During the last few decades global warming has held the climatic headlines. The earth's atmosphere as a whole, for whatever reason, has been getting warmer, especially during the last quarter of the 20th century. North Carolina and the rest of the southeastern United States, however, have shown no distinct warming trend during the past 100 years (Figure 1). The Southeast, along with one other region, southeast China, is unique in this. There have been periods of warmer weather, periods of colder weather, but no overall change. The other major aspect of climate, precipitation, has also shown year-to-year variability but no trend in the annual total amounts. This is in line with the rest of the world. But for North Carolina the consistent annual totals mask an important change: summers have been getting drier, while falls are getting wetter. As a consequence, North Carolinians tend to have less water available for their use than they did 100 years ago.
The long-term changes are difficult to detect without careful analysis of lots of weather observations. People rarely notice them directly as they go about their everyday business. But they do notice unusual or extreme weather events. And they have had plenty of them recently. In the 5-year period between 1998 and 2002, for example, hurricanes, floods, ice storms, heat waves and droughts have all visited the state, and in one way or another affected almost all parts of it (Figure 2). It is difficult to determine whether these events are more frequent than in the past, since not only is the ability to observe the weather continually getting better, but also there are simply more of us to notice and be inconvenienced by any event. Nevertheless, an examination of the number and types of events decade by decade suggests that extreme events which cause trouble have become more frequent recently, possibly going back towards the situation last seen in the 1950s. Although our skill in predicting the weather very far into the future is extremely limited, these past conditions can serve as a rough guide that suggests that for the next decade or so troublesome events will continue to be regular visitors.
 ©2003 Hugh Morton's NC, UNC Press The Charlotte skyline as seen from Grandfather Mountain on an exceptionally clear day. |
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