This paper is part of an extensive study of secondary school students' preconceived ideas about climate change. Here, we undertake a survey in the province of Valencia (Spain) to ascertain secondary school students' notions of the causes and consequences of climate change. Results show, among other things, that students clearly relate the misuse of motor vehicles and factory emissions to the problem. However, the obvious correlation with household energy use is not observed. The usual confusion with other environmental problems, such as the hole in the ozone layer, as described in previous studies, is also detected. Students know almost no greenhouse gases other than CO[subscript 2], while the socio-economic consequences of climate change are the least perceived. (Contains 4 tables and 3 figures.)