New data is revealed about Antarctic ice that has been losing mass in recent decades.
New study of NASA for Antarctica, which includes the first map detachment of icebergsdetails how the continent is changing.
The biggest uncertainty in predicting global sea-level rise is how Antarctic ice loss 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 about how the Antarctic ice sheet has been losing mass in recent decades.
Last March a huge chunk of ice, the size of New York City, broke off for the first time in East Antarctica, an area previously thought to be unaffected by climate change.
A study, published in the journal Naturemaps how iceberg calving – the breaking away of ice from a glacier front – has changed the Antarctic coastline over the past 25 years.
The researchers found that the edge of the ice sheet causes icebergs to fall before the ice can be replaced. This unexpected finding bolsters previous estimates of ice loss from the Antarctic ice floes since 1997, from 6 trillion to 12 trillion metric tons.
Losses of ice from detachments have greatly reduced floating ice sheets and allowed Antarctic glaciers to flow faster into the ocean, accelerating the rate of global sea-level rise.
The other study, published in Earth System Science Data, shows in stunning detail how thinning Antarctic ice as ocean water melts has spread from the continent’s outer edges to its interior, nearly twice as much ice sheet area as the past decade.
These complementary reports when combined provide the most complete picture of how the frozen continent is changing.
Detachment of icebergs
“Antarctica is collapsing at its edges,” says JPL scientist Chad Green, lead author of the iceberg breakup study. “And when the floating ice floes shrink and shrink, the continent’s massive glaciers tend to accelerate the rate of global sea-level rise.”
Most Antarctic glaciers flow into the ocean, where they end up as floating sheets of ice up to 2 miles (3 km) thick and 500 miles (800 km) wide. These pieces of ice act as a buffer to the glaciers, preventing the ice from simply sliding into the ocean. When these ice volumes are stable, they have a natural cycle of detachment and replenishment that keeps their size fairly constant over the long term.
But in recent decades, ocean warming has been destabilizing the Antarctic ice sheets by melting them underneath, making them thinner and weaker.
Satellite altimeters measure the thinning process by recording the changing height of the ice, but until this study, there hasn’t been a comprehensive assessment of how climate change might be affecting detachment across the continent.
This was partly because the satellite images were difficult to interpret. “For example,” Green said, “imagine looking at a satellite image and trying to tell the difference between a white iceberg, a white floating ice mass, white sea ice, and even a white cloud. This was always a difficult task. But now we have enough data from multiple satellite sensors to see a clear picture of how the Antarctic coastline has evolved in recent years.”
For the new study, Green and his colleagues composited satellite images of the continent in visible, thermal infrared (heat) and radar wavelengths since 1997.
By understanding the flow of the ice through an ongoing NASA glacier mapping project and combining the measurements, the scientists mapped the edges of the ice masses along about 30,000 linear miles (50,000 km) of the Antarctic coast.
Losses from the detachments have so far outstripped the growth of natural glaciers that researchers believe it is unlikely that Antarctica will be able to grow back to its pre-2000 extent by the end of this century. In fact, the findings suggest that greater losses can be expected: the largest volumes of Antarctic ice appear to be headed for major break-offs in the next 10 to 20 years.
Mapping 36 years of ice loss
In the companion study, JPL scientists combined nearly 3 billion data points from seven space-based altimetry instruments to produce the largest continuous data set of changing ice sheet height — an index of ice loss — dating back to 1985. They used radar and laser measurements of ice elevation with centimeter accuracy to produce the highest resolution monthly change maps of ice loss ever.
This truly unparalleled detail 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 fill and empty miles below the surface.
“Subtle changes like these, combined with the improved understanding of long-term trends from this data set, will help researchers understand the processes that influence ice loss, leading to improved future estimates of sea-level rise.” said Johan Nilsson, lead author of the JPL study.
Synthesizing and analyzing the massive measurement files into a single high-resolution data set took years of work and thousands of hours on NASA servers.
Nilsson says it was worth it: “Condensing the data into something more broadly useful can bring us closer to the big discoveries we need to better understand our planet and help us prepare for the future impacts of climate change.” .
Read the News today and get the latest news. Follow us on Google News and be the first to learn all the news from Skai.gr.
I have worked in the news industry for over 10 years. I have a vast amount of experience in covering health news. I am also an author at News Bulletin 247. I am highly experienced and knowledgeable in this field. I am a hard worker and always deliver quality work. I am a reliable source of information and always provide accurate information.
