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What is climate change?

The Earth's climate is not static. Over the billions of years of earth’s existence, it has changed many times in response to natural causes.

However, when people talk about 'climate change' today, they mean the changes in temperature over the last 100 years caused by human activity. During this time, the average temperature of the atmosphere near the Earth’s surface has risen by about 0.75 degrees Celsius.

Nearly all climate scientists agree that global temperatures will rise further – by how much depends on future emissions of greenhouse gases, and other human activities.

If the temperature rise is high, the impact is likely to be extreme and it will be difficult to cope with. There are likely to be more intense and frequent extreme weather events – like heatwaves, floods and tropical storms – and sea levels will rise further.

• Effects of climate change

• Guide to climate change from the Met Office Opens new window

Early discoveries about climate change

The first discoveries that helped explain recent climate change and global warming were in the 18th and 19th centuries:

• in 1753, Joseph Black discovered carbon dioxide
  
• in 1827, Jean-Baptiste Fourier suggested that an atmospheric effect kept the earth warmer than it would otherwise be – he used the analogy of a greenhouse
  
• in 1896, Svante August Arrhenius proposed that carbon dioxide emissions from the burning of coal would enhance the earth's greenhouse effect and lead to global warming

• Causes of climate change

• Climate change timeline: American Institute of Physics Opens new window

First warnings about climate change

From the late 1950s, carbon dioxide (CO2) measurements were made on a mountain top in Hawaii. Over the next decade, these measurements confirmed that levels of CO2 in the atmosphere were rising year on year. In 1967, an early computer simulation suggested that global temperatures might increase by more than 4 degrees Fahrenheit, depending on CO2 levels.

Improved climate models developed over the next 20 years confirmed the link between CO2 emissions and global warming. Then an ice core from Antarctica first revealed a link between carbon dioxide levels and temperature going back more than 100,000 years. Warnings like these encouraged international action on climate change.

The world’s response to climate change

The first major international climate science conference was held in 1979. The conference called on governments “to foresee and prevent potential man-made changes in climate”.

United Nations takes action
In 1988, the United Nations set up the Intergovernmental Panel on Climate Change (IPCC) to analyse and report on scientific findings. The IPCC warned that only strong measures to stop greenhouse gas emissions would prevent serious global warming.

Global targets for reducing emissions
In 1992, the Earth Summit took place in Rio de Janeiro. Here, the United Nations Framework Convention on Climate Change (UNFCCC) was signed by 154 nations. It agreed to prevent 'dangerous' warming from greenhouse gases and set voluntary targets for reducing emissions. The UK is one of a small number of countries which met this voluntary target.

Kyoto: legally binding cuts in emissions
In 1997, the Kyoto Protocol was agreed. Where the UNFCCC agreed voluntary targets, Kyoto was the first international treaty to set legally binding emissions cuts for industrialised nations. It was signed by 178 countries and came into force in 2005.

• The Intergovernmental Panel on Climate Change Opens new window

• The United Nations Framework Convention on Climate Change (UNFCCC) Opens new window

• More on the Kyoto protocol from the UNFCCC Opens new window

Latest international action on climate change

In 2007, the IPCC announced that the planet has warmed about 0.75 degrees Celsius since the beginning of the 20th century. It said there is a greater than 90 per cent chance that global warming over the last 50 years is due to human activity. At the 2007 UN climate change conference in Bali, the world’s nations agreed to negotiate on a deal to tackle climate change.

At the United Nations (UN) conference in Cancun 2010 the attendees agreed a global deal to tackle climate change. The key parts of this agreement were:

• an overall target limit of 2 degrees Celsius on temperature rise
• to include measures that developed and developing countries are taking on climate change in the UN agreement
• a system to assess how countries are living up to their promises on emissions
• the Green Climate Fund to help developing countries go low carbon
• to slow, halt and reverse the destruction of trees
• to set up ways to help developing countries access low carbon technologies

You can find out more about the Cancun conference agreement from the Department for Energy and Climate Change (DECC) website.

• The Cancun conference agreement Opens new window

The UK’s reaction to climate change

The UK signed both the UNFCCC and the Kyoto Protocol, and is on track to exceed its Kyoto target for reducing greenhouse gas emissions.

In 2006, the Stern report was published in the UK by HM Treasury. It was the first report of its kind into the economic impact of climate change. It found that the costs of inaction far outweighed the costs of action.

In November 2008, the UK government passed the Climate Change Act. The Act sets legally binding targets for reducing emissions by 80 per cent on 1990 levels by 2050.

• Read the Stern Report from HM Treasury Opens new window

• Climate Change Act 2008 Opens new window

What you can do about climate change

Some further changes to the Earth's climate are inevitable, but there is still time to have a positive influence on the future. You can help minimise further changes and adapt to those that will happen through your decisions and actions. Read about simple things you can do to make a difference in 'Greener living: a quick guide to what you can do'.

• Greener living: a quick guide

More useful links

• More on climate change from the UNFCCC Opens new window

• Climate change guide from the BBC Opens new window