Stone masonry response to changing environmental conditions is complex. Growing recognition of the problems associated with stone exposed to prolonged wet conditions means that it is increasingly necessary to understand environmental controls on stone decay, not just in a dynamic world, but also in a world in which the nature of the environmental dynamics themselves are changing. This thesis assesses the impact of climate and changing dynamics on the environmental controls on sandstone decay in three ways: 1) Environmental monitoring, to identify links between external conditions and sandstone temperature and moisture response; 2) Experimental simulation, exploring material-environment interactions during heating/cooling and wetting/drying of sandstone; 3) Modelling techniques, to develop future climate projections for Northern Ireland (statistical downscaling) and to simulate the stone thermal and moisture response to observed and potential future environmental change (hygrothermal simulation). Results demonstrate that stone microenvironmental conditions differ from external environmental conditions and exhibit distinct variability in, and of, themselves. Sandstone temperature and moisture conditions vary with aspect and depth, depending on incident radiation and material properties, and the nature and timing of moisture inputs and outputs, respectively. Asynchronous surface/subsurface stone moisture dynamics relate to the nonlinearity between wetting and drying processes, with 'deep wetness' potential much more widespread than previously thought. Material heterogeneity during drying contributes to complex and spatially variable rates of evaporation. Under projected future changes in seasonal air temperature and precipitation totals, stone moisture conditions are projected to experience little change. Stone temperatures are projected to increase at a rate proportional to ambient change and, with all things remaining equal, stone thermal gradients and rates of change should experience little change. Ambient conditions should not be used as a substitute for stone microenvironmental dynamics - it is necessary to consider the material-environment interactions that mediate stone micro environmental response to wider environmental trends.