Climate change projections for New Zealand

By Barbara Stuart

Many places will see more than 80 days a year above 25C by 2100, which will have a significant impact on ryegrass growth (it prefers temperatures of 5-18C) and animal performance.

Winter and spring are very likely to have increased rainfall in the west of the North and South Islands and be drier in the east.

Summer is likely to be wetter in the east of both islands, while the west and central North Island will be drier.

All areas are likely to get more very extreme rainfall, especially shorter, more intense events.

Increased drought frequency in many regions of New Zealand and farmers in dry areas can expect up to 10% more drought days by 2040.

Farming will be very different, and we need to sort out water policies because irrigation will be crucial in many areas to balance use and food production and for people.

NZ’s gross emissions are increasing, therefore action to reduce them is crucial.

In 2020, NZ gross emissions were 78,778 kilotons of carbon dioxide equivalent (Mt CO2-e), comprising 44% carbon dioxide, 44% methane, 11% nitrous oxide and 2% fluorinated gases.

This represents a 21% increase in emissions since 1990 (which is when international reporting obligations for greenhouse gas emissions began).

In 2020, 73.1% of NZ’s reported agricultural emissions was enteric methane from ruminant animals. A further 20% of agricultural emissions was nitrous oxide, largely from the nitrogen in animal urine and dung, with a smaller amount from the use of synthetic fertilisers.

The remainder of agricultural emissions in 2020 were mostly methane from manure management (4.4%) and carbon dioxide from fertiliser, lime and dolomite.

A frequently heard belief is, there had always been large numbers of ruminant animals on the planet emitting greenhouse gases.

The number of ruminant animals in the world has never been greater than today.

In North America it’s estimated there were once 70 million bison, but today there are more than 200 million cattle in the USA reports Phil Journeaux an agriculture economist with AgFirst.  

He says, “It might not be possible to farm in the same way as we do now in New Zealand.

"If you go back a few hundred years, there were no ruminant animals here. Today we have around 40 million in NZ, those growth trends have happened all around the globe.

“Some say climate change doesn’t matter to New Zealand but it will have implications globally and for us.

"It will cost us to mitigate but cost us a lot more if we don’t,” Sinead Leahy, Principal Science Advisor New Zealand Agricultural Greenhouse Gas Research Centre (NZAGRC) said during a recent seminar designed to expand rural professionals’ understanding of climate change.