El Niño - Climate Change in the Pacific Ocean


El Niño refers to the change in climate across the Pacific Ocean.  Although it normally occurs every two to seven years, the El Niño phenomenon has taken place more often in the past three decades. El Niños have an effect on climate and weather around the globe.  A single phase can last for about one and a half years and is often followed by an opposite climate pattern called, La Niña.

The term El Niño means “Christ child” and  was first used by Peruvian fisherman. They discovered that in some years there were fewer fish around Christmas time.

In normal years, cold water comes from the Antarctic region and flows along the eastern coast of South America. A high-pressure area develops, warms the water on the surface and pushes it in a westward direction. In the western Pacific, the air becomes warmer. A low-pressure area forms and leads to tropical rainfall in Indonesia and northern Australia.

Because of this climate cycle cold water rises from deeper regions of the South American coast to replace the warmer water on the surface. This part of the ocean belongs to the richest fishing regions of the world because fish can find more than enough food.

During a typical El Niño phase, the air pressure is higher than normal in the western Pacific and lower than normal on the South American coast.  Ocean temperatures along Peru and Chile become higher and the water does not have the nutrients that fish need to survive. They stay in the colder regions near the Antarctic. Other animals that feed on fish also suffer so that the whole food chain is affected.. In addition, more rainfall comes to a normally dry area and occasional flooding also occurs. On the other side, eastern Australia and Indonesia are hit by unusual periods of dry weather. Climate experts have seen more tropical storms in the central Pacific during an El Niño year.

El Niño does not only affect the climate of the Pacific regions but has an impact on global climate. Climatologists claim that frequent occurrences of El Niño are another sign of global warming.


Extreme weather caused by El Nino

Extreme weather caused by El Niño - Photo courtesy PDPhoto.org


Related Topics




  • affect = influence, change
  • air pressure = how heavy the air is in a certain region
  • although = while
  • claim = to say that something is true
  • climatologist = a person who studies climate and the weather
  • cycle = if something happens over and over again in the same order
  • decade = a period of ten years
  • develop = create
  • discover = find out
  • effect = result, influence
  • feed on = eat
  • flow = move softly
  • global = worldwide
  • high-pressure = here: when the air is heavy and moves downwards; high-pressure areas bring along very sunny and dry weather
  • in addition = also
  • low-pressure = here: the air is light and move upwards; it creates clouds which lead to rainfall
  • nutrient = food that is needed for plant and animals to grow
  • occasional = once in a while, sometimes
  • occur = happen
  • occurrence = event, when something happens
  • opposite = opposing, the other way around
  • phase = time, period
  • refer to = to be about, means
  • replace = to take the place of
  • richest = here: area with the most fish
  • rise = move to the top
  • sign = signal
  • suffer = here: the situation becomes worse
  • surface = the top part of something
  • survive = live on
  • unusual = not normal