A fisherman tries his luck at Pilot Bay, Mt Maunganui, on a sunny November day. The year ended one of the warmest NZ has ever seen in and out of water. Photo / George Novak
Last year was not only one of the 10 hottest for New Zealand, but also for our wider ocean area, new figures show.
Climate scientist Professor Jim Salinger said his calculations – placing 2020 as the ninth hottest year on record for New Zealand’s land and ocean regions combined – underlined the need for urgent action to slow the rate of warming.
According to state officials, Niwa ran The “seven stations” temperature series, which Salinger pioneered, 2020 is New Zealand’s seventh warmest in 110 years.
The national average of 13.24C follows a climate change trend that places six of our last eight years among the warmest on record, and was pushed for 47 consecutive months without temperatures below the overall average.
Salinger said the wider picture could be seen as more climate stations and ocean temperatures were added.
Nonetheless, it is also consistent with planetary changes.
Sea surface temperatures around New Zealand’s four million square kilometers of exclusive economic zone averaged 14.16C last year, which was 0.38C above normal and the 11th warmest on record.
And the extended data set for ground temperatures, covering 22 stations, recorded a 2020 average of 13.75C – 0.58C above normal and the eighth warmest year in the series.
When those extra ocean and land temperatures put together, the result was 13.93C – or 0.39 above average and the ninth warmest year on record for a combined 150 years.
Salinger said it was important to consider how New Zealand’s vast marine area is also warming, given its economic and environmental importance to our country.
About 20 times the size of our landmass, New Zealand’s oceans support a marine economy that is estimated to be worth $ 4 billion a year.
The resources it relies on are increasingly threatened by rising sea temperatures.
The Tasman Sea, in particular, is warming at one of the fastest speeds on Earth – up to three times the global average.
“If we are in a situation where we are effectively taking a warm shower, it will affect us dramatically,” he said.
“These numbers really show that warming is leaping forward, and we need to do it now, both in terms of mitigation and adaptation.”
The share acquisition followed Salinger, with fellow scientists Professor James Renwick and Dr. Howard Diamond, published findings indicate that the New Zealand region has warmed to 0.66C since 1871.
All of the warmest years have been recorded since 1998, in line with global warming.
Salinger noted that the La Nina system have an influence on ocean temperatures in 2020.
The formation of naturally occurring climate drivers later in the year coincides with the coastal waters around parts of New Zealand close to ocean heat wave conditions.
Annular Southern Mode, or SAM – a key climate indicator – is also in a positive phase for the 2020 period, bringing westerly winds further south over the southern oceans but lighter winds and clearer skies over New Zealand.
This week our coastal waters are warmer than usual – ranging from 0.5C to 0.9 above average – but ocean temperatures are expected to drop as the south changes.