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I'm taking a much-needed vacation next week, so the intrepid Alison Snyder will bring you this newsletter next Thursday.

1 big thing: Ice sheets run AMOC

Landscape on the Greenland Ice Sheet near Kangerlussuaq, Greenland. Photo: Martin Zwick/REDA&CO/UIG via Getty Images

Sea level rise isn't the only thing we have to worry about as the Greenland and Antarctic ice sheets melt. A fascinating new modeling study finds that runoff from these ice sheets could significantly alter crucial ocean currents in ways that disrupt the Gulf Stream and accelerate ice loss in West Antarctica.

The big picture: Scientists are racing to better understand and anticipate the pace, extent and impacts of melting ice sheets, both in Greenland and Antarctica. Since the last report from the UN Intergovernmental Panel on Climate Change in 2014, sea level rise estimates have increased, but uncertainties remain high.

  • The new study, published in the journal Nature on Wednesday by an international research team, is one of the first to pair a climate model with an ice sheet model — fed with the latest observational data on ice loss — to see how ice melt might alter the planet's climate.
  • It finds that the influences may be profound.

The threat: If the Greenland or Antarctic ice sheets melt quickly and significantly enough, they could pour cold, relatively light freshwater into adjacent areas of the ocean that can disrupt global ocean circulation, the study finds.

  • In particular, the study adds to the growing concern in the scientific community about a slowdown in a current known as the Atlantic Meridional Overturning Circulation, or AMOC.
  • This current is a component of the global conveyor belt, or thermohaline circulation, carrying heat and oxygen from the bottom of the world to the far north, and back again.
  • There are clear signs that part of this current is already slowing down, due to freshwater inputs from Greenland.

The new study says this could lessen the heat transported to Europe and may make weather more variable in the northeastern U.S., among many other areas.

Worse yet, in the Antarctic, adding freshwater to the surface ocean would serve to reduce the amount of mixing between ocean layers, the study says.

  • This would trap salty and warm water well below a film of cool freshwater on the surface.
  • Such warm, salty waters are melting marine-terminating glaciers in West Antarctica by eating away at their floating ice shelves and infiltrating the ice bed in areas where the bedrock is below sea level.

What's missing: The study assumes that the ocean is not playing a large role in melting Greenland's glaciers, which is at odds with observations, according to Eric Rignot, a professor of Earth system science at UC Irvine, who was not involved in the new study.

  • Rignot says Greenland will melt faster and more extensively than the study's models show.

What they're saying: Luke Trusel, a study co-author and geology professor at Rowan University, told Axios that melting ice sheets will have effects far beyond sea level rise.

"Ice sheets aren't passive bodies of ice, they're dynamic, interactive components of the Earth system. They change in response to climate, and climate then responds to their change."
— Luke Trusel, Rowan University, Glassboro, New Jersey

Study co-author Kaitlin Naughten of the British Antarctic Survey, tells Axios that glacial runoff "affects deep ocean circulation, surface ocean currents and weather patterns across the globe."

Go deeper: Read the full story.

2. Unraveling why some kids get recurrent tonsillitis

Streptococcus Pyogenes. Photo:BSIP/UIG Via Getty Images

Scientists may have discovered one of the mysterious causes behind why some children have recurrent tonsillitis (RT) when they have a strep infection, Eileen Drage O'Reilly writes.

Why it matters: There are an estimated 600 million cases of strep globally and 750,000 tonsillectomies performed in the U.S., mostly caused by RT. It can greatly disrupt children's education, force parents to miss work, and in developing countries without large amounts of antibiotics, it can lead to dangerous acute rheumatic fever or rheumatic heart disease.

What they did: Over a 7-year period, the team collected and tested tissue samples from tonsils and blood tests from 66 children with RT and 80 children with sleep apnea (as a control group).

What they found: The study, published in Science Translational Medicine Wednesday, found some people may have a genetic predisposition to RT.

Children with RT had smaller germinal centers in their tonsils with fewer key immune cells. Plus, their blood tests showed much lower antibodies to the strep bacteria Streptococcus pyogenes (group A Streptococcus, or GAS) in their blood, study author Shane Crotty tells Axios.

  • They also identified two variations in genes associated with RT.
  • "That is relevant for clinical practice as well as interesting from an infection biology perspective. Their results indicate that some children are genetically more prone to get recurrent GAS tonsillitis, and they shed light on both the genes and the biological mechanisms involved," says Georgia Institute of Technology's Kristofer Wollein Waldetoft, who was not part of this study.
  • "The study does suggest something is different about the immune response of children labelled as having recurrent tonsillitis, and further study might clarify the exact components of this immune response that would then guide streptococcal vaccine development," Children's National Health Systems' Bernhard L. Wiedermann, who was not part of this study, tells Axios.

Yes, but: Wiedermann points out the number of children studied is very small, which limits its applicability to children overall.

What's next: Larger multi-institutional studies could be used to validate these results, with the goal of leading to a diagnostics test and possible vaccine.

Go deeper: Read the full story.

3. The glacier with a 1,100-foot missing piece

Sea smoke and sea ice in front of the Stange ice shelf in the Bellingshausen Sea. Photo: Mark Brandon

Two other important studies on Antarctic ice shed light on how much progress scientists are making in predicting the continent's future, and also how little we know.

The threat: The first study, published on Jan. 30 in Science Advances, used synthetic aperture radar from satellites and aircraft to determine the motion and structure of the rapidly meting Thwaites Glacier in West Antarctica.

  • If there were a "Most Wanted List" for glaciers, Thwaites would be No. 1. Scientists are desperately trying to determine its fate.
  • Thwaites acts as a gateway to vast quantities of inland ice that rests on bedrock well below sea level.
  • If ocean waters were to access that inland ice, it could all melt, raising sea levels by at least 10 feet.

Geoscientist Richard Alley of Penn State University, who was not involved in the new study, called Thwaites a "geometric accident" that could lead to "large and rapid" ice loss.

Details: The study reports that the ebb and flow of salty, dense and relatively warm ocean waters had taken a gigantic bite out of the base of Thwaites, leaving a gap between the glacial floor and the bedrock below. Its dimensions are staggering. The gap is:

  • 2.5 miles wide and 6 miles long.
  • About 1,100 feet high.
  • It once contained about 14 billion tons of ice that melted in the past few years.

What they're saying: "What we are seeing with high resolution data is the ocean eating away large portions of the ice, taking big bites at a time instead of eroding slowly," UC Irvine's Rignot, a co-author of the new study, told Axios.

A second study on West Antarctic glaciers was published Wednesday in Nature, scrutinizing the alarming findings of a study published in 2016. That study showed that marine-terminating glaciers become inherently unstable when their calving front forms tall cliffs, upwards of 330 feet tall.

  • This marine ice-cliff instability causes such glaciers to rapidly break apart.
  • Observations of this physical process in Greenland's outlet glaciers has lent credence to this hypothesis.

The catch: The new research uses statistical techniques to find that past episodes of rapid sea level rise could've happened without this ice cliff instability.

  • The study suggests sea level rise will be lower than the numbers the 2016 study put forward, projecting only a 5% chance that the Antarctic contribution to sea level rise will top 15 inches by 2100.
  • "Our study demonstrates that the jury’s still out on marine ice-cliff instability," study lead author Tamsin Edwards, a geographer at Kings College in London, told Axios via email.

Rob DeConto of U-Mass Amherst, who co-authored the 2016 study, said the new study is useful but does not rule out the more alarming possibilities.

"I don't really see ice fracture as an optional process that can be excluded from ice sheet models," DeConto told Axios. "Ice that flows into the ocean essentially always ends in a cliff regardless of the setting or spatial scale."

The bottom line: More work is needed in order for scientists to confidently winnow down the forecast range of sea level rise. A new, multiyear U.S.-British research campaign focused on Thwaites should help.

Go deeper: Read the full story.

4. Axios stories worthy of your time
Expand chart
Data: NASA GISS; Graphic: Harry Stevens/Axios

Warming planet: 2018 was Earth's fourth-warmest year on record, NASA and NOAA found. The past 5 years have been the warmest such period since at least 1880, and NASA found that 18 of the 19 warmest years have occurred since 2000.

Cancer disparities: The majority of the increase in cancer deaths between 2007 and 2017 was in low- and middle-income countries, Axios Expert Voices contributor Thomas J. Bollyky writes.

The North Pole is on the move: The magnetic north pole is rapidly migrating to Siberia, forcing NOAA to issue a rare, unscheduled update to the World Magnetic Model.

Australia's brutal climate milestone: Australia just had its hottest month on record, as a blistering heat wave continued to topple all-time temperature records.

Third Pole: A comprehensive new science report shows climate change could melt the glaciers that comprise Earth's "Third Pole" in the Hindu Kush Himalayan region, which is a major water source to more than 1 billion.

Millennials and cancer: Millennials are facing a much higher risk of obesity-related cancers than baby boomers did at their age, according to a study published in The Lancet Public Health Monday, Eileen writes.

Jenga robot: MIT researchers are using a wooden Jenga tower to tackle one of the hardest robotics challenges — to build a bot that can grab, pack and assemble things with the dexterity of a human hand, Kaveh Waddell writes.

5. What we're reading elsewhere

Biological researcher He Jiankui. Photo: VCG/VCG via Getty Images

CRISPR babies: The role played by outside scientists from prestigious U.S. institutions in the controversial gene-editing experiments by Chinese scientist He Jiankui is still being uncovered. MIT Tech Review

Mosquito diet: Scientists were surprised to find feeding an appetite-suppressing human drug to mosquitos made them lose their attraction to blood by around 80%. The Atlantic

240 million years: It took this long before a rare bone cancer was diagnosed in the fossil of a Pappochelys, an ancestor of turtles, found in Germany and analyzed in JAMA Oncology. NYT

Look at that: Read how photographer Felice Frankel helps MIT students explain complex scientific concepts through visuals. National Geographic

6. Something wondrous: The Andromeda galaxy

A new, composite image of the Andromeda galaxy made by combining three bands of visible light captured by ZTF. Credit: ZTF/D. Goldstein and R. Hurt/Caltech

A new sky survey telescope has already observed more than 1,100 supernovae, according to its operator, Caltech. The Zwicky Transient Facility, or ZTF, went online in March of last year and uses the 48-inch Samuel Oschin Telescope at Palomar to scan the northern skies each night. Astronomers are particularly interested in objects that explode, move or change in brightness.

The big picture: So far, the instrument has helped astronomers discover 50 small near-Earth asteroids, including a 1-km-wide object between the orbits of Mercury and Venus. That asteroid has an orbital period of just 165 days — the shortest known "year" for any asteroid yet discovered.

  • The ZTF has also observed more than 1 billion stars, and each night it surveys a swath of the sky large enough to get about 260 full moons in 1 image, according to ZTF project scientist Matthew Graham.
  • Its ability to catch short-lived stellar events is important, Graham says, since some of these — such as neutron star mergers — could be sources of gravitational waves.

How it works: “The advantage of ZTF is the wide field of view really," Graham tells Axios.

  • For example, he says the telescope was able to catch two stars get shredded into oblivion by black holes, which are known as tidal disruptions.
  • When transient objects are detected, ZTF automatically generates alerts that go out to astronomers, who can then train their telescopes to look for the phenomena. Researchers also plan to make the detailed data — terabytes of it are generated each night — available to the research community, Graham says.

“We’re really just a discovery engine,“ he says. “Every day it is what did we discover last night?”

Thanks for reading!