Effects of El Nino and La Nina on climate change
Effects of El Nino and La Nina on climate change
El Nino and La Nina
El Nino and La Nina are Spanish words. El Nino means boy or little boy, and La Nina means girl or little girl. Both names are closely associated with the sea. Because these two conditions are the result of sea breeze circulation. These natural disasters are caused by continuous changes in sea surface temperature and atmospheric pressure. This global climate phenomenon is caused by cyclical changes in the water temperature of the Pacific Ocean. Due to this both temperature and precipitation are affected.
Originally this phenomenon was first understood by Peruvian fishermen around 1600. They observed that the water near South America began to warm in December. In Spanish this phenomenon is called El Nino. The arrival of El Niño coincided with Christmas time, so Peruvian fishermen named it the Son of Jesus. Then in 1963, scientist Gilbert showed that there is a close relationship between sea surface temperature and air pressure with El Nino or La Nina.
The climate cycle of the Pacific region revolves around three processes. And this process is known as ENSO cycle. This Enso cycle has three phases: El Niño, La Nina and the Enso neutral phase. The dry season of the climate is the El Niño phase, when rainfall is lower than normal and floods are less frequent. But at this time the temperature rises excessively. And during La Niña there is more rainfall and flooding. The temperature also drops below normal.
In normal times the equatorial trade winds or ionospheric winds bring warm water from the tropical Pacific Ocean. As the wind moves westward, it carries warm water from the eastern Pacific Ocean into cooler areas of the ocean. Normal sea surface temperatures in the tropical Pacific range from -2 to 30 degrees Celsius at the neutral stage.
During an El Nino phase, the waters around the Pacific equator tend to warm. At this time, the trade winds from the east weakened. Upwelling ocean currents along the coast of Peru and along the equator also weaken. Surface water in the tropical Pacific becomes warmer than normal. During this time the sea surface temperature may increase by 1-3 degrees Celsius for several months or even more than 1 year. During the La Niña phase, the easterly trade winds become stronger. Strong cold ocean currents along the equator and the coast of Peru keep the water warm in the western Pacific. Surface water temperatures in the tropical Pacific become cooler than normal. This cycle typically lasts from 9 months to 1 year. And sometimes it lasts up to 3 years. Usually after 2-7 years this cycle may return. La Nina usually comes after El Niño ends. However, it is not always guaranteed that La Nina will be followed by El Niño. Because after the El Nino of 1976-77, there was another El Nino in 1977-78. Then came La Niña in 1988.
History
El Nino and La Nina are a natural phenomenon. This has happened many times in the history of the world. Very strong El Niños in 1965, 1966, 1982, 1983, 1997 and 1998 caused extensive flooding and damage from California to Mexico and Chile. And the 1988 La Niña event caused drought across North America.
A persistent La Nina effect over the past few years has brought down temperatures and heavy rains in Canada and Australia. But despite the global cooling effects of a rare La Nina, which is running for the third consecutive year, 2022 was the sixth warmest year on earth. And it was the second warmest year on record for Asia and Europe.
The strong El Nino of 2015-16 marked the warmest year on record. During this time, massive fires were raging in Indonesia, and Peru was experiencing terrible floods. By analyzing sea surface temperature records over the past 70 years, researchers have found changes in the El Niño Southern Oscillation, or Enso. They hypothesize that global warming will lead to stronger La Nina and El Niño events in the eastern Pacific Ocean by 2030. El Niños have occurred 14 times and La Ninas have occurred 12 times in the past 50 years. Climate scientists believe that the number of these incidents is increasing as a result of global warming. The last El Nino occurred in 2016. El Nino also works behind the increase in the temperature of the Earth's atmosphere. But scientists are still trying to unravel the mystery of El Nino and La Nina.
Effect
Usually every year heat flows from South America to Asia due to Pacific Ocean winds. But the central and eastern tropical Pacific becomes significantly warmer during El Niño phases. This results in large changes in cloud formation and weather across the Pacific Ocean, with drier conditions in eastern Australia. Rainfall decreases in India, Indonesia and northern Australia. And during La Niña phases the water in the central and eastern tropical Pacific cools considerably. This results in an increase in average rainfall over much of Australia.
Due to El Nino and La Nina, the overall climate of the world changes quite a bit, for example, the North America and Canada get warmer winters. In the American West, Peru and Ecuador receive heavy summer rainfall. During El Nino, the frequency of hurricanes in the Atlantic Ocean is greatly reduced and changes in ocean salinity occur.
La Niña in the tropical Pacific causes warm and dry winters across the southern United States and wet and cold conditions in the Pacific Northwest, Alaska. La Niña also generally reduces hurricane activity in the Pacific and increases it in the Atlantic. El Niño causes extreme winters in the southern United States and mild winters in Alaska and northwestern Canada.
During El Niño, surface pressure over the Indian Ocean, Indonesia, Australia increases, atmospheric pressure increases over the eastern Pacific, atmospheric temperatures near Peru rise, and this warm air rises aloft and causes rain north of Peru. Warm water from the eastern part of the ocean moves to the west and the sea level there rises by more than 30 cm. Drought occurs in eastern Pacific regions. As the temperature of the sea water increases, the survival of aquatic animals becomes difficult. Fish species decline in Peru's coastal areas. On the other hand, the complete opposite of El Niño occurs during La Nina. At the same time, sea temperatures along the east coast of Peru and Chile were favorable for aquatic life, resulting in abundant fish, increased rainfall in parts of North America, and severe winters and snow in Canada. throw away These include Central and South America, the Caribbean, Southeast Asia, and East and South Africa. Most of these countries are poor regions. And these regions are more dependent on agriculture. Lack of rain or excess rain can be devastating to crops. Residents of areas in Africa such as Ethiopia, Somalia, Niger, Chad, the Sahara Desert and Sudan are already facing challenges. Being close to the equator, these regions are mostly dry, as the monsoons lose moisture before reaching these countries. Drought caused by El Nino worsened the food security situation in Ethiopia in 2015 and 2017, causing crop and livestock losses.
The water level of the Mekong River has dropped abnormally due to El Nino. As a result, the drought situation in Vietnam, the top rice exporting country, has become severe. Almost half of the cultivated land there has become saline. More than five lakh people are suffering from shortage of clean water. There are also crises in Malaysia, Thailand and Cambodia.
According to the researchers, strong El Niños in the eastern Pacific in 1982 and 1997 had a substantial impact on marine ecosystems. Parts of Ecuador and Peru suffer from severe flooding due to the eastern Pacific El Nino. University of New South Wales climate change research center professor. Agus Santoso said, “We should be more prepared for prolonged droughts and extreme floods in the future. Floods are more destructive to infrastructure than droughts, although droughts have a greater impact on agriculture. In both cases there is substantial economic damage.
Is 2023 going to be an El Nino year?
Scientists estimate that the whole world will face disaster in 2023. That is, the possibility of El Niño returning this year is high. The result could be heavy rains in North America, intense heatwaves in Europe and droughts in countries from Brazil to Indonesia. Meteorologists say climate change and the expected return of El Niño could set a new global average temperature record in 2023 or 2024.
The scientific body IPCC, which regularly reports research on climate change. They showed that changes in global warming are occurring due to El Niño. As a result, El Nino is getting stronger in the future. According to Reuters, 2016 was the world's warmest year on record, and a strong El Nino was active during that time. And the last eight years were the eight warmest years in the world. Apart from this, the long-term warming caused by the greenhouse effect has also increased its level. Global average temperatures over the three years were near record levels, but would have been higher without the cooling effect of a prolonged La Niña.
Frederic Otto, a senior lecturer at Imperial College London, said, “El Nino could worsen the situation in countries that are already affected by climate change. Countries may experience severe heat waves, droughts and wildfires. Also, the world is getting warmer as humans continue to burn fossil fuels. So 2023 is likely to be warmer than 2016 when El Niño starts.”
The burning of fossil fuels and the destruction of forests have increased the Earth's temperature by about 1.2 degrees Celsius since the Industrial Revolution. If El Niño returns in 2023, global average temperatures could exceed 1.5 degrees Celsius. It should be noted that the world leaders promised to keep the temperature of the world at this level by the end of this century.
Impact of El Niño in Bangladesh
Due to the influence of El Nino, the global climate conditions are erratic. Temperatures in many parts of the world have soared above 42 degrees Celsius under the influence of a very strong El Niño. The temperature in different parts of Bangladesh has already exceeded 40 degrees, in some places it has even reached 42 degrees. Crop fields, paddy and vegetable fields are burning due to intense heat, fruit buds are dropping prematurely. The number of people suffering from various diseases including diarrhea and heat stroke is increasing.
There is an 80% chance of El Nino occurring this year by July, August or September, or it could occur in the months of October, November or December. Either way, El Niño will have a massive global impact. And due to this year's El Nino, Bangladesh may experience below-normal rainfall, warmer-than-normal temperatures, drier climate and even increased frequency of cyclones for the next six to eight months. Generally, during El Nino years, the greater Ganga-Meghna-Brahmaputra basin receives less than normal rainfall, resulting in There is a drought. For example, the drought of 1982-83 and 1997. This year the rainfall in Bangladesh has also decreased. Cyclones in Bangladesh in 1963, 1970, 1985, 1991, 1997 also occurred during El Nino years. However, exceptionally 2007 Cedar and 2009 Bijli occurred in La Nina years. And Aila happened between La Nina and El Nino. In other words, big storms have occurred in Bangladesh during El Nino or La Nina years. Due to the drought caused by El Nino, there will be shortage of water supply in Bangladesh. In addition, water supply will also be disrupted due to low rainfall. Desiccation of river levels will lead to intrusion of brackish water from the sea, causing drinking water shortages for residents who depend on this source. But this problem of water is not new in Bangladesh; In addition to RL Nino, Bangladesh has severe water shortage.
Also, if agricultural production declines, cities will face food security challenges. As a result, the number of poor people in the city will increase. El Nino can have a strong impact on agriculture in Bangladesh. Such as water scarcity, soil erosion and disruption of planting season. Rice yield will decrease due to less rainfall. This can significantly reduce food production. Droughts and devastating cyclones can strike during El Nino, as happened in 1991 and 1997. Biodiversity, wildlife will also be threatened due to drought conditions.
Climate change in the world, El Niño and La Niña are normal but the reckless activities of the people are making the situation more dire. Humans are destroying the balance of the environment by cutting down more trees for their own needs, polluting the air by burning fossil fuels and increasing carbon-emitting activities, including excessive amounts of vehicles and factories. As a result of this, living on earth is becoming very difficult. So if we want to bequeath a habitable planet to our next generation, it is imperative that we become aware immediately.
