University of Bristol
Wellcome Trust
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Climate change

Evidence and future predictions

The evidence:

In recent years, the reliability and the interpretation of the evidence for climate change and future predictions has been questioned by a number of scientists. However as time has passed, more and more evidence has emerged that supports climate change theories. As a result only a very few scientists still doubt climate as a genuine phenomenon, though there is still uncertainty as to how severe the effects of it will be.

The Precautionary Principle

At the Rio Earth Summit in 1992 the world’s governments signed up to the United Nations Framework Convention on Climate Change. This was based on the  precautionary principle; the consquences of climate change are so dire that action needs to be taken even in the light of scientific uncertainties about the evidence for climate change and its impacts. It was decided to take a precautionary approach and to aim to reduce global greenhouse gas emissions by 60% or more as soon as possible.

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The first and most famous evidence came from the high altitude observatory at Mona Loa in Hawaii, which measured atmospheric concentration of carbon dioxide monthly since the mid 1950’s.

Evidence for climate change and global warming come from many different sources, although most rely on observing ‘anomalies’ and ‘trends’ over time. The following selection has been obtained from the Met Office's
 Hadley Centre for Climate Prediction and Research and
National Oceanic and Atmospheric Administration of
the United States (NOAA)

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Global Temperature 

Global Surface temperature –
3 sources.

Arctic Sea Ice extent

Central England Temperatures -

Major Global Climate Anomalies - 1997


There are many uncertainties about climate change predictions due to an incomplete understanding of:

  • Sources and sinks of greenhouse gases
  • The effects of clouds
  • Oceans and their influence on climate change
  • How polar ice-sheets will affect sea level rises

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The Hadley Centre for Climate Prediction and Research has developed computer models that have been greatly improved and are now considered to be far more accurate. These predictions rely on projections which are deduced from separate models which take into account population growth, energy use, economics, technological developments, and so forth. The table summarises how climate change models are predicted.

The following selection shows some of the predictions based on these advanced computer models. Predictions differ depending on the rate at which we control carbon dioxide emissions.

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Temperature rises.  

UK temperature

Arctic sea ice

UK precipitation

UK wind speed prediction

For more tables and graphs, visit the  Hadley Centre climate change presentation web page


  1. Using this long list of New Scientist articles, find more evidence for Climate change and global warming.
  2. Create a poster showing important climate change predictions which might affect you personally.


 Consequences of Climate Change

All diagrams on this page (c) Crown copyright 2005 Published by the Met Office. Reproduced with their kind permission.


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