The magnitudes of these predicted growing season changes indicate potential shifts in climate maturity types for many regions at or near a given threshold of ripening potential for varieties currently grown in that region (Table I). For example, if a wine region with a mean growing season average temperature of 14◦C (cool climate) warms by 1.5◦C, then that region is climatically more con- ducive to ripening some varieties (intermediate maturity group), while potentially less so for those that are currently being grown. If the magnitude of the warming is 2◦C or larger, then a region may potentially shift into another climate matu- rity type (e.g., from intermediate to warm). While the range of potential varieties that a region can ripen will expand in many cases, if a region is a hot climate maturity type and warms beyond what is considered viable, then grape growing becomes challenging and maybe even impossible. In addition, Table V shows that many of the wine regions/categories of wine are at or near their optimum growing season temperature and further increases, as predicted during for 2000– 2049, will place some regions outside their theoretical optimum growing season climate.