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El Nino

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El  Nino El Nino Presentation Transcript

  • Q1) What were the impacts of the El Niño event on Peru? It was the Peruvians who coined the term El Niño as far back as 1891. Following the usual El Niño pattern, in the 1997/8 event warm water piled up off the country’s Pacific coast, blocking the usual colder current, taking nutrients, and therefore fish, from the shores. Catastrophic floods inundated towns and villages throughout the country. Rock and mudslides in the village of Corcona. River Nepeña, normally gentle, turned into a raging torrent. Traditional mud-brick building material, commonly used in LEDCs, disintegrated in the flood waters. Chiclayo was one of many northern towns badly affected. In all, Peru lost 30 major bridges and the country ground to a halt. The normally bone-dry Sechura Desert, also in northern Peru, was transformed by El Niño. Six months after the El Niño rains stopped, a lake here was still 20ft deep. Fish, washed down from mountain streams, provided refugees with an unexpected harvest. Heavy El Niño rains had been predicted in the north, but they also reached down into central Peru. Eg, town of Chosica inundated unexpectedly. 370 miles of major roads destroyed. The Peruvians had thought the 1982/3 El Niño event was as bad as it could get, but 1997/8 was worse. Several years’ worth of rainfall fell in just three months. Floods swept down to the outskirts of the capital Lima itself, for the first time in living memory. The city of Ica, 180 miles further south of Lima, was devastated. 250 people drowned here, and thousands had to be evacuated. Those who survived the initial deluge were left with ruined homes. Floods deposited thick mud everywhere. Throughout the country, more than a third of a million people lost their homes. Only a few of the young and needy could be airlifted to safety.
  • Q2) What were the impacts on Chile? Storms carried on down the South America coast into northern Chile. 80,000 lost their homes. Even the Atacama Desert in northern Chile was affected, normally the driest place on Earth. Local legend said it hadn’t rained there for over 400 years. In 1998 rains formed a temporary lake and the desert bloomed. Flowers sprang up from seeds that may have laid dormant for hundreds of years (actually became a tourist spot where people came to see the ‘desert in bloom’). But it was only the desert that welcomed El Niño – some towns were struck by summer blizzards. Farmers were not used to the freak conditions and freezing temperatures that slaughtered their livestock. Q3) What happened beyond the Andes mountain range in Brazil and Argentina? In Brazil, El Niño replaced moisture with drought and fires spread across the parched land. Beyond this band of drought, El Niño created another band of floods, eg in Argentina the great Paraná River rose 27ft higher than normal to flood 30,000 sq miles, an area the size of Scotland. Q4) In what ways did Mexico suffer? El Niño‘s wave of destruction spread up into Central and North America. In late 1997, storms lashed the Pacific coast of Mexico – eg in Acapulco. Hurricanes are rare in the eastern Pacific, but three of them smashed ashore causing severe destruction. The worst of them, hurricane Pauline, dumped 16 inches of rain in the hills behind Acapulco in just 24 hours. Flash floods roared down into the town towards the sea. In a single day, the floods claimed 400 lives. Hurricane Pauline had sounded a warning bell for the whole of North America. Snow fell in subtropical Guadalajara, Mexico, in December of 1997, where people had never seen a snow storm before.
  • Q5) How was El Niño’s presence felt in California? In late 1997, California prepared for El Niño. The normal winter sunshine was replaced by torrential rain, and with the rain came floods. There were landslides in several parts of the state. Eg, Laguna Canyon was ripped apart by storms in February 1998. On the hills above the canyon, waterlogged earth began to liquefy causing mudslides. Residents and their homes were engulfed in mud. One man died. The name El Niño spread across America; it seemed anything that went wrong could be blamed on the phenomenon. Q6) What occurred further north still in Canada? Where winter snow is expected in Canada, El Niño produced an ice storm. Much of Quebec province paralysed in January 1998. Electricity pylons collapsed under the weight of three inches of ice. Unusually powerful jet streams had driven warm humid air far into the north, then rain turned to ice as it hit the freezing landscape. Ice storm blacked out half of Montreal for a week. Q7) What were the impacts of tornadoes in America? The 1997/98 El Niño had one other effect on North America’s weather: it created tornadoes where they were not expected. There were 1,200 tornadoes in 1998, compared to the expected figure of about 1,000. More people were killed by them than in previous years: over 125 died. Well ahead of the regular season, several tornadoes ripped through the south-eastern states. In April, the most powerful tornado of the year struck near Birmingham, Alabama, just one of 40 to strike Alabama that month. Especially in south-eastern states, a correlation was found between increased frequency of tornadoes and El Niño. El Niño also believed to have triggered an outbreak of tornadoes in the early part of 1998 in central Florida, just south of Orlando. 400 homes destroyed and 42 dead. People here were used to 100mph hurricanes, not 200mph tornadoes.
  • Q8) How else was North America affected? El Niño had reached right across a continent to inflict its damage. Across the sunbelt states to Nevada, in April 1998 plague of locusts was triggered by unusually moist condition in the desert. Hundreds of forest fires in Florida and Mexico. Smoke was a hazard for both aircraft and car traffic across the Gulf states for several months. Q9) On the other side of the world, how was Indonesia affected? Even before El Niño hit the Americas, it had already started to inflict disaster. On the other side of the Pacific, moisture had been drawn out to sea, leaving the land tinder-dry (remember, in an El Niño event there is the reversal of the Walker circulation leading to high pressure over the Indo-Australian region). Fires raged out of control. Eg drought and forest fires in Indonesian islands and Borneo. Entire countries were covered in paralysing smog. Air travel ground to a halt. Kuala Lumpur, the capital of Malaysia, was in September 1997 choked with smoke from fires burning hundreds of miles away. People wore masks to help them breathe. Q10) What information is given about the history of El Niño since the 1970s? In the 1972-73 event Africa was ravaged by drought and famine, the most disastrous consequence of El Niño. India also ravaged by drought, with monsoon rains over a month late. These were two events teleconnected to El Niño. It was not until the El Niño of 1982-3 that governments took notice. Here, the Australian outback was turned into a dustbowl of drought. Melbourne was engulfed by an unprecedented dust storm with 100million tonnes of soil dumped on the city. There were uncontrollable bush fires. 8,000 families lost their homes, there was over £2billion of damage and 73 killed. The 1982/3 event was therefore the wake-up call to many governments.
  • Q11) How has El Niño been monitored over recent decades? An array of over buoys laid out across the Pacific to measure water temperatures. Scientists hoped to find out what happens both before and during an El Niño event. The 1982/3 event was the El Niño of the century up until that time and it was neither predicted nor detected until it was nearly at its peak. The aim was to detect events before they struck in full. Now can get information by satellite relay to monitor Pacific and put data into computer models. However, we still can only give a few months’ warning of when warm El Niño waters might hit Peru. The computer models have yet to be refined though and inaccuracies remain. We have not measured enough El Niño events yet to fully understand what happens. Q12) Why is predicting El Niño important? El Niño’s impacts reach around the globe. As it changes the weather in one part of the world, it has a domino effect in other places. These linkages are known as teleconnections. Being able to better forecast El Niño events will also help us predict its teleconnections. Many scientists fear that global warming may be having an influence on the severity of El Niño events. Q13) Often El Niño events are preceded or followed by La Niña. What did La Niña produce in 1998? A dramatic increase in Atlantic hurricanes. Q14) What were the 1997/8 El Niño and La Niña’s impacts on hurricane formation? During 1997, there were few Atlantic hurricanes. Before they could develop, El Niño winds blew them apart. But by late 1998 El Niño was over and a new regime was in charge: La Niña, effectively the opposite of El Niño. Here, cold water welled up in the mid-Pacific. Data from pacific buoys showed a dramatic fall in the surface water temp, a plunge of nearly 8oC. It immediately became dry in Peru, and unusually wet in Indonesia, quite the opposite of El Niño. One of the main observations that scientists have made is a reduction in the number of hurricanes in the Atlantic and Gulf states during El Niño, but an increase during La Niña.
  • Q15) What were the impacts of Hurricane Bonnie? When the hurricanes eventually came, they came with fearsome force. Hurricane Bonnie, with winds up to 150mph, roared in from the ocean at struck North Carolina, at a place that had already been struck twice by hurricanes only two years before. Bonnie flooded streets and homes, knocked down power lines and knocked cars sideways off the road. Q16) How many hurricanes formed at the same time in the Atlantic in October 1998, and which was the most dangerous? Hurricane activity rose to alarming levels, with four in the Atlantic at the same time: Karl, Ivan, Jeanne and Georges. Hurricane Georges was the most dangerous. Q17) What was the impact of Hurricane Georges? Headed straight for the Caribbean and North America. It left a trail of destruction at every stop, from Puerto Rico to Cuba. The Dominican Republic was hardest hit, with the rains causing swollen rivers and mudslides across the islands. Rescuers found bodies piled up in the mud. More than 300 were killed. Over 100,000 were left homeless. After its rampage through the Caribbean, Georges headed straight for the Florida Keys. Most holiday-makers were evacuated but about half the population stayed. Luckily its impact on the Keys was less severe, causing one death. But Georges was not finished. It moved into the Gulf of Mexico, towards the Mississippi/Alabama coastline. Dauphin Island, Alabama, was particularly badly hit where 40 houses were flattened, new and old, by 90mph winds and huge waves on top of an 8ft storm surge. 30 miles north, Mobile Bay, Alabama, was badly hit.
  • • Q18) When did Hurricane Mitch strike and what were its impacts? • After Georges, La Niña kept the hurricanes coming. Three weeks later, in late October 1998, Hurricane Mitch developed, a much bigger storm covering half the Caribbean. It was a category 5, one of the biggest ever. • Mitch dumped more rain and caused more flooding damage in Central America than anything in living memory. • Across Honduras, Nicaragua and El Salvador, 10,000 were killed and a million lost their homes. • Disaster on this scale brings whole countries to a halt, with survivors facing famine and disease. Mitch set the economies of some of these countries back by over 30 years. • The violence of a hurricane such as Mitch may be a result of global warming. The warmer our climate becomes the more moisture evaporates from the oceans into our atmosphere. More moisture means more storms. • In 1982/3 and 1997/8 we’ve had the two strongest El Niños of the century, and with 1998, an exceptionally powerful La Niña.