1 Natural climate change?
The chart below shows a record of the global mean surface temperature of the Earth compiled for the past 140 years. Clearly there is an upward trend, but what does a chart like this really show?
To understand what the chart shows, it is necessary to take the ‘long view’, looking back through the whole history of the Earth.
How can we know the temperature of the planet over time-scales of billions of years?
Is this current warming part of the Earth's natural temperature variation?
What factors affect and force changes to the global temperature, and to what extent are these being affected by human activity?
What are the best predictions for change over the next 100 years?