.6 thousand m3 per capita per year.
These resources are not uniformly distributed, Eastern and Southern Africa having 3.87 and 4.8m3 per capita per year respectively, the Sahel region having only of 2.2 of m3 per capita per year.
In West Africa as quoted, rainfall is associated with the latitudinal movement of the Inter-tropical Convergence Zone (ITCZ), i.e. the convergence zone between humid air masses from the south and dry air masses from the north. The ITCZ reaches its northernmost position in August, which corresponds to a period of maximum rainfall across the Sahel. This mechanism characterizes the Sahelian area’s North-South annual rainfall gradient.
Accordingly, annual rainfall amounts range from zero in the desert (Sahara) to over 900mm in the Sudanian sub-humid zone. In arid, semi-arid and sub-humid zones, there is a two to five month wet season unlike in countries located along the Gulf of Guinea, which have two rainy seasons. In that sub-zone, average annual rainfall amounts are in excess of 900mm.
No doubt, rainfall, which is a determining factor of the climate, is highly variable and a number of countries have experienced droughts since the 1970s which have led to a general decrease in river discharges, and a consequent reduction in lake areas. For example, the Lake Chad is now 5% of its former size 35 years ago. Between 1970 and 1995, Africa has experienced a 2.8 times decrease in water availability.
The reduction in precipitation projected by some GCMs for Sahelian and Southern African countries, which will certainly be accompanied by higher inter-annual variability, could be highly detrimental to the hydrological balance of the continent and water-dependent activities.
With regards to precipitation in Western Africa, that there is an agreement between models to predict a progressive increase in precipitation (between 10 and 35%) for the December, January, February period (which is normally dry). A similar trend is predicted for the September, October, November period (between 7 and 28%) but some models predict a small decrease (less than 10%) for the 2070-2099 period.
But the organization IUCN, had earlier described the Sahel (or area bordering the desert) of West Africa, referred to as the Sahel climatic conditions, as being characterized by spatial and temporal variability, and having become prone to disturbances of significant magnitude, particularly since the early 1970s.
There is therefore an emerging urgency for African leaders to come together to discuss the climate change threats and make case for adaptation. This is very important and urgent at this time when extreme events are becoming a daily occurrence. It is also desired that African leaders take a position on this critical issue before the Copenhagen Climate Change meeting holds later in the year on the same issue. Any further delay is dangerous.

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