El Nino is expected to arrive with a vengeance. It could be as devastating as the Super El Nino of 1997/98, writes Bruce Munro. But what exactly is this phenomenon, how will it affect us, and is there anything we should be doing about it right now?
On a fine day like today, Doug Brown can look west across his rolling Maheno farmland and see the saw-toothed Kakanui Mountains silhouetted against the rich blue sky.
Even though it is late spring, a careful look confirms there is still some snow on those distant peaks; a tantalising suggestion of moisture that would be more than welcome on the pasture beneath his boots.
For four decades, Mr Brown has farmed this coastal Otago land, as his father and his grandfather did before him. In a fortnight, Punch Bowl Farm will celebrate 100 years of stud ram breeding.
It is a comparatively dry climate here on the undulating hills south of Oamaru. Mr Brown's 520ha farm, on which he runs upward of 4000 sheep and a few cattle, averages 500ml of rainfall a year. Dunedin, by comparison gets more than 800ml.
Right now, the short grass on Mr Brown's paddocks is green, but the ground has little moisture. Last year was particularly dry, and, worryingly, that trend is continuing. In the past three weeks, the area has had rain only twice, providing a paltry 20ml of precious life-giving water.
But Mr Brown is an optimist. He reckons you have to be.
The area is often drier in September than December, he says. He recalls a drought declaration that was followed a week later by significant flooding. About 50ml of rain right now would be perfect, he adds.
Buoyant comments, given that government scientists this week upgraded to 100% the chance of potentially disastrous El Nino climate conditions for the next three months.
National Institute of Water and Atmospheric Research (Niwa) scientists also say the weather pattern is likely to intensify, raising the spectre of an El Nino as strong as that experienced in the summer of 1997/98. Some of the signs are already there, Mr Brown agrees.
The southwesterly wind of the past couple of months is classic El Nino. And the lack of rain appears to be quite widespread.
''We are just at the stage now that things are starting to brown off,'' he says. "That's one of the scary things: it's such a wide area.''
And it will not only affect farmers. Everyone from urban water users and recreational fishers to wilderness trampers and yellow-eyed penguins are likely to feel El Nino's tightening grip.
EL NINO DE NAVIDAD
El Nino is one extreme of a Pacific climate pendulum. To understand the phenomenon, it is helpful to first grasp what is going on with water and wind under ''normal'' conditions, Niwa's Chris Brandolino says.
When normal, or neutral, conditions are in play, winds from north and south of the equator push towards each other and then promenade from east to west. The moving air has enough force to push seawater from South America across the Pacific Ocean towards Australia and Asia.
Off the coast of Peru and Chile, cold water rises from the depths to replace the water blown westward by the trade winds. This is good for anchovies, which enjoy the cooler water, and for anchovy fishermen hoping for a bumper Christmas catch, Mr Brandolino adds in a small aside which soon makes sense.
But sometimes, those trade winds slacken, or even reverse. The warm water sloshes back towards South America, and deeper water is drawn up around Asia and Australia instead.
''This is how El Nino was discovered in modern terms,'' Mr Brandolino says. ''Because these anchovy fishermen noticed that it wasn't very good fishing. And it was all at Christmas time. El Nino [de Navidad] means the Christ child.''
Under El Nino conditions, all that warm water produces showers and storms along the west coast of the Americas, while towards Asia, the water and air are cooler than average, producing less rain than usual.
The bottom line: more cyclones in Polynesia; starving, drought-stricken farmers in Brazil and Africa; drownings following floods in Argentina; billions of dollars in lost agricultural production, health, transport, tourism and forest degradation as a result of El Nino-exacerbated forest fires in Southeast Asia; extensive bleaching of Great Barrier Reef coral ...
El Nino's pernicious reach has even been blamed for earthquakes triggered by changing volumes of water and eroded soil allowing tectonic plates to shift. The relationship of El Nino to climate change is still being investigated.
OUR PATCH
Scientists say El Nino 2015/16 is a done deal; ocean and atmosphere have linked arms and begun the El Nino foxtrot.
For New Zealand, El Nino typically means an intensification of normal patterns - higher rainfall in the west and the potential for drought in the east.
Farmers in wetter parts of the country could face significant pasture damage from too much rain and the prospect of stock struggling to thrive in the wet. Those in the east could struggle to produce enough feed for their animals.
For inland Otago and Southland, Niwa is predicting below-average temperatures, normal or above-normal rainfall, and uncertain river flows. For East Otago the likelihood is below average temperatures and soil moisture, and normal to below-normal rainfall and river flows.
But every dance has variations. How this one will play out is a guessing game; one with potentially serious consequences.
A month ago, predictions were that it would on the scale of the 1997/98 Super El Nino. This week, Niwa revised that, saying this year's El Nino was, at this time, slightly weaker than the event of 18 years ago, but that it was expected to intensify, peaking during the summer months.
Memories of the 1997/98 El Nino, the strongest on record since 1950, linger still, providing a salutary warning.
SUPER EL NINO 1997/98
In the east of New Zealand, there was less rain than normal from mid-1997. By the end of the year, a drought was undeniable.
Mr Brown was forced to truck about 2000 sheep from Maheno to Southland. It meant he could keep his stock, but he had to sell four years' worth of silage to pay for transport and off-farm grazing.
By April, 1998, it had been 12 months since there had been an easterly rainstorm, the sort needed to break the North Otago drought. Several Otago rivers were at desperately low levels.
In Dunedin, compulsory water restrictions were introduced after the hill suburbs of Belleknowes, Mornington, Brockville and Corstorphine had no water for nine hours.
In May, penguin expert John Darby predicted up to 90% of yellow-eyed penguin (hoiho) chicks born on the mainland that year would die. El Nino appeared to have disrupted marine ecosystems, making food scarce, he said.
Kevin Kinney was farming sheep near Hyde. The farm took the winter of 1998 ''quite badly'' because he had not been able to grow any feed during summer.
Mr Kinney sold store lambs and old ewes and bought in ''a lot of feed'' for the remaining stock. ''I remember the dust coming up behind the sheep as I was feeding out,'' he recalls.
Beekeepers were also hit hard. One from Ranfurly said honey production had been cut from 70 tonnes to 17 tonnes in 1998 and was expected to drop further the next year.
By early 1999, Otago had had 19 months of below-average rainfall. The North Otago/Central Otago Drought Relief Committee was organising meetings and petitioning the Government. In February, the Government announced a $60,000 relief package for Otago farmers. A month later, the drought broke.
The then Ministry of Agriculture and Forestry estimated the drought cost farmers $256 million in the year to mid-1998 and a further $169 million during the following 12 months.
Adding in flow-on effects, the probable cost of the 1997/98 Super El Nino to the country has been put at more than $1 billion. With that in the rear-vision mirror, it seems sensible to buckle up and prepare for a bumpy ride.
GET READY
Federated Farmers is doing just that, Philip Hunt, who is the organisation's Otago president, says. ''We are geared up to deal with adverse events ... We'll certainly be doing that in a difficult El Nino summer,''he says.
The Rural Support Trust and the Ministry for Primary Industries are working together to ''keep an eye'' on the situation.
Farmers who have not been through an El Nino summer should talk to other farmers or get in contact with Federated Farmers, Mr Hunt says.
Ron Jones, of Matarae Station, says the 6000ha merino and Romney farm near Middlemarch is better placed to face El Nino, compared with 18 years ago.
Strath Taieri has had a bit more rain than North Otago during recent months, and irrigation has been extended on the farm. ''It's probably our life-saver. It's allowed us to put down four or five pits of silage,'' Mr Jones says.
He has heard that more heavily stocked farms in the area are already out of feed. ''You have to farm to the conditions, and keep a little bit up your sleeve.''
Anglers are being advised to fish early, before river levels drop. Gavin Palmer, the Otago Regional Council's director of engineering, hazards and science, says it is monitoring rainfall, groundwater and river water levels in preparation for a ''low-flow event of some sort''.
''People rely on our river-flow information to make decisions,'' Dr Palmer says. ''There are some powers under the Resource Management Act for regional councils to issue a water shortage direction ... But the preference is for people to work together and share the water that is available.''
Only 10% of existing water take consents in Otago have a condition requiring them to cease drawing water when river flows reach a minimum level.
Among that select few is Dunedin City Council (DCC).
''We have ... conditions that mean that we must leave a minimum water flow in the rivers, and that limit how much water we can take from the Mosgiel bores,'' Dr Laura McElhone says.
To manage the expected low-water supply and high demand, the city council will be busy encouraging people to conserve water and reduce consumption, the DCC's group manager for water and waste says.
''Our water sources for much of the city are `run of river', meaning that we don't have large reservoirs,'' Dr McElhone says.
''We take water directly from rivers, treat it and put it into supply. We do have some emergency storage, but this is really designed to deal with a major pipe breaking rather than a prolonged drought situation.''
Fixing leaking taps, reporting leaking mains, washing cars with a bucket, watering plants with a handheld hose ... there is plenty people can do to help, she says.
The likelihood of damaging fires this summer is significant, the New Zealand Fire Service and Otago Rural Fire Authority say.
''Otago is already dry and will get much drier as the effects of the El Nino weather pattern take hold,'' NZFS East Otago fire risk management officer Michael Harrison says.
''It'll take very little for vegetation fires to start, and if fires spread they will be difficult to contain. Water supplies in rural areas are also likely to become very low. This is going to make it a difficult summer for our firefighters.''
''Prevention is key,'' Principal Rural Fire Officer Stephanie Rotarangi says.
''Avoid any activities that are likely to cause sparks or heat that can start a fire and make sure all machinery is correctly maintained. If you see smoke, dial 111 immediately.''
Whether another disastrous season is in store for hoiho (yellow-eyed penguin) is unclear. Early indications are that nest numbers are down.
But Department of Conservation, Yellow-Eyed Penguin Trust and tourism operator staff are still checking sites as far south as Stewart Island A fuller picture should be available next week, Sue Murray, who is the trust's general manager, says.
Whatever El Nino brings, the economy will stay afloat, economists say.
The New Zealand Institute of Economic Research (NZIER) has done its sums. It reckons a sizeable drought could put a 0.7% dent in GDP; not enough to tip the country into recession.
It is the sort of talk that would get Mr Brown's stamp of approval.
''You have to keep positive and keep thinking ahead and making decisions; that's the key to it really,'' he says.
This week he has organised alternative grazing for some stock, just in case. And he is looking forward to irrigating about 100ha of land when stage two of the North Otago Irrigation Scheme reaches his farm in about spring next year.
''It [irrigation] is expensive, but you have to take a long-term view. I've got a boy who has decided he wants to come home and farm. I don't wish these droughts on him.''
