Feeding in the different agents that cause climate change into our models – like greenhouse gases, output from the Sun, volcanoes - we’ve looked at the patterns of change they cause across the surface of the Earth and through the atmosphere. We compare them to what’s actually been observed and find the best match between computer simulations and the observations. This has indicated to us that over the past 30 or 40 years that most of the warming has been due to human activities.〔()〕