Climate change

The climate is changing and will continue to change in the future. While the extent and rate of change is dependent on the extent that greenhouse gas emissions are reduced globally, some change to our climate is already in motion and inevitable. The Ministry for the Environment (MfE) recognises the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report provides the most up-to-date climate science outlining what New Zealand can expect because of climate change.


What we know

Climate change will worsen other hazards

Climate change is not a natural hazard. It does, however, lead to increasing the risk from hazards such as floods from rivers, rainfall and rising groundwater, liquefaction potential where some types of soil are presently close to the ground surface, and coastal erosion and inundation.


National guidance recommends considering four possible scenarios

In 2017 Ministry for the Environment released guidance for councils to manage and adapt to the increased coastal hazard risks posed by climate change and sea-level rise . This guidance includes four future climate scenarios, known as Representative Concentration Pathways (RCPs) , which reflect how much solar radiation the earth would receive (warming) based on different concentrations of emissions. These include RCP 2.6 which represents a low to eventual net-zero emissions scenario, to RCP 8.5+ which represents a continuing high emissions scenario and accounts for possible instabilities in polar ice sheets.

Likely pathwaysRCP2.6RCP 4.5RCP 8.5RCP 8.5+
Sea level rise 20650.30m0.33m0.41m0.55m
Sea level rise 21200.55m0.67m1.06m1.36m

Sea level rise projections based on the four representative concentration pathways (RCP) scenarios. Adapted from Ministry for the Environment workshop on Coastal Hazards and Climate Change guidance (2018)


Expect changes in temperature rainfall and storms

Climate change is expected to have a range of effects on natural processes including higher temperatures, changes in rainfall patterns, more intense storms, changes in airflow patterns, and rising sea levels. What this means for the Canterbury region is higher average temperatures and temperature extremes, increased intensity of rainfall and changes to seasonal patterns, increased frequency and intensity of dry days, drought, and storms, small-scale wind extremes, and ex-tropical cyclones .


Why this is important

The RCP 2.6 scenario is globally accepted as inevitable, meaning that even if emissions are reduced immediately, and some of the greenhouse gases are able to be extracted back out of the atmosphere and stored, we have already set in motion a sea level rise of at least 0.2-0.4m by 2065 . This can be considered our baseline, or new normal.

According to the Ministry for the Environment. the current track is the RCP 8.5 scenario in which a sea level rise of 0.41m by 2065 and 1.06m by 2120 is a likely outcome for New Zealand. If emissions increase at faster rates, a sea level rise is likely to be greater than these predictions.


What we don’t know

When these changes will occur

The key uncertainty in climate change projections is not if, but when changes will reach a certain threshold. This uncertainty is based not only on the natural processes themselves, but the human behaviour that influences them. Here's a diagram that shoes global emission scenarios and the four RCPs compared with the Paris agreement and current global policies.


Effects of less conservative projections

The IPCC scenarios are based on the current emissions pathway continuing or on emissions being reduced or mitigated . They do not consider significant increases in emissions practices, or non-linear polar ice sheet and ice shelf responses, such as irreversible collapse of the ice sheets in Antarctica and Greenland which could cause sea level to rise at a much faster rate .

The climate is changing and will continue to change in the future. While the extent and rate of change is dependent on the extent that greenhouse gas emissions are reduced globally, some change to our climate is already in motion and inevitable. The Ministry for the Environment (MfE) recognises the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report provides the most up-to-date climate science outlining what New Zealand can expect because of climate change.


What we know

Climate change will worsen other hazards

Climate change is not a natural hazard. It does, however, lead to increasing the risk from hazards such as floods from rivers, rainfall and rising groundwater, liquefaction potential where some types of soil are presently close to the ground surface, and coastal erosion and inundation.


National guidance recommends considering four possible scenarios

In 2017 Ministry for the Environment released guidance for councils to manage and adapt to the increased coastal hazard risks posed by climate change and sea-level rise . This guidance includes four future climate scenarios, known as Representative Concentration Pathways (RCPs) , which reflect how much solar radiation the earth would receive (warming) based on different concentrations of emissions. These include RCP 2.6 which represents a low to eventual net-zero emissions scenario, to RCP 8.5+ which represents a continuing high emissions scenario and accounts for possible instabilities in polar ice sheets.

Likely pathwaysRCP2.6RCP 4.5RCP 8.5RCP 8.5+
Sea level rise 20650.30m0.33m0.41m0.55m
Sea level rise 21200.55m0.67m1.06m1.36m

Sea level rise projections based on the four representative concentration pathways (RCP) scenarios. Adapted from Ministry for the Environment workshop on Coastal Hazards and Climate Change guidance (2018)


Expect changes in temperature rainfall and storms

Climate change is expected to have a range of effects on natural processes including higher temperatures, changes in rainfall patterns, more intense storms, changes in airflow patterns, and rising sea levels. What this means for the Canterbury region is higher average temperatures and temperature extremes, increased intensity of rainfall and changes to seasonal patterns, increased frequency and intensity of dry days, drought, and storms, small-scale wind extremes, and ex-tropical cyclones .


Why this is important

The RCP 2.6 scenario is globally accepted as inevitable, meaning that even if emissions are reduced immediately, and some of the greenhouse gases are able to be extracted back out of the atmosphere and stored, we have already set in motion a sea level rise of at least 0.2-0.4m by 2065 . This can be considered our baseline, or new normal.

According to the Ministry for the Environment. the current track is the RCP 8.5 scenario in which a sea level rise of 0.41m by 2065 and 1.06m by 2120 is a likely outcome for New Zealand. If emissions increase at faster rates, a sea level rise is likely to be greater than these predictions.


What we don’t know

When these changes will occur

The key uncertainty in climate change projections is not if, but when changes will reach a certain threshold. This uncertainty is based not only on the natural processes themselves, but the human behaviour that influences them. Here's a diagram that shoes global emission scenarios and the four RCPs compared with the Paris agreement and current global policies.


Effects of less conservative projections

The IPCC scenarios are based on the current emissions pathway continuing or on emissions being reduced or mitigated . They do not consider significant increases in emissions practices, or non-linear polar ice sheet and ice shelf responses, such as irreversible collapse of the ice sheets in Antarctica and Greenland which could cause sea level to rise at a much faster rate .