Peak times of snowmelt water runoff have become 10-15 days earlier over the past 50 years. Grand Teton National Park photo: Getty Images
Recently we wrote about some rather significant underestimations of the severity of extinction rates and of the amount of soot emitted from cargo ships. Well here's one more in a continuing series of, "whoops, things are a bit worse than we thought" posts.
Melting Snow Plus Global Warming Causes Positive Feedback Loop
Science Daily brings us the news that, "According to a new study, global warming could lead to larger changes in snowmelt in the western United States than was previously thought, possibly increasing wildfire risk and creating new water management challenges for agriculture, ecosystems and urban populations."
The reason for this ominous-sounding conclusion is that a study conducted by a group Purdue University researchers has discovered that a critical surface temperature feedback is twice as strong previously believed: The influence of melting snow on regional climate is far greater than greenhouse gases alone. Melting snow, when combined with global warming, contributes to a feedback loop further accelerating warming and water runoff.
Sara A. Rauscher, lead author of the paper:
Because snow is more reflective than the ground or vegetation beneath it, it keeps the surface temperatures lower by reflecting energy from the sun. When snow melts of does not accumulate in the first place, more solar energy is absorbed by the ground, warming the surface. A feedback loop is created because the warmer ground then makes it more difficult for snow to accumulate and perpetuates the effect.
Melting Occuring Earlier in Season, Ecosystem Consequences Potentially Great
Noah Diffenbaugh, senior author of the paper, points out that over the past 50 years, peak runoff time has moved 10 to 15 days earlier in the season. This means that reservoirs could receive too much water early in the season and not enough as the summer progresses. This is turn could lead to massive forest mortality, changes in wildlife habitat and increased wildfire risk.
via :: Science Daily
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