INSIGHTS | PERSPECTIVES
ogy of the planet. But although the funda-
mental physical and biological limits to the
planet are indisputable, each concept still has
Some critics have raised good points (13).
For example, the initial version of the planetary boundaries was criticized for defining
a single global limit to highly complex, geographically variable phenomena, such as the
use of land and water, and the cycling of nitrogen and phosphorus. What is a meaningful global limit of land use, which is mainly
manifest at local and regional scales? Similarly, how much water can humans use globally, when water is mainly a local resource?
The most recent version of planetary boundaries (7) addresses many of these concerns,
but more work is needed to define appropriate environmental boundaries at local, regional, and global scales.
Critics believe that too much attention has
focused on the biological and physical limits
of the planet and the seemingly inevitable
environmental crises that crossing them may
precipitate, but have ignored the extraordinary levels of human ingenuity that can
happen within them. Rather than looking at
the limits that the planet ultimately imposes,
should scientists not instead focus on the opportunity for human advancement to thrive
Ultimately, these criticisms come down
to the intrinsic worldview held by differ-
ent authors. Whether we perceive the fi-
nite physical and biological capacity of the
planet as hard limits and boundaries, or as
the opportunity space for humans to op-
erate and innovate within, reflects deeply
held human beliefs and cultural narra-
tives about scarcity and abundance. We
can each look at the same planet, with the
same data, with the same laws of physics
and biology in mind, and reach different
conclusions. The limits and boundaries
still exist, of course, but each person’s view
of them depends on whether they look
through the lens of scarcity (with limits)
or abundance (and opportunity). In other
words, whether one considers the plan-
etary glass half full or half empty depends
on whom you ask. But either way, it would
be foolish not to acknowledge the intrinsic
limits of the glass.
A FRAMEWORK FOR SOLUTIONS
The next step will be to move on from descriptions of planetary limits and boundaries, to developing frameworks for how
to live within them. Any such framework
must recognize that the
laws of physics and biology
ultimately govern what happens on this planet. For all
of the human technological
advances, ingenuity, and
hard work, we cannot break
the laws of physics. Moreover, Earth’s ecosystems can
still do many things that
humans cannot match. For
example, the rest of the biosphere operates on renewable energy and with zero
waste, something humans
cannot yet do.
In this context, some of
the ideas embodied in the
emerging circular economy
framework, the “natural
step” (14) and the “
ecological footprint” (15), are extremely helpful. These ideas
are based on the observations that the Earth system is, to very good
approximation, materially closed (very little
matter comes into the planet, and very little
leaves, over geologic time) and energetically
open (essentially all of the energy that fuels
our climate, biology, and Earth system processes comes from the Sun).
Based on these ideas, and adding to
them, I would suggest that natural ecologi-
cal systems on Earth succeed—often where
humans do not—because they adhere to the
following guidelines: They do not consume
resources faster than they are regenerated
by the environment; do not produce wastes,
especially those that disrupt the environ-
ment and the climate system, faster than
they are assimilated or removed by the en-
vironment; are highly diverse, making them
more robust in the face of changing condi-
tions; and power nearly everything they do
with the Sun.
These are not new ideas, of course, but
they may present a helpful framework for
reinventing our food, water, and energy
systems. For example, they can help guide
a shift to high-efficiency, renewable energy
systems; to using high-efficiency irrigation
instead of wasteful practices seen around
the world today; or to developing more sustainable forms of agriculture that avoid biodiversity loss and deforestation. Doing so
will be necessary to avoid dangerous global
environmental damage, including climate
change and biodiversity collapse, while providing for human well-being. The scientific
and technical challenges are enormous. But
the most substantial challenge will be implementing them within the current political, social, and economic systems.
We humans must ultimately respect the
biological and physical limits of our world,
and follow the lessons of the planet, if we
hope to build a thriving and enduring civilization. The longer we delay doing so, the
lower the chances of success. But the sooner
we get started, the quicker we may be able
to transition to a truly sustainable and prosperous future. j
REFERENCES AND NOTES
1. T.R.Malthus, An Essay on the Principle of Population(John
Murray, London, ed. 6, 1826).
2. P. R. Ehrlich, The Population Bomb (Ballantine Books, New
3. United Nations (UN), Department of Economic and Social
Affairs, Population Division, “World Population Prospects:
The 2015 Revision” (Working Paper no. ESA/P/WP 241,
4. D. H. Meadows, D. L. Meado ws, J. Randers, W. W. Behrens
III, The Limits to Growth (Universe Books, New York, 1972).
5. J. Rockström etal ., Ecol.Soc.14, 32 (2009).
6. W. Steffen et al ., Science 347, 1259855 (2015).
7. W. Steffen, J. Grinevald, P. Crutzen, J. McNeill, Philos. Trans.
R. Soc. 369, 842 (2011).
8. J. Foley et al., Nature 478, 337 (2011).
9. C.J.Vörösmarty et al., Nature 467,555(2010).
10. R.A. Watson et al., Fish Fish. 14,493(2012).
11. S.C.Doney,V.J.Fabry,R.A.Feely,J.A.Kleypas, Annu. Rev.
Mar. Sci. 1, 169 (2009).
12. Intergovernmental Panel on Climate Change (IPCC),
“Climate Change 2014: Synthesis Report. Contribution of
Working Groups I, II and III to the Fifth Assessment Report
of the Intergovernmental Panel on Climate Change,”
Core Writing Team, R. K. Pachauri, L. A. Meyer, Eds. (IPCC,
13. L.Blomqvist, T.Nordhaus, M.Shellenberger, The Planetary
Boundaries Hypothesis. A Review of the Evidence
(Breakthrough Institute, 2012); https://thebreakthrough.
14. D. Cook, The Natural Step: Towards A Sustainable Society
(Green Books, Cambridge, UK, 2004).
15. M. Wackernagel, W.E.Rees, Our Ecological Footprint:
Reducing Human Impact on the Earth (New Society
Publishers, Gabriola Island, BC, Canada, 1996).
J.F. is a coauthor on the original paper describing planetary
boundaries (5) and has written about this concept since then.
Thanks to B. McNally for assistance with the manuscript.
252 21 APRIL 2017 • VOL 356 ISSUE 6335
Fishers haul a seine net onboard a commercial fishing boat as they
fish for Alaska pollock in the Peter the Great Gulf.
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