The paper summarizes some aspects of the effects of climate change on Mediterranean agriculture. Differences between climate change and climate variability are stated. The role of CO2 is established as promoter of greenhouse and global warming effects and concern is expressed on the effect that human activities have on the increase of CO2 and other greenhouse gases. The positive and negative effects of the climate change on the Mediterranean rainfed agriculture are analyzed through the prediction of models and changing scenarios. Key questions for the assessment of vulnerability and adaptation of agriculture to climate change are discussed.