Auckland’s Historic Flooding Linked to Climate Change?

Aucklanders experienced their worst flooding ever, as record amounts of rain poured on the city starting Friday, 27 January, and continued through the weekend.

The downpour has flooded many houses, caused at least four deaths, landslips that destroyed properties, outages in 3500 homes, and evacuation of residents (Auckland floods, 2023).

NZ emergency services have been busy over the weekend with responding to weather-related calls and rescuing people from their properties hit by landslips or trapped by floodwaters (Auckland floods, 2023).

On Thursday, just the day before the downpour, Met Services warned Auckland of potentially heavy rain coming on Friday night. Still, throughout the day, it has already been raining across the city at Auckland Airport, with around 70mm of rain recorded from sunrise and early evening, with the amount of rain doubling within the next four hours, flooding the airport’s terminal with shin-high waters, causing operations to shut down from Friday until Saturday. Although flights resumed Sunday morning, more rain forecasts for the following day could close operations again (Earley, 2023).

Sir Elton John’s two-day concert was also cancelled due to the severe weather scheduled on Friday and Saturday nights.

Regarding the downpour that started Friday night, MetService meteorologist Lisa Murray, which has issued its worst-event Red Warning, said, “Until now, Auckland’s wettest January was in 1986 with 206mm, but already in January 2023, we have had an extraordinary 320mm of rain at Auckland Airport” (Morton, 2023).

“In addition, it looks like Auckland is having its wettest month ever since records began,” she said, adding totals now topped July 1998, when 304mm fell over the month (Morton, 2023).

The city declared a state of emergency on Friday night, 27 January 2021, to deal with unprecedented flooding. The state of emergency in the city remained until Monday, 30 January, as of writing this blog post.

NZ Herald reports that heavy rains are also forecasted for the city and surrounding areas for the following week, and authorities urge highly vulnerable areas to prepare (Weather: Auckland, 2023).

NIWA says that Auckland has already received 38% of its annual rainfall and 769% of its usual January rainfall. If more rain comes within a few days, it can topple its “wettest month” record (Weather: Auckland, 2023).

Is climate change behind all these flood events?

The deluge on Friday that continued over the weekend, bringing severe flooding and massive damages to the city, was caused by a combination of events.

NZ Herald’s article, “Explained: What caused Auckland’s wettest day – and where climate change fits in” states that “an ocean-atmosphere state primed by La Niña, Coastal waters warmed by relentless marine heatwave conditions, and A moisture-packed, slow-moving subtropical low-pressure system bearing a long band of squeezed thunderstorms that unloaded torrents of water in the space of hours.”

“Auckland’s wettest day in history was driven by what experts are calling a freak combination of elements, making it a standout event even when set against major deluges of our last three years under La Niña”, the article says.

NIWA’s meteorologist and forecaster Ben Noll, who had been tracking the storm, tweeted what he believes is the reason behind Auckland’s unprecedented rainfall.

• La Niña (northerly low, blocking high)
• Precipitable water values above the 90th percentile
• Saturation through the atmospheric column
• Low-level jet, convergence & convection
• Marine heatwave
• All on the backdrop of a warming climate.

Victoria University climate scientist Professor James Renwick said more events like these would continue to happen unless we can get a grip on climate change, the NZ Herald article mentioned.

The video below shows footage of the flooding in New Zealand.