The clouds over the northeastern U.S. have been getting higher for the past 30 years, as warmer temperatures near the Earth push them upwards. This could damage forests in the Appalachian Mountains. When the cloud base moves up, many spruce and fir trees can’t get water from the clouds. If the trend continues, deciduous trees such as sugar maple and yellow birch, that don’t use clouds for water, will move up the mountains, taking the place of fir trees. Researcher Andrew Richardson looked at data from 24 airports near the Appalachians, because they routinely keep track of the cloud ceiling. They found that in 18 of the airports, the cloud ceiling has climbed an average of (19 feet) per year since 1973. “Over 30 years, that’s (almost 600 feet), which is about six tree heights,” says Richardson. “It is pretty stunning.”
Ironically, cleaner air may make the problem worse. Dirty air contains particulates, which are bad for our lungs but which act as nuclei for condensation, causing clouds to form at lower altitudes.
News trees growing in new places?it’s all a part of Earth’s future climate.
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