La Niña phenomenon leads to Asian flooding with threat of more disasters to come
admin July 29th, 2010
Opinion is growing that a La Niña phenomenon has officially arrived and this means that disaster response teams probably need to brace themselves for heavier monsoons, bigger and more frequent hurricanes, and angrier cyclones.
“There is global consensus that we are at the beginning of a La Niña, but we cannot pronounce the intensity of the event yet – we have to wait for it to evolve,” Rupa Kumar Kolli, Chief of the World Climate Applications and Services Division at the World Meteorological Organization (WMO) told IRIN News.
And some of the early ‘fruits’ of this metereological phenomenon are already manifesting themselves with fierce flash flooding in Pakistan and Afghanistan in the wake of a heavier than usual monsoon season.
In Pakistan flash floods caused by heavy rain since July 20th have killed at least 50 people and affected 50,000.
And in Afghanistan, the Afghan Red Crescent Society (ARCS) and the International Committee of the Red Cross (ICRC) have provided emergency assistance in May and June to over 44,000 people displaced by natural disasters and conflict. There are some 300,000 internally displaced persons (IDPs) in the country, mostly as a result of the ongoing conflict.
The National Aeronautics and Space Administration (NASA) explains on its website that La Niña is characterised by unusually cold ocean temperatures in the eastern equatorial Pacific Ocean; El Niño, on the other hand, is characterised by high temperatures in the same part of the ocean.
These colder-than-normal ocean temperatures prevent rain-producing clouds from forming over the eastern equatorial Pacific region, including the open ocean south of Mexico and Central America, but enhance rainfall over the western equatorial Pacific region of Indonesia, Malaysia and northern Australia.
As far as Africa is concerned, the impact of a La Niña season is hard to predict, especially before it becomes clear how extreme it might be. La Niña is usually associated with more rain, but an analysis of rainfall patterns for African countries south of the equator tells a different story.
Cobus Olivier, a scientist in the Prediction Research section of the South African Weather Service, and his colleagues used rainfall data collected during La Niña events from 1961 to 2002, for the months of August, September and October, when the event is expected to be more pronounced.
Olivier told IRIN News, “Uganda and the southern parts of Sudan usually seem to have wetter conditions during La Niña … but parts of Angola, DRC [Democratic Republic of Congo], Mozambique, Tanzania, Kenya, Somalia and Madagascar tend towards drier conditions,” he said.
In South Africa the situation is “very variable”, but “Generally it looks like we may have favourable spring rains [in September-October], and this is also supported by our latest forecast.”
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[...] Thursday’s post we reported that floods were affecting Pakistan – possibly brought on by the La Niña effect. [...]