Climate change refers to long-term shifts in temperatures and weather patterns. These shifts may be natural, but since the 1800s, human activities have been the main driver of climate change, primarily due to the burning of fossil fuels (like coal, oil, and gas), which produces heat-trapping gases. The largest and most important short-term climate changes are the oscillations between an El Niño and a La Niña. This cycle is called the El Niño southern oscillation, or ENSO, and it repeats every 2 to 7 years. To understand the ENSO, it is important to know what happens during a normal year.... Show more Climate change refers to long-term shifts in temperatures and weather patterns. These shifts may be natural, but since the 1800s, human activities have been the main driver of climate change, primarily due to the burning of fossil fuels (like coal, oil, and gas), which produces heat-trapping gases. The largest and most important short-term climate changes are the oscillations between an El Niño and a La Niña. This cycle is called the El Niño southern oscillation, or ENSO, and it repeats every 2 to 7 years. To understand the ENSO, it is important to know what happens during a normal year. Normally, the trade winds blow across the Pacific Ocean near the equator from east to west. This causes warm water to pile up in the western Pacific. In the eastern Pacific, along the west coast of South America, the water is cold, and upwelling occurs offshore. During an El Niño, surface water temperature in the Pacific is warmer than usual, and the trade winds weaken or reverse direction. The winds blow east instead of west, so warm water piles up off the west coast of South America. With warm, low-density water at the surface, upwelling does not occur. By altering atmospheric and oceanic circulation, an El Niño changes global climate patterns. Some regions receive more rainfall than normal, including the west coasts of North and South America. Other regions receive less rainfall than normal, including parts of South America, Australia, and Indonesia. An El Niño typically lasts for one or two years. Following an El Niño, the normal circulation pattern may resume. Often, however, an El Niño is followed by an exaggeration of the normal pattern. When the reaction is extreme, this is a La Niña. During a La Niña, trade winds blow from east to west and warm water piles up in the western Pacific, the same as occurs during a normal year. However, ocean temperatures along coastal South America are colder than normal, and cold water reaches farther into the western Pacific than usual. These events change global climate patterns as well. In many locations, a La Niña produces the opposite climate variations from an El Niño. For instance, parts of Australia and Indonesia that are drier than normal during an El Niño are typically wetter than normal during a La Niña. Show less
Climate change refers to long-term shifts in temperatures and weather patterns. These shifts may be natural, but since the 1800s, human activities have been the main driver of climate change, primarily due to the burning of fossil fuels (like coal, oil, and gas), which produces heat-trapping gases. The largest and most important short-term climate changes are the oscillations between an El Niño and a La Niña. This cycle is called the El Niño southern oscillation, or ENSO, and it repeats every 2 to 7 years. To understand the ENSO, it is important to know what happens during a normal year. Normally, the trade winds blow across the Pacific Ocean near the equator from east to west. This causes warm water to pile up in the western Pacific. In the eastern Pacific, along the west coast of South America, the water is cold, and upwelling occurs offshore.
During an El Niño, surface water temperature in the Pacific is warmer than usual, and the trade winds weaken or reverse direction. The winds blow east instead of west, so warm water piles up off the west coast of South America. With warm, low-density water at the surface, upwelling does not occur.
By altering atmospheric and oceanic circulation, an El Niño changes global climate patterns. Some regions receive more rainfall than normal, including the west coasts of North and South America. Other regions receive less rainfall than normal, including parts of South America, Australia, and Indonesia. An El Niño typically lasts for one or two years.
Following an El Niño, the normal circulation pattern may resume. Often, however, an El Niño is followed by an exaggeration of the normal pattern. When the reaction is extreme, this is a La Niña. During a La Niña, trade winds blow from east to west and warm water piles up in the western Pacific, the same as occurs during a normal year.
However, ocean temperatures along coastal South America are colder than normal, and cold water reaches farther into the western Pacific than usual. These events change global climate patterns as well. In many locations, a La Niña produces the opposite climate variations from an El Niño. For instance, parts of Australia and Indonesia that are drier than normal during an El Niño are typically wetter than normal during a La Niña.
Join 4M+ learners. Unlock unlimited quizzes, wrong-answer tracking, flashcards + reminders, study guides, and 1-on-1 challenges.