GRACE consists of twin co-orbiting satellites that fly in a near polar orbit separated by a distance of 220 km. GRACE precisely measures the distance between the two spacecraft in order to make detailed measurements of the Earth's gravitational field. Since its launch in 2002, GRACE has provided a continuous record of changes in the mass of the Earth's ice sheets.
Credits: NASA Goddard's Scientific Visualization Studio
GRACE (NASA's Gravity Recovery and Climate Experiment (GRACE), consiste en co-satélites en órbita gemelas que vuelan en una órbita polar alrededor separados por una distancia de 220 km. GRACE mide con precisión la distancia entre las dos naves espaciales con el fin de realizar mediciones detalladas del campo gravitatorio de la Tierra. Desde su lanzamiento en 2002, GRACE ha proporcionado un registro continuo de los cambios en la masa de las capas de hielo de la Tierra.
The Greenland ice sheet, covering 660,000 square miles -- nearly the area of Alaska -- shed an average of 303 gigatons of ice a year over the past decade, according to satellite measurements. The Antarctic ice sheet, covering 5.4 million square miles --larger than the United States and India combined -- has lost an average of 118 gigatons a year.
La capa de hielo de Groenlandia, que cubre 660.000 millas cuadradas - casi el área de Alaska - arrojar un promedio de 303 gigatoneladas del hielo al año en la última década, de acuerdo con las mediciones por satélite. La capa de hielo de la Antártida, que cubre 5,4 millones de millas cuadradas --larger que Estados Unidos y la India combinado - ha perdido un promedio de 118 gigatoneladas al año
“We’ve seen from the paleoclimate record that sea level rise of as much as 10 feet in a century or two is possible, if the ice sheets fall apart rapidly,” said Tom Wagner, the cryosphere program scientist at NASA Headquarters in Washington. “We’re seeing evidence that the ice sheets are waking up, but we need to understand them better before we can say we’re in a new era of rapid ice loss.”
Although Antarctica’s contribution to sea level rise currently is much smaller than that of Greenland, recent research indicates this could change in the upcoming century. In 2014, two West Antarctica studies focused on the acceleration of the glaciers in the Amundsen Sea sector showed its collapse is underway.
East Antarctica’s massive ice sheet remains the primary unknown in sea level rise projections. Though it appears to be stable, a recent study found under a major glacier two deep troughs that could draw warm ocean water to the base of the glacier, causing it to melt.
“The prevailing view among specialists has been that East Antarctica is stable, but we don’t really know,” said glaciologist Eric Rignot of the University of California Irvine and JPL. “Some of the signs we see in the satellite data right now are red flags that these glaciers might not be as stable as we once thought. There’s always a lot of attention on the changes we see now, but as scientists our priority needs to be on what the changes could be tomorrow.”
One of the keys to understanding future rates of ice loss is determining the role ocean currents and ocean temperatures play in melting the ice sheets from below its edges. A new six-year NASA field campaign took to the waters around Greenland this summer to probe how warming ocean waters are triggering Greenland glacier degradation. The Oceans Melting Greenland (OMG) project is taking coastal ocean temperature measurements, observing glacial thinning at the ice’s edge, and producing the first high-resolution maps of the seafloor, fjords and canyons in the continental shelf surrounding Greenland.
NASA uses the vantage point of space to increase our understanding of our home planet, improve lives, and safeguard our future. NASA develops new ways to observe and study Earth's interconnected natural systems with long-term data records. The agency freely shares this unique knowledge and works with institutions around the world to gain new insights into how our planet is changing.
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Last Updated: Aug. 26, 2015
Editor: Karen Northon
NASA
Guillermo Gonzalo Sánchez Achutegui
