would more readily hitch a lift on the wind.
The algae were more surprising. Being
relatively large, so harder to disperse,
you might expect geographically distant
populations to comprise distinct
combinations of species. However, they were
remarkably similar, even when comparing
sites in Europe and the US, with one species
dominating. The apparent similarity suggests
that these algae are highly adapted to living
in snow, says Brown, and may have had little
pressure to change.
Brown has been studying temperate
latitudes where snows form ephemeral, secret
gardens that flower in winter and dissolve in
spring. Things are different in permanently
frozen regions where snow persists year on
year, like Antarctica.
In 2012, a project began to drill through a
glacier in West Antarctica to reach a lake that
lay entombed beneath it and look for possible
life cut off from the surface for half a million
years. Before drilling began, David Pearce at
Northumbria University, UK, and his team
were asked to survey snow in the vicinity of
the drill site to find out what microbes lived
there as a precaution against contamination.
Pearce was also keen to discover whether
the same species lived across Antarctica,
or whether there were local variations. So the
researchers shouldered sterilised shovels and
began digging at a range of locations with
different types of snow, including islands
north of the Antarctic peninsula and various
sites in the continent’s interior.
Arctic and Antarctic harboured microbes
that were consuming chemicals known
as methyl halides, which degrade ozone
in the atmosphere and affect the
breakdown of other atmospheric gases
such as the greenhouse gas methane.
Exactly how snow microbes affect
Earth’s climate is unknown, for now.
Their metabolism is very slow because
of the extreme cold, says Pearce, but
the sheer volume of snow on Earth
suggests that they could make a significant
contribution to the overall story.
Even as scientists start to explore snow life,
its future is under threat from global warming.
Snows are melting earlier in the season in
some parts of the world, and other areas get
more snow than they once did. All this will
have unknown effects on snow microbes
and the processes they might be involved
in. “There’s certainly a lot of new life and new
biodiversity to be described in these systems,”
says Brown. “We just don’t know enough about
them to know what we’re going to lose.” ❚They found different communities of
microbes in different areas. Some of the
bacteria matched those known to exist in
other parts of the world, but there were also
some that seemed to be unique to Antarctica.
A major concern of Antarctic scientists is
bio-contamination, bringing in microbes
from elsewhere in the world or moving around
those that are already present. In this regard,
Pearce’s findings are reassuring because there
was no evidence that humans had introduced
any microbes. Yet they also indicate that
intense activity could accidentally change the
natural balance of species. Pearce suggests that
there should be no-go zones in areas of special
scientific interest until we understand the
ecosystem better. “We don’t know enough
about the diversity of the Antarctic microbial
flora to know that if we go somewhere and
do something we’re not upsetting the
environment,” he says.Microbes all around
What we do know is that snow microbes
aren’t inert. “Everywhere we look, we find
microbes, and they are active, and they are
involved in biogeochemical cycling and
climate active gas production,” says Pearce.
In other words, snow microbes play a part
in processes that are crucial for maintaining
a healthy biosphere on Earth. For example,
his team found that snow taken from theClaire Ainsworth is a freelance
writer based in Hampshire,
UK. She is pure as the
driven snow21/28 December 2019 | New Scientist | 71