ENSO, more commonly known as El Niño, is a climate event that occurs every three to seven years. It is caused by a rise in temperature of the Pacific Ocean as well as a change in surface pressure. Predicting when the next ENSO event is going to occur can be difficult, but there are a number of early warning signs, such as an increased surface pressure above the Indian Ocean. The effects of an ENSO event can be seen across the world, with floods, droughts, and other weather events. Extreme changes in weather and climate patterns can also affect local trade and industries in many countries.
The full name for ENSO is El Niño Southern Oscillation. When ENSO occurs, the temperature of the Pacific Ocean increases. This is merged with a change in surface pressure of the Pacific and this combination that causes the weather effects. The definition of this event is when the sea warms at least 0.9°F (0.5°C). La Nina, a similar event, happens when the sea cools by the same amount.
ENSO occurs periodically, with the time frame fluctuating between three to seven years. When ENSO emerges, it can cause changes in weather across the globe for approximately 12 months. This time period can range from a few months to two years, however, and it is difficult to predict how long a particular event will last.
There are a number of initial warning signs of an El Niño event. Some of these include rain in deserts of Peru, which is caused by warm air rising in this region, and a measurable increase in pressure above water in the Indian Ocean. The pressure above waters in Australia may also increase. Some regions, such as the central Pacific Ocean, may experience a decrease in air pressure.
The effects of an ENSO event can be severe. Regions of Asia and Australia will often be subjected to large amounts of rainfall. This is due to lower air pressure above areas of warm water, which causes moist air to rise, and in turn leads to heavy rain. South America will also usually experience heavy rain. Other consequences include droughts in parts of Africa and weather changes in North America.
People and industries are often directly affected by ENSO. Fisherman in some regions, for example, may find it more difficult to continue their trade. This is due to the event causing a lack of nutrients in the water, which leads to decreased stock. Along with flooding and droughts, this impact on local industries can be hugely damaging and costly.