Impact of Climate Change on NZ’s Oceans, Coasts and Communities

The ocean surrounds New Zealand and sits close to the centre of the water hemisphere, where half of the Earth’s surface is covered by water. Its identity, culture, and livelihoods are deeply connected to the sea.

A new report from the Ministry for the Environment and Statistics New Zealand, Our Marine Environment 2025: Tō Tātou Taiao Moana, released in October 2025, explores how climate change is affecting Aotearoa New Zealand’s marine and coastal environment, and how these changes, in turn, affect communities across the country.

“Aotearoa New Zealand has more than 15,000 kilometres of varied coastline. As an island nation, we are never far from the coast. For many of us, our connections to beaches and the ocean are fundamental to who we are as New Zealanders.”

“The ocean and coasts of New Zealand are more than part of our identity, they support the homes, livelihoods and cultural practices of communities across the country.”

Climate change effects on the ocean around New Zealand

The report, published every three years and now in its fourth edition since 2016, begins with how global climate change is transforming ocean systems before narrowing its focus to New Zealand’s waters.

Section 1: Effects of climate change on the ocean around New Zealand examines large-scale drivers of ocean change, including sea-temperature rise, ocean acidification, declining oxygen levels and shifting currents. These processes illustrate the complex and interconnected nature of climate and Earth systems, with the report using local examples to show how global trends are experienced in New Zealand.

Average sea-surface temperatures around New Zealand increased by 0.16-0.26°C per decade from 1982 to 2023, warming 34% faster than the global average. Projections indicate further increases of 1.0–1.5°C by 2050 and 1.0–3.0°C by 2100. As the ocean warms, surface layers become more stratified, limiting the vertical mixing of nutrients, heat and oxygen. This also reduces the ocean’s ability to absorb carbon dioxide, contributing to deoxygenation and threatening marine ecosystems, biodiversity and fisheries.

Satellite measurements of chlorophyll-a indicate that primary productivity has risen across most coastal regions between 1998 and 2022, increasing by 5–13% per decade. The most significant increases occurred along the west and east coasts of the South Island, while the North Island showed slight declines. These trends are linked to shifting marine habitats driven by warming waters.

Rising seas, changing coasts: Impacts on New Zealand’s shores

Section 2: Our coasts and estuaries are affected by a changing ocean focuses on how global ocean and climate changes manifest in New Zealand’s coastal environments. Sea-level rise is highlighted as a significant threat, driving inundation, flooding and erosion that put ecosystems, infrastructure and communities at risk.

Intertidal flats may begin to decline this decade if relative sea-level rise exceeds 5 mm/yr in sediment-limited areas. By 2100, under a projected increase of 0.2–1.4 metres, 14 estuaries could lose 27–94% of their intertidal areas. Salt-marsh extent may fall by 11–12% by 2050 and 25–31% by the end of the century.

Low-lying communities face growing risks, including erosion, saltwater intrusion and drainage challenges. These hazards could lead to infrastructure damage, displacement, and ecological disruptions.

Impacts on people, communities and the economy

Section 3: Impacts of our changing ocean on people, society and the economy examines how changes to marine and coastal environments affect people, the economy and cultural wellbeing.

New Zealand has experienced increasingly destructive extreme weather events. Cyclone Gabrielle and the Auckland Anniversary Day floods in 2023 each caused insured losses more than 10 times those of previous major events. Cyclone Gabrielle also triggered significant sediment erosion and deposition in Hawke’s Bay and Gisborne, damaging seafloor habitats and ecosystems.

In 2023, approximately 219,000 residential properties, valued at $180 billion, were located in coastal inundation or inland flood zones. Around 1,300 homes could face more than 20% damage from extreme weather between 2026 and 2060.

A projected 0.6-metre sea-level rise (based on 2019 assessments) would put 2,273 kilometres of roads, 5,572 kilometres of water pipes and buildings worth $26.18 billion at risk. Popular outdoor recreation areas and conservation sites are also vulnerable, including 50 amenity areas, 127 buildings and critical assets such as boardwalks and bridges.

Sea-level rise also threatens archaeological heritage. Of 9,054 mapped coastal sites, 1,564 are vulnerable to flooding and 1,954 are highly vulnerable to erosion.

Climate change is also affecting fisheries and aquaculture, which employed 14,580 people in 2023 and contributed $1.1 billion – 0.3% of national GDP.

Addressing knowledge gaps and preparing for the future

Section 4: Towards a better understanding of our marine environment, the report outlines data and monitoring gaps that must be addressed to understand climate-driven changes better.

It recommends a strategic approach that maximises benefits by:

• Addressing interconnected pressures, including overfishing, pollution and habitat loss
• Prioritising coastal frontline communities, where impacts are felt most strongly
• Restoring critical habitats such as seagrass beds, kelp forests and wetlands
• Integrating mātauranga Māori (Māori knowledge) and tohu (environmental indicators) into monitoring
• Downscaling climate and ocean projections to support local decision-making, with open and accessible data

This report draws on material licensed for re-use under the Creative Commons Attribution 4.0 International licence from the Ministry for the Environment, Stats NZ and other data providers.

Please read the report: Our Marine Environment 2025 Tō Tātou Taiao Moana