Observations confirm that climate is changing and it is projected to continue changing rapidly. Adaptation is needed to mitigate the projected adverse impacts of climate change, such as climate-change-related exposures which could affect the health status of many people. Climate projections for this century are available with a high spatial and time resolution. But they are afflicted with uncertainties because of the unknown future emissions of greenhouse gases as well as natural variability and the imperfect understanding of climate science and modelling. The evaluation of climate impacts further increases the uncertainty of the result. Is it justified to act on the basis of uncertain climate information? The results of climate models often differ slightly but they show robust and one-to-one trends in the future development. A quantitative or qualitative estimation of the probability of the climate projection facilitates the appraisal of the climate projection. In accordance with the precautionary principle, stakeholders should act in order to mitigate adverse effects of climate change even under the conditions of uncertainty for instance by using methods of risk assessment and risk management. The inclusion of uncertainties should be a part of this risk assessment process.