What is climate change?

Climate change as defined by the Intergovernmental Panel on Climate Change (IPCC) is the identifiable change in the climate over an extended period of time (decades or longer). This can be due to natural variability or as a result of human activity. Scientists have measured warming of the climate and have attributed this to an increased concentration of greenhouse gases in the atmosphere which causes changes in weather patterns, and the frequency and intensity of extreme weather events, such as heavy rain, heatwaves and droughts.

Another way of explaining this is: Earth’s climate is a delicate balance of trapping just enough heat from the sun to enable life on earth. This trapping is possible due to a small part of Earth’s atmosphere called greenhouse gases. The remaining atmosphere is mostly made up of oxygen and nitrogen.

There are natural changes in Earth’s climate; over millennia we’ve seen ice ages and interglacial periods (this is when we see warmer global average temperatures lasting thousands of years).

More recently, since the industrial revolution, we’ve also seen human impacts on the Earth’s climate, with increasing carbon dioxide and greenhouse gas emissions which means more heat is trapped in our atmosphere.

The Intergovernmental Panel on Climate Change (IPCC) has concluded that human influence on our climate is clear. Burning fossil fuels like coal and oil, for example, is increasing the level of greenhouse gases in our atmosphere, causing warming at an unprecedented rate.


So, what does this mean?

This global warming causes changes to New Zealand’s climate, which will likely include more extreme weather events such as floods and droughts, higher temperatures, change in rainfall patterns and rising sea-levels. The impacts will vary across different areas of New Zealand.

Lessening climate change and our influence needs substantial reduction of greenhouse gas emissions. Even if this is achieved, the effects of climate change will continue because of the gases already released and those that may continue to be released. The impacts of climate change will be ongoing and we need to adapt to these impacts.

For more information on climate change visit the MfE website.


What does climate change mean for Otago?

Otago’s climate is varied and, at times, extreme – resulting in hazards that affect many of our communities. Longer-term trends in climate (including temperature and rainfall patterns) and sea-level changes have already been observed in Otago.

Climate-related events are expected to change further over the coming decades as a result of human-induced global warming. This means events that can have a negative effect on Otago communities may become more common.

Climate change in Otago could result in:

  • Warmer temperatures (more hot days, fewer frosts)
  • Wetter conditions (winter and spring)
  • Significant decreases in snow
  • More windy days
  • An increase in storm intensity
  • Local wind extremes
  • More thunderstorms
  • Sea-level rise

While climate change is not new to us at ORC, our latest piece of work in this area is a Climate Change Risk Assessment. As part of this, we have commissioned a report from NIWA that describes projected climate changes for Otago. The report looks at expected changes for different climate factors, like temperature and rainfall as far ahead as 2100. The report draws on climate model simulations from the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report. It also looks at the hydrological impacts of climate change.

Find the report here.

For more information about the Intergovernmental Panel on Climate Change (IPCC) visit their website.


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