Science correspondent
19 February 2018
It’s been dubbed "the loneliest tree on
the planet" because of its remote location, but the Sitka spruce might
represent something quite profound about the age in which we live.
The tree, sited on Campbell Island in the
Southern Ocean, records in its wood a clear radioactive trace from the A-bomb
tests of the 1950s and 60s.
As such, it could be the "golden
spike" scientists are seeking to define the start of the Anthropocene
Epoch - a new time segment in our geological history of Earth.
The suggestion is that whatever is taken as
the golden spike, it should reflect the so-called "Great
Acceleration" when human impacts on the planet suddenly intensified and
became global in extent.
Chris Turney, from the University of New
South Wales, Australia, and colleagues, say the Sitka spruce captures this
change exquisitely in the chemistry of its growth rings.
"We're putting this forward as a serious
contender to mark the start of the Anthropocene. It's got to be something that
reflects a global signal," Prof Turney told BBC News.
"The problem with any Northern
Hemisphere records is that they largely reflect where most major human activity
has happened. But this Christmas tree records the far-reaching nature of that
activity and we can't think of anywhere more remote than the Southern
Ocean."
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