NZ’s climate in ‘uncharted territory’, with more extreme weather events ahead

Much is being made of a record-strength El Niño event that could well spell a drier, windier summer for the north and east of New Zealand. But, as a major new stocktake shows, it is forming against a backdrop of warming that’s pushed the country’s climate into “uncharted territory”.

The Our Atmosphere and Climate 2026 report shows New Zealand has warmed by 1.36°C since record keeping began in 1909, with seven of the ten warmest years within the decade since 2016.

Carbon dioxide (CO₂) levels, as measured at a monitoring station at Baring Head, are up by 30% since 1972 and the annual rate of increase has tripled since the 1960s. Globally, CO₂ levels are now higher than they have been for millions of years.

Ocean surface temperatures around New Zealand have warmed 34% faster than the global average and the Tasman Sea region has become a hotspot for marine heatwaves, with profound effects on marine ecosystems.

The warming will continue to accelerate an already dramatic loss of glacial ice in New Zealand, with glaciers expected to lose 50% to 85% of their remaining mass this century and some possibly disappearing completely unless emissions are brought down fast enough.

With the El Niño on top of the ongoing warming, some parts of the country can expect stronger rainfall extremes this summer, particularly in the west of the South Island, while some eastern regions will experience more intense drought.

New Zealand’s global role

The report also highlights New Zealand’s contribution to global emissions. While New Zealanders account for only 0.06% of the world’s population, they add 0.17% to total emissions. On a per-capita basis, New Zealanders are among the top 40 emitters internationally.

While tracking background warming trends, the report also discusses changes in episodic extreme events that can cost lives and damage housing, infrastructure and livelihoods.

New Zealand is set to see a future of more frequent and extreme droughts, heatwaves and fires, along with bigger floods. However, cold extremes will be rarer, along with huge changes to cooler parts of the country that will affect water and food security.

Higher temperatures and drying imply a greater reliance on dryland agriculture, and reduced cooling in winter will affect where pip and stone fruit can be grown because they require winter chilling to flower and fruit successfully.

Melting ice and warming oceans lead to sea-level rise, which is accelerating around New Zealand’s coasts. This will continue for centuries and have the most serious impacts along the many parts of New Zealand’s coastline where the land is sinking.

This puts pressure on coastal communities and ecosystems, with virtually inevitable loss of infrastructure and private property in coastal floods over the course of this century and beyond.

Climate impacts are not evenly distributed and will affect different communities in different ways. Māori communities and business interests are especially exposed.

Many marae are built in exposed coastal area or on floodplains, and more than 80% of Māori households are exposed to flood risk.

Economic impacts

Significant parts of New Zealand’s economy, including agriculture and tourism, are directly exposed because they rely on the environment.

As the report shows, there are already major and expensive impacts in many sectors. In the agriculture sector, drought lowers dairy production and raises the costs of water storage. Horticulture impacts are mostly around what can grow successfully where, with shifts in preferred regions expected for kiwifruit, avocados and blueberries.

Many Māori businesses tend to focus on agriculture, forestry and aquaculture – all sectors exposed to climate change impacts.

In the oceans, warming moves commercial fish stocks, likely reducing catches. The report says algal blooms and marine heatwaves will affect commercially farmed salmon and shellfish.

Tourist numbers are also likely to fall, as has already been seen after the ex-tropical cyclone Gabrielle. Combined with likely increases in the cost and desirability of international travel in the future, this may deter more international tourists from coming to New Zealand.

The impacts from flooding and land slips on transport and energy networks can also be profound, flowing through to interruptions in supply chains.

All of the impacts of climate change discussed above are bad enough, but the cascading effects from multiple, consecutive events can be devastating for regional communities. For example, the Auckland anniversary weekend floods came on the back of several heavy rain events, with soils already saturated.

These climate updates are published every three years and are mandated under the Environmental Reporting Act 2015, with the first published in 2017.

They show a comprehensive trajectory of climate change impacts in New Zealand which are only going to get worse unless we collectively reduce emissions globally.

In New Zealand, most emissions come from agriculture and transport. Reducing emissions from these sectors would be an appropriate response to obligations New Zealand has under the Paris Agreement.