‘Prudence dictates extreme care’
By Summit Voice
SUMMIT COUNTY — While there are still a few prominent TV weather announcers who publicly question the overwhelming body of global warming science, the American Meteorological Society has updated its official position on climate change, acknowledging unequivocally “that Earth’s lower atmosphere, ocean, and land surface are warming; sea level is rising; and snow cover, mountain glaciers, and Arctic sea ice are shrinking. The dominant cause of the warming since the 1950s is human activities.”
“This statement is the result of hundreds of hours of work by many AMS members over the past year,” said AMS executive director Keith Seitter. “It was a careful and thorough process with many stages of review, and one that included the opportunity for input from any AMS member before the draft was finalized,” Seitter said. The full statement is online at the AMS website.
After describing in detail what’s known about climate change, the AMS statement ends with a poignant warning: “Prudence dictates extreme care in accounting for our relationship with the only planet known to be capable of sustaining human life.”
The organization recently took some flak from environmental activists who want weather forecasters to discuss how climate change might be affecting what people experience in their day-to-day weather. One group, Forecast the Facts, publicly called out TV weather forecasts by name. The group also published a study suggesting that 27 percent of TV weather forecasters call global warming a scam, while half deny that global warming is caused by emission of greenhouse gases. Grist.org covered this topic here.
It’s not clear if the revised statement will change the way forecasters present their weather info, but for other purposes, the new document provides a clear and elegant outline of climate change, including impacts to the polar regions, where “Arctic sea ice extent and volume have been decreasing for the past several decades.” The statement explains that both the Greenland and Antarctic ice sheets have lost significant amounts of ice and that most of the world’s glaciers are in retreat.
The AMS also touched on the hotly debated subject of links between climate change and extreme weather, referencing studies showing that the amount of rain falling in very heavy precipitation events (the heaviest 1 percent of all precipitation events) has increased over the last 50 years throughout the U.S.
Other climate-change impacts are also discussed directly:
“Freezing levels are rising in elevation, with rain occurring more frequently instead of snow at mid-elevations of western mountains. Spring maximum snowpack is decreasing, snowmelt occurs earlier, and the spring runoff that supplies over two-thirds of western U.S. streamflow is reduced. Evidence for warming is also observed in seasonal changes across many areas, including earlier springs, longer frost-free periods, longer growing seasons, and shifts in natural habitats and in migratory patterns of birds and insects.”
There no dithering about sea level, which according to the best available measurements has risen by about 7 inches in the 20th century, with the rise accelerating since the early 1990s.
The statement also makes it clear that the observed changes are “beyond what can be explained by the natural variability of the climate.” Extensive scientific evidence makes it clear that “the dominant cause of the rapid change in climate of the past half century is human-induced increases in the amount of atmospheric greenhouse gases, including carbon dioxide (CO2), chlorofluorocarbons, methane, and nitrous oxide”