Barry Brill: Was our recent extreme flooding caused by an undersea volcano?

If the 2023-26 warming spike was the result of Hunga-Tonga, we need not spend a fortune on strengthening the national infrastructure.

Water, water, everywhere….

New Zealand's summer of 2023 saw catastrophic flooding. In late January, an atmospheric river—a concentrated flowing band of tropical moisture—parked itself over Auckland and a record 261mm fell in just 18 hours. Four people died. Over 19,000 properties were damaged. The economic cost reached NZ$2.2 billion.

Chris Morrison: Sensational Findings Point to Hunga Tonga Eruption....

Sensational Findings Point to Hunga Tonga Eruption as Prime Suspect Behind Recent Temperature Spike

In January 2022, a massive underwater volcano called Hunga Tonga suddenly erupted and shot so much water into the upper atmosphere that levels in the stratosphere rose suddenly by at least 10%. It was a genuine one in 100, even 200 year event and was reasonably expected to produce temporary weather changes around the globe. Sure enough, subsequent temperatures showed a 0.3-0.4°C upward spike.

Barry Brill: 'Greenhouse Theory’ is Threatened by the Confounding 2023 Warmth

In March 2023, sea surface temperatures in the North Atlantic began to shoot up.

By June the extent of sea ice around Antarctica was by far the lowest on record. Based on the 30-year midwinter trend, a patch of sea-ice six times larger than New Zealand was suddenly missing.

At that time, there was no El Niño. There had been nothing unusual in the slow build-up of greenhouse gas emissions

Karl du Fresne: Are we allowed to suggest Hunga Tonga might be to blame for the weather mayhem?

The most powerful volcanic eruption of the 21st century happened on January 22 last year in Tonga.

Scientists measure the force of eruptions using something called the Volcanic Explosivity Index, or VEI. (I learned about this from my teenage grandson, who has an encyclopaedic knowledge of volcanoes.)

The eruption of Hunga Tonga-Hunga Ha’apai had a VEI of 5 or 6, depending on which source you believe. According to NIWA, it was the biggest atmospheric explosion recorded in more than a century. As a point of comparison, the cataclysmic Oruanui (Lake Taupo) eruption about 26,500 years ago had a VEI of 8. Krakatoa (1883) scored a 6.