A sailing club in the Bay of Islands could be one of Northland's first victims of rising sea levels.
Russell Boating Club, at Matauwhi Bay just south of Russell township, is based in a historic building on piles over the bay. The former fish factory was once well clear of the water but now each king tide brings it closer to flooding.
The threat isn't new but was highlighted this month, a few days before the club's annual tall ships race, when the biggest king tide of recent years — raised further by low air pressure from a storm — swamped the deck and came within centimetres of entering the building.
The close call has given fresh impetus to a fundraising campaign to lift the clubrooms out of harm's way.
Club member Kiki Nicolson started the campaign after the club's 40th anniversary in 2016. She wanted to make sure the ''unique and special place'' was still around in another 40 years' time, so she started a 40 Years, 40k Challenge with the aim of raising $40,000.
While that would not be enough to lift the building, it would allow the club to start applying for more substantial grants.
So far more than $17,000 had been raised through raffles, baking, events and donations.
Ms Nicolson hoped the fund would hit $20,000 by the time of the club's 42nd anniversary on February 4.
Long-time club member and former commodore Tony Hanlon had no doubt the sea level was rising. He had seen the change as a car ferry driver, a job he held until last year.
At high tide in Opua in recent years he'd noticed the ferry's loading ramp, even when fully lowered, didn't come down on to the asphalt so he'd have to back the vessel off.
''The change might be only 50mm but when you get a king tide and low pressure, it all adds up. And it's getting worse,'' he said.
Mr Hanlon believed the rise in sea level was cyclic with a contribution from mankind but, whatever the cause, the club's predicament was the same.
''The logical thing is to lift the building. I believe it has to go up by 1200-1500mm. The sea level is predicted to rise by up to 300mm by 2050, and that's not too far away.''
Club commodore Jay Howell said extreme high tides weren't a thing of the distant future but were happening now.
Even without a rising sea level, however, the historic building would need serious maintenance at some stage. The sea level issue just gave it more impetus, he said.
According to the Fifth Assessment Report by the United Nations' Intergovernmental Panel on Climate Change, the global rise in sea levels is likely to be in the range of 20-30cm by 2050. By the end of the century the rise could be anywhere between 50 and 100cm, depending on mankind's efforts to reduce carbon emissions, believed to be the main driver of climate change and rising sea levels.
Closer to home, a report called Coastal Hazards and Climate Change, published in December by the Ministry for the Environment, put the rise at 40cm within the next 50 years and 1m by 2115.
The actual change at specific locations would depend on factors such as land movement.
In the lower North Island, which is subsiding by 4mm a year, the effects of sea-level rise would be compounded. Vertical land movement in Northland is minimal.
Coastal flood and erosion maps prepared last year by the Northland Regional Council identified about 14,000 properties that could experience severe flooding once a year by 2100, if the UN panel's worst-case scenario comes true.
Dargaville, Whangarei CBD, Awanui, Ruakaka and Waipu Cove would be among low-lying areas at greatest risk.
The stormy weather and king tides this month didn't affect only Russell.
Homes at Horeke narrowly escaped flooding by what residents said was the biggest tide they'd seen in more than 20 years, new erosion defences at Sandy Bay on the Tutukaka Coast were damaged, and chunks of shoreline were washed away at Waitangi and Omapere.
The only time so far the sea is thought to have entered Russell Boating Club was during Cyclone Bola in 1988.