Science of climate change

What climate change is and how it works.

What climate change is

Climate change refers to long-term changes to average weather patterns. This includes changes to average temperatures, seasons, wind patterns and rainfall.

Our changing climate. Infographic.
Our changing climate. Infographic.

What causes climate change

Our climate changes in response to human activities and natural influences. 

Natural influences include:

  • volcanic eruptions
  • changes to the Earth’s orbit
  • weather patterns. 

Human activities include:

  • burning fossil fuels
  • agriculture
  • any activities that release greenhouse gas emissions into the atmosphere. 

While natural influences can cause the climate to change slightly, human activities have made the climate change rapidly over the past 200 years.   

During the industrial revolution, new fuel sources with high greenhouse gas emissions were adopted to power new technology like cars. Since then humans have continued to produce greenhouse gas emissions, increasing the global average temperature by 1 degree Celsius.

How greenhouse gas emissions contribute to climate change

Earth’s atmosphere is made up of:

  • oxygen
  • a large amount of nitrogen
  • a small amount of greenhouse gases such as carbon dioxide and methane.

Greenhouse gases act like a blanket by retaining energy from the sun. They are important for regulating the temperature on Earth.

Human activities like burning fossil fuels, cutting down trees and agriculture increase the amount of greenhouse gases in the atmosphere.

This causes more energy to be trapped by the Earth’s blanket. This extra energy is then absorbed by the oceans and raises sea temperatures and sea levels. Some energy is held in the atmosphere and makes our climate warmer.

Different types of emissions affect the climate differently

There are many different greenhouse gases.

The most important ones for climate change are:

  • carbon dioxide
  • methane
  • nitrous oxide.

Carbon dioxide is the biggest contributor to climate change and can stay in the atmosphere for thousands of years. It is emitted in large quantities by many different processes. In fact, many of our daily activities – the transport we use and the products we make and buy – continue to be sources of carbon emissions.

Nitrous oxide can stay in the atmosphere for about 120 years.

Methane has a more intense but shorter-term warming effect. The good news is if methane emissions were reduced rapidly the warming caused by past emissions would naturally decrease within a few decades.

Find out more in Our atmosphere and climate 2020 report

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