As New Zealand begins the long, costly task of clearing up after Cyclone Gabrielle cut a devastating path across much of the North Island on Feb 12 and 13, the recriminations and finger pointing have started.

The cleanup and rebuilding may take years, and even longer in remote parts, with costs running into the billions of dollars.

What made the cyclone worse for New Zealand was that it followed nearly a week of torrential rain in late January that caused the worst flooding in the nation's history.

Green Party leader James Shaw delivered an impassioned speech in Parliament on Feb 14, saying: "I struggle to find words to express what I am thinking and feeling about this particular crisis. I don't think I've ever felt as sad or as angry about the lost decades that we spent bickering and arguing about whether climate change was real or not, whether it was caused by humans or not, whether it was bad or not, whether we should do something about it or not, because it is clearly here now, and if we do not act, it will get worse."

Shaw's speech highlighted the growing concern in New Zealand and across the world on the increasing impact of climate change on global weather patterns.

Sandeeka Mannakkara, a lecturer in the Department of Civil and Environmental Engineering at the University of Auckland, said it was high time the country moved away from reactive responses to natural hazard events and adopt a proactive approach.

Joao de Souza, director of the Moana Project, which aims to improve understanding of coastal ocean circulation, connectivity, and marine heat waves, said the waters in the Tasman Sea and around New Zealand have been unusually warm in recent years.

"In the next decades down to the end of this century, we anticipate that ocean temperatures will steadily climb and extreme events such as marine heat waves and storms will become more common, intense, and long-lasting," he said. "The actual trajectory, however, depends on how society will tackle the climate change challenge."

Writing jointly for academic website The Conversation, Alex Lo, senior lecturer in climate change at the Victoria University of Wellington, and Faith Chan, associate professor of environmental sciences, University of Nottingham, said the two extreme weather events in New Zealand this year "have brought the consequences of climate change into sharp focus".

Most expensive event

The flood in Auckland, which began on Jan 27, was the most expensive weather event ever seen in New Zealand while Cyclone Gabrielle prompted a national state of emergency, only the third in the country's history.

Storms, floods and heat waves are expected to become more frequent and intense, yet many cities are poorly prepared.

"Perhaps not surprisingly, there is now a lot more talk about the need for 'sponge cities', with Auckland being a prime candidate. The basic principle is to manage urban flood risks by utilizing more natural drainage and flood-resilient systems and material," Lo and Chan said in their article, published Saturday.