by Michael W. Mehaffy & Nikos A. Salingaros, Ecologist:
http://www.theecologist.org/green_green_living/2234983/the_biological_basis_of_resilient_cities.html
Biological systems offer design strategies for
successfully adapting to an age of climate change and resource
depletion.
Insights from nature will be essential in creating a green
and sustainable future for humankind.
The word 'resilience' has become the new buzzword of the day for
environmental designers.
In some quarters, it's even displacing that
other popular word, 'sustainability'.
This is clearly a reflection of the growing recognition that
disruptive weather (and other) events are a part of life, and we must
adapt to them.
We know it's not possible to design in advance for such unpredictable
events, but we could make sure our buildings and cities are better able
to survive disruptions and bounce back afterwards.
Nor is it only weather events we need to worry about, or even other
random external events (like earthquakes).
We need to account for the
disruptions that we ourselves cause too: technological failures,
resource destruction and depletion, economic shocks, and a host of other
growing self-made challenges to human well-being.
We are going to need more resilient design, not as a fashionable buzzword, but out of necessity for our long-term survival.
Aside from a nice idea, what is resilience really, structurally
speaking? What lessons can we as designers apply towards achieving it?
In particular, what can we learn from the evident resilience of natural
systems? Quite a lot, it turns out.
Resilient and non-resilient systems
Let's start by recognizing that we have incredibly complex and
sophisticated technologies today, from power plants, to building
systems, to jet aircraft. These technologies are, generally speaking,
marvelously stable within their design parameters.
This is the kind of stability that C. H. Holling, the pioneer of resilience theory in ecology, called
"engineered resilience". But they are often
not resilient
outside of their designed operating systems. Trouble comes with the
unintended consequences that occur as 'externalities', often with
disastrous results.
Figure 2. On the left, an over-concentration of large-sale
components; on the right, a more resilient distributed network of nodes.
Drawing by Nikos Salingaros.
A good example is the Fukushima nuclear reactor group in Japan. For
years it functioned smoothly, producing reliable power for its region,
and was a shining example of 'engineered resilience". But it did not
have what Holling called "ecological resilience', that is, the
resilience to the often-chaotic disruptions that ecological systems have
to endure.
One of those chaotic disruptions was the earthquake and tsunami that
engulfed the plant in 2010, causing a catastrophic meltdown. The
Fukushima reactors are based on an antiquated US design from the 1960s,
dependent upon an electrical emergency cooling system.
When the electricity failed, including the backup generators, the
emergency control system became inoperative and the reactor cores
melted. It was also a mistake (in retrospect) to centralize power
production by placing six large nuclear reactors next to each other.
The trouble with chaotic disruptions is that they are inherently
unpredictable. Actually we can predict (though poorly) the likelihood of
an earthquake and tsunami relatively better compared to other natural
phenomena.
Think of how difficult it would be to predict the time and location
of an asteroid collision, or more difficult yet, to prepare for the
consequences. Physicists refer to this kind of chaos as a
"far from equilibrium condition".
This is a problem that designers are beginning to take much more
seriously, as we deal with more freakish events like Hurricane Sandy -
actually a chaotic combination of three separate weather systems that
devastated the Caribbean and the eastern coast of the USA in 2012.
As if these unforeseen dangers were not enough, we humans are
contributing to the instability. An added complication is that we
ourselves are now responsible for much of the chaos, in the form of our
increasingly complex technology and its unpredictable interactions and
disruptions.
Climate change is one consequence of such disruptions, along with the
complex and unstable infrastructures we have placed in vulnerable
coastal locations. And In fact, Japan's technological infrastructure has
been heavily damaged over a much wider area by the chaotic "domino"
effects of the Fukushima disaster.
Our technological intrusion into the biosphere has pushed natural
systems into conditions that are far from equilibrium - and as a result,
catastrophic disruptions are closer than ever.
Biology lessons
So what can we learn from biological systems? They are incredibly
complex. Take, for instance, the rich complexity of a rainforest. It too
generates complicated interactions among many billions of components.
Yet many rainforests manage to remain stable over many thousands of
years, in spite of countless disruptions and 'shocks to the system'. Can
we understand and apply the lessons of their structural
characteristics?
It seems we can. Here are four such lessons extracted from
distributed (non-centralized) biological systems that we will discuss in
more detail below:
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These systems have an inter-connected network structure.
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They feature diversity and redundancy (a totally distinct notion of "efficiency").
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They display a wide distribution of structures across scales, including fine-grained scales.
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They have the capacity to self-adapt and "self-organize". This generally (though not always) is achieved through the use of genetic information.
The Internet is a familiar human example of an inter-connected
network structure. It was invented by the U.S. military as a way of
providing resilient data communications in the event of attack.
Biological systems also have inter-connected network structures, as
we can see for example in the body's separate blood and hormone
circulation systems, or the brain's connected pattern of neurons. Tissue damaged up to a point is usually able to regenerate, and
damaged brains are often able to re-learn lost knowledge and skills by
building up new alternative neural pathways.
The inter-connected, overlapping, and adaptable patterns of
relationships of ecosystems and metabolisms seem to be key to their
functioning.
Focusing upon redundancy, diversity, and plasticity, biological
examples contradict the extremely limited notion of "efficiency" used in
mechanistic thinking.
Our bodies have two kidneys, two lungs, and two hemispheres of the
brain, one of which can still function when the other is damaged or
destroyed. An ecosystem typically has many diverse species, any one of
which can be lost without destroying the entire ecosystem.
By contrast, an agricultural monoculture is highly vulnerable to just
a single pest or other threat. Monocultures are terribly fragile. They
are efficient only as long as conditions are perfect, but liable to
catastrophic failure in the long term. Come to think of it, that may be a
pretty good description of our current general state!
Why is the distribution of structures across scales so important? For
one thing, it's a form of diversity. By contrast, a concentration at
just a few scales (especially large scales) is more vulnerable to
shocks.
For another thing, the smaller scales that make up and support the
larger scales facilitate regeneration and adaptation. When the small
cells of a larger organ are damaged, it's easy for that damaged tissue
to grow back - rather like repairing the small bricks of a damaged wall.
Figure 2. Distribution of inter-connected elements across several scales. Drawing by Nikos Salingaros.
Self-organization and self-adaptation are also central attributes of
living systems, and of their evolution. Indeed, this astonishing
self-structuring capacity is one of the most important of biological
processes.
How does it work? We know that it requires networks, diversity, and
distribution of structures across scales. But it also requires the
ability to retain and build upon existing patterns, so that those
gradually build up into more complex patterns.
Often this is done through the use of genetic memory. Structures that
code earlier patterns are re-used and re-incorporated later. The most
familiar example of this is, of course, DNA.
The evolutionary transformation of organisms using DNA gradually
built up a world that transitioned from viruses and bacteria, to vastly
more complex organisms.
Applying the lessons to resilient human designs
How can we apply these structural lessons to create resilient cities,
and to improve smaller vulnerable parts of cities by making them
resilient? Developing the ideas from our previous list, resilient cities
have the following characteristics:
-
They have inter-connected networks of pathways and relationships. They are not segregated into neat categories of use, type, or pathway, which would make them vulnerable to failure.
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They have diversity and redundancy of activities, types, objectives, and populations.
There are many different kinds of people doing many different kinds of
things, any one of which might provide the key to surviving a shock to
the system (precisely which can never be known in advance).
-
They have a wide distribution of scales of structure,
from the largest regional planning patterns to the most fine-grained
details. Combining with (1) and (2) above, these structures are
diverse, inter-connected, and can be changed relatively easily and
locally (in response to changing needs). They are like the small bricks
of a building, easily repaired when damaged. (The opposite would be
large expensive pre-formed panels that have to be replaced in whole.)
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Following from (3), they (and their parts) can adapt
and organize in response to changing needs on different spatial and
temporal scales, and in response to each other. That is,
they can "self-organize". This process can accelerate through the
evolutionary exchange and transformation of traditional knowledge and
concepts about what works to meet the needs of humans, and the natural
environments on which they depend.
Resilient cities evolve in a very specific manner:
- They retain and build upon older patterns or information, at the
same time that they respond to change by adding novel adaptations.
- They almost never create total novelty, and almost always create only very selective novelty as needed.
- Any change is tested via selection, just as changes in an evolving
organism are selected by how well the organism performs in its
environment.
This mostly rules out drastic, discontinuous changes. Resilient
cities are thus 'structure-preserving' even as they make deep structural
transformations. How do these elements contribute to resilient cities in practice, in an age of resource depletion and climate change?
It's easy to see that a city with networked streets and sidewalks is
going to be more walkable and less car-dependent than a city with a
rigid top-down hierarchy of street types, funneling all traffic into a
limited number of 'collectors' and 'arterials'.
Similarly, a city designed to work with a mix of uses is going to be
more diverse and be able to better adapt to change than a city with
rigidly separated monocultures.
Figure 3. A complex resilient system coordinates its multi-scale
response to a disturbance on any single scale. Drawing by Nikos
Salingaros.
A city with a rich and balanced diversity of scales, especially
including and encouraging the most fine-grained scales, is going to be
more easily repairable and adaptable to new uses.
It can withstand disruptions better because its responses can occur
on any and all different levels of scale. The city uses the disruption
to define a 'pivot' on a particular scale, around which to structure a
complex multi-scale response.
And it's more likely to be able to self-organize around new economic
activities and new resources, if and when the old resources come to be
in short supply.
The evolution of non-resilient cities
So where are we today? Many of our cities were (and still are) shaped
by a model of city planning that largely evolved in an era of cheap
fossil-fuel energy and a zeal for the mechanistic segregation of parts.
The result is that in many respects we have a rigid non-resilient
kind of city; one that, at best, has some 'engineered resilience'
towards a single objective, but certainly no 'ecological resilience'.
Response is both limited and expensive. Consider how the pervasive model of 20
th century city planning was defined by these non-resilient criteria:
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Cities are "rational" tree-like (top-down "dendritic") structures, not only in roads and pathways, but also in the distribution of functions.
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"Efficiency" demands the elimination of redundancy.
Diversity is conceptually messy. Modernism wants visually clean and
orderly divisions and unified groupings, which privilege the largest
scale.
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The machine age dictates our structural and tectonic limitations.
According to the most influential theorists of the modernist city,
mechanization takes command (Giedion); ornament is a crime (Loos); and
the most important buildings are large-scale sculptural expressions of
fine art (Le Corbusier, Gropius, et al.).
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Any use of "genetic material" from the past is a violation of the machine-age zeitgeist,
and therefore can only be an expression of reactionary politics; it
cannot be tolerated. Novelty and neophilia are to be elevated and
privileged above all design considerations. Structural 'evolution' can
only be allowed to occur within the abstracted discourse of visual
culture, as it evaluates and judges human need by its own (specialized,
ideological, aestheticizing) standards.
From the perspective of resilience theory, this can be seen as an
effective formula for generating non-resilient cities. It is not an
accident that the pioneers of such cities were, in fact, evangelists for
a high-resource dependent form of industrialization, at a time when the
understanding of such matters was far more primitive than now.
Le Corbusier
Here, for example, is the architect Le Corbusier, one of the most
influential thinkers in all of modern planning, writing in 1935, and
providing a blueprint for modern sprawl:
"
The cities will be part of the country; I shall live 30 miles
from my office in one direction, under a pine tree; my secretary will
live 30 miles away from it too, in the other direction, under another
pine tree. We shall both have our own car. We shall use up tires, wear
out road surfaces and gears, consume oil and gasoline. All of which will
necessitate a great deal of work ... enough for all."
Sadly, there is no longer enough for all! This relatively brief age
of abundant fossil fuels - and the non-resilient urban architecture that
it has spawned all over the globe - is rapidly drawing to a close. We
must be prepared for what has to come next.
From the perspective of resilience theory, the solutions are not
going to be simple techno-fixes, as so many naively believe. What is
required is a deeper analysis and restructuring of the system structure:
admittedly not an easy thing to achieve since it doesn't make money
short-term.
Postscript: a lesson from our own evolution
People tend to be carried along by the present, and put both past and
future out of their mind. Even in our information-glutted age, the past
is remote and abstract - just another set of images like any movie.
And so we ignore where we have come from, and the path that brought
us here to our marvelous technological culture. We are ill-prepared to
see where we must go next. For our techno-consumerist culture, tomorrow
will bring no surprises.
But new research in anthropology, anthropogeny, and genetics suggests
that we humans are, quite literally, creatures of climate change.
Thanks to ingenious detective work, we now know that some time around
100,000 years ago, our species very nearly became extinct - down to
hardly more than 1,000 survivors clinging, it appears, to the southern
African coast, as a mega-drought swept that continent - according to
work by paleoanthropologist Curtis Marean
(see Bibliography).
Our evident response was to diversify, and to develop many new
sources of food as well as new technologies for acquiring them:
fishhooks, barbs, baskets, urns, and other innovations.
More complex
language probably followed, allowing us to coordinate more sophisticated
strategies for hunting and gathering.
10,000 years ago, it now appears, we adapted once again to a mini-ice
age, prompting us to innovate with new agricultural technologies, and
new forms of settlement around them. These innovations arose more or
less simultaneously in many parts of the then-disconnected world,
suggesting that the trigger was very likely the changing climate.
Now we are facing the third great adaptation of our history to
climate change. But this time it is we, ourselves, who have triggered it
with our own technologies.
If we are going to adapt successfully, we
will need to understand the opportunities to innovate yet again, in the
way we design and operate our technology.
Our comfortable lifestyle (in the wealthy West, and among those
socioeconomic classes that can afford to copy us) is significantly less
resilient than most people would care to admit, or even dare think
about.
If we are going to continue our so-far remarkably successful run as a
technological civilization, we had better take the lessons of
resilience theory to heart.
Bibliography:
Charles C. Mann (2012) "State of the Species",
Orion Magazine, Issue November/December.
http://www.orionmagazine.org/index.php/articles/article/7146
Pinnacle Point, Wikipedia entry
http://en.wikipedia.org/wiki/Pinnacle_Point
This article is a slightly revised version of: "Toward Resilient
Architectures 1: Biology Lessons", published in Metropolis Magazine,
March 2013.
Michael Mehaffy is an urbanist and critical
thinker in complexity and the built environment. He is a practicing
planner and builder, and is known for his many projects as well as his
writings. He has been a close associate of the architect and software
pioneer Christopher Alexander.
Currently he is a Sir David Anderson Fellow at the University of
Strathclyde in Glasgow, a Visiting Faculty Associate at Arizona State
University; a Research Associate with the Center for Environmental
Structure, Chris Alexander's research center founded in 1967; and a
strategic consultant on international projects, currently in Europe,
North America and South America.
Nikos A. Salingaros is a mathematician and polymath known for his work on urban theory,
architectural theory, complexity theory, and design philosophy. He has
been a close collaborator of the architect and computer software pioneer
Christopher Alexander. Salingaros published substantive research on
Algebras, Mathematical Physics, Electromagnetic Fields, and
Thermonuclear Fusion before turning his attention to Architecture and
Urbanism.
He is Professor of Mathematics at the University of Texas at San Antonio and is on the Architecture faculties of universities in Italy, Mexico, and The Netherlands.