Climate Action 2014-2015

RESILIENT CITIES
"Developers will still need
to convert a significant
amount of land from rural to
urban uses to accommodate
burgeoning urban
populations."
published Fifth Assessment Report of the
Intergovernmental Panel on Climate
Change (IPCC) estimate that, between
2000 and 2030, the urban footprint will
increase between 56 and 310 per cent.
They reckon that “55 per cent of the
total urban land in 2030 is expected to
be built in the first three decades of the
21st century”. Given that some significant
amount of rural-to-urban land conversion
will occur in coming decades, it behoves
us to develop that land in as sustainable a
manner as possible.
Given these circumstances, how can
a planned approach to city extensions
provide for more climate-friendly urban
development? By designing urban areas
well from the very beginning we begin
to accrue substantial climate benefits and
co-benefits now – and avoid locking
in unsustainable development patterns
that may require costly retrofits and
redevelopment schemes in the future.
On the mitigation side, well-planned
city extensions can reduce greenhouse
gas emissions by providing for more
compact urban development , with
well-integrated public transport options
and a mix of land use types. Today,
such conditions are found more often
in urban centres than in low-density,
single-use-zoned suburbs. The problem
is that this latter pattern of suburban
development, which has prevailed in
North America and elsewhere since
World War II, results in higher emissions
Figure 1. Urban densities have generally declined over the past
200 years
Source: Angel, Parent, Civco & Blei, 2011.
of greenhouse gases. For example, for
the United States Glaeser estimated
in 2009 what the ‘average household’
would emit if it settled in a high density
central city and what it would generate
in the suburbs. Of his review of 48
metropolitan areas he concluded that, in
almost all cases, “carbon emissions are
significantly lower for people who live
in central cities than for people who live
in suburbs.”
Why does more compact urban
development, be it in centre cities
or city extensions, typically result in
lower emissions? One reason is that
shorter travel distances, and the greater
viability and attractiveness of public
transport, result in lower transportrelated
emissions. For New York
City, for example, Glaeser estimated
that an average resident “emits 4,462
pounds less of transport-related carbon
dioxide [per year] than an average
New York suburbanite.” Similarly the
provision of other urban basic services
such as district heating or solid waste
collection is generally more efficient
in more compact communities. This
translates into lower energy costs,
with correspondingly lower carbon
emissions.
Well-planned city extensions can
also confer adaptation and resilience
benefits. Planners can, for example,
map floodplains, and then require new
development in those areas either to
be flood-proofed or else prohibited
entirely. Such measures reduce
vulnerability to flooding (which in
many locations is projected to increase
under future climatic conditions).
Planners of city extensions can also take
steps to preserve functional ecological
systems, e.g. watersheds that promote
drainage and the absorption of storm
water runoff. Preserving functionality
makes ecosystem-based approaches
to adaptation more viable options.
In almost all cases such planning
measures are more cost-effective when
undertaken proactively, at the moment
of urbanisation, rather than through
costly and politically difficult reactive
steps such as relocating families located
in flood-prone areas, or trying to restore
degraded ecosystems.
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