Climate change is now perceived as the greatest environmental challenge facing the world today and one which can only be resolved with a coordinated approach.


What is climate change?

In the past, the Earth’s climate has varied as a result of natural causes, such as volcanic eruptions, changes in the Earth’s orbit and fluctuations in the sun’s intensity.

These climate changes have had varied results; from the absence of any ice at the poles, to massive ice sheets across Europe, Asia and North America. Some have even triggered mass extinctions.

However, when we talk about climate change today, we are generally referring to how our climate has altered since the early 1900s.


How do greenhouse gases affect the climate?

The Earth’s natural greenhouse effect keeps the Earth much warmer than it would otherwise be. Greenhouse gases such as carbon dioxide (CO2), methane and water vapour behave like a blanket around Earth. These gases allow the Sun’s energy to reach the Earth’s surface, but instead of allowing all of the heat to escape back into space, the greenhouse gases absorb some of the energy, trapping the heat within the atmosphere and keeping the Earth in a comfortable temperature range. Whilst the greenhouse effect is a natural phenomenon, human industrialisation has caused large amounts of greenhouse gases to be released into the atmosphere, enhancing the greenhouse effect and pushing temperatures up globally.

An idealised model of the natural greenhouse effect.


If our climate changes naturally, what impact do we have?

Whilst the greenhouse effect makes the Earth warm enough for life, human influence has upset the natural balance and the Earth’s climate is now changing outside the rate of natural variability.

The human impact can be attributed to the burning of fossil fuels for things like energy, transport and manufactured goods, which has led to an increase in the release of greenhouse gases (carbon dioxide and methane) into the atmosphere.

As a result, the average global temperature has steadily warmed over the last hundred years and is continuing to do so. Between 1970 and 2004, greenhouse gas emissions rose by 70% and the 10 hottest years on record have all been since 1997.

The Intergovernmental Panel on Climate Change (IPCC), a body of over 2,000 scientists and experts from around the world, concluded in 2007 that there is a “90% probability that the observed increase in global average temperatures since the mid-20th century is due to the observed increase in man-made greenhouse gas concentrations”.

You can find more information on the IPCC website. The scientific community has reached a consensus based on overwhelming evidence; our climate is changing and we are a driver of this change.



What will happen if we don’t reduce greenhouse gas emissions?

If we don’t act to reduce greenhouse gas emissions, the level of greenhouse gases in the atmosphere is predicted to double that of pre-industrial levels by 2050.

If this happens, global temperatures are likely to rise by around 2 to 6°C by the end of the 21st century.  This will result in more intense heat waves, droughts and flooding, as well as more frequent storms and severe weather events.

Even if emissions peak in 2015 and decrease rapidly at 3% every year after that, there’s only a 50% chance of keeping global temperature rise below 2°C.

Every delay of 10 years in the peak emissions would add about 0.5°C of warming.

The impacts of climate change will have more effect on developing countries and the poor; those who can least afford to adapt. Thus a changing climate will increase inequalities in essential matters, such as health and access to food and clean water.


What are the economic implications of climate change?

In October 2006, Lord Stern, the former World Bank Chief Economist, presented his report on the Economics of Climate Change. He warned that climate change has the potential to cause major disruption to economic and social activity, on a scale similar to those associated with the great wars and the economic depression of the first half of the 20th century.

He concluded that ignoring climate change will eventually damage economic growth, that “the costs of stabilising the climate are significant, but manageable, delay would be dangerous and much more costly”.


Where can I find more information about climate change?

  • For a comprehensive guide to climate change science, news and research, look at the Met Office website.
  • Lord Stern’s report, which concluded that taking action to reduce greenhouse gas emissions is an economic imperative, is available on the HM Treasury website.
  • The Intergovernmental Panel on Climate Change is a scientific body set up to provide decision makers with an objective source of information about climate change. Have a look at the IPCC website.
  • For the latest climate change news, policy and research, see the DEFRA website.
  • For information about what is happening nationally to tackle climate change in the UK, visit the Department of Energy and Climate Change website.
  • A short climate change guide summarising the key facts, terms and background science available on climate change, is provided on The Royal Society website.
  • English Heritage has produced an interactive web portal, looking at the potential impacts of climate change on older homes. To find out more, visit the web portal.
  • RealClimate is a site on climate science by working climate scientists for the interested public and journalists. For more information, visit the RealClimate website.