Ice Sheet Melting on Track With Worst-Case Scenario

Scientists are surprised about the rate at which melting has accelerated.

Sea ice melting in Greenland
Melting ice in Greenland has added 10.6 mm to sea level rise since the 1990s. steve_is_on_holiday / Getty Images

Ice sheets in Greenland and Antarctica are melting so quickly that they are matching worst-case scenarios forecasts from climate scientists, according to a new study. The melting has raised the global sea level by 0.7 inches (1.8 centimeters) in the past two decades.

If rates continue at this pace, sea levels are expected to rise by an additional 6.7 inches (17 centimeters) by the end of the century, putting 16 million people at risk of annual coastal flooding, reports a team of British and Danish researchers.

The results of their findings are published in a study in the journal Nature Climate Change.

Melting of ice in Greenland has increased global sea levels by 0.42 inches (10.6 millimeters) since the sheets were first monitored by satellite in the 1990s. Melting in Antarctica has pushed up global sea levels by 0.28 inches (7.2 millimeters). The most recent measurements show that the world's oceans are rising by 0.15 inches (4 millimeters) each year.

The researchers warn that sheets are losing ice in the worst-case scenario predicted by the Intergovernmental Panel on Climate Change (IPCC) from the United Nations.

"We did anticipate that the melting of the ice sheets would increase in response to the warming of the oceans and atmosphere," the study’s lead author, Tom Slater, a climate researcher at the Center for Polar Observation and Modelling at the University of Leeds, tells Treehugger.

"What has surprised us is the rate at which this melting has accelerated. Antarctica and Greenland are now losing ice six times faster than they were in the 1990s and account for about a third of all sea level rise today."

"It's Not Too Late"

Because melting is overtaking climate models scientists use, researchers face the risks of being unprepared for what comes next, Slater says.

"Because the ice sheets are tracking our current worst-case scenario, we need to come up with a new one in order to allow policymakers to plan better informed sea level rise mitigation and adaptation strategies," he says. "Governments need to account for possible scenarios in their planning and act in advance. If we underestimate the amount of sea level rise we will face in the future then the measures taken may be insufficient, leaving coastal communities vulnerable."

Up until this point, global sea levels have increased mostly due to thermal expansion, which means the volume of seawater expands as it gets warmer. However in the last five years, water from melting ice sheets and mountain glaciers has become the primary cause of rising sea levels, the researchers point out.

It's not only Antarctica and Greenland causing sea level rise. The researchers say that thousands of smaller glaciers are melting or disappearing completely.

"It’s not too late for us to act, however," Slater says. "We can still curb emissions and protect our coastal communities. This would reduce the likelihood of extreme sea level rise and the risk of coastal flooding to those who live and rely on low-lying land."