Environmentalists are saying that a green Christmas and spring-like temperatures during peak winter months in Saskatoon is caused by a global weather pattern called El Niño. What does this mean for our climate and world?

Temperatures in Saskatoon are at record highs this year with the average maximum and minimum temperatures in December being 1 C and -10 C respectively. In comparison to the same time last year, the average maximum and minimum temperatures were -14 C and -23 C. This 13 to 15 degree difference in temperature is related to a global weather pattern known as El Niño.

The World Meteorological Organization, a United Nations agency responsible for international cooperation regarding Earth’s atmosphere, climatology and hydrology, made the declaration that El Niño has returned on July 4th 2023. The last El Niño was observed from 2015 to 2016 which is the world’s hottest year on record.  

El Niño is a naturally occurring climate pattern where the ocean surface temperatures in the central and eastern tropical Pacific Ocean become warmer. El Niño means “little boy” in spanish. Earlier Spanish fishermen called it El Niño de Navidad as they noticed the weather phenomenon occurring around Christmas time. 

Normally in the Pacific Ocean, winds blow west along the equator and a process called upwelling takes place. Surface water is taken from South America towards Asia and deep, cold water rises to replace it, hence the name “upwelling”. However, during El Niño, these winds are weakened and warm water can also instead be pushed back east. 

The opposite of this is called La Niña, where the surface of the Pacific Ocean cools as these winds become stronger. El Niño, La Niña and the normal conditions combined make up the three phases of the El Niño-Southern Oscillation (ENSO) cycle. 

The ENSO cycle refers to the variations in sea-surface temperatures and air pressure. A change in air pressure over the Pacific Ocean is referred to as the Southern Oscillation. During El Niño the atmospheric pressure above the ocean decreases. On average El Niño occurs every two to seven years and lasts nine to twelve months. La Niña typically occurs every three to five years and lasts one to three years. 

In 2023 we had just been coming out of a three year period of La Niña, which still had some of the warmest global temperatures on record. During the La Niña period in 2021, roughly 600 people died because of the devastating heat waves. Lytton, British Columbia had a particularly damaging wildfire season and held the record high temperature in Canada of 49.6 C. Without the cooling effects of La Niña, Earth’s warming could become even more pronounced. 

A more extreme El Niño has devastating consequences on not only our winters but also our wildlife and climate. The thermocline is the transition layer that separates the warm surface water from the cold deep water. During an El Niño event, that layer dips farther into the ocean – even as far as 500 feet. As normal upwelling isn’t happening the nutrient rich colder water is not getting to the euphotic zone. This zone is the upper 200 meters of the ocean where many important ecosystems live. Many coastal economies are negatively impacted as fish populations die or migrate. 

An increase in precipitation also occurs during an El Niño event in South America and the southern United States. This is caused by the convection above the warming ocean surface waters which can lead to flooding and erosion. Looking elsewhere, areas in the northern United States and Canada are dryer and warmer which can lead to droughts and negatively impact agriculture.

An El Niño event typically peaks in intensity during the winter months. While we are entering the tail end of winter and experts are predicting that by sometime around April or June of this year El Niño will end, time will only tell how Saskatoon and Canada’s spring and summer will be affected by these warm winter temperatures and reduced snowfall.