19 February 2022 | New Scientist | 47>and ice can contain thriving communities
of microscopic life. For example, in 2013,
Trista Vick-Majors at Michigan Technological
University was part of a team that drilled into
Lake Whillans, which lies 800 metres beneath
the surface of the West Antarctic ice sheet.
“I thought we were going to be lucky to
measure anything,” she says. “There was a
lot more going on there than we expected.”
Subsequent studies revealed entire ecosystems
of bacteria and other microorganisms with
diverse lifestyles all living together, despite
the cold and darkness.Pathogens on ice
Perhaps we shouldn’t be surprised: Lake
Whillans is made of liquid water, even if it is in
a rather extreme site. When temperatures are
within a few degrees of 0°C, many microbes
can survive. For example, on glaciers in the
Andes mountains in South America, where
there are trickles of water between the ice
crystals, Pamela Santibáñez at the Ministry
of Science, Technology, Knowledge and
Innovation in Chile, has found multitudes.
“I can see bacterial activity in between the
snow and the ice,” she says.
However, as you dig deeper into ice sheets –
into layers that are thousands of years old
and far colder than 0°C – life becomes sparser.
Santibáñez and her colleagues also looked for
microbes in the West Antarctic Ice Shelf Divide
ice core, which contains ice laid down over
68,000 years. Concentrations of microbes
varied over the millennia, with shifts following
changes in the climate. What’s more, microbes
in older layers were badly damaged. “Cells that
have been in the ice for 25,000 years or 30,000
years, at -30°C, they are in really bad shape,”
says Santibáñez.
This carries a reassuring message: although
we can detect microbes in ice that isMelting permafrost in Russia’s
Yamal peninsula (left) has
exposed nomadic reindeer
herders (above) to anthrax“ We might even be
exposed to ancient
diseases that once
infected Neanderthals”
Anything stored in melting ice, snow and
permafrost is going to come out. So we need
to know what microbes are in there.
One of the first attempts to find out took
place just over a century ago. The Australasian
Antarctic Expedition of 1911 to 1914 was a
difficult affair in which two team members
died and a third had a mental breakdown.
But the expedition’s chief doctor, Archibald
McLean, succeeded in growing cultures
of bacteria, fungi and protozoa from Antarctic
ice. Even when he dug more than 2 metres own
into the ice, he found life. McLean described his
findings in the journal Nature in 1918. With
considerable foresight, he suggested that the
microbes were carried to Antarctica on winds
and fell to the ground in snowflakes. When
they reach the icy surface, he wrote, “the frozen
organisms... commence a new life-history”.
Since then, it has become clear that snow