NAIROBI, 14 March (IRIN): More frequent and more severe droughts are likely to blight (hjemsøge) the Horn of Africa as global warming increases and commercial activities continue to destroy the environments ability to bounce back from dry spells, leading environmental experts have cautioned.
Deforestation and commercial exploitation of wetlands have brought about climate change and decreased rainfall on a massive scale across eastern Africa, and if these harmful practices continue, millions of people could face starvation annually.
Global warming has exacerbated the situation: According to a March 2006 report from the University of Cape Town, global warming could cause a 25 percent drop in surface water across Africa by the end of the century.
– Drought is a natural climatic phenomenon, but what has dramatically changed in recent decades is the ability of nature to supply essential services like water and moisture during hard times, said Klaus Töpfer, outgoing director of the United Nations Environment Programme (UNEP), adding:
– This is because so much of natures water and rain-supplying services have been damaged, destroyed or cleared.
Disappearing forests
Between 2000 and 2003, Kenya lost more than 7.000 hectares of forest cover, drastically reducing the environments natural moisture production and leading to the current dry spell.
Deforestation has also caused soil erosion, which in turn has caused a build-up of silt at the Masinga dam, 100 km northwest of Nairobi, which provides half of Kenya’s electricity. Masinga was built 25 years ago with a capacity of 1.400 million cu.m. but has since lost an estimated 20 percent of its volume – and thus its output – to siltation, reported power firm Kengen. Clearing out the silt (slam) would require 1.000 large trucks to work nonstop for six years, it is estimated.
Wanton destruction of woodlands across southern Somalia to feed an unregulated international export trade in charcoal (trækul) is leaving whole districts empty of vegetation.
Abdulkadir Shirwa, an agronomist with the USAID-funded Famine Early Warning Systems Network (FEWS Net), said a lack of central government made it impossible to calculate the number of trees being cut down or the volumes exported, mostly to the Gulf states, where a bag that would cost 3 to 4 US dollar in Mogadishu fetches up to 10 dollar.
Acacia forests between Brava and Kismayo are being decimated to feed the trade, which flourished after a ban introduced under former ruler Mohamed Siad Barre fell when his regime was overthrown, Shirwa said. In Ethiopia, as across the Horn of Africa, poverty drives subsistence farmers to chop wood where they find it.
The environmental impact of regional deforestation has increased the frequency of drought in eastern Africa.
Whereas drought used to hit the region once every five to seven years, these conditions now occur more often: The last dry spell happened between 2001 and 2002; prior droughts occurred in 1999, 1997, 1992 and 1987.
It is the cumulative (samlede/gentagne) effect of successive droughts that prevents the environment from bouncing back and erodes communities coping mechanisms.
Dry rivers, shrinking lakes
The International Research Institute for Climate and Society estimated that rainfall across the Horn of Africa between March and May 2006 was likely to be between 40 percent and 50 percent below normal.
Results from a University of Cape Town study published in March 2006 have shown that even a relatively small drop in rainfall can have a powerful effect on the amount of precipitation that ends up in rivers and lakes.
According to the study, even a 10 percent drop in rain in a marginal, semi-arid area like much of the Horn of Africas lowlands can lead to rivers running dry, lakes shrinking and wetlands withering.
The scientists, Maarten de Wit and Jacek Stankiewicz, used climate-change models to predict rainfall patterns across Africa over the next 100 years and what effect those changes would have on the amount of water in the continents rivers.
They found that in three-quarters of the countries in Africa, which normally receive between 400 mm and 1.000 mm of rain a year, almost none of the water reached rivers and lakes if the precipitation level dropped below 400 mm.
“Using predicted precipitation changes, we calculate that the decrease in perennial drainage will significantly affect present surface water access across 25 percent of Africa by the end of this century,” the researchers concluded.
The poor performance across eastern Kenya, southern Ethiopia and southwest Somalia of the 2005 March to May seasonal rains and the failure of the October-December rainy season have resulted in rainfall totals for the year 2005 that are only 20 percent to 50 percent of the long term mean, FEWS Net reported in January.
In Mandera, 550 miles north of Nairobi, no measurable rain fell in 2005, according to the Kenyan Meteorological Department. In Wajir, 150 miles southwest of Mandera, less than 10 percent of the expected annual 300 mm fell in 2005.
Across the Lake Victoria Basin, including eastern Uganda, northwestern Tanzania and far eastern Rwanda, rainfall since 1 October 2005 has totalled only 100 mm to 250 mm.
This is only 40 percent to 60 percent of normal and has contributed to the lowest water levels recorded on Lake Victoria since 1951. Some passenger ships failed to find docking stations due to the shallow water levels, down by 50 mm to 200 mm.
Silver lining?
The researchers also found, however, that the situation may improve. Climate- change models suggested rainfall across parts of East Africa could increase in the coming century, which would have the effect of exponentially increasing water reserves. However, that prediction is only likely to come true if vital rainmaking machinery is preserved by slowing the rate of deforestation.
Christian Lambrechts, an expert in UNEPs Division of Early Warning and Assessment, debunked (punkterer) the commonly held assumption that most rainfall comes from clouds formed above oceans, which then dump their moisture when they pass over high ground inland.
– Globally, something like 62 percent of precipitation (fordampningen) occurs over land as a result of evapo-transpiration from lakes and wetlands and dense vegetation, in particular forests pumping water held in the soils into the air, he said.
– In comparison, only around 38 percent of precipitation is generated over oceans and seas. It is impossible to do anything about precipitation from oceans and seas, but there is a lot we can do about the land.
– Trees not only assist the land in absorbing water when it rains, helping to feed rivers and lakes, wetland and underground aquifers. But they also act as natural pumps, bringing moisture from around two metres below into the air. Here it can fall back as showers and rainfall, he explained.
Reforms must be put in place now to stop the cycle of drought and famine, Töpfer said.
National governments, under international pressure if necessary, should introduce workable policies to halt deforestation, to repair damage to forest and wetland areas and to stop wasteful use of scarce resources.
Micro-credit schemes can bolster the ability of a subsistence farmer to weather tough times, and drought-proof crop strains should be introduced in areas that are likely to be prone to repeated dry spells.
Finally, investment in infrastructure, like roads and electrification regionally, would allow farmers to increase their wealth and lift themselves out of poverty and cut their dependence on wood for charcoal and heat.
– Without these actions, countries currently again facing water shortages and power rationing will continue to do so into the future, with all the misery and economic damage this entails, Töpfer noted.
What is a drought?
There are three definitions covering different classifications of drought:
Meteorological drought: a prolonged period with less than average precipitation.
Agricultural drought: when there is not enough moisture to produce an average crop at harvest. Agricultural drought can occur even when there is good rainfall due to poor soil conditions or damaging agricultural techniques
Hydrologic drought: when water reserves available in sources like aquifers, lakes and reservoirs falls below the statistical average. A spike in demand for water can bring about hydrologic drought even if rainfall is average or above average.
Source:Wikipedia Encyclopaedia
Kilde: FN-bureauet IRINnews
