'The phenomenon is of sufficient
scale to be considered as part of the Geological Time Scale'
By Ian Johnston
 |
Nuclear bomb tests in the mid-20th century deposited a layer of radioactive particles
around the world Rex Features
|
Planet Earth has entered a new
epoch dubbed the Anthropocene because of the extent of humanity’s impact on the
planet, according to a group of experts.
An international working group
set up to consider the question voted by 34 to zero, with one abstention, that
the Anthropocene was real in a geological sense.
The warming temperature, higher
sea levels, ash from fossil fuels, plastic waste, a dramatic increase in erosion,
the spread of animal species around the world and radioactive particles left
around the world from nuclear bomb tests would all contribute to permanent
changes in the Earth’s rocks, the scientists said.
They
are still considering what date should be chosen for the so-called “Golden
Spike” – a line in the rock the marks the boundary between the Holocene and Anthropocene
epochs, but believe it should be in the mid-20th century.
The
announcement was made at the 35th International Geological Congress in South Africa
A
statement issued by Leicester University
“The
phenomenon is of sufficient scale to be considered as part of the International
Chronostratigraphic Chart, more commonly known as the Geological Time Scale.”
The idea that the world had entered
an epoch defined by humans was first suggested in 2000 by scientists Paul Crutzen and Eugene Stoermer.
“Human
impact has left discernible traces on the stratigraphic record for thousands of
years – indeed, since before the beginning of the Holocene,” the statement said.
“However, substantial and
approximately globally synchronous changes to the Earth system most clearly
intensified in the ‘Great Acceleration’ of the mid-20th century.
“The mid-20th century also
coincides with the clearest and most distinctive array of signals imprinted
upon recently deposited strata.
“Changes to the Earth System
that characterise the potential Anthropocene Epoch include marked acceleration
to rates of erosion and sedimentation, large-scale chemical perturbations to
the cycles of carbon, nitrogen, phosphorus and other elements, the inception of
significant change to global climate and sea level, and biotic changes such as
unprecedented levels of species invasions across the Earth.
“Many of these changes are
geologically long-lasting, and some are effectively irreversible.
“These and related processes
have left an array of signals in recent strata, including plastic, aluminium
and concrete particles, artificial radionuclides, changes to carbon and
nitrogen isotope patterns, fly ash particles, and a variety of fossilizable
biological remains. Many of these signals will leave a permanent record in the
Earth’s strata.”
"In the last century we have
had such a huge impact that we’re actually taking the planet away from that
natural [climate] oscillation and changing the trend for global temperatures
from what should have been a cooling trend to a warming trend,” he said.
The working group had been
expected to make the recommendation and they are now likely to look for a
symbolic line that will mark the beginning of the Anthropocene. This could be
in a sediment that will turn into rock in the future, in a coral reef or even
in tree rings.
Writing in the journal Nature, Professor
Clive Hamilton, an ethicist at Charles
Sturt University Australia , cautioned
against scientists who declared "Welcome to the Anthropocene".
"At first I thought they
were being ironic, but now I see they are not. And that’s scary," he said.
"The idea of the Anthropocene is not welcoming. It should frighten us. And
scientists should present it as such."
