It is also robust to the
use of different climate models, different methods for estimating the responses to external forcing and variations in the analysis technique.
Recent experiments with a
number of different climate models indicate that the inclusion of natural climate forcings such as volcanic eruptions, stratospheric ozone depletion, and solar variability can lead to a broad spectrum of simulated 20 - year surface and lower to mid-tropospheric temperature trends.
Through further, independent scientific work involving statistical methods and a
range of different climate models, these changes have been detected as significant deviations from natural climate variability and have been attributed to the increase of greenhouse gases.
While the underlying report showed projected future warming for a range
of different climate models, the Technical Summary focused on a central estimate.