900 4 phase runs have successfully completed and returned results to climateprediction.net since the new experiment was launched in June 2004.

The global mean temperatures produced by all of these through the 4 phases have been plotted in the figure below. The data is entirely unfiltered - the unstable models are included as well as the stable ones.

Phase 4

Phase 4 is a continuation of phase 3, but at the year 2064 the thermohaline circulation is slowed down. Most, but not all, of the models we have had back so far which cool a lot in phase 4 also cooled in phases 2 (green lines) & 3 (blue lines), i.e. they are not stable. Of the other models, most cooled a little bit in phase 4 (yellow lines), offsetting the warming due to the doubling of CO₂ in phase 3.

Click here to find out more about the 4 phase experiment.