Saturday, April 13, 2024

I do wish they’d dry up about wetlands

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Wetlands have a place but they aren’t the answer to all our water and climate change problems, says Alan Emerson
Reading Time: 3 minutes

It is with some cynicism that I’ve been following the great wetland debate. How wall-to-wall wetlands will be our salvation, that they’re sacrosanct if they’re a real wetland or not. It is enough to say that if local government designates a wetland then that’s it, regardless of the facts.                                                      

The Resource Management Act of 1991 defines a wetland thus: A wetland includes permanently or intermittently wet areas, shallow water and land water margins that support a natural eco-system of plants and animals that are adapted to wet conditions.

There are many different types of wetlands.

Greater Wellington Regional Council is effusive in its support of wetlands. They “form a critical interface between land and water”, and, “they are crucial for the health of our environment and ecosystems, are of significant cultural importance for Māori”.

It goes on to add that they “help protect water quality”, which I will dispute.

They conclude by telling me that if I discover “a wet, soggy or spongy patch on your land, it could be a wetland”.

In winter over half our property could be defined as a wetland using the Greater Wellington description.

In fact on one occasion a Greater Wellington employee insisted there was a wetland where a truck had slid off a track in the middle of winter and had to be recovered.

The reality was it was a temporary mud hole, which would completely dry out come summer.

Environment Canterbury told me that “90% by area of wetland was lost in the last 150 years due to human impact”. 

You’d hold your breath for that one: swamps were drained to provide fertile land that produces food and earns good money for the area. Just imagine where the country would be if we hadn’t drained the swamps.

It added that “wetlands remain a vital part of Canterbury’s ecosystem”.

In its fact sheet, the Ministry of the Environment tells me that wetlands stop further degradation of our water and enable water quality to improve within five years.

I’d dispute the claim.  

A paper was presented to Grasslands headed The Benefits and Costs of a Constructed Wetland on a Wairarapa Dairy Farm. 

It was prepared by a representative of Greater Wellington, a NIWA scientist, Groundtruth Limited and a local dairy farmer, so Greater Wellington should be well informed.

The direct costs of the wetland were $55,000 with the opportunity cost of reduced grazing put at $1700 a year plus there was the possibility of losing $24,000 in capital value.

While N runoff decreased by around 40% assisted by oxidation, DRP arrived and departed the wetland at the same level.

E coli contamination increased markedly, going from an input to the wetland of 6 cfu/100 ml to releasing 700 cfu/100 ml into the environment.

Wetlands encourage ducks and other highly polluting waterfowl.

As the authors noted, “wetland is not a silver bullet but could be part of an integrated farm plan”.

The debate becomes murkier with carbon sequestration.

Water NZ told me the humble wetland is “a carbon super-hero”,

A recent cabinet paper prepared by NIWA recommended that the government incentivise carbon removal activities like restoring wetlands.

Greater Wellington wants carbon sinks such as wetlands to be included in the Emissions Trading Scheme.

Environment Canterbury rapturously announced that “wetlands store large amounts of carbon therefore are an essential ecosystem for reducing the impacts of climate change”.

There is another side to the debate, as Dr Jacqueline Rowarth recently pointed out. 

Methane is naturally released from wetlands (marsh gas), but they also release carbon dioxide and nitrous oxide.

She said that “the balance of growth and decomposition of organic matter is what determined whether wetlands are a sink or source of greenhouse gases”.

The research, published in Nature Climate Change in March, suggested that warming temperatures are weakening the ability of wetlands to act as a carbon sink. The authors said that under a global temperature increase of 1.5degC to 2degC the “100-year global warming potential of wetlands” could rise by 57%. That’s massive.

Professor Rowarth summarized thus: “The fact that natural methane from wetlands is not being targeted with a tax in contrast to the natural methane from ruminants burping comes down to global politics.”

I totally agree.

My view on wetlands is that they have a place, but they aren’t the answer. They do not in any way deserve the massive accolade that regional government is bestowing on them.

Farmers do not deserve all the pressure from local government to develop or restore wetlands.

Finally, local government are not qualified to be missionaries for wetlands.

A simple example of that missionary zeal is that Greater Wellington spent millions of ratepayers’ money taking two of its ratepayers, a farmer and a property developer, to court over the supposed destruction of wetlands.

Interestingly, the court decided the council had it wrong. There was no wetland in the first place.

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