Predicted impacts of climate change on New Zealand’s biodiversity.

Abstract

In New Zealand, climate change impacts have already been observed, and will increase in future decades. Average air temperature is predicted to warm by 2.1°C by 2090 for a mid-range IPCC scenario (A1B), with larger increases possible for some IPCC scenarios with higher rates of future emissions. Sea-level rise projections range between 0.18 – 0.59 m by 2100, based on six IPCC future emission scenarios excluding future rapid dynamical changes in polar ice-sheet flow. Global surface ocean pH is predicted to decrease by an additional 0.14 – 0.35 units by 2100, with a similar decrease expected in New Zealand waters. Rainfall is predicted to change significantly, with increased precipitation in the west, and reduced precipitation in the east, and more intense rainfall events. Increasing temperature is likely to result in species’ range shifts southward and upward, and mortality during extreme heat events. Ocean acidification is expected to cause declines in carbonate communities, with cold water communities predicted to decline first due to a lower aragonite saturation horizon in cold waters. Sea-level rise is likely to impact on coastal biota, reducing coastal habitats, changing inundation patterns, and increasing vulnerability to storm surges and tides. Changes in storm and rainfall intensity are predicted to increase disturbance to terrestrial and aquatic communities. Areas with increased precipitation will amplify rates of disturbance, erosion and sedimentation into aquatic, estuarine and coastal ecosystems, while areas with low precipitation will experience increased fire risk. In New Zealand, climate change projections are being integrated into management, including increasing protection and improving management of coastal habitats. Contributing to a global reduction in greenhouse gas emissions, New Zealand is the first country to include forestry in their Emissions Trading Scheme, already positively affecting biodiversity by reducing deforestation.