Ideas about change of climate

Everybody (at least in Germany) is talking about change of climate. The hottest and dryest month of April in Middle Europe is regarded as proof of this thesis. In the TV-channel Phoenix at 4/30/07 a meteorologist contradicted in this point of view. The weather in April could be a singularity of climate. Only if there is a significant accumulation of such events, you have a certain degree of probability, that this phenomenon is a proof of the thesis of change of climate. Nevertheless there was an increase of temperature in the last few years. Theoretical calculations are obviously able to confirm the experimental values of temperature in the past. But what about other climate parameters like accumulation and duration of rain and snow, amount and direction of wind, amount and number of hurricans and the percentage change of concentration of the "climate killer gases" carbondioxide and methan in the atmosphere? Isn't it necessary to improve the climate model calculations in order to get better statements about the development of world wide climate in the furure?