Keep Watching the Ice
Meet the satellites bringing data to the discussion of global warming
- By Ben Iannotta
- Air & Space magazine, September 2006
(Page 2 of 7)
Armed with these satellite measurements, glaciologists are taking the first steps toward predicting how much ice will disappear from Earth in the coming decades—the critical figures of “how much and when,” Zwally calls them.
At the moment, water that might otherwise flood coastal cities and towns around the world remains locked away as ice, much of it in Antarctica and Greenland. “The glaciers have in them on the order of 70 meters—200 feet—of potential sea level rise,” says Bruce Wielicki, a senior scientist at NASA’s Langley Research Center in Hampton, Virginia. “No one is talking about us getting all 200 feet in the next 100 years, but the point is, even if you only got five of that 200 feet, where I live, our average elevation is about three feet. So the costs of dealing with sea level change are one of the huge potential issues.”
Initial data from GRACE has already sparked debates and some concern. “We’re seeing very quick responses to changes in temperature, responses that people used to think would take hundreds or thousands of years,” says Zwally’s boss, glaciologist Waleed Abdalati, head of the Cryospheric Sciences Branch at the Goddard Space Flight Center. “It’s not a ‘run for the hills’ kind of story, but it’s ‘Wow, this is serious.’ Things seem to be stirring in a way that is going to contribute to [an increase in] sea level.”
But there is no agreement among scientists on how quickly the sea level will rise, how quickly the global climate will heat up, or even how warm Earth might get. According to a panel of scientists who looked into the question for the Bush administration in 2001, the temperature could rise an average of 2.5 to 10.4 degrees Fahrenheit in the next 90 years.
What is certain, even among scientists who have criticized their colleagues for over-hyping global warming, is that at least some of Earth’s warming is due to a buildup of carbon dioxide from the burning of fossil fuels. These gases trap heat from the sun, resulting in the greenhouse effect. The main disagreement is over the urgency of the problem.
“This issue is not going to come and kill us all, despite the apocalyptic renditions you see in newspapers,” says University of Virginia climatologist Pat Michaels, whose book Meltdown criticizes the methods used by most climate scientists. Michaels calculates the pace of human-caused warming to be slow enough for correction: “We have time to invest in future [energy] technologies.”
More information is needed to gauge the seriousness of the problem. If ICESat corroborates the GRACE findings, Earth’s coastlines could look dramatically different within 100 years.
GRACE is the first satellite system of its kind. It consists of two satellites that follow the same orbit about 120 miles apart, says Mike Watkins, the GRACE project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California. “This is not like the 13th mission to make the same measurement a little bit better,” Watkins says. “It’s really a revolutionary thing.”