El Nino vs La Nina: A Weather Story

Chanel Turner

“If you want to understand how interconnected our planet is – how patterns and events in one place can affect life half a world away – study El Nino.” (Nasa)

Weather is something we as humans are so vulnerable to. Whether it be the increasing heat waves and wild fires sweeping the world, or heavy rain causing flooding and landslides, or heavy ice and snow seeing our winter days get a lot more frantic. We are so often victim to Mother Nature.

But what if we could understand nature better? What if we could see weather through new eyes? And try to not just be a step ahead of it, but also understand these natural causes with greater rationale? We are as humans a key part of these natural processes, and with the onslaught of climate change, strong weather patterns will only become more common. So today, we have chosen to use our resources to better understand the natural weather patterns called El Nino and La Nina.

Natural phenomena like El Nino and La Nina have been noted by fisherman in Peru since as far back as the 1800s. Occurring at regular intervals, these phenomena have immense effects on weather patterns in regions surrounding the Pacific Ocean, even effecting jet streams; and can be strong enough to temporarily disrupt weather patterns around the world. These patterns are thought to have even influenced expeditions of historians like Claudio Pizarro. In the words of NASA: “If you want to understand how interconnected our planet is - how patterns and events in one place can affect life half a world away - study El Nino.” (Nasa) Visualisation by ENSO.

So, what exactly is El Nino? What are the differing effects of El Nino versus La Nina? And how can we use data to tell a visual story of just how powerful weather really is?

What is El Nino?

El Nino is a ‘weather phenomenon that occurs irregularly in the eastern tropical Pacific every two to seven years. When the trade winds that usually blow from east to west weaken, sea surface temperatures start rising, setting off a chain of atmospheric impacts.’ (Vox) It happens in a certain spot of the Pacific Ocean, right along the equator, aptly placed to wreak havoc on weather patterns across the globe. Here we see El Nino visualised by NOAA.

Named by Peruvian fisherman in the 1800s, El Nino means ‘little boy’ or ‘Christ child’ in Spanish; and was named when fisherman ‘noticed a mysterious warm current that would appear around Christmas’ (Vox). It can bring heavy rain to California, but can also bring huge droughts to Australia, destructive floods in Peru; and this phenomenon even saw 2015’s record breaking temperatures around the world, as seen in this visualisation by EarthObservation.Nasa.

Noticeable El Nino effects


  • Jet Stream shifts south

  • Heavy rain, floods and thunderstorms

  • Disruptive heat waves

  • Droughts in other regions

  • Fish dying where water is too warm and there is a lack of needed nutrients

What is La Nina?

As with El Nino, La Nina takes a Spanish name from Peruvian fisherman, but this time meaning ‘little girl’. Unlike her brother however, La Nina is associated with the circulation of colder than usual oceans: ‘Winds push so hard west, that surface water of Pacific close to the Americas gets colder than usual.’ Here we see La Nina visualised by NOAA.

La Nina can have a strong impact on rainfall across different seasons in Pacific countries like New Zealand.

Seeing what are usually dry, sunny and warm summers turn to rainy, humid summers, with both New Zealand’s North and South Island seeing above average rain fall through their warmest months of November to February. (NIWA)

Noticeable La Nina Effects


  • Displaces the Jet Stream north

  • Flooding and rain in North-west America

  • Droughts in the southern half of US and other regions

What global effects do they cause?

“Episodic shifts in winds and water currents across the equatorial Pacific can cause floods in the South American desert while stalling and drying up the monsoon in Indonesia and India. Atmospheric circulation patterns that promote hurricanes and typhoons in the Pacific can also knock them down over the Atlantic. Fish populations in one part of the ocean might crash, while others thrive and spread well beyond their usual territory.” (Earthobservatory.NASA)

Once an El Nino is declared, any extreme weather event that occurs thereafter can be blamed on this powerful circulation of warm water. El Ninos can even transfer heat stored in the deeper layers of the ocean to the surface, and can not only cause ocean temperature changes, it can also affect the sea surface height - as seen in this visualisation of Ocean temperature from December 2015 (NEO). As you can imagine, when combined with the effects of global warming, these events can lead to record hot years, as in 2015.

Effects on Chlorophyll Concentrations

During El Nino, warmer water is less nutrient rich for fish and other sea life, thus there is a lower Chlorophyll concentration (from plankton bloom). This means less food supply for fish. In April 2016, nearly 8,000 tons of sardines died and washed up along the coast of Chile; and it was attributed to the November 2015 – February 2016 El Nino effect. We can also see in this visualisation from December 2015, there is a clear lack of Chlorophyll along the equator through El Nino (NEO).

Effects on the Jet Stream

“Because of the vastness of the Pacific basin - covering one-third of the planet - these wind and humidity changes get transmitted around the world, disrupting circulation patterns such as jet streams (strong upper-level winds). We know these large-scale shifts in Pacific winds and waters initiate El Nino. What we don't know is what triggers the shift. This remains a scientific mystery.” (NASA)

So, there we have it – equatorial weather at its most complex!

Weather is a complex, powerful and truly commanding presence. With over 70% of Earth covered in water, it’s no surprise our Oceans can dictate global weather patterns, and have such destructive effects on human life. We at Pufferfish believe knowledge is power, and the more we can unearth and understand about our world, the more we can adapt, react and survive.

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