12 | New Scientist | 22 February 2020Climate changeAdam VaughanMELTING Antarctic ice could
cause sea levels to rise up to
58 centimetres by the end of the
century under a worst-case climate
scenario, an increase three times
bigger than the world saw in the
20th century from all sources.
Adding other sources of sea level
rise as the world warms, including
Greenland ice melt and global waterexpansion, means seas could
climb about 1.5 metres by 2100,
according to researchers.
“We know sea level is going to
consume eventually a number of
coastal cities and regions we hold
dear. That will likely be in a few
hundred years. What we show here
is this could come earlier than we
thought,” says Anders Levermann
at the Potsdam Institute for Climate
Impact Research in Germany.
His team combined 16 ice sheet
models – up from just three in a
similar exercise six years ago – and
incorporated uncertainties in how
the world will warm in response
to carbon emissions, and how
ocean currents will transport heat
to Antarctica.
The group found that if carbon
emissions go largely unchecked
and temperatures rise by almost 5°C
by 2100, Antarctica would have a
more than 90 per cent likelihood
of causing sea level rise of between
6 and 58 centimetres by the end
of the century. The median was
17 centimetres (Earth System
Dynamics, doi.org/dmsd).
Andy Smith at the British
Antarctic Survey says the new
projections seem reasonable.
“If we really get 58 centimetres
from Antarctica then it’s very
likely we get 1.5 metres [in total],”
Smith adds. ❚Antarctic melt may
lead to 1.5-metre
sea level risePalaeontologyBethan AckerleyLargest turtle shell found
Turtle twice the size of a leatherback was among largest ever known
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News
NEW fossils of the largest
non-marine turtle to have ever
lived have been discovered in
the Tatacoa desert in Colombia.
These include the biggest
complete turtle shell ever
found, a 2.4-metre-long
carapace that is more than
twice the size of the largest
living turtle, the leatherback
sea turtle.
This shell of Stupendemys
geographicus is pictured here
next to Rodolfo Sánchez atthe Urumaco Palaeontology
Museum in Venezuela. Sánchez
and his colleagues studied the
newly found fossils alongside
several other specimens
discovered in 1994. Although
S. geographicus was first
described in 1976, little was
known about the turtle due to
a lack of complete specimens.
Analysis of the fossils suggests
the turtles lived during the late
Miocene, around 12 to 5 million
years ago, in warm wetlands andlakes that researchers believe
created just the right habitat
and food supply for the huge
animal to survive.
It may have evolved to be
so big to help protect it from
other large species, such as
giant crocodilians, with which
it shared a habitat. Some male
shells had horn-like structures
that may have been used
in combat against other
males (Science Advances,
doi.org/dmns). ❚58cm
The contribution Antarctic ice could
make to sea level rise by 2100