The severe weather expected to hit the country over the next few days could become a lot more common.
Heavy rain and winds are expected for most of the North Island and upper South, due to the remnants of Cyclone Debbie.
New research has found heat waves, droughts and floods have increased because of global warming.
Study leader Professor Michael Mann from Pennsylvania State University told Mike Hosking that's causing dangerous changes to jet streams.
"Changing the jet stream in a way that slows it down and leads to an amplification of these low and high pressure systems gives us the unprecedented weather extremes," he said.
Mann said this is something scientists have suspected for a long time.
"Not only are these types of extreme weather events increasing, but we can show that in the climate models, it's clearly a result of the warming of the planet."
LISTEN ABOVE AS PROF MICHAEL MANN SPEAKS WITH MIKE HOSKING