Zealand, Australian and US scientists have just published a study on
last summer's heatwave, finding sea water temperatures around the
South Island turned almost sub-tropical.
Tasman Sea warmed on average by 3.7C above normal to reach 20.6C,
with fish normally found in the tropics straying further south than
they are supposed to.
of Otago physical oceanographer Dr Robert Smith said while this may
be good for recreational fishers, it pointed to the disruption of
ecosystems that could be devastating to some species.
started coming in over summer from local fishermen. On average over
the last 10 years they've caught one or two kingfish per summer
they started catching one or two kingfish per day off the Otago
coastline and there are even a couple of days where they've caught 10
to 12 kingfish."
forests along Otago's coastline, which provide habitat, food and
nursery grounds for fish and species dwelling on the sea floor, were
also unusually absent last summer.
you were a surfer, you could wear board shorts instead of a wetsuit
in Dunedin - almost unheard of - with sea temperatures around the
20-21 degree mark at St Clair.
multi-disciplinary work has shown that regional heat waves can
develop rapidly and have widespread impacts on ecosystems."
study found that the heat wave was driven by the dual effects of warm
atmospheric air and low wind speeds, which would usually have a
cooling effect on the sea.
Smith said a parallel study carried out by Australian-based
scientists showed last year's marine heat wave would likely not have
happened without man-made influence.
conditions be at all like they were last summer - as they appear well
on track to be - sea temperatures could rise further.
is what some children today can expect to see in their lifetimes,"
Dr Smith said.
study, just published online in Environmental Research Letters, found
the summer of 2017-2018 heat wave was the most intense on record when
it came to ocean temperatures.
New Zealand, Australian and US collaborative study was led by climate
scientist Jim Salinger, and involved scientists from Otago's Marine
Science, Geography and Surveying Departments, as well as from
Victoria University and the National Institute of Weather and
Atmospheric Research (NIWA).
used data sets by scientists from Victoria University of Wellington,
NIWA, the National Oceanic and Atmospheric Agency, the University of
Otago and the University of New South Wales.