Nearly 1,500 academics, researchers and scientists specializing in Antarctica gathered in southern Chile for the 11th conference of the Scientific Committee on Antarctic Research this week to share the most advanced research on the vast white continent.
Almost every aspect of science, from geology to biology and glaciology to the arts, was covered, but one major undercurrent ran through the conference. Antarctica is changing, faster than expected.
Extreme weather events on the ice-covered continent were no longer hypothetical presentations, but first-hand accounts from researchers of heavy rainfall, intense heat waves and sudden Foehn events (strong, dry winds) at research stations that led to mass melting, giant glacier calving and dangerous weather conditions with global implications.
With detailed data from weather stations and satellites going back just 40 years, scientists wondered whether these events meant Antarctica had reached a tipping point, or a point of accelerated and irreversible loss of sea ice from the West Antarctic Ice Sheet.
“There is uncertainty about whether current observations indicate a temporary decline or a sharp decline (in sea ice),” said Liz Keller, a paleoclimate expert at Victoria University of Wellington in New Zealand who led a session on predicting and detecting tipping points in Antarctica.
NASA estimates that the Antarctic ice sheet has enough ice to raise global sea levels by up to 180 feet (58 meters). Studies show that about a third of the world’s population lives below 330 feet (100 vertical meters) above sea level.
While it’s difficult to determine whether we’ve reached a “point of no return,” Keller says it’s clear the rate of change is unprecedented.
“You can see the same increase in CO2 over thousands of years, and now it’s happened in 100 years,” Keller said.
Mike Weber, a paleoceanographer at the University of Bonn in Germany who specializes in the stability of the Antarctic ice sheet, says sediment records dating back 21,000 years show similar periods of accelerated ice melt.
The ice sheet has experienced similar accelerated ice mass loss at least eight times, Weber said, with the acceleration beginning over a few decades, kicking off a phase of ice loss that could last centuries, leading to dramatically higher sea levels around the world.
Weber says ice loss has accelerated over the past decade, and the question is whether this has already begun a centuries-long phase or not.
“Maybe we’re entering that phase now,” Weber said. “If we are, at least for now, there’s no stopping it.”
Keeping emissions low
While some say climate change is already set in stone, scientists agree that worst-case scenarios can still be avoided by drastically reducing fossil fuel emissions.
Weber says the Earth’s crust rebounds in response to retreating glaciers and that their decreasing weight could balance rising sea levels, and new research published weeks ago shows that a balance is still possible if the rate of change is slow enough.
“If we keep emissions low, we can end this eventually,” Weber said. “If we keep them high, we’ll have a runaway situation and we won’t be able to do anything.”
Mathieu Casado, a paleoclimate and polar meteorologist at the Laboratory of Climatic and Environmental Sciences in France, specializes in studying water isotopes to reconstruct historical temperatures.
Casado said data from dozens of ice cores collected across the ice sheet allowed him to reconstruct temperature patterns in Antarctica dating back 800,000 years.
Casado’s research showed that the current temperature rise over the past 50 years was clearly outside of natural variability, highlighting the role of industry in producing carbon emissions that drive climate change.
He added that the last time Earth was this warm was 125,000 years ago and sea levels were 6 to 9 meters higher, “with a big contribution from West Antarctica.”
Temperature and carbon dioxide were historically in balance and balanced each other, Casado said, but we currently have much higher levels of CO2 and are far from equilibrium.
Casado and other scientists noted that the speed and amount at which carbon is being pumped into the atmosphere is unprecedented.
Gino Casassa, a glaciologist and head of Chile’s Antarctic Institute, said current estimates show sea levels will rise 4 meters by 2100 or more if emissions continue to rise.
“What happens in Antarctica doesn’t stay in Antarctica,” Casassa said, adding that global atmospheric, oceanic and climate patterns are tied to the continent.
“Antarctica is not just an ice cooler that is isolated from the rest of the planet and has no impact.”
This content was originally published in Scientists in Chile question whether Antarctica has reached a point of no return on the CNN Brasil website.
Source: CNN Brasil
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