Evidence for climate change

This page outlines evidence that our climate is changing, why it is happening and the impacts of humans.

Watch this video from the World Meteorological Organization on our changing climate

Our changing climate

There is lots of evidence that our climate is changing.

We know this from:

  • direct surface temperature measurements
  • changes in rainfall and weather patterns
  • an increase in the frequency of extreme weather events
  • loss of Arctic sea ice
  • sea level rise
  • melting of the Antarctic and Greenland ice sheets, and from the NZ Southern Alps - watch this video: Glaciers don’t lie on the retreat of New Zealand glaciers [NIWA Taihoro Nukurangi website]
  • shifts in the geographic ranges distribution of some plant and animal species
  • earlier unfolding of new leaves in spring 
  • changes in bird migration patterns.

Many of these changes pose serious risks to human life and property. Exposure to extreme drought, heat, rainfall, and coastal inundation are projected to worsen in many parts of New Zealand and around the world. 

Why is our climate changing?

Earth’s atmosphere is made up of oxygen, a large amount of nitrogen and a small percentage of greenhouse gases, such as carbon dioxide and methane.

Greenhouse gases act like a blanket around the Earth. They trap warmth from the sun and make life on Earth possible. Without them, too much heat would escape and the surface of the planet would freeze. However, increasing the concentration of greenhouse gases in the atmosphere causes the Earth to heat more and the climate to change.

This process is often called global warming, but it is better to think of it as climate change. This is because it is changing other aspects of climate as well as temperature. Changes in weather patterns are also occurring, and the frequency and intensity of extreme weather events, such as heavy rain, heatwaves and droughts, are changing in many regions.

Climate change and the impact of humans

Since the industrial revolution, there has been a marked and growing increase in greenhouse gas producing activities such as industry, agriculture and transportation. These activities are increasing the level of greenhouse gases in the atmosphere. They are causing the Earth to heat up at a rate unprecedented in recent history. This recent warming can only be explained by the influence of humans.

Studies of ice cores tell us that greenhouse gases are at their highest levels in at least 800,000 years. 

The worst effects of climate change can be mitigated if greenhouse gas emissions are reduced to net zero over the course of this century.

Find out more about climate change and its impacts

Information from New Zealand’s National Institute for Water and Atmospheric Research Taihoro Nukurangi

Information from other sources

Reviewed:
20/05/19