**4. Conclusions**

Polyphenols are the key secondary metabolite of grapes and have ample amounts of antioxidants. The production and biosynthesis of phenols is regulated by varying climatic conditions in addition to genotypic traits. Elevated temperature impairs phenolic biosynthesis pathways hence lesser accumulation, while lowers temperatures favor their production. On the other hand, excessive radiation may cause degradation of these compounds. Optimum sun light penetration is necessary for the activation of genes of phenolic biosynthesis pathways. Water balance is also important as modest water deficit near verasion can also promote their activity. For elevated carbon dioxide levels (eCO2) despite limited studies, no major negative effects have been reported. However, there is need to study grapes phenolic compounds in relation to global climate change.
