Scientists confirm warming seas around New Zealand
25 January, 2019
The water in the New Zealand region is significantly warmer than it was 30 years ago, and all indications are the warming trend will continue, said a NIWA scientist.
Oceanographer Dr Phil Sutton is the lead author on a scientific paper published today, that analyses ocean temperature changes around New Zealand for the last 36 years.
He said the strongest warming near NZ has occurred off the Wairarapa Coast, and the weakest along the northeast coast between North and East Capes.
The increased warmth isn't only at the surface – around New Zealand the increased warmth penetrates in places to 200m deep while in the Tasman Sea it reaches down to at least 850m.
"Since 1981 we are talking of warming of about 0.1 to 0.3ᵒC per decade. That may not sound like a huge amount but slightly stronger warming of about 0.4ᵒC per decade off the east coast of Tasmania has resulted in significant changes to ecosystems which has led to concerns of similar impacts in New Zealand," Sutton said.
The results have been published in the New Zealand Journal of Marine and Freshwater Research.
Sutton and co-author Dr Melissa Bowen, of Auckland University, analysed three data sets and applied mathematical equations to determine if the changes were statistically significant.
The longest data set is daily satellite measurements of sea surface temperatures which began in 1981.
The second set is derived from ship-based measurements of the ocean down to 850m depth along two transects, or lines, from Sydney to Wellington which began in 1991, and Auckland to Suva which started in 1987.
The final data set was information from floats used in the Argo programme, an international network of floats in the world's oceans that measure temperature, salinity and currents in the top 2000m of the oceans.