a new study on Antarcticaincluding the first map of the iceberg calving, ice shelves and details the transformation of the continent.

The biggest uncertainty in predicting global sea level rise is how ice loss from Antarctica will accelerate as the climate warms. Two studies, published Aug. 10 and led by researchers at NASA’s Jet Propulsion Laboratory in Southern California, reveal unexpected new data. Explains about research How the Antarctic ice sheet is losing mass It has caused icebergs to calve in recent years.

A study published in the journal Natureshows how iceberg calving has changed the Antarctic coastline. last 25 years. The researchers found that the edge of the ice sheet was shedding icebergs faster than the ice could be replaced.

This surprising finding doubles previous estimates of ice loss on Antarctica’s floating ice shelf since 1997. The numbers went from 6 billion to 6 billion. 12 billion metric tons. Ice loss from calving has weakened the ice shelves and allowed Antarctic glaciers to flow faster into the ocean, accelerating the rate of global sea level rise.

Another study published in the journal Earth Systems Science Data, It shows in unprecedented detail how thinning of Antarctic ice spread from the continent’s outer edges to its interior as ocean water melts, and that the ice sheet has nearly doubled in western parts over the past decade. Combined, additional reports provide the most comprehensive view ever. how the continent is changing frozen.

falling apart

“Antarctica is breaking apart,” JPL scientist Chad Greene, lead author of the iceberg calving study, said in a statement. “And when ice shelves shrink And as it weakens, the continent’s massive glaciers tend to accelerate and increase the rate of global sea level rise.”

Most Antarctic glaciers flow into the ocean, where they end up on floating ice shelves. up to 3 kilometers thick and 800 kilometers wide. Ice shelves act as buttresses for glaciers, preventing ice from sliding into the ocean. When ice shelves are stationary, they have a natural cycle of shedding and replenishment that keeps their size fairly constant over the long term.

But in recent years, ocean warming has destabilized Antarctica’s ice shelves. melting them from below. Satellite altimeters measure the thinning process by recording the changing height of the ice. However, until this study, there had been no comprehensive assessment of how climate change has affected iceberg calving across the continent.

This is partly because satellite images are difficult to interpret. “For example,” Greene said, “you can imagine looking at a satellite image and trying to tell the difference between a white iceberg, a white ice shelf, white sea ice, or even a white cloud. It’s always been hard work. But now there’s senough data from multiple data Satellite sensors to get a clear picture of how the Antarctic coastline has evolved in recent years.”

new studio

For the new study, Greene and his co-authors synthesized satellite images of the continent from 1997 at visible, infrared thermal (heat), and radar wavelengths. Combining these measurements with insights from ice flow from an ongoing project that maps NASA’s glaciers around the edges of ice shelves 50,000 linear kilometers from the Antarctic coast.

Losses from calving so far outpace the natural growth of the ice shelf, which researchers believe is unlikely for Antarctica to return to its former size. Until the end of this century until 2000. In fact, the findings suggest that more losses can be expected: Antarctica’s largest ice shelves appear to be on track for major calving events in the next 10 to 20 years.

In the accompanying work, JPL scientists combined nearly 3 billion data points from seven space-sourced altimetry instruments to produce the longest continuous dataset on the varying height of the ice sheet, an indicator of ice loss since 1985. Laser measurements of precise ice height to the centimeter, to produce monthly maps ice loss change The highest resolution ever made.

The unique detail in the new record reveals how long-term trends and annual weather conditions affect the ice. It even shows the rise and fall of the ice sheet, as subglacial lakes regularly fill and empty miles below the surface.

“Combined with a better understanding of the long-term trends in this dataset, subtle changes like this will help researchers understand the processes that affect them. ice loss. “This will lead to better future predictions of sea level rise,” said Johan Nilsson, lead author of the study at JPL.