“Humanity is at a crossroads now, where we have to make an active choice.”
A prestigious 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.
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
percent 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.”
No comments:
Post a Comment