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.
Many new wine drinkers have a decidedly sweet tooth, having been raised on coke, candy and chocolate as their 'normal sweetness level'. Red wines are known for their health benefits - and also for their tannic, non-sweet flavors. Many new wine drinkers therefore seek a sweet red wine that is as sweet as possible. As a bit of background, the tannic, leathery flavor of red wine comes from the red grape skins. All grape insides are white in color.