2018 may be warmest year on record for New Zealand

NIWA are set to release an analysis of last year’s weather records next week, but Jim Salinger has jumped the gun on them, unofficially stating the 2018 was the warmest year on record for New Zealand.

NZ Herald:  2018 NZ’s hottest year on record – climate scientist

Niwa isn’t due to release its official summary for the year until early next week, but Professor Jim Salinger has already picked it the warmest on records stretching back to 1867.

His calculations put 2018’s mean annual land surface temperatures at 13.5C – or 0.85C above the 1981-2010 average.

His figure also surpassed the scorching years of 1998 and 2016, which were 0.80C and 0.84C above normal respectively.

Niwa meteorologist Chris Brandolino said people would have to wait until next week to see the climate agency’s final numbers – but added Niwa’s preliminary figures showed 2018 tracking extremely close to 2016’s record.

So it looks like being one of the warmest years on record, if not the warmest.

The New Zealand extended temperature record, 1867 - 2018, compared with the 1981 - 2010 normal. Bars represent individual years, the orange line smoothed trends, and dotted red line the overall trend. Source / Professor Jim Salinger

Fluctuations on that temperature record are to be expected, but an apparent surge trend over the last couple of decades could be a concern.

New Zealand is just a small part of the world, but is not the only place to record a warm year – but not the warmest.

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Phys Org in November:  2018 temperatures set to be among hottest on record: UN

Global temperatures in 2018 are set to be the fourth highest on record, the UN said Thursday, stressing the urgent need for action to rein in runaway warming of the planet.

In a report released ahead of the COP 24  in Poland, the World Meteorological Organization pointed out that the 20 warmest years on record have been in the past 22 years, and that “2018 is on course to be the 4th  on record.”

“This would mean that the past four years – 2015, 2016, 2017 and 2018 – are also the four warmest years in the series,” the UN agency said in its provisional report on the state of the climate this year.

2018, fourth hottest year on record?

The “warming trend is obvious and continuing,” WMO chief Petteri Taalas told reporters in Geneva.

The report shows that the global average temperature for the first 10 months of the year was nearly 1.0-degree Celsius above the pre-industrial era (1850-1900).

So there will be ongoing pressure to try to reduce the human effect of warming, and to mitigate possible issues.

Meanwhile, we have had a couple of weeks of generally very pleasant weather here in Dunedin, with a possible high into the thirties forecast for today. However this is just weather top enjoy (if you like 30+ temperatures, I prefer mid twenties.

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So what’s in store for 2019?

This summer might not be a record breaker, as a weak El Nino brings unsettled weather.

We’re unlikely to get weeks on end of hot, dry weather, NIWA principal scientist Chris Brandolino says, but there’ll be periods of settled warm weather between blocks of cooler temperatures.

“This summer, variability is going to be the theme.”

This season the Pacific Ocean is signalling El Nino weather but the atmosphere is not, which makes it a “messy” driving force of the climate, he says, compared to when the two work in tandem.

Temperatures are about or above average and rainfall is forecast to be around normal – other than a bit drier in the Upper North Island and wetter in the West Coast of the South Island.

New Zealand is close to 1C warmer than a century ago. As the atmosphere warms it holds more water vapour, leading to heavier rainfall, Prof Renwick says. Along with rainfall extremes, more moisture in the air can lead to heavier or more unseasonal snowfalls.

But with underlying temperatures getting warmer, heat waves are also more likely.

Heat waves are rare here due to our usual weather variability.

January warmest month on record

It has been confirmed what was expected and well signalled – January was the warmest month on record for New Zealand. All that means definitively is that January was the warmest month on record.

It certainly seemed to be one of the most consistently warm and sometimes hot months that I can recall in Dunedin. I’ve experienced hotter, in Central Otago the summer of 1972/73 was a scorcher (and I worked through it outside most of the time), and they had another hot one this year.

NZH: January hottest NZ month in 150 years

Dr Jim Salinger, who pioneered Niwa’s benchmark seven-station series, used to analyse climate trends, said January’s temperature had come in at a scorching 20.2C – 3C above average.

That’s way above average.

“This makes it the warmest of any month in reliable temperature records dating back to 1867,” said Salinger.

Final figures have yet to be officially confirmed by Niwa, which will be releasing its summary for January tomorrow.

Former record-breaking months were February 1998 at 19.6C and February 2016 at 19.5C.

The previous warmest January was in 1956 with 18.8C.

1956 was before my time, and 2016 didn’t seem extraordinary in Dunedin (it must have been elsewhere). 1998 is notable as one of the hottest years on record.

In November, December and January, the temperature had come in at 17.7C, or 2.2C above average.

The hot early summer of 1934/35 – long used to compare warm seasons to – was 17.C.

“The main reason for the hot early summer and the marine heatwave around New Zealand over this period was a strongly positive Southern Annular mode, causing the storms whirling around the Southern Oceans to contract towards the Antarctic continent, with no cold outbreaks into the Tasman Sea and New Zealand area,” Salinger said.

“The frequent anticyclones tracking over the Tasman Sea across the South Island and to the east have allowed the seas to heat up, producing the marine heatwave.”

A marine heatwave also happened in 1934-35, but this period had been warmer by 0.4C, because of global-warming-producing climate change, Salinger said.

The New Zealand temperature series – better known as the seven-station series – was developed in 1981, as part of Salinger’s PhD work.

The stations are at Auckland Airport, Masterton Airport, Kelburn in Wellington, Hokitika Airport, Appleby near Nelson, Lincoln in Canterbury and Musselburgh in Dunedin.

“These are complete since 1909, and that is why Niwa uses the records from 1909, and they have been adopted as the standard,” Salinger said.

“I have extended this record back to 1867 using a smaller network of available stations. So this is the warmest month on record, since reliable records commenced in 1867.”

Most years this century have been warmer than almost all other years as far back as the record goes.