Saturday, July 17, 2010

Disasters to surge as La Niña Returns?

Adios, El Niño. Hola, La Niña. Don't mistake it for the victory cry of Spanish supporters at the world cup. That is the present chant among meteorologists and climatologists.With the end of the El Niño episode, we are presently transitioning to its alter ego. La Niña, the feminine counterpart to the climatic system known as El Niño ("the boy" in Spanish), is characterized by a sharp decline of eastern equatorial Pacific Ocean temperatures and a steering of the polar jet stream (which delivers wintry weather) farther north.
During La Niña years, water in the central and eastern Pacific Ocean can drop as much as 5F degrees. The 2008 La Niña for instance was one of the strongest we have had since 1988-89, saw Pacific waters plunge 1.5C (2.7F) cooler than normal. It is not understood why these episodes are limited to the Pacific and absent in the Atlantic Ocean. The back and forth rhythm of la Niña and El Niño however is a normal part the Pacific Ocean's life-cycle and the Incas in Peru knew of them thousands of years ago so much so they used this knowledge to plan their agricultural operations.
Called also as the Children of the Tropics, they are additionally the short-term cousins of another natural climatic phenomenon called Pacific Decadal Oscillation (PDO) - a widespread pattern of sea-surface temperatures in the Pacific Ocean that alternatively cycles between two opposite phases every 25-30  years.
In the recent past, a La Niña follows only about 35-45% of all El Niños. However, studies indicate that the positive phase of the PDO, which has been taking place since 1977 ended in 2007-8. Whenever PDO turns negative, La Niña tends to increase its frequency as seen this decade. La Niña conditions typically last approximately 9 to 12 months, though some episodes may persist for as long as two years. The current La Niña should start around August and last until the second quarter next year.

If El Niño causes global temperatures to temporarily spike upwards, La Niña has the reverse effect, causing global temperatures to plunge below its long-term mean - nature’s way, perhaps, of rectifying the global heat imbalance that El Niño represents. However, it can also occasionally demonstrate temperature-neutral behaviour. As La Niña cools the Pacific, less warm air rises off the sea. It influences the atmospheric temperatures, largely because the Pacific is our largest ocean. This in turn affects the jet streams, or strong wind-flows, in the upper levels of the atmosphere and the behaviour of storms outside of the tropics in both the northern and southern hemispheres.

The UN Office for the Coordination of Humanitarian Affairs (OCHA) has already warned governments and the humanitarian community for the need to brace themselves against a possible surge in the frequency and intensity of natural disasters that can take the shape of heavier monsoons, bigger and more frequent hurricanes, and angrier cyclones. Only a few governments like the Philippines and the US are overtly on maximum alert while there is no visible evidence of the pro-activeness on the part of humanitarian agencies.

Rupa Kumar Kolli, Chief of the World Climate Applications and Services Division at the World Meteorological Organization (WMO) cautioned against any speculation on the intensity of La Niña as the phenomenon is still in its formative stages. However, initial data of sea surface temperature (SST) dropping like a stone, trade winds remaining strong and cloudiness suppression along the equator, all taken together suggests that we well maybe in for a moderately stronger than average La Niña episode and hence a busier than normal disaster season. However, to officially declare the presence of La Niña, there must at least three months of consecutive drop in the SST, and we now in the middle of the third consecutive month of a SST drop that makes its likelihood very highly probable.

Both El Niño and La Niña are global in impact. As they are the reverse of each other, weather phenomena of regions are reversed in impact as they inter-change play, enhancing its impact. Yet, as seen from the chart, all regions of the globe are not equally affected, nor is La Niña's impact uniform throughout the year.

Though often described as the singular phenomenon that affect global climate, its link to anthropogenic global warming (AGW) has yet to be established, mainly because we are yet know its causative factors or its behaviour fully. If we cannot figure out what the natural variability does, it will be highly disingenuous to claim a "fingerprint" of AGW. However, by knowing how La Nina previously affected various regions of the world in the recent past, we may have a better idea what it has in store for us this season, which this posting attempts to do.

North; Central Americas & Caribbean

Increased wind shear in an El Niño tends to rip apart embryonic storms in the Atlantic basin and Caribbean Sea. However, those winds are limited in a La Niña year, allowing storms to flourish. Consequently, the chances for the continental United States and the Caribbean Islands to experience hurricane activity increase substantially during La Niña summers and springs.  Hurricane and tropical storm landfalls are also twice as common as illustrated by Atlantic hurricane seasons of 1999-2001. Hurricane Mitch devastated Honduras and Nicaragua in October 1998, killing at least 10,000 people.

On the Caribbean side of Central America, therefore La Niña is bad news for vulnerable islands such as Haiti, which is still recovering from the earthquake that struck it in January 2010. This immediately put the Haiti relief operations under the shadow of this threat, which should be a concern for humanitarian agencies.

To help disaster officials and aid workers in Haiti, the UN Office for the Coordination of Humanitarian Affairs (UN OCHA) approached the International Research Institute for Climate and Society (IRI) based at the Earth Institute of the Columbia University and their partners to develop an on-line resource on the best available hurricane, landslides, weather and climate information related to Haiti. The website is available at:

In May, the National Oceanic and Atmospheric Administration (NOAA) in Miami predicted this Atlantic storm season could be the worst since the record-breaking 2005, when Hurricane Katrina ravaged New Orleans, Hurricane Wilma slammed into Florida's citrus groves, and Hurricane Rita hit hard the oilrigs in the Gulf and refineries along the Gulf Coast. Though we should be skeptical of such devastating forecasts, to err on the side of caution should characterize disaster preparedness planning. On a 70% confidence level, NOAA predicts there may be as much as 14 to 23 named storms, with wind speeds of more than 62km per hour, 8 to 14 are expected to be hurricanes and 3 to 7 major hurricanes. The first Atlantic hurricane of the season, Alex, hit Mexico on 30 June. NOAA said it was the first hurricane to be recorded in June in the Atlantic Basin since 1995, and the strongest in that month since 1966. Whether Hurricane Alex is, a precursor of what can follow is difficult to predict, as much of the dynamics that characterize hurricane frequency or intensity is not fully understood yet. 

The emergence of a La Niña is of particular concern to the oil industry in the Gulf of Mexico, already reeling from the massive oil spill caused by a leaking BP oil well. An increase in the number of hurricanes boosts the chances that at least one storm will slam into the Gulf, home to about 30 percent of U.S. oil and 12 percent of U.S. natural gas production.

Accordingly this hurricane season possess a huge risk of affecting US natural gas and oil production and therefore could send global prices soaring. BP Plc and Royal Dutch Shell Plc, the biggest oil producers in the Gulf, are already evacuating hundreds of workers from platforms in the western and central Gulf as a safety precaution. Median outcomes for production shut-ins in the Gulf because of hurricanes may be 26 billion barrels of oil and 166 billion cubic feet of natural gas, according to a June U.S. Energy Information Administration simulation. A cooler La Niña winter in the U.S. besides may drive heating oil and natural gas consumption that adds to price pressure. However, currently the U.S. has above-average inventories that act as a preventive cushion.

As for the cleanup of BP Gulf Oil Spill, La Niña can either equally aid or even worsen its already devastating impact. When a hurricane, like Alex, hits the Gulf, there is likely to be upwelling of water that would generally mix up the water and oil. According to Greg Holland of the National Centre for Atmospheric Research in Boulder, Colorado, who is on the panel of scientists briefing the US Congress and Senate on the BP Oil Spill, this is really good news because the dispersed oil would be easier for bacteria to break down and consume than the larger clumps.

Nevertheless, Holland also cautions that hurricanes also by their very nature move in a counter-clockwise direction and so tend to move water from east to west. This is in the opposite direction from the way the oil has generally been spreading so far. In such a scenario, the oil slick could well run into the delta of Louisiana, New Orleans and into its marshlands. However, the likelihood of it doing so is dim as these distances are too far. The net import of Holland's assessment suggests that the likelihood of Atlantic hurricanes worsening the BP oil spill cleanup is rather low. The chances are that nature will clean up man's messes of ecology.

La Niñas of the past have demonstrated that they have a wider affect on the weather than just hurricanes. If this region received higher precipitation and lower temperatures during El Niño, then during a La Niña year, we could see below-average precipitation over the central equatorial Pacific.

In the past, for the contiguous United States, potential La Niña impacts include above-average precipitation in the Northern Rockies, the Pacific Northwest, and the Ohio and Tennessee Valleys. Below-average precipitation can be expected across the South, particularly in the southeastern states. Severe weather is likely to be further north and west during La Niña than in the case of an El Niño year. The cooling patterns often bring dryer, warmer weather to the southern half of the U.S., increasing the wildfire threats in Florida and California. La Niña could affect corn, soybean and orange production.  In Canada, La Niña generally causes a cooler, snowier winter, such as the near record-breaking amounts of snow recorded during the La Niña winter of 2007/2008 in Eastern Canada.

South America

La Niña affects different parts of the region and sometimes, within the same country, very differently. La Niña tends to provoke intense rains often accompanied with catastrophic floods in Northern Brazil, Colombia, and Ecuador, the high plains of Bolivia and Peru and northwestern Argentina.  These rainy spells are often accompanied by outbreaks of cholera and leptospiris. During the last La Niña episode: 
-  Lima, Peru's capital suffered from a very cold winter.
-  Bolivia, severe mountain weather caused mudslides on roads joining the capital of La Paz with Cochabamba and Santa Cruz, with its national capital suffering from freezing weather and hailstorms.
-  Flooding heavily damaged roads around the northern port of Africa in Chile.
-  In Ecuador, heavy rains and flooding on the coast left roads and bridges in ruins. Damage to infrastructure was so severe the government estimated it would take a decade to recover.

At the same time, colder-than-normal ocean temperatures prevent rain-producing clouds from forming over the open ocean that lines south of Mexico and Central America, causing droughts in coastal and central Uruguay, southern Brazil, northeastern Argentina, Chile. During the last La Niña, Roraima, in Brazil faced excessive drought led to more than 200 fires, destroying more than 37,000 square kilometres (an area nearly the size of England) of forest, displacing an estimated 10,000 people.

La Niña years for that reason make the task of food output forecasting very nightmarish because of this dual character impact of La Niña on South America. Output losses in the U.S., Argentina and Brazil, which make up 82 percent of global soybean output, may end a 13 percent slump in prices because of record crops.  La Niña years are among the worst for grain and oilseed crops in Brazil. Aside from sugar cane, that may also affect coffee production in Brazil, the world's top producer. The Latin American country is the world's second biggest exporter of soybeans. Argentina is the biggest exporter of soymeal and soyoil.

Asia &Oceania

During La Niña years, the easterly winds from the Americas are stronger than usual. That drives more than the normal amount of warm sea-surface water westward, in turn causing larger than normal volumes of deep, chilly water to rise to the surface and producing a ‘cold tongue’ that extends 4,800 kilometres along the Equator from Ecuador to Samoa

With so much warm water flowing towards Asia, La Niña causes floods, massive cyclones, and endless rain.  Typical La Niña events are usually associated with stronger monsoons in South Asia, Southeast Asia, parts of East Asia and parts of Australia. In March 2008, La Niña caused a drop in sea surface temperatures over Southeast Asia by an amount of 2 °C.

It also causes heavy rains over much of Far East, Malaysia, Philippines, Indonesia, Australia and New Zealand. However regions of the world that show the highest correlation to warm or cold events are Indonesia, Australia, and the tropical Pacific islands.

India’s benchmark wholesale-price inflation accelerated to 10.16 percent in May this year, near the fastest pace in 17 months. Prices of staples, including wheat, lentils and sugar, have increased by between 10 percent and 33 percent in the past year. June rainfall was 16% deficient. Yet the central government raised fuel prices, a step usually considered as inflationary.

The government, led by one of the world’s most prominent economist, was basing their calculations on a more than average rainfall this monsoon. This confidence was coming from past data that indicate that in a La Niña year, during June-August, it would  be likely that there would be above than normal rainfall

OCHA’s forecast though similar were more nuanced: “The region struggled with poor rains caused by an El Niño that affected food production in India, Pakistan, Bangladesh, Nepal, Vietnam, the Philippines and Thailand and are presently experiencing a normal monsoon season. But if the La Niña gets more pronounced, there is a stronger chance of monsoon depressions turning into cyclones that would affect Bangladesh and its surrounding areas [India and Myanmar], with heavier monsoons leading to flooding and mudslides.”

The Indian Met Department sounded more confident. Though at the end of July first week, rainfall was over 10% deficient, the Met Department updated their April forecast to still predict normal to above average (more than 105%), with the monsoon progressively gain in intensity in the coming months.

In fact, India this monsoon is likely to receive the highest rainfall for this season in September. Further, October may receive more than normal rainfall.  The central assumption is La Niña formation in August would amplify the normal climatic events and their associated phenomena, which in this case are the monsoons, especially in the northwestern part of the country. The only exception to the normal or above-normal rainfall outlook during June-July-August seems to be central and east-central India – mainly parts of Madhya Pradesh, Chhattisgarh, Orissa and Jharkhand. However, the slight deficit is forecasted to be covered to some extent during September-October-November when the rains are projected to be widespread across the country.

For the region as a whole, it is the period September to end of the year, which poses the maximum risk of cyclones. The hugely swollen warm-pool (ocean) generates much greater convection than usual, resulting in a massive increase in rainfall in the western Pacific. The Yangtze Basin floods and there is an increased frequency of cyclones (typhoons) hitting the coast of Japan, Korea & Australia.

Areas west of Japan and Korea tend to experience much higher September-November tropical cyclone impacts during La Niña. The storms, also known as hurricanes, typhoons and tropical cyclones, can cause landslides and push up food prices because of crop damage. They can also disrupt transportation and disable offshore oil and gas rigs, reducing production.

Floods in the beginning of the season can force farmers to replant crops. In 2008, floods hit India's sugar output. Excess rain causing water logging is bad for cane. Last year when many parts of India were parched during the rainy season, floods in Bihar and Karnataka damaged sugar cane and corn crops. Government data shows average annual crop damages from floods in India amounts to $575 million per year.

An Asian Development Bank (ADB) forecast read:
Projected maximum and minimum monthly flows in major river basins in Southeast Asia suggest increased flooding risk during the wet season with the maximum monthly flow of the Mekong River projected to increase between 35 percent and 41 percent in the basin and 19 percent in the delta.” 

The situation may worsen this year. Last year’s El Niño adversely affected agriculture production almost throughout the region. The Philippines is the world's eighth largest producer of the crop, and Asian nations collectively produce 90 percent of the world's rice. The El Niño drought last year completely devastated their rice production so much so they became the world’s largest importer of rice. India overtook China as the world’s biggest palm oil buyer and became the largest sugar importer after the weakest monsoon in more than three decades last year created food shortages.

Global food inflation was experienced the last time La Niña (2007/08) struck, as it badly disrupted plantings and harvest in Latin America, sending soft commodity prices higher whilst the southern US states experienced terrible drought conditions. Now with good rains within the Asian region that come with the La Niña, initial data for the region indicate that sowing is considerable up. In India’s case sowing significantly up enough to generate a 4% growth rate for agriculture, an all-time, bumper production. By their sheer scale, Chinese and Indian imports together, can influence global food commodity prices. However, as data from the Chicago commodity exchange indicate, both were conspicuous by their absence as buyers from the October futures, reflecting their confidence of self-sustaining their food demand which has led to a softening of global prices.

Yet, despite submergence-tolerant varieties being propagated for adoption in most of these countries; the risk of La Niña storms to standing crops, particularly in September-October months remains. The impact of factors such as the timing, duration, and intensity of La Niña events at various stages of crop development remain unclear.

For instance, the Philippines may have 60 percent more rainfall than average in the fourth quarter. This may possibly cause similar damage to crops as experienced in 2009. Nevertheless, it is likely that bigger Asian giants like China and India may withstand these shocks but it may prove critical for smaller countries like Philippines who may need to return to imports and countries like Solomon Islands and East Timor to get increased food aid.

Palm oil prices would be an interesting commodity to track in a La Nina year. Last week, crude palm oil futures (July contracts) fell below the crucial support $730 a tonne on Bursa Malaysia or the Malaysian Derivatives Exchange. However, fears should a hurricane hit a major oilrig led a pullback rally on the prospect that high crude oil prices may lift demand for bio-diesel and as sales from Indonesia grew for the first time in five months, led by Chinese orders.


In 1999, two years after El Niño’s floods killed thousands of people and caused havoc across Eastern and Horn of Africa, little sister La Nina destroyed the region’s crops, threatening millions with starvation by spreading drought.  Kenya found itself with a shortfall of at least 500,000 tonnes in its grains production for the year and had to lash import duties to make sure enough grain is imported to feed its people. “It is severe. In some areas, we have rains at only 10 percent of what they should be. I would call it a crisis. I believe this is the worst drought we have had," said Evans Mukolwe, director of the Kenya Meteorological Department.  Kenya was forced to launch a huge relief operation for pastoral and agricultural communities in the north and east.

A similar shortfall was experienced in neighboring countries. Central Tanzania had seen a collapse in its harvests, and areas of Rwanda, Uganda and Djibouti had also been hit as severely. This forced seven million Ethiopians to depend upon food aid for their survival and a million people were put at risk in Somalia. Sudan’s southern war-torn areas still relied totally on United Nations airdrops. Ironically, some of those areas that suffered the most severe drought were those that were battered by El Nino in late 1997.

 Africa lives December-February wetter than normal conditions in the Sahel region, which is equatorial Africa) along the southern edge of the Sahara desert. There as well come drier than normal conditions within south-central Africa, primarily in Zambia, Zimbabwe, Mozambique and Botswana.

The Horn of Africa is no stranger to famine and millions of its people are so poor and their means of livelihood so precarious that any climatic change—whether flooding or drought—quickly pushes them over the edge. Eastern Africa could face dry conditions early next year, with the possibility of seasonal rains being delayed by the effects of a climate phenomenon called La Niña, climatologists say. The second rainy season starts now for the Horn of Africa and Eastern Africa, rains can be expected to be near normal over much of the Greater Horn of Africa. There is a fear that La Niña could have a delayed impact on the rainy season, which starts in March 2011; the worst may be yet to come.

Cobus Olivier, a scientist in the Prediction Research section of the South African Weather Service, said the possible impact of La Niña on Africa, and particularly southern Africa, was unclear."At the moment the La Niña event is only starting out and will most probably take a month or two before it's considered a true La Niña event." He said it was very difficult to predict the impact as this could vary within the African region and from one La Niña event to another. 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.
"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.  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."
In 2007, La Niña prompted some of the most widespread rain recorded in Africa since the turn of the 1900s, according to Omar Baddour, head of the World Climate Data and Monitoring Programme at the UN's World Meteorological Organisation (WMO). More than a million people had been affected by flooding in over 20 African countries stretching in an arc across sub-Saharan Africa from Mauritania to Kenya. NASA scientists using satellite data have shown that shifts in rainfall patterns from one of the strongest El Niño events of the century in 1997 to a La Niña event in 2000 significantly changed vegetation patterns over Africa.

Baddour told journalists that the link between "La Nina" and flooding in western Africa had been closely studied since the 1990s. "We have found a very close relationship between La Nina and the phenomenon of flooding in West Africa. It was therefore very probable that a rather rainy season would occur in the region extending from Sudan in the east to Senegal in the west," he added.  In 2007, at least 1.5 million people have been affected and 270 have died in some of Africa's worst flooding in decades, which struck 18 countries. West African nations including Ghana and Nigeria were amongst the worst affected, along with Sudan and Uganda on the other side of the continent.

The WMO said the greater probability of wet weather in West Africa at the end of summer had been highlighted in a long term forecast given at a regional forum of African weather experts in May."The season started a little later compared to the average, but the months of August and September especially has been very very rainy in West Africa," Baddour underlined.” 

Assaf Anyamba and Compton Tucker of NASA's Goddard Space Flight Center, Greenbelt Md., and Robert Mahoney of Global Science and Technology Inc (GST) analyzed satellite derived images of vegetation from 1997 to 2000.They noticed regions of above normal "greenness" over East Africa associated with patterns of above normal rainfall during the 1997-1998 El Niño event. At the same time, they observed below normal "greenness" over southern Africa associated below normal rainfall conditions there.  

During the transition to La Niña, rainfall patterns reversed. Southern Africa experienced above normal rainfall and East Africa received below normal rainfall, resulting in a corresponding reversal of vegetation greenness patterns. "These changes vegetation patterns have implications for agriculture, livestock farming and vector borne disease outbreaks especially is semi-arid land of Africa," Above normal vegetation conditions are an indicator of improved pasture conditions which boosts livestock production in these areas."

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