Climate Change and Environmental Challenges in NZ’s Coasts

New Zealand’s Southland (Murihiku) Coastal Waters are warming faster than the global average. Outside of Fiordland, waters in Southland are warming at the fastest rate, with an average increase of 0.4 degrees over the past decade.

In fact, New Zealand’s entire coastal waters are warming by 34% above the global average, according to the country’s recent Environmental report published in April 2025.

Aside from harming the country’s coastal ecosystems, including valuable fisheries and habitats, warming waters also fuel extreme weather events and sea level rise, leading to coastal flooding and erosion that could impact properties, businesses, farms, and infrastructure near coastal areas.

Nutrient pollution and sedimentation from land-based activities, such as agriculture and forestry. Sedimentation in estuaries and coastal areas has accelerated over the last 20 years and can affect habitats, smothering sensitive species and reducing their numbers.  These affected species include cockles, pipi, and scallops.

Nutrient pollution is increasing due to dairy farming and horticulture activities.  Elevated amounts of nitrogen and phosphorus entering New Zealand’s estuaries and coastal areas can lead to eutrophication and algal blooms, which deplete oxygen levels.

Land activities also cause pathogens such as faecal bacteria to enter rivers, lakes, estuaries, and coastal waters. These bacteria come from animal excrement, wastewater discharges, and contaminated soil run-off, and can harm ecosystems and people.

Plastic waste is also a significant problem affecting freshwater and marine environments in New Zealand.  A 2023 survey found that 67% of beach litter was plastic. Additionally, hazardous additives in plastics have also been detected in plastic debris on New Zealand’s beaches. Marine species and seabirds can also ingest this plastic or become entangled in it, causing harm or even death.  

Microplastics, a result of larger plastics breaking down, are also ingested by species in the food chain and could pose risks to human health.  They have been found in many of New Zealand’s fish species eaten by humans, as well as in green-lipped mussels. There is a growing body of research to understand the effects of microplastics on ecosystems and human health.

Threats to extinction stem from the effects of climate change, intensifying pressures, and the acceleration of changes in land, freshwater, marine, and air ecosystems. Additionally, the spread of non-native species can contribute to the decline of native species and habitat changes.

Lastly, the report highlights that many species that depend on New Zealand’s marine environment, including estuaries, rocky reefs and shores, fiords and seamounts, and open and deep-water habitats, are at risk of extinction.