{"id":5898,"date":"2023-03-28T22:00:00","date_gmt":"2023-03-28T22:00:00","guid":{"rendered":"https:\/\/modernsciences.org\/staging\/4414\/?p=5898"},"modified":"2023-03-17T05:27:31","modified_gmt":"2023-03-17T05:27:31","slug":"the-flap-of-a-butterflys-wings-why-autumn-is-not-a-good-time-to-predict-if-el-nino-is-coming","status":"publish","type":"post","link":"https:\/\/modernsciences.org\/staging\/4414\/the-flap-of-a-butterflys-wings-why-autumn-is-not-a-good-time-to-predict-if-el-nino-is-coming\/","title":{"rendered":"The flap of a butterfly\u2019s wings: why autumn is not a good time to predict if El Ni\u00f1o is coming"},"content":{"rendered":"\n
\n \n
\n \n Shutterstock<\/span><\/span>\n <\/figcaption>\n <\/figure>\n\nNandini Ramesh<\/a>, CSIRO<\/a><\/em><\/span>\n\n

Remember the butterfly effect? It was a popular summary of chaos theory suggesting a butterfly flapping its wings in the Amazon could cause a tornado in Texas. <\/p>\n\n

Right now, a version of this is making it hard for us to predict whether an El Ni\u00f1o event<\/a> is coming. <\/p>\n\n

After three consecutive La Ni\u00f1a years, that part of the cycle is officially over<\/a>. But it\u2019s not certain an El Ni\u00f1o will replace it. Australia\u2019s Bureau of Meteorology this week announced an El Ni\u00f1o watch<\/a> \u2013 a \u201cwait and see\u201d forecast giving us a 50% chance of an El Ni\u00f1o forming later this year. Other climate forecasting agencies around the world are sending a similar message<\/a> to the Bureau of Meteorology\u2019s, that we are on an El Ni\u00f1o watch. <\/p>\n\n

While the conditions seem right for El Ni\u00f1o to form and likely bring hotter, drier weather to Australia, the world\u2019s chaotic climate system is in a very unpredictable state. Fast forward three months, and our models will be much more certain about whether El Ni\u00f1o really is coming \u2013 or whether the system will remain in a neutral, or near-normal, state. <\/p>\n\n\n\n

Why can\u2019t we predict what\u2019s going to happen?<\/h2>\n\n

At this time of year, the El Ni\u00f1o-Southern Oscillation (ENSO) cycle is at its most susceptible to change. Right now, the subsurface waters of the equatorial western Pacific are warmer than usual. If this water rises from deeper down to the surface of the ocean, it will interact with the atmosphere. This usually leads to more rain and floods for Chile, drier, hotter weather for Australia, and a variety of other effects worldwide. <\/p>\n\n\n\n

But this isn\u2019t inevitable. Let\u2019s say a sudden burst of wind strikes, forcing warmer water to stay down deeper. This can disturb the whole cycle. Unexpected windbursts at this time of year can even tip the system into a different mode, ending up neutral or as a La Ni\u00f1a event. <\/p>\n\n

Among climate scientists, this is known as the predictability barrier<\/a> \u2013 and it\u2019s why we can\u2019t say for certain an El Ni\u00f1o is coming until later in the year. <\/p>\n\n

Have we seen unexpected swings in the cycle before?<\/h2>\n\n

Yes, most recently in 2014. Early that year, climate models were predicting a truly enormous El Ni\u00f1o was set to begin. <\/p>\n\n

But the monster El Ni\u00f1o didn\u2019t happen<\/a>. Cooler water flowed into the south-eastern Pacific at a critical time of year, while the unusual timing of westerly windbursts kept the warmer water down deeper. <\/p>\n\n

The end result was that the whole system was nudged into a different configuration of a weak El Ni\u00f1o. It took another year for a full El Ni\u00f1o to develop. This time, it was very strong<\/a>. <\/p>\n\n

Could we really see a fourth La Ni\u00f1a? It could happen but it would be very unusual, given we\u2019ve never seen four years of successive La Ni\u00f1a conditions. At present, the heat build-up under the surface of the equatorial Pacific suggests an El Ni\u00f1o is coming, but it\u2019s not a given. <\/p>\n\n

Why do we get these cycles anyway?<\/h2>\n\n

We believe the El Ni\u00f1o-La Ni\u00f1a cycle has a very long history, dating back to the formation<\/a> of the Pacific Ocean about 190 million years ago. <\/p>\n\n

That\u2019s because this ocean basin is the largest on Earth \u2013 and has a lot of seawater sitting along the equator. In our models, we can see the El Ni\u00f1o cycle forming out of the fluid dynamics, as warmer or cooler water moves<\/a> across the ocean. <\/p>\n\n

The Atlantic has a smaller version, named the Atlantic Ni\u00f1o. Why is it smaller? Because there\u2019s much less water along the equator in the Atlantic. As a result, the Atlantic Ni\u00f1o has much less of an effect on weather globally. <\/p>\n\n

\n \"Pacific<\/a>\n
\n The El Nino cycle\u2019s significance is due to the sheer size of the Pacific \u2013 and the amount of water along the equator. By contrast, the Atlantic\u2019s equatorial waters are more limited.<\/span>\n Shutterstock<\/span><\/span>\n <\/figcaption>\n <\/figure>\n\n

So when will we know for sure?<\/h2>\n\n

El Ni\u00f1o and La Ni\u00f1a are at their strongest over December and January, though the effects and their timing can differ in Australia depending on where in the country you are. These cycles usually end some time between February and May. <\/p>\n\n

The popular understanding of the butterfly effect and chaos science often gets one thing wrong. Chaotic systems like the world\u2019s weather are not always unpredictable, but can be more or less sensitive to small changes at different times. Between March and May, it can take just a small nudge to flip the system. Later in the year, as either an El Ni\u00f1o, neutral phase or La Ni\u00f1a gathers pace, it is much harder to change course. <\/p>\n\n

It\u2019s like a ball poised on top of a high hill. A very tiny push is enough to send the ball rolling down either one side of the hill or another. The push might even be so tiny you can\u2019t measure it accurately. <\/p>\n\n

That\u2019s why it\u2019s so difficult to predict what\u2019s going to happen, even though we understand the physics behind these events fairly well. The Pacific Ocean and the air overhead are extremely sensitive to \u201cpushes\u201d in any direction from March to May. <\/p>\n\n

But once the ball rolls down one side rather than another, it\u2019s much easier to predict which way it will keep rolling. By June or July, the ball is already rolling down the hill on whichever side it\u2019s going to go, and there\u2019s a lot more confidence and clarity in our predictions. Stay tuned. \"The<\/p>\n\n\n\n

Nandini Ramesh<\/a>, Senior Research Scientist, Data61, CSIRO<\/a><\/em><\/span><\/p>\n\n

This article is republished from The Conversation<\/a> under a Creative Commons license. Read the original article<\/a>.<\/p>\n\n","protected":false},"excerpt":{"rendered":"Shutterstock Nandini Ramesh, CSIRO Remember the butterfly effect? It was a popular summary of chaos theory suggesting a…\n","protected":false},"author":416,"featured_media":5892,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"nf_dc_page":"","fifu_image_url":"","fifu_image_alt":"","footnotes":""},"categories":[13,17],"tags":[727,580,474],"class_list":{"0":"post-5898","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-earth","8":"category-math-and-the-sciences","9":"tag-butterfly-effect","10":"tag-el-nino","11":"tag-the-conversation","12":"cs-entry","13":"cs-video-wrap"},"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/posts\/5898","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/users\/416"}],"replies":[{"embeddable":true,"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/comments?post=5898"}],"version-history":[{"count":1,"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/posts\/5898\/revisions"}],"predecessor-version":[{"id":5899,"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/posts\/5898\/revisions\/5899"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/media\/5892"}],"wp:attachment":[{"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/media?parent=5898"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/categories?post=5898"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/tags?post=5898"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}