El Niño

El Nino is famous as the cause of the severe weather that battered the South Pacific during the years 1982-1983

Every few years unusually warm currents occur in the South Pacific Ocean off South America. This rise in temperature is due to a relaxation of the trade winds that move the ocean waters throughout the globe. Without the trade winds, the surface water’s rate of evaporation declines and heat loss slows. With the cooling of the South Pacific disrupted, unusually high temperatures occur along the coastal shores of Chile all the way up to Ecuador. Called El Niño, this periodic increase in temperature fluctuates from a small increase in temperature (2-3ºC) to a large one (8-10ºC). A strong El Niño can influence climate worldwide! For example, 1997 - 1998 were predominated by a very strong El Niño. In North America, the effects of El Niño were felt most in winter with warmer temperatures than usual in the north, and colder temperatures than usual in the south. In years like these, cyclones and hurricanes develop in response to the high ocean temperatures, which in turn release more heat and humidity into the surrounding climate system. These systems then move up the coasts, affecting weather in both North and South America.

The most intense El Niño of the last century occurred in 1982-1983. Around this time, the surface water temperatures of the South Pacific rose about 10ºC higher than normal. The effects were devastating - drought in Australia, flooding in Chile and typhoons in the South Pacific Islands. The Canadian west coast felt the effects of this El Niño as well, experiencing unusually stormy weather throughout the entire winter.