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Climate change intensifies El Niño and La Niña

Posted by: Saving Water SA (Cape Town, South Africa) – partnered with Water Rhapsody conservation systems – 29 Aug 2011

The severe drought in the Horn of Africa, which has caused the death of at least 30 000 children and is affecting some 12 million people, especially in Somalia, is a direct consequence of weather phenomena associated with climate change and global warming, environmental scientists say.

The intensification of La Niña will see growing desertification in Africa. Photo UNCCD.

“The present drought in the Horn of Africa has been provoked by El Niño and La Niña phenomena in the Pacific Ocean, which unsettle the normal circulation of warm and cold water and air, and dislocate the humidity conditions across the southern hemisphere,” Friedrich-Wilhelm Gerstengarbe, senior scientist at the German Potsdam Institute for Climate Impact Research (PIK, after its German name), told IPS.

Both phenomena are a part of the southern oscillation climate pattern that occurs across the tropical Pacific Ocean every five to seven years. It is characterised by variations in the temperature of the surface of the tropical eastern Pacific – warming or cooling known as El Niño and La Niña respectively – and a changing air surface pressure in the western Pacific.

Both phenomena are coupled – the warm oceanic phase, El Niño, accompanies high air surface pressure in the western Pacific, while the cold phase, La Niña, accompanies low air surface pressure in the western Pacific.

Such conditions can particularly affect regions north of the Equator, such as the Horn of Africa. Some 12 million people are facing starvation across the region, Djibouti, Sudan, South Sudan and parts of Uganda, besides Somalia. So far, famine has only been declared in Somalia, a state without a functioning government.

“El Niño and La Niña exacerbate the weather conditions across the southern hemisphere, escalating the rainy season in some areas, especially in Asia and Australia, and droughts in others, especially in Africa,” Gerstengarbe said.

He said climate change and the rising global temperatures caused by it had intensified both El Niño and La Niña, leading to severe floods in Pakistan and Australia, and drought in the Horn of Africa.

Both phenomena had led during the last two years to particularly dry rainy seasons and to extreme hot temperatures over east Africa.

According to the US National Oceanic and Atmospheric Administration (NOAA), La Niña has since 2008 caused a strong drop in water temperatures in the Pacific Ocean, leading to a “below-average precipitation over the central equatorial Pacific”.

These cold episodes (referred to as La Niña episodes), the NOAA adds, are characterised by lower than normal pressure over Indonesia and northern Australia and higher than normal pressure over the eastern tropical Pacific.

During cold episodes the normal patterns of tropical precipitation and atmospheric air circulation become disrupted. The abnormally cold waters in the equatorial central Pacific Ocean suppress cloudiness and rainfall, especially between November and April, that is, precisely during the regional rainy season.

The phenomenon leads to hotter temperatures in east Africa. Both the suppression of rain and the higher temperatures this year have caused the worst drought in the Horn of Africa for 60 years.

“Unfortunately, due to the intensification of La Niña, we must reckon with growing desertification in Africa, and with more droughts in the region around the Horn of Africa,” Gerstengarbe added.

Jean-Cyril Dagorn, in charge of environment and economic justice for the French branch of the humanitarian organisation Oxfam, concurred that climate change and global warming were exacerbating extreme weather conditions in Africa.

“For two years, rain precipitation has been below average in east Africa, due to La Niña,” Dagorn told IPS. “But this year, the drought has been extreme, provoking the present humanitarian catastrophe in Somalia and other adjacent regions.”

Dagorn said that the coming rainy season, scheduled to start in October, might intensify the crisis. “Torrential rain falling on extreme dry earth will wash away the most fertile soil, making the food crisis even more dramatic,” Dagorn warned.

Dagorn said droughts had so far occurred every five to seven years in the Horn of Africa, but almost never with the extreme conditions of today.

“We estimate that due to climate change and the droughts it causes, agricultural productivity in the region will fall by up to 20% in the coming decades, especially in the maize and bean plantations,” Dagorn said.

Besides, he said, the region’s cattle breeders and shepherds had lost between 30% and 60% of their livestock due to extreme weather conditions, aggravating the food crisis.

Dagorn said that both the agricultural policies of the countries affected by the droughts, and international cooperation had failed to address the issue.

The UN has said €1.6bn (about R16.6bn) would be needed to address the crisis. “But France, for instance, has only allocated less than €10m,” Dagorn said. “It announced urgent meetings of donors – which never took place.”

Dagorn said humanitarian organisations were buying cattle in poor condition to distribute the meat among the communities most affected by the famine.

Gerstengarbe said climate change and associated phenomena, and bad agricultural practices such as overgrazing, were leading to increasing desertification across Africa.

“Deserts are growing worldwide by some 150km² a day, but especially across Africa.”

In July, the head of the US agency for international development, Rajiv Shah, said that climate change had contributed to the severity of the crisis.

“There’s no question that hotter and drier growing conditions in sub-Saharan Africa have reduced the resiliency of these communities,” Shah told US media. “The change in climate has contributed to this problem, without question.”

Source: IPS

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