Although I am not an expert in CMIP5 models, however, if your data had an increasing trend in recent years, future trend will definitely be increasing. This is because prediction after 2070 would based on the  current and some predicted values. Therefore, determining magnitude may worthy if you mention that  these values are based on your current assumption that is future climate will act like as you assumed. Simply, the trend value will effective, if the present scenario exists.

As per George Zittis the last three lines of his answer may holds good for local region other wise that violates the global atmosphere mass balance.

Thanks all for your valuable comments.