The study, led by authors from the United States Geological Survey and published in the journal Science, found the rate of tree deaths has more than doubled in the last few decades even in apparently healthy, well-established forests. Death rates have increased at all elevations, and for trees of all sizes and types, leading the researchers to worry that the U.S. may soon suffer massive and sudden die-backs of its seemingly healthy forests, a cascading effect that could release carbon dioxide into the air, further speeding global warming. ()
Adapting to changes already underway: As the Climate Hot Map demonstrates, the impacts of a warming world are already being felt by people around the globe. If climate change continues unchecked, these impacts are almost certain to get worse. From sea level rise to heat waves, from extreme weather to disease outbreaks, each unique challenge requires locally-suitable solutions to prepare for and respond to the impacts of global warming. Unfortunately, those who will be hit hardest and first by the impacts of a changing climate are likely to be the poor and vulnerable, especially those in the least developed countries. Developed countries must take a leadership role in providing financial and technical help for adaptation.
Hemp scrubs the air of excess CO2 gas - a contributing factor in global warming - as it grows. Growing massive amounts of hemp - like what was done in the World War II HEMP FOR VICTORY program - can radically reduce the amount of CO2 gas in the atmosphere.
The controversial technique could one day be used to block incoming solar radiation and cool down Earth to combat the effects of global warming.
Stephenson added that the Science study could help the U.S. Forest service improve its husbandry measures by, for example, responding differently following forest fires. "We might want to think about planting a different species of trees perhaps one from further south or lower elevations that are better adapted to warmer temperatures," he said. But even that would be a band-aid solution. According to Stephenson, the best chance of saving American forests is to slow and eventually cease the cause of their distress. "Anyway you cut it, the best solution is to get a lid on humanity's carbon output," he says.
The Science study suggests that such a troubling cycle might befall U.S. forests, as warming was listed as the most likely cause and result of the increase in tree mortality. The study ruled out increasing competition among trees, changes in the composition of tree species, pests, fires, air pollution or logging as the reason for the increase. The likely culprit, the researchers said, was stress from warming temperatures. ()
act as huge carbon sinks, capturing and storing carbon dioxide. Along with oceans and other plant life, trees removed approximately 54% of all carbon dioxide created by human activities globally during the period 2000-2007, according to research group The Global Carbon Project. But when they die, trees release their sequestered carbon as they decompose, leading some scientists to the theory that mass tree deaths from global warming could lead to a worsening cycle in which each stage of warming sets off another. Such a cycle could hasten climate change from the predicted timescale accepted by the U.N.'s Intergovernmental Panel on Climate Change.
All the pupils in our class took part in preparing a large collage about global warming. We were divided into groups to work on it. It took lots of time to finish. And we had lots of fun. Our teachers helped us too.