14 DAY TRIAL // A collaboration of experts from NASA and a number of European partner institutions announce that they have just finished a new study on how water is transported on Earth's surface.
At the same time, the investigation was also oriented on determining how the solid crust that covers our planet responds to the retreat of glaciers, or to the way they move around.
The work covered a period of time spanning from the last major Ice Age until present day. Also a target in the new analysis was the changes and shifts that Earth's center of mass recorded.
Experts from the NASA Jet Propulsion Laboratory (JPL), Pasadena, California, the Delft University of Technology, and the Netherlands Institute for Space Research, in Utrecht, collaborated for the study,
The scientists were able to piece together gravity data obtained from the Gravity Recovery and Climate Experiment satellites, and thus calculate the changes.
The satellites belong to the NASA/German Aerospace Center. Their readings were also added to those of global surface movements, made via GPS.
The team then added a computer model developed by the JPL in the mix, so as to create a clear picture of all the variations, shifts and changes.
The team details its work in the September issue of the top-rated scientific journal Nature Geoscience, Space Fellowship reports.
JPL investigator Xiaoping Wu led the joint research team. The group was able to calculate that ice loss in Greenland and Antarctica is in fact lower than previously estimated.
The new results show that, between 2002 and 2008, Greenland lost about 104 (+/-23) gigatons of ice each year, whereas the Alaska/Yukon area lost about 101 (+/-23) gigatons.
At the same time, West Antarctica lost about 64 (+/- 32) gigatons of ice each single year. A gigaton is equivalent to a billion metric tons, or about 2.2 trillion pounds.
These changes also influence the planet as a whole, researchers say. It would appear that they are currently shifting Earth’s surface relative to its center of mass by no less than 0.88 millimeters (.035 inches) yearly.
“The new estimate of shift is much larger than previous model estimates of 0.48 millimeters [.019 inches] per year/ This suggests that either Earth’s lower mantle must be much more viscous than previously believed, or that the history of Earth’s deglaciation needs to be significantly revised,” Wu says.
“Both the GPS and gravity measurements are accurate on their own, but untangling the relative contributions of the two processes as observed by satellites is difficult. This technique provides a first global attempt at doing that,” adds JPL scientist Michael Watkins. “The Earth system is so complex that measuring and understanding it requires scientists to combine observations from as many satellites and ground-based measurements as possible,” says the expert, who is also a GRACE project scientist.
“With each new study like this one, we learn more and more about how to conduct future studies and interpret their data. The more data, and different types of data we collect, the better we’ll be able to answer fundamental questions about how our planet works,” Watkins concludes.