Saturday, February 16, 2008

La Nina or Global Warming ?

A sea-surface cooling in the Pacific, which may have contributed to strong hurricanes in the United States and a freeze-up in China, could last at least until mid-year, the U.N. weather body WMO said on Monday.

The cooling pattern, known as La Nina, alternates naturally with a warming effect called El Nino, and both have been associated with extreme weather around the globe.

"Information coming in indicates that the likelihood of La Nina conditions in the central and eastern Pacific remains heightened through the second quarter," said Rupa Kumar Kolli, climatological expert at the World Meteorological Organisation.

Presenting the Geneva-based body's latest update on the ocean cycle, he said it was also possible, if less likely, that the present La Nina cycle could stretch into the third quarter.

Longer-term statistics suggested that the decline of the La Nina would be followed by a "neutral" period at least for the second half of 2008, Kolli added, rather than a rapid transition to an El Nino.

The two closely linked natural phenomena have probably occurred since before recorded history and are popularly blamed for unusual weather extremes, but specialists say they are not the sole cause.

Kolli said the two, which follow each other with a neutral break in between, create favorable conditions for changing local and regional weather patterns around the globe to spark floods, droughts, hurricanes and freeze-ups.

Experts say it is not clear if the El Nino/La Nina cycle -- which occurs around once every five years -- is intensified by global warming, but they say it makes it more likely that climate changes caused by warming will bring disasters.

In an El Nino, the sea surface heats up, leading to drier than normal weather over northern Australia, the Philippines and Indonesia and wetter conditions than usual over much of Latin America and in parts of the United States and Africa.

In La Nina, these regional patterns are reversed.

Both also contribute to abnormal temperature swings around the globe, especially during the December-April period when they are strongest, experts say. El Nino generally helps bring hotter weather than normal and La Nina leads to unusual cold.

The last El Nino, whose intensity caused devastation along the western coast of North and South America in 1997-98, lasted for nearly 12 months, just slightly more than average.

The La Nina which followed lasted nearly 2 years. The current one started in the third quarter of 2007.

The La Nina Phenomena Explain

At times ocean surface temperatures in the equatorial Pacific are colder than normal. These cold episodes, sometimes referred to as La Nina episodes, are characterized by lower than normal pressure over Indonesia and northern Australia and higher than normal pressure over the eastern tropical Pacific. This pressure pattern is associated with enhanced near-surface equatorial easterly winds over the central and eastern equatorial Pacific.

During cold (La Nina) episodes the normal patterns of tropical precipitation and atmospheric circulation become disrupted. The abnormally cold waters in the equatorial central give rise to suppressed cloudiness and rainfall in that region, especially during the Northern Hemispherel winter and spring seasons. At the same time, rainfall is enhanced over Indonesia, Malaysia and northern Australia. Thus, the normal Walker Circulation during winter and spring, which features rising air, cloudiness and rainfall over the region of Indonesia and the western Pacific, and sinking air over the equatorial eastern Pacific, becomes stronger than normal.

Globally La Nina, in very general terms, will mean that those parts of the world that normally experience dry weather will be drier and those with wet weather will be wetter. The Atlantic and Pacific hurricane activity will increase with La Niña and the effects of severe droughts are likely in those already dry parts of the world.

Broadly speaking, the La Niña event could give drier conditions in Central East Africa, SW USA, Northern Mexico, South America etc. Wetter conditions could be experienced in North/North East Australia, South Africa, Southern Asia (during the monsoon) and the northern half of South America, Central America and the Hawaiian Islands.

The Atlantic and Pacific hurricane activity will increase with La Nina...

Killer Waves in Indonesia - Feb 13, 2008.

High waves that struck coastlines across Indonesia's eastern islands killed one and forced hundreds to flee their homes, an official said Wednesday.

"A local tourist aged 16 was swept away yesterday (Tuesday) by waves as high as three metres (10 feet) while he was fishing on the beach,"

Hundreds of houses along beaches in Sikka district and about 50 others on the nearby island of Alor were damaged by the high waves. Some 300 people were evacuated to emergency shelters, he added.

Winds on Wednesday were moving at speeds of up to 70 kilometres (43 miles) per hour. They were whipping up six-metre-high waves lashing areas on Sumba, Flores and Alor islands in East Nusa Tenggara, he said.

The wild weather is due to a low pressure system off Australia's north.

HIgh Ocean Tides in Vietnam - January 21, 2008

HIGH ocean tides battering Vietnam's southern coast have swept away or damaged dozens of homes and led authorities to evacuate scores of residents, local officials said.

"Very high waves completely destroyed 18 houses and damaged 17 others," said Nguyen Thi Ngoc Suong, chairwoman of Phuoc Loc ward people's committee in Binh Thuan province, after the houses collapsed into the sea on Saturday.

"In total 174 people have been evacuated," she said.

State media reported that hundreds more homes in the area were threatened by the high sea swells.

Climate experts warn that global warming will hit Vietnam worse than most countries because its 3200km coast and low-lying Red and Mekong River deltas are vulnerable to storms, floods and rising sea levels.

Australia Floods - January 2008

Thousands of people remain stranded by some of the worst flooding eastern Australia has seen in 20 years.

Australia endured bushfires, floods and record high temperatures in its drought-ravaged foodbowl in 2007 as global warming brought the nation's sixth hottest year on record.

The mean maximum temperature of 28.6 Celsius (83.5 Fahrenheit) was almost a full degree above normal, bringing record average temperatures to the heavily populated southeast. "Such conditions are usually, but not always, associated with above-average rainfall across much of Australia. However, the 2007 La Nina event was slow to develop and its influence during winter and spring was confounded by a counter influence from the Indian Ocean," the bureau said.

La Nina, meaning "little girl" and the opposite of the El Nino weather phenomenon, brings rains to Australia's east and parts of Indonesia, as well as to the western United States.

Australia's Climate Institute said the bureau data showed global warming was not only about warmer weather, but also wilder and more unpredictable weather such as powerful storm cells and cyclones.

Parts of the country's most populous state, New South Wales, have been cut off by heavy rain and have been declared natural disaster zones.

There are similar problems further north in Queensland, which has also been battered by wild conditions.

Long drought

Others parts of the country had also been suffering from the weather.

Heavy downpours have affected Queensland, triggering flash floods in the south-east of the state. Many coastal areas have been affected by the wild weather and beaches have been closed during the busy holiday period.

In the Northern Territory, the city of Darwin is recovering after being pounded by Cyclone Helen over the weekend. Trees were uprooted and officials are busy restoring power and water supplies.

The bad weather follows months of drought in Australia.

The BBC's Phil Mercer in Sydney says that although rain is desperately needed, to receive so much at once is - to say the least - unfortunate.

Experts have associated the inclement conditions in the eastern states with the La Nina weather pattern. More summer rain is anticipated but climatologists believe it is far too early to declare Australia's drought to finally be over.

They say that the continent's long dry spell has built up massive rainfall deficits that will take a lot more than one reasonable wet season to fix.

Australia Floods - February 2008

Australia’s weather continues to be a roller coaster ride with the southern states of the country looking at ways to combat a water shortage resulting from the ten year drought whilst the north eastern peninsula of Queensland and northern parts of New South Wales including Sydney are being inundated with torrential rains and flooding. Warnings for a ‘Flood Watch’ from the Australian Bureau of Meteorology have also been issued for some of the southern parts of New South Wales.

A ‘Severe Weather Warning’ remains in place for Queensland with dangerous surf and abnormally high water levels expected. Strong Easterly swells from tropical cyclone ‘Gene’ are causing a surge in wave energy.

Up to 62% of Queensland remains drought declared but at the same time 70% has been declared a disaster area due to the current floods. It is anticipated that once the flood waters recede there will be benefits to the local rural economies in increased levels in water catchments but the state will initially face a flood bill in the hundreds of millions of dollars. The capital of Queensland, Brisbane, had water reserves of just 20% before the current rains which are expected to bolster that figure significantly.

The rain has caused havoc with some train lines in Queensland being all but washed away and estimates of repairs taking up to three weeks.

In New South Wales flash flooding isolated parts of Wollongong north of Sydney, whilst in Sydney some roads have also been cut off due to flooding. It is forecast that a further 200 millimetres of rain could fall over the next 24 hours along the eastern coast of Australia with some parts of the state already receiving almost 300 millimetres of rain in the past five days. Sydney’s water reserves are now at about 60%

BHP, the world's largest exporter of coking coal -- used for steel making, has already said it was unable to meet contractual commitments on coal deliveries.

"The rain will continue to impact operations over a number of months as all parts of the integrated mining processes were affected and the effects of the flooding will be evident for up to six months."

High Waves in Indonesia and Malaysia

The Meteorology and Geophysics Agency (BMG) said it expected severe conditions to continue at sea at least until the end of January. “The high waves are being caused by low air pressure in waters off Australia and an unusual 19-year lunar cycle,” said the agency’s spokesman, Suratno. He warned passenger ships, tankers, and fishermen to cancel operations for the time being.

Four-to-five-meter waves are expected to occur in the South China Sea, Banda Sea and Kai and Tanimbar waters in Maluku, the Aru Sea, and off the south coast of Papua. High waves will also occur in the Java Sea, in the Indian Ocean affecting Bengkulu and Lampung provinces and eastward across Java to East Nusa Tenggara.

“Four-meter waves will also hit Riau waters, Bangka-Belitung, Pontianak in West Kalimantan and the Makassar Strait up to Sangihe Talaud in North Sulawesi,” Suratno said.

High waves were reported to have damaged the fishing port at Kerayaan Island, Kotabaru and South Kalimantan. Damage to the port has delayed food supply distribution to the island from the mainland. The agency had warned the vessels and fishermen in southern Papua coastline about four to six meters high wave that most likely will hit the area this week.

Flooding In Indonesia

Feb 1 JAKARTA (Reuters) - Floods and landslides triggered by heavy rains have killed at least 12 people across Indonesia and the capital's main airport was briefly shut on Friday as more than 40 flights were delayed due to low visibility.Scores of cars were stranded and people had to wade through murky knee-high water in many parts of Jakarta, a city of 14 million that is regularly hit by floods at this time of year.

Last year about 50 people died in Jakarta, many due to electrocution, and more than 400,000 people were displaced after days of heavy rain.

After the 2007 floods, the then governor of Jakarta said the city administration needed more help from the central government to deal with the annual hazard. There were no reports of deaths in Jakarta on Friday after flood waters rose to 20-50 cm, but a health ministry official said four people were killed and thousands displaced from their homes after heavy rains in parts of Java and Sulawesi islands.

More than 10,000 houses in East Java's Pasuruan region were inundated by floods, forcing people to erect tents on streets,

In the Singkil district of Aceh, a province on the tip of Sumatra island, eight people died after a landslide buried two houses, Pakaya said.

During Indonesia's rainy season deadly landslides often occur as tropical downpours can quickly soak hillsides stripped of trees with little vegetation to hold the soil.

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