Ice sheets melting at a faster rate than expected©I.Joughin/ESA-European Space Agency
Greenland and Antarctica are losing ice six times faster than in the 1990s. The loss of ice has reached 6.4 trillion tonnes between 1992 and 2017. This represents a push of global sea levels up by 17.8 millimeters (or 0.709 inches). In 2019, the European Space Agency (ESA) reported that glaciers lost nine trillion tonnes of ice in half a century.
An international team of 89 polar scientists used observation data spanning three decades to produce a single estimate of Greenland and Antarctica's loss of ice, known as mass balance.
The new study was published in Nature Climate Change. It compares ice-sheet mass-balance results from satellite observations with projections from climate models. The team of scientists come from the University of Leeds (U.K.) and the Danish Meteorological Institute (DMI). They are also part of the ongoing Ice Sheet Mass Balance Inter-comparison Exercise (IMBIE).
The systematic monitoring of ice sheets began in the early 1990s. Since then, Greenland and Antarctica combined lost 6.4 trillion tonnes of ice between 1992 and 2017. If these rates continue at this alarming pace, ice sheets are expected to raise sea-levels by a further 17 centimeters (or 6.90 inches), exposing an additional 16 million people to annual coastal flooding by the 2100s.
According to Professor Tom Slater, lead author of the study and climate researcher at the Centre for Polar Observation and Modelling at the University of Leeds in The United Kingdom, satellites are the only means the scientists have to routinely monitor the vast and remote areas of the planet, "so they are absolutely critical in providing measurements which we can use to validate ice sheet models."
"Satellite observations not only tell us how much ice is being lost, they also help us to identify and understand which parts of Antarctica and Greenland are losing ice, and through what processes --both are key in helping us improve ice sheet models," says Professor Slater.
Antarctica and Greenland sea-level contribution with projection from 2020 to 2100: Time to get serious about it?
The graph above shows the Antarctic and Greenland ice sheet contribution to global sea level change according to IMBIE (black), compared to satellite observations and projections between 1992-2040 (left) and 2040-2100 (right).
IMBIE, established in 2011 as a community effort to reduce uncertainties in different satellite-based measurements of ice sheet mass balance, is an international collaboration of polar scientists supported by ESA and NASA, and providing improved estimates of the ice sheet contribution to sea-level rise.
Global sea rise: Causas and impact
According to IMBIE, fluctuations in the mass of the Greenland and Antarctic ice sheets are of considerable societal importance. They have a direct impact on global sea levels.
Since 1901, ice losses from Antarctica and Greenland, alongside the melting of small glaciers and ice caps around the globe as well as thermal expansion of the oceans, have caused global sea levels to rise at an alarming average rate of 1.7 mm/year (or 0.066 in/year).
Up to this date, many live in denial, or pretend not to know about the scientific evidence of the reality and consequences of Climate Change. Meanwhile, sea-level rise is likely to continue at an even faster rate during the current 21st century.
Scientists at IMBIE have predicted that the sea-level rise is going to affect more than 95 percent of the world's oceans by 2100, with 70 percent of coastlines experiencing rising sea-levels.
Sea-level rise has been linked to human activities, and not to changes in Earth's orbit as some had suggested in the past. Sea-level rises threaten to inundate densely populated coastal cities as well as other low-lying lands by 2100.
Now is the time to take this new evidence and warning seriously, and stop believing that if we ignore the risks and consequences, the problem will disappear by itself.