How is the climate expected to change in the future?

Science Centres: Climate

Future climate changes will be affected, amongst other things, by how much extra greenhouse gas goes into the atmosphere. For this reason, NIWA has looked at likely changes in New Zealand across six greenhouse gas emission scenarios from the Intergovenmental Panel on Climate Change (IPCC), but focusing on the mid-range. These scenarios do not include major efforts to reduce greenhouse gas emissions.

  • There are likely to be more severe droughts and/or floods in some places, and less severe droughts and/or floods in others. Some models suggest a possibility of more extreme (i.e. high) rainfall events. It is not yet possible to predict whether changes are likely in the occurrence or geographical distribution of severe storms, such as tropical cyclones.
  • Model projections for increases in global sea level by 2100, for the same scenarios, range from about 15 to 95 cm. The projection for the mid-range emission scenario (about 50 cm) is about 25% lower than the IPCC 1990 "best estimate". Regional sea level changes may differ from the global mean value.
  • Model projections, based on a range of emission scenarios and climate sensitivities, suggest an increase in global mean surface temperature of between about 1 °C and 3.5 °C by 2100. Regional temperatures could vary significantly from the global mean value, and actual annual to decadal changes would include considerable natural variability.
  • Predictions are still subject to uncertainties, and there is less confidence in predictions for regions the size of New Zealand than for the entire planet. Because of limits in understanding of aspects of the climate system some future changes may come as a surprise.