The Greenland Ice Sheet is on track to lose mass at about four times the fastest rate observed over the past 12,000 years. At its current clip, such melting would dump huge quantities of freshwater into the sea, raising global sea levels and disrupting ocean currents, scientists concluded in research released Wednesday.
The findings, published in the journal Nature, warn that the only way to avoid a drastically accelerated meltdown of the massive ice sheet in coming decades is for humans to curtail emissions of greenhouse gases soon.
Greenland is the largest contributor to sea-level rise, though Antarctica has the potential to raise waters even more. As sea levels rise, coastal storms from hurricanes to nor'easters become more destructive. Recent trends in more frequent sunny-day flooding at high tide in places such as Annapolis, Md., Norfolk, Va., Charleston, S.C., and Miami are also linked to sea-level rise.
Researchers found that the current rate of mass loss from the Greenland Ice Sheet is comparable to that seen at the end of the last ice age, during a geological period known as the early Holocene. At that time, the global average surface temperature was about 5.4 degrees above the preindustrial average, a temperature the world is on track to exceed by the end of this century, depending on the amount of global emissions.
"It is no secret that the Greenland Ice Sheet is in rough shape and is losing ice at an increasing rate," said Jason Briner, a geology professor at the University of Buffalo and lead author of the new study. "I think this is the first time that the current health of the Greenland Ice Sheet has been robustly placed into a long-term context."
Briner and colleagues were able to put together an unbroken history of Greenland Ice Sheet mass change relying on computer modeling and field research in southwestern Greenland.
The researchers' projections show that after little change in ice mass loss over thousands of years, a sudden uptick occurred in recent decades. This steep rise is projected to accelerate through 2100 if humans fail to drastically cut the greenhouse gas emissions fueling the globe's warming.
According to the study, the current mass loss rate of about 6.1 billion metric tons per century that occurred between 2000 and 2018 is comparable to rates in the early Holocene. But, depending on greenhouse gas emissions in the next few decades, future mass loss will be far more devastating — on the order of 8.8 billion metric tons to 35.9 billion metric tons over the rest of the century.
"We're basically committed to losing ice at a faster clip than we did at that last period of rapid loss 12,000 years ago," Briner said, "and that was for me a surprising finding."