The severe impacts of Cyclone Gabrielle on the North Island, and the five severe weather events experienced by the Thames–Coromandel region in just the first two months of 2023, are merely the latest examples of more frequent erosion-triggering rainfall events over the past decade.

Inevitably with the heavy rain, soil, rocks and woody material (also known as “slash”) from landslides have flowed down onto valleys and flood plains, damaging the environment and risking human safety.

Clear-fell harvesting of pine forests on steep erosion-prone land has been identified as a key source of this phenomenon.

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So we need to ask why we harvest pine forests on such fragile land, and what needs to change to prevent erosion debris and slash being washed from harvested land.

Pine was a solution
Ironically, most of these pine forests were planted as a solution to soil erosion that had resulted from the clearing of native forests to create hill country pastoral farms.

The clearing of native forests happened in the 19th and early 20th centuries, but the consequences — erosion, flooding and floodplains covered in silt and rocks — only became apparent decades later.

Research has shown that pastoral farming on our most erosion-susceptible soils is not sustainable. The productivity of the land is being degraded by loss of soil and large areas have been buried with sediment eroded from hill country farms upstream.

So the need to reforest large areas of erosion-prone farmland is scientifically well accepted.

Why pine?
But why did we choose radiata pine for our reforestation efforts instead of other tree species?

Even today, it is hard to find affordable and feasible alternatives to radiata pine. Affordable is the key word here.

We are not a rich country and our liking for “Number 8 wire” solutions makes a virtue out of necessity — we don’t have the money to pay for anything fancier.

Radiata pine is a cheap and easy tree to establish and it grows fast and reliably. Planting native or other exotic trees, such as redwoods, is possible, but it costs more and needs more skill and care to grow a good crop.

‘Has to be done’: Forestry industry under fire as McAnulty calls for slash to be investigated https://t.co/7lx5G2t07W

— Newshub Politics (@NewshubPolitics) February 14, 2023

The problem with radiata pine is that if grown as a commercial crop, it is clear-fell harvested after about 28 years.

The clear-felled land is just as erosion-prone as it was before trees were planted — with the added threat of large amounts of logging slash now mixed in with the erosion debris.

It can take six years or more after harvesting before the replanted pine trees cover the ground and once again provide protection to the soil.

Benefits of pine come with a cost
If we take a long-term perspective, research shows that even a radiata pine forest that is clear-felled once every 28 years will still significantly reduce erosion, compared with a pastoral farm on erosion-prone hill country.

This is because the erosion from the clear-felled forest is outweighed by the reduced erosion once the replanted trees cover the land.

However, this is not much comfort to communities in the path of the flood-borne soil and logs from that clear-felled forest. It’s difficult to take a long-term perspective when your backyards and beaches are covered with tonnes of wood and soil.

Slash a byproduct of efficiency
Whatever benefits radiata pine forests bring, we need to transition forest management away from “business as usual” clear-felling on erosion-prone hill country.

This transition is possible, but one important problem is not often discussed. The pine forests are privately owned by a range of people including iwi, partnerships made up of mum-and-dad investors and large international forestry companies.

All these people have created or acquired these forests as an investment.

A typical pine forest investment makes a good financial return, but this assumes normal efficient forestry, including clear-felling large areas with highly-productive mechanised logging gangs.

It has become clear that we need to manage forests differently from this large-scale “efficient” model to reduce the risk of erosion and slash from erosion-prone forests.

Changing how we manage these forests will inevitably reduce the economic return, and forest investors will absorb this reduction.

When a cyclone bears down on the East Coast, it’s not just wind and rain residents brace for. https://t.co/h9TJr3Q2dv

— Stuff Business (@NZStuffBusiness) February 15, 2023

Time for a permanent fix
If we go back to when the pine forests being harvested today were planted, the forests had a social value — not just in reducing erosion but in providing employment in rural areas where few jobs were available.

This social value was recognised by government funding, initially through tree planting by a government department, the NZ Forest Service. With the rise of free market economics in the 1980s, such direct government investment was considered inefficient and wasteful.

The Forest Service was disbanded in 1987 and its forests were sold to forestry companies. However, the government continued to promote tree planting on erosion-prone land with subsidies to private investors.

As these forests grew, they came to be considered purely as business investments and were bought and sold on that basis. When the time came to harvest the trees, the expectation was that these could be clear-fell harvested in the same conventional way as commercial forests growing on land with no erosion risk.

As erosion started occurring on the harvested sites, it became clear why these trees were originally planted as a social investment to protect the land and communities from soil erosion.

Aotearoa New Zealand has achieved control of erosion with a Number 8 wire solution- encouraging private investors to grow commercial pine forests on erosion-prone land. The problem with Number 8 wire solutions is that after a while the wire fails, and you have to find a permanent fix.

Conventional commercial pine forestry was a good temporary solution, but now we need to find a more sustainable way to grow forests on our most erosion-prone lands – and it won’t be as cheap.

Mark Bloomberg, adjunct senior fellow Te Kura Ngahere — New Zealand School of Forestry, University of Canterbury.  This article is republished from The Conversation under a Creative Commons licence. Read the original article.

Aotearoa New Zealand’s new NZ SeaRise website, designed to show how the country’s coastline will be affected by rising sea levels and land subsidence, has been hit by a cyber attack.

Project co-leader and Victoria University of Wellington earth sciences Professor Tim Naish said the website went live this morning at 5am, and since then it had been getting 10,000 hits per second which had ”just killed” the website.

”We’re trying to get it back up and running,” he said.

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”The guess is that these are anti-climate change people or the Russians — who knows.

”We don’t know for sure, but we think they’re using an autobot. They’re coming from an overseas IP address.

”It’s just hitting us with thousands of hits and our website can’t cope.”

It was frustrating because local government mayors were being asked to comment on the website, but were unable to because it was inaccessible at the moment, he said.

Frustrating for residents
It was also frustrating for residents interested in what was going to happen on their own land.

The NZ SeaRise website shows location-specific sea level rise projections to the year 2300, for every 2km of the coast of New Zealand.

Climate change and warming temperatures are causing sea levels to rise by 3.5mm a year on average, but until now, the levels did not take into account local vertical land movements.

Professor Naish said continuous small and large seismic events were adding up to cause subsidence in many parts of New Zealand, and the new projections showed the annual rate of sea level rise could double.

Project co-leader and GNS Science associate professor Richard Levy said the team had connected vertical land movement data with climate-driven sea level rise to provide locally-relevant sea level projections.

“Property owners, councils, infrastructure providers and others need to know how sea level will change in the coming decades so that they can consider how risks associated with flooding, erosion and rising groundwater will shift,” he said.

”We have estimated future sea levels for 7434 sites around our coastline. The largest increases in sea level will occur along the southeast North Island along the Wairarapa coast.

Land subsidence rates are high
”Here, land subsidence rates are high and sea level could rise by well over 1.5m by 2100 if we follow the least optimistic climate change scenario.

”In contrast, land is rising near Pikowai, in the Bay of Plenty, and uplift rates may keep pace with climate change-driven sea level rise, causing a small fall in sea level if we follow the most optimistic climate scenario.”

Dunedin and Invercargill were not likely to be any closer to inundation by the sea than had already been predicted, because ground movement in the South was ”quite stable”, he said.

Based on present international emissions reduction policies, global sea levels were expected to have risen about 0.6m by 2100, but for large parts of New Zealand that would double to about 1.2m because of ongoing land subsidence.

”We know that global sea-level rise of 25cm-30cm by 2060 is baked in and unavoidable regardless of our future emissions pathway, but what may be a real surprise to people is that for many of our most populated regions, such as Auckland and Wellington, this unavoidable rise is happening faster than we thought.”

Vertical land movements mean sea level changes might happen 20-30 years sooner than previously expected.

For many parts of New Zealand’s coast, 30cm of sea-level rise is a threshold for extreme flooding, above which the 100-year coastal storm becomes an annual event.

Climate change adaptation options
Joint Otago Regional and Dunedin City Councils’ South Dunedin Future group programme manager Jonathan Rowe welcomed the new information and said it would feed into many aspects of the councils’ work, particularly that relating to the South Dunedin programme which was considering climate change adaptation options.

ORC operations general manager Gavin Palmer said the information would also feed into flood protection planning to mitigate the impacts of sea level rise in other parts of coastal Otago, such as the Clutha Delta and the Taieri Plain.

Rowe said for South Dunedin, the new data confirmed previous guidance, that further sea level rise of 24cm-35cm was predicted by 2050-60, and up to 112cm by 2100, depending on global emissions.

A climate change adaptation plan would be presented to both councils in June, he said.

Climate Change Minister James Shaw said the findings were “sobering” and the government’s first plan to cut emissions in every part of New Zealand, would be published later this month.

• The website appeared to be accessed normally later today with an earlier notice saying “The NZ SeaRise maps are down temporarily for maintenance” having been dropped.

This article is republished under a community partnership agreement with RNZ. It was first published on the Otago Daily Times website.

Nauru hosts the Pacific Islands Forum — whose membership includes Australia, New Zealand and 16 Pacific Islands nations — from today until Wednesday when lofty ideas may help soften present realities.

The island, 56km south of the Equator and thousands of kilometres from anywhere else, is 21 km in size and its population is 11,000, 40 percent of whom have type 2 diabetes, 90 percent are unemployed and 94 percent obese – the highest rate in the world.

The island’s recent history is one of rags to riches and rags again.

READ MORE: Nauru faces media, security pressure ahead of Pacific Islands Forum

For most of the past century millions of tonnes of phosphate from bird droppings were mined and exported as fertiliser to Australia and New Zealand, leaving much of the area barren.

In 1970, the British Phosphate Commission handed over control to the Nauru government. Mining increased, briefly making Nauru the second most wealthy nation on earth based on GDP per capita, second only to the United Arab Emirates.

Most of the phosphate was extracted through strip mining which leaves the earth largely barren, infertile, and unable to sustain plant life.

Currently, about 90 percent of the island is covered in jagged and exposed heaps of petrified coral, which is unsuitable for both building and agriculture. Additionally, runoff from mining sites has left the water in and around Nauru severely contaminated.

Marine pollution
Researchers estimate that approximately 40 percent of the marine life has been lost due to this pollution. Additionally, the only remaining phosphate on the island would not produce a profit if mined.

In 1989, Nauru took Australia to the International Court of Justice over its actions during its administration of Nauru, and particularly its failure to remedy the environmental damage caused by phosphate mining.

An out-of-court settlement rehabilitated some of the mined-out areas. By 2000 no marketable phosphate remained.

In 1993, the government won a legal case against Australia for its mismanagement. The reparations have been used for restoration projects, one of which is a detention centre for more than 1000 refugees seeking asylum in Australia.

Some have called Nauru an Australian “client state.”

Since then, the political and economic situation has worsened. The phosphate trust fund was mismanaged (thanks largely to the influence of a modern beachcomber) and most of its assets lost.

Corruption is reported as rampant. Searching desperately for an income, government
briefly facilitated and condoned money laundering, and now relies heavily on aid and income from the Australian refugee detention centre where conditions have been reported as “akin to torture”.

Disturbing report
This BBC report on the effects on refugee children is especially disturbing.

Both governments have kept the injustices perpetrated against these refugees quiet by limiting access to the island.

A media visa costs $8000, taking pictures inside the detention centre is forbidden; so is carrying a smart phone with a camera.

In 2015, Australia passed the Australian Border Force Act, which makes speaking out about the conditions inside its camps on Nauru, and Manus in PNG, punishable by a two-year prison sentence.

It will be interesting to see how both governments, and other members of the Pacific Islands Forum, including New Zealand that benefited greatly from Nauru phosphates, handle questions over the next two days — and whether the NGOs present ask the right ones.

Dr Croz Walsh is a retired development studies professor at the University of the South Pacific. In his blog, he comments on New Zealand, Fiji, and Pacific Islands issues of political and social interest.

• How phosphate mining in Nauru has led to environmental catastrophe