by Robert Sanders
June 6, 2012
A prestigious group of scientists from around the world is warning
...may be driving Earth toward an
irreversible change in the biosphere, a planet-wide tipping point
that would have destructive consequences absent adequate preparation
UC Berkeley professor
Tony Barnosky explains
how an increasing human
population, coupled with climate change,
could irreversibly alter
(Video produced by Roxanne
“It really will be a new world,
biologically, at that point,” warns Anthony Barnosky, professor
of integrative biology at the University of California,
Berkeley, and lead author of a review paper appearing in the
June 7 issue of the journal Nature.
“The data suggests that there will
be a reduction in biodiversity and severe impacts on much of
what we depend on to sustain our quality of life, including, for
example, fisheries, agriculture, forest products and clean
water. This could happen within just a few generations.”
The Nature paper (Approaching
a State Shift in Earth’s Biosphere), in which the
scientists compare the biological impact of past incidences of
global change with processes under way today and assess evidence for
what the future holds, appears in an issue devoted to the
environment in advance of the June 20-22 United Nations Rio+20 Earth
Summit in Rio de Janeiro, Brazil.
The result of such a major shift in the biosphere would be mixed,
Anthony Barnosky noted, with some plant and animal species disappearing, new
mixes of remaining species, and major disruptions in terms of which
agricultural crops can grow where.
The paper by 22 internationally known scientists describes an urgent
need for better predictive models that are based on a detailed
understanding of how the biosphere reacted in the distant past to
rapidly changing conditions, including climate and human population
growth. In a related development, groundbreaking research to develop
the reliable, detailed biological forecasts the paper is calling for
is now underway at UC Berkeley.
The endeavor, The Berkeley Initiative in
Global Change Biology, or BiGCB, is a massive undertaking involving
more than 100 UC Berkeley scientists from an extraordinary range of
disciplines that already has received funding:
a $2.5 million grant from the Gordon
and Betty Moore Foundation and a $1.5 million grant from the
The paper by Barnosky and others emerged
from the first conference convened under the BiGCB’s auspices.
“One key goal of the BiGCB is to
understand how plants and animals responded to major shifts in
the atmosphere, oceans, and climate in the past, so that
scientists can improve their forecasts and policy makers can
take the steps necessary to either mitigate or adapt to changes
that may be inevitable,” Barnosky said.
“Better predictive models will lead
to better decisions in terms of protecting the natural resources
future generations will rely on for quality of life and
Climate change could also lead to global
political instability, according to a U.S. Department of Defense
study referred to in the Nature paper.
Barnosky discusses the Berkeley Initiative in Global Change Biology,
an effort to improve our
understanding of the past impacts of climate change
so as to improve our forecasts
for the future.
(Video produced by Roxanne
“UC Berkeley is uniquely positioned
to conduct this sort of complex, multi-disciplinary research,”
said Graham Fleming, UC Berkeley’s vice chancellor for research.
“Our world-class museums hold a
treasure trove of biological specimens dating back many
millennia that tell the story of how our planet has reacted to
climate change in the past.
That, combined with new technologies
and data mining methods used by our distinguished faculty in a
broad array of disciplines, will help us decipher the clues to
the puzzle of how the biosphere will change as the result of the
continued expansion of human activity on our planet.”
One BiGCB project launched last month,
with UC Berkeley scientists drilling into Northern California’s
Clear Lake, one of the oldest lakes in the world with sediments
dating back more than 120,000 years, to determine how past changes
in California’s climate impacted local plant and animal populations.
City of Berkeley Mayor Tom Bates, chair of the Bay Area Joint
Policy Committee, said the BiGCB,
“is providing the type of research
that policy makers urgently need as we work to reduce greenhouse
gas emissions and prepare the Bay region to adapt to the
inevitable impacts of climate change.
To take meaningful actions
to protect our region, we first need to understand the serious
global and local changes that threaten our natural resources and
“The Bay Area’s natural systems, which we often take for
granted, are absolutely critical to the health and well-being of
our people, our economy and the Bay Area’s quality of life,”
How close is a global
The authors of the Nature review - biologists, ecologists,
complex-systems theoreticians, geologists and paleontologists from
the United States, Canada, South America and Europe - argue that,
although many warning signs are emerging, no one knows how close
Earth is to a global tipping point, or if it is inevitable.
The scientists urge focused research to
identify early warning signs of a global transition and an
acceleration of efforts to address the root causes.
Image courtesy of Cheng (Lily) Li.
“We really do have to be thinking
about these global scale tipping points, because even the parts
of Earth we are not messing with directly could be prone to some
very major changes,” Barnosky said.
“And the root cause, ultimately, is
human population growth and how many resources each one of us
Co-author Elizabeth Hadly from
Stanford University said,
“we may already be past these
tipping points in particular regions of the world. I just
returned from a trip to the high Himalayas in Nepal, where I
witnessed families fighting each other with machetes for wood -
wood that they would burn to cook their food in one evening.
In places where governments are
lacking basic infrastructure, people fend for themselves, and
biodiversity suffers. We desperately need global leadership for
The authors note that studies of
small-scale ecosystems show that once 50-90 percent of an area has
been altered, the entire ecosystem tips irreversibly into a state
far different from the original, in terms of the mix of plant and
animal species and their interactions.
This situation typically is accompanied
by species extinctions and a loss of biodiversity.
Currently, to support a population of 7 billion people, about 43
percent of Earth’s land surface has been converted to agricultural
or urban use, with roads cutting through much of the remainder.
population is expected to rise to 9 billion by 2045; at that rate,
current trends suggest that half Earth’s land surface will be
disturbed by 2025.
To Barnosky, this is disturbingly close
to a global tipping point.
“Can it really happen? Looking into
the past tells us unequivocally that, yes, it can really happen.
It has happened. The last glacial/interglacial transition 11,700
years ago was an example of that,” he said, noting that animal
diversity still has not recovered from extinctions during that
“I think that if we want to avoid
the most unpleasant surprises, we want to stay away from that 50
The paper emerged from a conference held at UC Berkeley in 2010 to
discuss the idea of a global tipping point, and how to recognize and
Following that meeting, 22 of the attendees summarized available
evidence of past global state-shifts, the current state of threats
to the global environment, and what happened after past tipping
They concluded that there is an urgent need for global cooperation
reduce world population growth
and per-capita resource use
replace fossil fuels with
develop more efficient food
production and distribution without taking over more land
better manage the land and ocean
areas not already dominated by humans as reservoirs of
biodiversity and ecosystem services
“Ideally, we want to be able to
predict what could be detrimental biological change in time to
steer the boat to where we don’t get to those points,” Barnosky
“My underlying philosophy is that we
want to keep Earth, our life support system, at least as healthy
as it is today, in terms of supporting humanity, and forecast
when we are going in directions that would reduce our quality of
life so that we can avoid that.”
“My view is that humanity is at a crossroads now, where we have
to make an active choice,” Barnosky said.
“One choice is to acknowledge these
issues and potential consequences and try to guide the future
(in a way we want to). The other choice is just to throw up our
hands and say,
‘Let’s just go on as usual and
see what happens.’
My guess is, if we take that latter
choice, yes, humanity is going to survive, but we are going to
see some effects that will seriously degrade the quality of life
for our children and grandchildren.”
The work was supported by UC Berkeley’s
Office of the Vice Chancellor for Research.