Evidence for climate change

Our climate is changing. We know this from the evidence. Find out why it is happening and the impact humans are having.

Scientific evidence is clear 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

Extreme drought, heat, rainfall, and coastal inundation are projected to get worse in many parts of New Zealand and around the world. They pose risks to our safety, property, and infrastructure such as roads.

Understanding climate change

Earth’s atmosphere is made up of oxygen, a large amount of nitrogen and a small amount 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. 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. It is changing other aspects of climate as well as temperature (eg, frequency and intensity of extreme weather events).

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.

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

Video: WMO

2018 State of the Global Climate.

2018 was the fourth warmest year on record.

2015-2018 were the four warmest years on record as the long-term warming trend continues.

Ocean heat content is at a record high.

Global mean sea level continues to rise.

Arctic and Antarctic sea ice extent are well below average.

Extreme weather impacted lives and sustainable development on every continent.

Average global temperature reached approximately 1°C above pre-industrial levels.

We are not on track to meet climate change targets and rein in temperature increases.

Every fraction of a degree of warming makes a difference.

The WMO Statement on the State of the Global Climate seeks to inform annual UN climate change negotiations.




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

Information from other sources

Environmental reports 'our atomosphere and climate'