The paper on “on the return period of the 2003 heat wave” has been published online here, before Christmas. It should be published soon by Climatic Change, http://link.springer.com/article/...

“Extremal events are difficult to model since it is difficult to characterize formally those events. The 2003 heat wave in Europe was not characterized by very high temperatures, but mainly the fact that night temperature were no cool enough for a long period of time. Hence, simulation of several models (either with heavy tailed noise or long range dependence) yield different estimations for the return period of that extremal event.“

To go further on the impact on mortality (which was not the aim of the paper), there is a paper in Nature (here).