A
group of scientists from around the world is warning that
population growth, widespread destruction of natural ecosystems, and
climate change may be driving Earth toward an irreversible change in the
biosphere, a planet-wide tipping point that would have destructive
consequences absent adequate preparation and mitigation.
“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, 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, 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.
UC Berkeley begins work predicting looming global impacts
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 Keck
Foundation. 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 prosperity.” Climate
change could also lead to global political instability, according to a
U.S. Department of Defense study referred to in the Nature paper.
“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 biodiversity.”
“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,” added Bates.
How close is a global tipping point?
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.
“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 uses.”
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 planet Earth.”
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% of Earth’s land
surface has been converted to agricultural or urban use, with roads
cutting through much of the remainder. The 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 time. “I think that if we want to avoid the
most unpleasant surprises, we want to stay away from that 50 percent
mark.”
Global change biology
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 avoid it.
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 points.
They
concluded that there is an urgent need for global cooperation to reduce
world population growth and per-capita resource use, replace fossil
fuels with sustainable sources, develop more efficient food production
and distribution without taking over more land, and 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 said. “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.