快猫短视频

LIFE can thrive even in the extreme environment beneath glaciers, say
researchers in Canada. What鈥檚 more, these microbial communities could have had
an impact on our climate during the transitions between ice ages and
interglacials.

Bacteria have been found underneath glaciers before, but it has been assumed
they are dead or dormant. Now a team from the University of Alberta in Edmonton
has found that these subglacial bacteria flourish in dark cold conditions like
those under glaciers. 鈥淚t does seem to be increasingly true that microorganisms
can live just about everywhere on just about everything,鈥� comments Michael Bird
of the Australian National University in Canberra.

The bacteria live in or near the thin layer of liquid water that forms below
many glaciers because of geothermal heat and friction. Martin Sharp, a
geochemist on the team, says that such conditions would have been common under
many mid-latitude glaciers during ice ages, so there might have been extensive
subglacial microbial communities during these times. 鈥淚t鈥檚 a component that
hasn鈥檛 been considered previously,鈥� he says, 鈥渂ut we think it needs to be.鈥�

Ice cores and other sources show that the levels of greenhouse gases carbon
dioxide and methane fell during ice ages, while the land lost its plant cover.
Researchers assumed that all this carbon was locked up in the ocean, but isotope
records in oceanic sediments suggest that less carbon was stored in the seas
than they thought.

The missing carbon may have been trapped under glaciers in dead vegetation
and soil, Sharp suggests. As the subglacial microbes munched away on it during
ice ages, they converted it into CO₂ and, possibly, methane. When the
climate began to warm up, melting glaciers would have released these gases into
the atmosphere, speeding up climate change, he says.

鈥淭his is a very interesting observation,鈥� says Yair Rosenthal, a geochemist
at Rutgers University in New Jersey. 鈥淐ertainly, this is something to think
补产辞耻迟.鈥�