New satellite images reveal that the Antarctic ice sheet is now losing 159 billion tonnes of ice each year - twice as much as when it was last surveyed.
The European Space Agency’s CryoSat satellite has been monitoring the ice sheet for the past three years and the latest findings indicate that the losses will raise global sea levels by 0.45mm each year. The research found that, between 2010 and 2013, east and west Antarctica, and the Antarctic Peninsula lost 134,
3 and 23 billion tonnes of ice each year, respectively. It also discovered that the average rate of ice thinning in west Antarctica had increased compared to previous assessments.
Now, the yearly loss in this area is one third more than previously measured.
“We find that ice losses continue to be most pronounced along the fast-flowing ice streams of the Amundsen Sea sector, with thinning rates of 4–8m a year near to the grounding lines – where the ice streams lift up off the land and begin to float out over the ocean,” said Dr Malcolm McMillan from the University of Leeds and lead author of the study.
Researchers at Utrecht University, meanwhile, have found that land subsidence in many coastal and delta cities now exceeds absolute sea-level rise by up to a factor of 10. Without action, parts of Jakarta, Ho Chi Minh City, Bangkok and other coastal cities will sink below sea level, says the study, published in Geophysical Research Abstracts. The authors report that excessive groundwater extraction after rapid urbanisation and population growth is the main cause of severe land subsidence, which they say increases flood vulnerability.
Separate Dutch research reveals that extreme and catastrophic flooding in Europe, such as that seen in 2013, and which currently occurs about once every 16 years may increase to once every 10 by 2050. The study, conducted as part of the EU Enhance project, also suggests that annual average economic losses caused by extreme floods could reach almost fivetimes higher than 2013 values.
According to the researchers, average annual economic losses due to flooding in Europe by the middle of the century will be in the region of €23.5 billion. They say that investing €1.75 billion now in better flood defences could stem the annual estimated losses by about €7 billion.