{"id":344906,"date":"2026-03-24T06:55:12","date_gmt":"2026-03-24T06:55:12","guid":{"rendered":"https:\/\/www.newsbeep.com\/nz\/344906\/"},"modified":"2026-03-24T06:55:12","modified_gmt":"2026-03-24T06:55:12","slug":"what-the-coming-el-nino-climate-pattern-means-for-nz-in-a-warming-world","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/nz\/344906\/","title":{"rendered":"What the coming El Ni\u00f1o climate pattern means for NZ in a warming world"},"content":{"rendered":"

By Jim Salinger of \"The<\/a><\/p>\n

\"The<\/p>\n

\"Drought<\/p>\n

\nDrought conditions on a farm in South Taranaki in March last year.
\nPhoto: RNZ \/ Robin Martin\n<\/p>\n

After the planet’s 11 hottest years on record<\/a>, scientists are warning the return of an El Ni\u00f1o climate pattern could push global temperatures even higher.<\/p>\n

Today, the World Meteorological Organisation reported that the past decade has been the warmest observed, with rising greenhouse gas emissions driving record ocean heat, melting ice and more extreme weather.<\/p>\n

On top of those findings comes the growing prospect of El Ni\u00f1o, which could emerge by New Zealand’s spring and amplify the effects of global warming in the months beyond.<\/p>\n

At this stage, the event is expected to be moderate, resulting in global mean sea surface temperatures of around 1C warmer than average. However, there is still considerable uncertainty in how it will develop.<\/p>\n

For the planet, El Ni\u00f1o can bring a wide range of damaging impacts, from wildfires and drought in some regions to heavy downpours and flooding in others.<\/p>\n

It can also have significant impacts for New Zealand and its primary sector. Some stand-out events – such as in 1982-83, 1997-98 and 2015-16 – caused severe droughts that cost the economy hundreds of millions of dollars.<\/p>\n

Notably, it follows a rain-soaked start to the year across much of New Zealand, partly owing to the lingering, warm-and-wet influence of El Ni\u00f1o’s climate driver counterpart: La Ni\u00f1a.<\/p>\n

As that La Ni\u00f1a fades out over coming weeks, as it is forecast to, scientists will be monitoring the potential seesaw-like shift to El Ni\u00f1o.<\/p>\n

But, in New Zealand’s part of the world particularly, such swings do not play out in isolation: other large-scale patterns are likely to influence how El Ni\u00f1o’s effects are felt.<\/p>\n

El Ni\u00f1o explained<\/p>\n

The name El Ni\u00f1o – meaning “Christ Child” – was given by Peruvian fishers who noticed warm waters appearing off their coast around Christmas. Its global significance was recognised over time.<\/p>\n

It occurs when the usual trade winds across the tropical Pacific weaken, sometimes reversing direction, allowing warmer water to spread eastward and raise sea surface temperatures. In contrast, La Ni\u00f1a features stronger trade winds and cooler waters.<\/p>\n

Together, these phases form the El Ni\u00f1o\/Southern Oscillation (ENSO), which typically cycles every two to seven years and is measured by sea surface temperatures in the central equatorial Pacific.<\/p>\n

\"This<\/p>\n

\nThis graph illustrates how El Ni\u00f1o climate patterns have historically coincided with warmer mean global sea surface temperatures, while its counterpart La Ni\u00f1a has come with the opposite effect. The data was sourced from the Copernicus Climate Change Service and the US National Oceanic and Atmospheric Administration.
\nPhoto: CC BY-NC-ND<\/a>\n<\/p>\n

At a global scale, El Ni\u00f1o events make for warmer years by raising air temperatures and reducing the rate at which the ocean absorbs heat.<\/p>\n

They tend to bring warmer conditions to parts of Asia and North America, wetter weather to parts of the United States and South America, and drier conditions in Australia and parts of Africa.<\/p>\n

In New Zealand, El Ni\u00f1o typically shifts atmospheric circulation patterns. Winters tend to feature more southerly winds, spring more south-westerlies and summer more westerlies.<\/p>\n

This generally leads to cooler conditions overall, although eastern areas such as Wairarapa, Hawke’s Bay and Gisborne can still experience warmer than average summers.<\/p>\n

Rainfall patterns also change. El Ni\u00f1o is often associated with drier conditions in the north and east of both islands, and wetter conditions in Southland and along the West Coast of the South Island.<\/p>\n

By contrast, La Ni\u00f1a tends to bring warmer temperatures and different regional rainfall patterns, often with wetter conditions in the north and east. Because El Ni\u00f1o produces a clearer signal for New Zealand, it is usually more predictable.<\/p>\n

The wider picture<\/p>\n

Alongside ENSO, longer-term climate variability also plays a role.<\/p>\n

Another cycle called the Interdecadal Pacific Oscillation (IPO) resembles ENSO and similarly influences patterns across the Pacific Basin, but operates on time scales of 20 to 30 years.<\/p>\n

In its positive phase, warmer-than-average sea surface temperatures occur in the central equatorial Pacific, while cooler conditions prevail elsewhere in the basin. The opposite occurs in the negative phase.<\/p>\n

\"The<\/p>\n

\nThe Interdecadal Pacific Oscillation (IPO) is a climate pattern that tracks long-term shifts in ocean temperatures across the Pacific. In its positive phase, warmer waters sit in the central Pacific (2), with cooler waters to the north (1) and south (3); the pattern reverses in its negative phase. The colour scale shows temperature differences from average, with reds indicating warmer-than-normal waters and blues cooler-than-normal conditions.
\nPhoto: CC BY-NC-ND<\/a>\n<\/p>\n

The IPO can either amplify or dampen the effects of global warming. In New Zealand, positive phases have tended to slow regional warming, while negative phases have accelerated it.<\/p>\n

Since 1998, the IPO has been in a negative phase. During this period, New Zealand’s warming rate has increased markedly, from about 0.14C per decade in earlier decades to around 0.27C per decade more recently.<\/p>\n

\"The<\/p>\n

\nThe Interdecadal Pacific Oscillation (IPO) is a climate pattern that shifts between positive and negative phases over decades. Values above zero indicate a positive phase, while values below zero indicate a negative phase, each linked to different patterns of ocean temperatures and climate. These shifts influence how quickly New Zealand warms, with recent decades dominated by a negative phase that has tended to accelerate regional warming.
\nPhoto: BY NC-NY-ND<\/a>\n<\/p>\n

Another important influence is the Southern Annular Mode (SAM), which affects the strength and position of westerly winds around New Zealand.<\/p>\n

In its positive phase, high-pressure systems tend to dominate, pushing the westerly winds further south and bringing calmer, warmer conditions. This can lead to drier weather in the west and south, but wetter conditions in the north.<\/p>\n

In its negative phase, lower pressure dominates, bringing stronger westerlies, cooler temperatures and wetter conditions, particularly in western regions.<\/p>\n

SAM operates year-round but has its strongest effects in summer, interacting with both ENSO and the IPO.<\/p>\n

How these three drivers play off one another will ultimately influence what unfolds in the coming seasons.<\/p>\n

With El Ni\u00f1o expected to develop over winter, warmer sea surface temperatures will spread across the Pacific. The IPO, meanwhile, remains firmly in its negative phase, meaning warmer conditions are likely to persist around New Zealand.<\/p>\n

At the same time, SAM is expected to fluctuate between positive and negative phases, although it has shown a tendency toward more positive conditions as the climate warms.<\/p>\n

Together, these influences point toward the possibility of a significant El Ni\u00f1o event unfolding against the backdrop of a steadily warming planet.<\/p>\n

Whether this evolves into another severe event for New Zealand remains to be seen. The climate of each season, after all, carries its own distinct personality.<\/p>\n

But, coming on the back of the world’s warmest period on record, it warrants our close attention.<\/p>\n

* Jim Salinger is an Adjunct Research Fellow at Te Herenga Waka – Victoria University of Wellington<\/p>\n

This story was originally published on The Conversation.<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"By Jim Salinger of Drought conditions on a farm in South Taranaki in March last year. Photo: RNZ…\n","protected":false},"author":2,"featured_media":344907,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[48,47,111,43,139,69,49,46,44,45],"class_list":["post-344906","post","type-post","status-publish","format-standard","has-post-thumbnail","category-new-zealand","tag-audio","tag-current-affairs","tag-new-zealand","tag-news","tag-newzealand","tag-nz","tag-podcasts","tag-public-radio","tag-radio-new-zealand","tag-rnz"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/344906","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/comments?post=344906"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/344906\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media\/344907"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media?parent=344906"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/categories?post=344906"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/tags?post=344906"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}