The trends are the slopes of the seasonal or annual temperature or precipitation values at each grid point from 2000-2099.  In the annual figures, the temperature is simply the mean of the minimum and maximum temperatures, rather than the true GCM screen temperature (which is not processed by VEMAP).  Units for temperature and apparant temperature trends are degrees F/100 years.  Units for precipitation are inches/100 years.  The historical trend maps at the bottom are replotted from data supplied by the NCDC.  You will have to open your browser window wide enough to see the two sets of figures side-by-side.