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A
sky full of lollipops
might sound like a can-
dy-filled dream, but these
“treats” aren’t what you
might think.
Researchers discovered tiny lolli-
pop-shaped ice crystals, or ice-lollies,
during research flights in 2009 and
2016 over the Atlantic Ocean. The
crystals — just a millimeter long and
found 1 to 2 kilometers up in the sky
— form in clouds when a shard of ice,
called an ice column, collides with a
liquid water droplet. Temperatures
in this part of the atmosphere rangefrom minus 3 to minus 8 degrees Cel-
sius, so the products of the collision
instantaneously freeze to create a lol-
lipop-shaped crystal.
The presence of ice-lollies may affect
the life cycle of clouds, altering the bal-
ance of liquid water and ice, and could
also impact the formation of precipita-
tion, the team suggested in Geophysical
Research Letters.
Ice-lollies haven’t been seen on the
ground: Either rising temperatures or
falling humidity can destroy the delicate
crystal as it falls. But Stavros Keppas, a
postgraduate at the University of Man-
chester in England and lead author of
the study, suggested in a statement that
ice-lollies might be formed on a regular
basis at high latitudes.
Sarah Derouin2ETTMRK1SYMWMEREƶWHMWETTIEVMRKWLSVIPMRI
S
ince the 1930s, Louisiana has lost
an area of coastal wetlands larger
than the state of Delaware. A new
map, published in GSA Today,
charts the land loss from a combina-
tion of man-made and natural factors,
including reduced sediment flow from
the Mississippi River, land subsidence
and sea-level rise.
To create the map, Jaap Nienhuis of
Tulane University in New Orleans and
colleagues used data from hundreds of
surface elevation tables installed along the
Louisiana coast after Hurricane Katrina hit
in 2005. The instruments allowed the team
to accurately measure the rate of subsid-
ence in the shallow subsurface. They found
that since 2005, subsidence has occurred at
a rate of 9 millimeters per year. Previously,
subsidence rates had only been estimated
by models, not measured in real time. The
newly calculated present-day subsidence
rates are higher overall than predictions
based on modeling and tide gages, with
higher than average subsidence rates
occurring in the eastern Chenier Plain,
the Atchafalaya and Wax Lake deltas, andalong the Mississippi River downstream
of New Orleans.
“This information will be valuable for
policy decisions about coastal restoration,
such as planning of large sediment diver-
sions that are intended to make portions
of Louisiana’s coast more sustainable,”
Nienhuis said in a statement.
Subsidence of the land surface is a
natural phenomenon seen along many
coastlines as sediments compact under
their own weight. In Louisiana, this is
compounded by a lack of new sediment
to balance the sinking in many areas, theresearchers wrote. “While a variety of
factors have contributed to Louisiana’s
wetland loss problem, the fundamental
culprit is the isolation of the sediment-de-
livery system (the Mississippi River)
from its delta plain and the adjacent
coastal zone due to the construction of
flood-protection levees. As a result, most
of the sediment carried by this system
is funneled into the deep waters of the
Gulf of Mexico, rather than offsetting
the naturally occurring high subsidence
rates,” they wrote.
Mary Caperton Morton7IWIEVGLIVW VIGIRXP] JSYRH XMR] PSPPM
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