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Sea level rise contributions from ice melt in different areas, including Greenland (a), West Antarctica (b), East Antarctica (c) and median of global glaciers (d). Values are ratios of regional sea level change to global mean sea level change. Adapted from Kopp et al. 2015.

News of Antarctica's accelerating ice melt garnered worldwide headlines yesterday, as scientists revealed that 3 trillion tons of ice has been lost to the sea since 1992 — mostly from the thawing West Antarctic Ice Sheet and Antarctic Peninsula.

Why it matters: The location of the ice melt is important for determining the future of coastal communities, according to climate scientists. And, due to West Antarctica melting, it turns out that the U.S. coastline will be hit extra hard, paying a sea level rise tax of about 25%.

Background: The reason the location of the ice melt is important is due to peculiarities of the Earth's climate system that have long been understood in academia, but not well-known by the public.

  • The U.S. would see far more sea level rise from the melting of West Antarctica when compared to the shedding of ice from the Greenland Ice Sheet. For example, for every 1 centimeter of sea level rise from West Antarctica, Boston would see an increase in local sea level of about 1.25 centimeters.

The science: The reason for the 25% sea level rise tax centers on gravity.

  • Rob DeConto, a climate scientist at the University of Massachusetts, says that as ice sheets melt, there's an elastic response from the Earth. "The Earth’s gravitational field changes because we’re redistributing mass around the planet,” he tells Axios.
  • When an ice sheet loses ice, it reduces its gravitational pull toward itself, which means the local sea level near the ice sheet — be it Greenland or Antarctica —is reduced.
  • Even if the entire Greenland Ice Sheet were to melt, places close to Greenland, such as northern Europe and northeastern North America, "wouldn't even know," DeConto says. “If you’re close to the ice sheet thats losing mass you don’t really feel the effects as much.”
  • It's the distant places that compensate for this loss in mass. “It’s totally flipped upside down for Antarctica," he says, as there is a "broad bullseye" around North America. “Sea level rise for the future, it’s not happening at the same rate in every part of the world… this gravity thing has a big impact,” DeConto says.

In addition, the loss of mass in Antarctica has a small change in the Earth's axis of rotation, which can also help to distribute sea level rise unequally.

  • De Conto and other researchers told Axios that projections in studies published Wednesday don't present a true worst-case scenario for Antarctic ice melt.

Worst-case scenario? The new research also presents a possible scenario for Antarctic ice melt through 2070:

  • In this, greenhouse gas emissions continue virtually unabated. This leads to global average surface temperatures rising to 3.5 degrees Celsius, or 6.3 degrees Fahrenheit, above the preindustrial average, and many of the most important ice shelves that hold back the West Antarctic Ice Sheet would be lost.
  • The rate of sea level rise would also increase to 5 mm per year, with economic losses from the flooding of coastal cities projected to exceed $1 trillion per year.

This sounds quite serious, and it is, but as Penn State University climate scientist Richard Alley said, it's not even the worst-case scenario. Rather, it's closer to a most likely scenario, based on recent emissions trends, Alley says.

"Considering sea level rise, for example, the future rise could be a little smaller or a little larger, or a lot larger — there is a "long tail" on the "bad" side," Alley says.

A decade to act: DeConto, for his part, said although the Antarctic melt rate is accelerating, there's still time to slow things down and ensure a less damaging future.

"I think there’s still a lot of room for optimism, that we can have a really big impact on the outcome for sea level rise," DeConto says. “It’s not like it’s completely too late and there’s nothing we can do about it. That’s not true.”

Helen Amanda Fricker, a researcher at the Scripps Institution of Oceanography, echoed this point and gave a more specific timetable:

"The next few years will be a pivotal period for decision making with regard to Antarctica. As we observe the system for longer, we see more and more changes of the type we feared could happen as the climate warms. Depending on what is decided, we could be looking at significant and irreversible changes over the next 50 years."

Get more stories like this by signing up for our weekly science newsletter, Axios Science.

Go deeper

Mike Allen, author of AM
58 mins ago - Politics & Policy

Biden's "overwhelming force" doctrine

President-elect Biden arrives to introduce his science team in Wilmington yesterday. Photo: Kevin Lamarque/Reuters

President-elect Biden has ordered up a shock-and-awe campaign for his first days in office to signal, as dramatically as possible, the radical shift coming to America and global affairs, his advisers tell us. 

The plan, Part 1 ... Biden, as detailed in a "First Ten Days" memo from incoming chief of staff Ron Klain, plans to unleash executive orders, federal powers and speeches to shift to a stark, national plan for "100 million shots" in three months.

Off the Rails

Episode 2: Barbarians at the Oval

Photo illustration: Sarah Grillo/Axios. Photo: Jim Watson/AFP/Getty Images

Beginning on election night 2020 and continuing through his final days in office, Donald Trump unraveled and dragged America with him, to the point that his followers sacked the U.S. Capitol with two weeks left in his term. This Axios series takes you inside the collapse of a president.

Episode 2: Trump stops buying what his professional staff are telling him, and increasingly turns to radical voices telling him what he wants to hear. Read episode 1.

President Trump plunked down in an armchair in the White House residence, still dressed from his golf game — navy fleece, black pants, white MAGA cap. It was Saturday, Nov. 7. The networks had just called the election for Joe Biden.

Fringe right plots new attacks out of sight

Illustration: Aïda Amer/Axios

Domestic extremists are using obscure and private corners of the internet to plot new attacks ahead of Inauguration Day. Their plans are also hidden in plain sight, buried in podcasts and online video platforms.

Why it matters: Because law enforcement was caught flat-footed during last week's Capitol siege, researchers and intelligence agencies are paying more attention to online threats that could turn into real-world violence.