New Zealand is grappling with two consecutive extreme weather events—massive floods followed by tornadoes—that have claimed the lives of at least 12 people and left hundreds of thousands no power. The high winds and water of Hurricane Gabrielle washed away coastal roads on the northern island and caused bridges to snap and break. Landslides have covered runways with slushy mud, and homes and streets have been submerged under water, just weeks after heavy rains also caused widespread flooding. This country has declared a national emergency only for the third time in its history.
New Zealand’s climate change minister, James Shaw, wasted no time pointing the finger at the root cause of weather disasters, telling New Zealand parliament: “This is climate change.”
James Renwick, a climate scientist and professor at Victoria University in Wellington, says he may be right, but there is still no evidence from attribution studies. He said: “Typhoons themselves are not unusual for New Zealand, as they regularly move out of the tropics and come close enough to cause alarm. “We queue for these on a regular basis. Some of them are unremarkable and some are downright catastrophic,” Renwick said.
Olaf Morgenstern, an atmospheric scientist at New Zealand’s National Institute of Atmospheric and Water Research, said our warming planet may have increased the intensity of this cyclone due to seawater. warmer. Hotter oceans mean that if a tornado hits, “it will be stronger, contain more moisture, more energy, and stay energized longer,” he said.
New Zealand has also experienced sea heat wave related to La Niña, a cyclical weather system in the Pacific Ocean that has dominated the region for the past three years. These may have prompted the tropical storm. “Because it was unusually warm, it didn’t lose that much intensity—it was still pretty strong when it got here,” says Morgenstern.
Record rainfall and flooding preceded the tropical storm that devastated the northern island in late January—which also appears to be linked to climate change. January broke a century record during Auckland’s wettest month, with 539 mm of rain recorded, half of which fell in a single day. That’s really unprecedented, Renwick said, but the likely impact of climate change on New Zealand will be more complex than simply more rain.
The biggest influence on the regional climate are the winds that blow across the country from west to east. These cause massive rainfall on the west coast of the southern island in particular. Sound Milford, the popular fjord there is popular with tourists, is one of the wettest places on Earth, receiving an average annual rainfall of 6.8 meters. The island’s mountains then push moisture out of the air as it passes through them, creating a rain shadow that leaves the east coast relatively dry.
But even introducing small changes in wind direction or wind speed, you can lead to big changes in local climate, says Renwick. Climate modeling shows that westerly winds are likely to be stronger. “Whether they lie to New Zealand a lot is a difficult question to answer, because there are some moving parts of that story, but the big picture is the winds get a little stronger over time,” he said. speak. The increase in strength is expected to bring more rain to the west coast and less to the east, leading to hotter temperatures.
