But he doesn't put it down to global warming. "I think climate change is bullshit. It's erosion that's causing the problem here, not climate change. The bloody water level hasn't altered."
Lawrence blames commercial gravel extraction further up the coast, not climate change: "A lot of these scientists make a lot of money - their bread and butter is council and government studies, the whole nine yards. They're just pushing agendas."
And this is the change. Ten years ago, few people disputed the role of humankindinreleasingclimategases like carbon dioxide, gases that were said to be accelerating the warming of the atmosphere in a greenhouse effect that would melt the polar ice caps and glaciers, expand the oceans and force us all to move to higher ground.
Ten years ago, well-known climate scientist Dr Jim Salinger wrote in the NZ Herald that damage to coastal properties in Wellington, Kaikoura and Haumoana was a timely reminder that communities and local authorities should be planning for the long-term consequences of rising sea levels.
Today, Salinger still believes global warming is partly to blame for Haumoana's troubles. The ocean surface has warmed by 0.6C since the 1870s, he says, contributing to a 20cm rise in sea levels.
But these views are no longer accepted uncritically. Right-wingers like former government ministers Barry Brill and Rodney Hide are among those challenging the science. Now, the Climate Science Education Trust has sought a High Court ruling that could discredit Niwa. So what went wrong?
Scientists, says the respected international journal Nature, need to accept they are in a street fight: "The integrity of climate research has taken a very public battering in recent months . . . Climate scientists are on the defensive, knocked off balance by a re-energised community of global-warming deniers who, by dominating the media agenda, are sowing doubts about the fundamental science."
Many of these doubts can be traced back to the Kyoto Protocol, and the demands it placed on nations to constrain their carbon dioxide emissions. Governments threatened to pass on the cost of those obligations to businesses, already tied up in red tape and taxes. Businesses gagged, then revolted, with support from well-funded business thinktanks like the US Heartland Institute.
It was the 3000-page report of the Nobel Peace Prize-winning Intergovernmental Panel on Climate Change (IPCC) in 2007 that provided critics with the biggest target to pick at. Scientists panicked, sending flurries of emails around the world debating their response. Then critics revealed the IPCC had no credible source for its claim the Himalayan glaciers would disappear by 2035, and it had wrongly attributed a rise in natural disasters to global warming.
At the centre of all this was New Zealand climate scientist Jim Salinger, an IPCC Nobel laureate who had earlier been unceremoniously sacked from Niwa for speaking to the media without authorisation. He was seen as a martyr by many environmentalists - but his work in charting New Zealand temperatures was regarded as flawed by climate sceptics.
To delve back into the troubled history of New Zealand's temperature records, you have to dig back into the history of 65-year-old Salinger.
As a 13-year-old in Dunedin, his parents gave him a thermometer and he built his own climate station, and fell in love with weather data.
Studying towards his geography PhD atWellington's Victoria University in the 1970s, he realised that different weather stations had recorded different temperatures, because of where they were placed.
"At this stage people were thinking we were due another ice age. Some people thought a whole series of cold winters in Europe was the start of it."
But his preliminary analysis indicated quite the opposite - that the New Zealand temperature was rising. The only problem with tracking this rise was that our cities did not have thermometers that had consistently measured temperature in the same space, with the same technology, over an entire century.
The differences meant it was difficult to track changes-so he set about revising the early data downwards to allow for shelter, urban warmth and other factors.
After graduation, Salinger took his adjustment techniques to the Meteorological Service and then Niwa, varying them slightly each time as new data and techniques became available. And it is that record - showing an average increase in temperature of just under 1C over 100 years - that has provided the basis of Niwa's advice to government on projecting the nation's climate change over coming decades.
It is called the "seven-station series" because it tracks temperatures in seven towns: Auckland, Masterton, Wellington, Nelson, Hokitika, Lincoln and Dunedin. "I stumbled on the fact that New Zealand was warming," says Salinger, now based at Stanford University in California. "I didn't try to attribute it to anything, certainly not global warming."
Ninety-year-old scientist Dr Vincent Gray got his PhD in chemistry from Cambridge University in 1946. "In those days, it seems to me, science was honest," he muses. Gray's career has taken him around the globe - working in Britain, Canada, France, NewZealand and most recently China where he was chief chemist for the Coal Research Association, but has retired to Wellington.
It was Gray's review of the "sevenstation series" that sparked the years of challenges that, this month, reached the High Court. Contrary to Niwa's finding, Gray says there has been no change in temperatures. He objects to Salinger's adjustments, and to the practice of extrapolating data from neighbouring stations, sometimes hundreds of kilometres away, to fill gaps in the data.
He believes scientists and governments are part of a "global conspiracy". They want to believe in global warming, to justify big, expensive projects, and to justify their existence, he says.
So, in 2006, Gray teamed up with expat Kiwi geologist Professor Bob Carter, who is on the Heartland Institute payroll, and other sceptics to form the New Zealand Climate Science Coalition.
Former energy minister Barry Brill joined the coalition three years ago and is now chairman. He believes there has been global warming, but New Zealand has not been affected by it and disputes the figures.
The group raised its concerns with former Act leader Hide who, over several weeks in late 2009, harassed the Government at Parliamentary question time until Cabinet minister Wayne Mapp brokered a meeting with Niwa chief climate scientist David Wratt, to discuss Hide's concerns.
Hide recalls: "They couldn't answer the most basic questions; were very defensive; and then just told me that I should run away and write my own scientific paper if I had a problem with their temperature record."
In 2010, the coalition wrote to Niwa to discuss its methodology, but Brill says the agency refused to meet - though Niwa did review its seven-station series at Mapp's direction.
So it was, says 71-year-old Brill, that he decided to invest tens of thousands of dollars of his own money in suing Niwa at the High Court. "We issued proceedings asking for the court to declare that the record was wrong. There is no other forum available to challenge public science."
Outside the High Court at Auckland, members of the Flat Earth Society of Middle Earth gather in medieval costume to lend their tongue-in-cheek support to the Climate Science Coalition.
Inside the courtroom, the Climate Science Education Trust (an offshoot of the Coalition) puts its case. Lawyer Terry Sissons occasionally confers with Brill, seated next to him as junior counsel, for advice on particular points.
Niwa's lawyer Justin Smith breaks down the trust's arguments piece by piece, arguing Sissons' science is flawed and furthermore, that the court should not even hear it. "The court is not the appropriate forum to resolve such scientific disputes," he says.
Justice Geoffrey Venning leafs through the mountain of paperwork before him about the two sides' conflicting claims, giving little signal of whose argument he finds more compelling. At the end of the four-day hearing, he reserves his decision to be delivered in the next few months.
To Niwa and the climate scientists who have worked there, this hearing is an inappropriate waste of time and money.
Niwa chief executive John Morgan says the agency has always vigorously resisted the coalition's "poorly-founded" allegations. "We firmly believe in the integrity of our science, and the people who do it, and were determined to defend them. We look forward to the outcome."
Climate change sceptics -"deniers", as they have been dubbed - justifiably claim to have been blackballed by their mainstream colleagues; their arguments ridiculed and marginalised. But now, climate scientists like Renwick and Salinger allege the tables are turned. They face abuse online, they say, and their friends and colleagues in the US and Australia have faced death threats.
Renwick worries how global warming will affect his 16-year-old son tomorrow; he doesn't worry about the criticisms against himself today.
"All of us have been disparaged in blogs and letters to the editors," he says.
"I've had colleagues in America who have received death threats. This court case was designed to cast doubt on the quality of the science that's done at Niwa, and on the quality of the integrity of people who do climate research in New Zealand - that was the point of it."
He wonders how much science will be involved if the trust wins on a technical point. "In the sceptic community worldwide, it would be huge news."
Back to Haumoana, and Salinger and Renwick say climate change is contributing to rising temperatures, rising sea levels, and to the king tides that are chipping away at the houses. Homeowner Bridgeman says that's "bullshit".
The question is, what does Justice Geoffrey Venning think?
