Presentation on theme: "A phenomenon with global ecological effects"— Presentation transcript:
1 A phenomenon with global ecological effects El NiñoA phenomenon with global ecological effectsGood Morning.My name is Marko Locher, and together with my colleagues Ulrich Leth and Christian Popovits I am going to talk about El Nino today.
2 As most of you might have already heard, El Nino is a phenomenon that greatly influences our today`s weather.And as this cartoon clearly shows, scientists still haven‘t uncloaked all of it`s secrets.
3 Contents Introduction History Basics El Niño & Southern Oscillation La NiñaEcological EffectsEconomical EffectsConclusionWhat are we going to talk about?We are starting with a short introduction of the phenomenon, then continuing with the historical overview. Afterwards we will explain some oceanographical and meteorological basics, needed to understand the conjunctions and links.We will then explain El Nino and its sister event La Nina, followed by the ecological and economical effects.Finally we are going to provide a short conclusion, summarizing the afore mentioned.
4 IntroductionLargest so far known disturbance of the global weather systemFirst documented by Peruvian SailorsOccurs every 2 to 7 yearsGlobal impacts on Economy and EcologyDifficult to predictEl Nino Southern Oscillation, or as it is referred to by most people just El Nino, is by far the largest yet known distubance of the global weather system. It‘s roots date back at least 500 years and it was first recorded by Peruvian fishermen.Today it is known to occur every 2 to 7 years, and to have effects on economies and ecological systems all over the world.Although great efforts are drawn to researching it, El Nino is still very hard to predict and probably always will be.
5 Contents Introduction History Basics El Niño & Southern Oscillation La NiñaEcological EffectsEconomical EffectsConclusion
6 History First documented in 1567 by Peruvian Sailors Plenty of Data since the arrival of the Spanish Conquistadores1920‘s, Sir Gilbert Walker discovered Southern Oscillation [SO]1960‘s, Jacob Bjerknes found link between El Niño & SO [ENSO]Although some people may think, that El Nino is a recent phenomenon linked with global warming and greenhouse effect, this is simply not true.As already mentioned, it was first documented by Peruvian sailors in 1567, when they noticed a major change in water flow and temperature, which leads to either drought, lack of fish or heavy rains and massive floods. As this usually started around Christmas, the sailors named it „El Nino“, meaning the Christ Child.Since the arrival of the Spanish Conquistadores, there exist plenty of records about this phenomenon, but at the turn of the last century it was stilll widely believed to have just local effects.The first to assume a greater link was Sir Gilbert Walker, a British meteorologist, studying the Monsoons in India. He found a connection between rains in South America and changes in the water temperature there, and he further noticed a link between barometer readings in South America and the Indo-Australian region. He named this phenomenon Southern Oscillation. But this theory was widely doubted by the rest of the scientific community.In the late 1960‘s, a Norvegian meteorologist named Jacob Bjerknes proved Walker‘s theory and to show the connection named it El Nino Southern Oscillation, or short ENSO.
7 HistoryW.H. Quinn investigated intensity and frequency of El Niño EventsModern research with buoys and satellitesLater W.H. Quinn sorted through the great amount of collected data and classified ENSO events according to their strength.Today scientists use buoys and satellites to research El Nino‘s causes and to predict further events. For example, by analyzing the growth of tree rings, which is directly linked with rainfalls, or the accumulation of trace elements in corals and glaziers, they can trace back the phenomenon some thousand years.
8 Contents Introduction History Basics El Niño & Southern Oscillation La NiñaEcological EffectsEconomical EffectsConclusionTo understand El Nino it is important to have a basic understanding of the meteorological and oceanographical system.
9 Meteorological Basics Innertropical Convergence Zone [ITCZ]Trade Winds [Tropical Easterlies]Coriolis ForceThe meteorological system is highly dependent on global wind patterns. These patterns are characterized by the Innertropical Convergence or ITC, a low pressure zone with clouds and heavy rains located directly above the equator.Air masses which rise in the ITC then spread North and South towards the tropics (Wendekreise) where they come down again, meanwhile warming up. As this warm air can bear more humidity, the subtropics are free of clouds and seldom face rains.Afterwards most of these masses flow back to the ITC, thus resulting in the trade winds, or as they are sometimes called the tropical easterlies. The smaller part blows towards the polar regions, and is deflected by the Coriolis forcs. These winds are known as the West winds.
10 Oceanographical Basics ThermoclineTransition zone between surface and deep watersRapid decline of water temperatureNutrient richThe thermocline is the transistion layer between the warm surface waters and the colder waters from the depth. Whereas the other two layers are nearly stable in water temperature, the thermocline is characterized by a rapid decline of temperature.Most of the organisms live in the uppermost layer, which is flooded with light and called the euphotic zone. Dead organism are decomposed, while sinking down to the thermocline, which the sunlight doesn‘t reach. That‘s why this layer is so rich in nutrients but poor in life.
11 Oceanographical Basics UpwellingWinds drag surface water to the WestRising of colder nutrient rich waters in the EastUpwelling is an oceanograhpical phenomenon which occurs when the wind drags the warm surface water away from the shore. It is then replaced by colder waters from the depth of the sea, which contain the nutrients from the thermocline.This is the reason why the coast of South America is one of the world‘s richest maritime ecosystems.
12 Contents Introduction History Basics El Niño & Southern Oscillation La NiñaEcological EffectsEconomical EffectsConclusion
13 Southern Oscillation A see-saw effect Caused by a shifting of air massesCorrelation between the Western Pacific and the Indian Ocean:Air pressureSea surface temperatureWater levelAs already said, Sir Gilbert Walker was the first to use the term SO, when he found a connection between air pressure in South America and the Indo-Australian region.Nowadays SO is known to be a see-saw effect caused by a shifting of air masses, and it corresponds to the correlation of air pressure, SST ans water level between the West Pacific and the Indian Ocean.The two extreme phases of SO are El Nino and it‘s sister event La Nina.
14 Normal SituationNormally the strong trade winds blowing towards the West keep the warm waters of the Pacific Ocean near New Guinea and Australia. There warm air rises, resulting in clouds and heavy rains, the Monsoons. The rising air flows towards the East, sinking and cooling down near South America because of the cold Humboldt current. This region of high pressure leads to the upkeeping of the easterlies and so the circulation starts again. This phenomenon is called the Walker Circulation.
15 El NiñoAn El Nino event is characterized by a fading or sometimes even a reversal of the trade winds. The warm water masses accumulated in the West by the easterlies, now swash back (Kelvin waves), overlaying the cold upwelling waters near the South American coast, thus forging a significant rise of the water temperature. The thermocline is pushed down below the reach of the upwelling process.The humid conditions, which normally dominate in the Indo-Australian region, now occur in South America, leading to heavy rains and floods. Vice versa the dry conditions, that are characteristic for Peru and Ecuador, now show up in Indonesia and Australia.
16 El Niño 4 Phases: Antecedent Conditions Onset Phase Peak Phase Dissipation StageAn El Nino event can be seperated in 4 phases:The Antecedent Phase starts about 18 months before the climax and is characterized by a strengthening of the South East trade winds, shifting even more water than usual from East to West. The sea level rises further in the West and the SST near the South American coast now appear to be even lower than normal. One could say that the Walker Circulation is intensified before an El Nino event.The Onset Phase starts autumn the year before the climax. The easterlies weaken, leading to the sinking of the water level in the West.The Peak Phase is the real beginning of El Nino. It starts around December and January when the Kelvin waves coming from the West reach the South American shore. The water level and temperatures there rise drastically, leading to the already mentioned effects. This phase lasts about half a year.The Dissipation Stage follows the Peak Phase and starts with the dwindling of the differences in the water temperature. It finds an abrupt end in february the following year.
17 Contents Introduction History Basics El Niño & Southern Oscillation La NiñaEcological EffectsEconomical EffectsConclusionThe other extreme of the Southern Oscillation is La Nina. Christian!
18 La NiñaAs the name indicates, La Nina, the „Little Girl“ is the exact opposite of El Nino.In the Western Pacific region the SST is even higher then usual, resulting in an increased cloud formation and heavier rains when these rise to higher altitudes. These air masses are then blown eastwards, sinking down off the coast of South America, being cooled down by the strengthened Humboldt current. The high diffenences in the surface temperature between East and West involve a higher air pressure gradient, thus strengthening the easterlies. As an effect, the upwelling of cold waters is increased, the thermocline rises, resulting in even lower SST.
19 La Niña Increases normal climate conditions Heavier Monsoons in South East AsiaIncreasing number of Hurricanes in North AmericaCauses less disaster than El NiñoSometimes called El Viejo, “The Old”La Nina is a strengthening of normal weather conditions.This includes heavier showers, which are common in South East Asia and increased probability and strength of hurricanes in North America.But as the Little Girl usually causes much less disaster and damage than her evil brother, El Nino always casts a shadow on her, and people normally aren’t nearly as afraid of La Nina as of El Nino.Sometimes La Nina is also called El Viejo, meaning “The Old”, another contrary to “The Child”.
20 Contents Introduction History Basics El Niño & Southern Oscillation La NiñaEcological EffectsEconomical EffectsConclusion
21 Marine Ecosystem Thermocline is pushed down Warm waters spread Fewer nutrients riseFish die or move to colder watersTropical fish, favouring warm water, invadeDuring an El Nino event the thermocline is pushed down and overlaid by warmer waters flowing back from the West. On the one hand this leads to an increase of water level and temperature, on the other hand it hinders the upwelling of nutrient rich waters from the depth.As organisms now lack their nutrient basis they move to colder waters or die trying to. That‘s why it is possible to find some fish species native to California off the coast of Canada, some even near Alaska.The abandoned water near the shore are then invaded by tropical fish, which are more adapted to the higher temperatures.
22 Terrestrial Ecosystem This map shows the worldwide effects of El Nino on the Weather system. These effects reach as far as Alaska and Canada, where El Nino leads to unusual warm winters, in the map shown by the red marking.Yellow regions mark dry weather conditions. These mainly occur in the South East Asian region, where the failing Monsoons have deep impacts on the ecosystem, leading to the loss of whole crops and causing famines.Australia has to face severe droughts and an increased ratio of bush fires, diminishing the natural vegetation and animal populations.Heavy rains in the South American desserts, namely the Peruvian and the Atacama dessert lead to flooding as the dried out dessert grounds can not absorb the huge amount of water. The parts which are not effected by the floods, spring with newly grown vegetation.On the other hand, the North East of South America, which is usually favored by a humid climate, has to face extreme droughts, greatly reducing the established flora and fauna.Meanwhile the South and the Midwest of the United States face heavy rains and floods.Until now there is no prove for a direct link to the European weather system.
23 Contents Introduction History Basics El Niño & Southern Oscillation La NiñaEcological EffectsEconomical EffectsConclusionThese severe ecological effects surely have an impact on the world‘s economy.
24 Economical Effects South America Flooding and Landslips, destroying the infrastructureFlood waves, demolishing harbours and docksFailing harvests, causing severe faminesWeakening of Fish industryFailing of the Guano ProductionIn South America the heavy rains lead to floods and landslips, destroying the infrastructure of the region. The harbours and docks along the coast, which were speared from the floods, are washed away by breakers and storm waves, caused by the rising sea level.But not only the local infrastructure has to face damages. Whole harvests are lost through floods or wither, causing fatal famines. The whole disaster is further emphasized by the breakdown of the fishing industry, which can not compensate the lack of fish or is not able to adopt in time to the new tropical fish species.As a result to the diminishing number of fish the populations of guano birds, that provided the natural fertilizer for more than 4000 years, decline, dragging down the second pillar, the guano industry.But as explained earlier, the consequences are not limited to the South American region.
25 Economical Effects South East Asia Failing of Monsoons leads to loss of entire crops and faminesDying of Rain Forests in BorneoReduction of Palm Oil Production in Malaysia and IndonesiaIn South East Asia, the failing of the heavy rains, the monsoons, leads to the loss of entire crops, thus resulting in famines too.In Borneo, located in the West Pacific, the tree mortality of the rain forest strongly increases and bush fires wipe out nearly all the vegetation.As Malaysia and Indonesia, the worlds biggest producers of palm oil, have to face drier conditions than normal, the yields of the palm oil industry drop about 20 to 25% due to smaller fruit sizes. As the effects of the lack of water are not encountered immediately, the real extent of El Nino‘s impacts show up not until 2 years later.
26 Contents Introduction History Basics El Niño & Southern Oscillation La NiñaEcological EffectsEconomical EffectsConclusionChristian is now going to summarize the most important facts of the presentation.
27 ConclusionLargest so far known disturbance of the global weather conditionsOccurs every 2 to 7 yearsPredictable only 1 year aheadNo proved link to greenhouse effect and global warmingNo direct impacts on the European weatherInfluence on economics world wideEl Nino is the largest so far known disturbance of the global weather systemIt was named “El Nino” because of its occurrence around Christmas time.The phenomenon occurs every 2 to 7 years, but despite of the modern technologies and computers for researches, it is still not possible or sensible to predict an El Nino Event longer than one year ahead.Against the opinion of some scientists, there is neither a proved link to greenhouse effect and global warming nor to the European weather conditions.Nevertheless there is no doubt of El Nino impacts on ecological systems and economies worldwide.[Christians Zitat von weiß nicht wem!]
28 University of Princeton “We have to stop to think of El Niño as an event, and start to think of it as part of earth‘s breathing. It‘s as natural for the earth to have El Niño as it is for a bell to ring.“George Philander,University of PrincetonBut El Nino is more than a weather phenomenon, or as George Philander from the University of Princeton puts it:We have to stop to think of El Niño as an event, and start to think of it as part of earth‘s breathing. It‘s as natural for the earth to have El Niño as it is for a bell to ring
29 for your kind attention! Thank youfor your kind attention!
30 As people nowadays tend to blame El Nino for about everything, we are going to do the same!