For PEAT’S sake

• Published date: 25 September 2021
• Publication title: Mix, The

A row of recycled egg cartons — free range, of course — is lined up on the window end of the dining room table to catch the light.

The cardboard cartons’ cells are filled with a light brown, fibrous soil — peat — an ideal seed germinating media that is naturally sterile and has an enormous capacity to hold life-giving water.

Emerging from the peat are dozens of slender shoots and tender, light green leaves; seeds brought to life by moisture and warmth; seedlings that will be transplanted to the backyard garden to produce this year’s bountiful crop of peas, tomatoes, lettuce, carrots, beans, spring onions, spinach ...

No chemically ripened, air miles-heavy, pesticide-laden produce here; just home-grown, money-saving, nutritious, delicious, goodness.

Or maybe not.

Little does this enthusiastic gardener know — nor most of the myriad other busy springtime green thumbs — that they are possibly damaging the planet with each seed they sprout.

Peat. Boggy, swampy ground that is not much good for anything except to be drained for farming, burnt for heating, added to potting mix for azaleas and blueberries or dried and then rehydrated to germinate seeds. That is what we used to think.

Peat is in fact a fascinating material and peatlands are an ecological and climatological marvel.

Peatlands provide unique and valuable ecosystems. They regulate water flows, preventing seawater intrusion as well as helping minimise the risk of flooding and drought. They are home to a rich variety of plants and animals found nowhere else.

In most environments, when something dies, it decays and its constituent parts are recycled.

But peat is different. Peat is the partially decomposed remains of ancient plants that have accumulated in waterlogged places high in acidity but deficient in oxygen and nutrients. These conditions prevent the material from fully decomposing. Over millennia, this material builds up and becomes several metres thick.

Because the plants that form peat do not fully decompose they do not release all the carbon they accumulated while living. This makes them an important carbon sink.

Peatlands cover an estimated 3% of the surface of the planet, but they punch well above their weight. They contain an estimated 644 gigatonnes to 1073 gigatonnes (Gt) of carbon — almost half of all soil carbon on the planet.

This is what makes the disturbance and destruction of peatlands significant in these crucial opening decades of the anthropocene — the current geological age marked by a dramatic increase in human activity. The central feature of this epoch is man-made climate change, caused by a dangerous build up of greenhouse gases, particularly carbon dioxide (CO2), in the atmosphere.

To date, much of the concern about greenhouse gas emissions has been focused on burning fossil fuels for electricity, heat and transportation, as well as, particularly in agriculture-dependent countries such as New Zealand, on emissions from farming.

Now peat is coming into the frame.

Worldwide, about 15% of the...