Regional effects of global warming vary in nature. Some are the result of a generalised global change, such as rising temperature, resulting in local effects, such as melting ice. In other cases, a change may be related to a change in a particular ocean current or weather system.
In general, white wines exhibit more acidity than red wines. Acidity gives wine its crispness on the palate. A dry wine needs good levels of acid to provide liveliness and balance; sweet wine needs acidity so it does not seem cloying. Too much acidity will make the wine seem harsh or bitter; too little and the wine will seem flabby and dull.
The subjective sweetness of a wine is determined by the interaction of several factors, including the amount of sugar in the wine, but also the relative levels of alcohol, acids, and tannins.Briefly: sugars and alcohol enhance a wine's sweetness; acids (sourness) and bitter tannins counteract it. sweet wine such as a Vouvray can actually taste dry due to the high level of acidity. A dry wine can taste sweet if the alcohol level is elevated. Medium and sweet wines have a perception among many consumers of being of lower quality than dry wines.