Fedaeff also said what may have been considered record-breaking in 1970 is now considered near average.

“For instance, the once record-breaking winter 1971 is 0.75 degrees Celsius cooler than the winter we have just experienced.”

A key difference can be found in carbon dioxide concentrations measured by NIWA at Baring Head, near Wellington.

In the early 1970s they were 320 parts per million, today they are 412 parts per million.

The years 1970 and 1971 were both La Nina years featuring warmer than usual coastal sea temperatures and higher than normal pressure over and to the east of the country which led to more northerly and north-easterly winds than normal.

The winters of 2020 and 2021 were also influenced by La Nina, warm coastal waters, frequent high pressure and more northerly and north-easterly winds than normal.

“These similar winters, decades apart, show us that there are key natural ingredients to getting a warm winter but adding climate change to the mix is like taking the same recipe and swapping plain flour for self-raising,” Fedaeff added.