After years of hemming and hawing, the American Meteorological Society released its official position on climate change yesterday, saying the Earth is warming and that warming is caused by humans.
Weather forecasters have been criticized for their silence on connecting the dots between the extreme weather they report and climate change, even amidst the drought that has effected most of the US this summer.
The public has indicated that they trust their weather forecasters and want to hear whether they connect weather events to climate change.
The American Meteorological Society position statement states:
"There is unequivocal evidence 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," they says in the policy statement.
"The dominant cause of the warming since the 1950s is human activities. This scientific finding is based on a large and persuasive body of research. The observed warming will be irreversible for many years into the future, and even larger temperature increases will occur as greenhouse gases continue to accumulate in the atmosphere."
While natural cycles of warming are to be expected, they say, the evidence clearly points to human activity as the cause of the climate change the earth is currently experiencing:
- All of the 10 warmest years in global temperature records up to 2011 have occurred since 1997, with 2005 and 2010 being the warmest two years in more than a century of global records.
- In the US, there have been twice as many record daily high temperatures as record daily low temperatures in the first decade of the 21st century.
- Freeze zones are rising in elevation, and spring snowpacks are decreasing in volume.
- There have been dramatic seasonal shifts, resulting in earlier springs, longer frost-free periods, longer growing seasons and changes to animal migration patterns.
- Globally averaged sea levels have risen by about 7 inches in the 20th century, with the trend accelerating since the early 1990s.
"It is clear from extensive scientific evidence 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," they write. "The most important of these over the long term is CO2, whose concentration in the atmosphere is rising principally as a result of fossil-fuel combustion and deforestation."
Simulations project there will be an increased proportion of global hurricanes that fall into the strongest categories (4 and 5 on the Saffir-Simpson scale), although the total number of storms may not change. Heat waves and cold snaps will continue, but there will be proportionally more extreme warm periods. There will be more droughts and high temperatures that will put pressure on the world's crop systems.
In July, Jeff Masters, director of meteorology at the Weather Underground (just bought by the Weather Channel), said he would take advantage of his larger audience to help educate Americans about climate change.
"I think it's important for the public to hear that what we're seeing now is the future," he said. "We better prepare for heatwaves, fires and storms. We better educate people on what's going on, give the best science that's out there on what climate change is doing and where it's likely to head. I think TV meteorologists are missing a big opportunity to educate and tell the population what is likely to happen."
For the complete statement:
