By use of open top chambers environmental warming was simulated in a field plot near Montfavet, Southern France. Differently (naturally and artificially) pigmented land snails (Theba pisana) were introduced and analysed for a number of biochemical, physiological and demographical parameters. A number of temperature measurements (internally in the snails and externally) were conducted. Furthermore, 35 Mediterranean field sites were characterized for their mean temperature of the warmest quarter of the year, and abundant T. pisana populations were morphometrically analysed for their pigmentation intensity.