Please read the attachments carefully.

spaces previously isolated by
railroad tracks.

REBUILDING BY
DESIGN

To tackle the food insecurity
that plagued New Orleans before
Katrina(achallengethatcontinues
there and in many communities
across the nation), one enterpris-
ing resident turned empty lots in
the devastated Lower Ninth
Ward, recognized as a food desert
by the US Department of Agri-
culture, into community or-
chards. Through a new nonprofit
organization, these rejuvenated
lots provide healthy food to resi-
dents who need it, teach people to
grow their own produce, and
serve as a source of community
unity and pride.

Events like Katrina provide
a unique opening for innovation
and creativity in building com-
munities that are both healthier
and more socially vibrant than
they were before disaster struck.
Indeed, after Superstorm Sandy
devastated communities along the
East Coast, the groundbreaking
Rebuild by Design contest called
on innovators and experts across

sectors to work with community
members to envision, design, and
build solutions to the region’s
most complex challenges. Atten-
tion to community factors that
affect health figured significantly
in those solutions.

Today, less than a month
after Harvey, Irma, and Maria
delivered back-to-back blows,
funding and resources are coming
into communities in Texas,
Florida, and Puerto Rico. Amid
the flurry of first response and the
outpouring of compassion and
support from across the nation
and the world, we hope affected
communities will capitalize fully
on the rebuilding opportunities
before them by using the funds
and resources strategically. The
blueprint should not be the status
quo; it should be a vision for an
infrastructure that also supports
optimal health and resilience for
every community.

REBUILD OUR
COMMUNITIES AS WE
WANT THEM

Far too many communities
in the United States are

suboptimally healthy and lack
adequate health-supporting
infrastructure, such as housing,
high-quality health care, strong
networks that prevent social iso-
lation, and easy access to healthy,
affordable food. Although no one
wishes a disaster on any com-
munity, we know that, inevitably,
they will continue to occur—and
withthemwillcomeopportunity.
Asthefamoussayinggoes:“Never
let a serious crisis go to waste.”
When planning for disasters, we
should also plan for what we
want our communities to look
like as they recover—including
careful consideration of what will
promote and sustain good health.

Political leaders, health offi-
cials, preparedness and response
professionals, and community
organizations should act now to
develop a shared vision of opti-
mal health for their community.
A long-term plan for health
and resilience should be a fore-
thought, rather than an after-
thought, when a disaster occurs.
A detailed framework to support
this kind of planning was rec-
ommended in a 2015 consensus
report from the Institute of
Medicine (now the National
Academy of Medicine), and

resources are available through
the federal government’s
National Disaster Preparedness
Framework (https://www.nap.
edu/read/18996/chapter/1;
https://www.fema.gov/
national-disaster-recovery-
framework).

As Harvey and Irma focus our
national consciousness on the
deadly impact of natural disasters,
each of us should consider what
can be done to make our com-
munities safer,healthier,andmore
resilient places to live.

Victor J. Dzau, MD
Nicole Lurie, MD, MSPH

Reed V. Tuckson, MD

CONTRIBUTORS
The authors contributed equally to this
editorial.

REFERENCES
1. Institute of Medicine Committee on
Post-Disaster Recovery of a Community’s
Public Health, Medical, and Social Ser-
vices. Healthy, Resilient, and Sustainable
Communities After Disasters: Strategies,
Opportunities, and Planning for Recovery\
Committee on Post-Disaster Recovery of a Com-
munity’s Public Health, Medical, and Social
Services; Board on Health Sciences Policy, In-
stitute of Medicine of the National Academies.
Washington, DC: National Academies
Press; 2015.

Climate Change, Hurricanes, and
Health

See also Zolnikov, p. 27; Lichtveld, p. 28;

Rodrı́guez-Dı́az, p. 30; and Dzau et al., p. 32.

The year 2017 has seen
a devastating series of hurricanes
across the Caribbean, Central
America, and the United States—
Harvey in August, Irma and
Maria in September, and Nate in
October. The first three caused
devastation along their paths and
reached the United States as
Category 4 hurricanes.

Inevitably, there has been dis-
cussion on the role of climate
change in increasing the severity
of tropical storms generally and
this series of hurricanes
specifically.

We address the causal attri-
bution of severe and extreme
weather events to climate change
and the associated health

consequences. This attribution is
of primary scientific interest but
comes with evident political
implications.

CAUSAL ATTRIBUTION
OF EXTREME
WEATHER EVENTS

The broad community of at-
mospheric scientists has brought
increasing attention to the causal
attribution of extreme weather
events to human activities.1 The
underlying approaches will be

ABOUT THE AUTHORS
Alistair J. Woodward is with the Department of Epidemiology and Biostatistics, School of
Public Health, University of Auckland, New Zealand. Jonathan M. Samet is with the
Colorado School of Public Health, University of Colorado, Aurora.

Correspondence should be sent to Jonathan M. Samet, Dean and Professor, Colorado School of
Public Health, Office of the Dean, 13001 East 17th Place, MS B119, Aurora, CO 80045
(e-mail: Jon.Samet@ucdenver.edu). Reprints can be ordered at http://www.ajph.org by clicking
the “Reprints” link.

This editorial was accepted October 16, 2017.
doi: 10.2105/AJPH.2017.304197

AJPH HURRICANES

January 2018, Vol 108, No. 1 AJPH Woodward and Samet Editorial 33

https://www.nap.edu/read/18996/chapter/1;

https://www.nap.edu/read/18996/chapter/1;

https://www.fema.gov/national-disaster-recovery-framework

https://www.fema.gov/national-disaster-recovery-framework

https://www.fema.gov/national-disaster-recovery-framework

mailto:Jon.Samet@ucdenver.edu

http://www.ajph.org

familiar to those knowledgeable
about causal attribution in public
health, particularly the adoption
of the potential outcomes
framework, which compares
what is observed with what is
expected under an alternative
scenario of no exposure to
the factor of interest. This hy-
pothetical state of no (or an al-
ternative to reality) exposure is
referred to as the counterfactual,
that is, counter to the facts.2

An analogy in public health is
the comparison of lung cancer
risk in smokers to the counter-
factual risk that smokers would
have had as never smokers. In the
attribution of weather events to
climate change, different coun-
terfactuals are relevant to differ-
ent questions. One example is the
current climate, as it is affected by
human activities, compared with
past climate conditions. Another
is the comparison of “business as
usual” scenarios—that is, con-
tinuing on the present trajectory
of increasing emissions of green-
house gases—with alternative
futures in which emissions plateau
and then decline.

FREQUENCY AND
SEVERITY OF STORMS

In approaching the attribution
of storms and other extreme
weather events to climate
change, atmospheric scientists
estimate probabilities of causa-
tion, a notion familiar to public
health scientists. For example, we
generally accept that it is not
possible to determine whether
smoking caused a particular case
of lung cancer, but we do know
that the odds of this being the case
are very high (about 8:1 in an
American male lifetime cigarette
smoker). On this basis, we can
estimate the likelihood that
the particular case resulted

from smoking and hence the
population-wide benefits of re-
ducing or eliminating altogether
tobacco smoking. Climate sci-
entists have adopted this ap-
proach and emphasize that the
question is not “Did climate
change cause event X?” but “By
how much did climate change
increase the chance that event
X would occur?”3

The approach taken for this
estimation is parallel to that used in
epidemiology to estimate the at-
tributable risk in those exposed to
a factor (i.e., the attributable risk in
exposed =(PE – P0)/PE, where PE
is the probability of the outcome
in those exposed and P0 is the
probability in the unexposed). For
hurricanes and climate change, PE
couldbetheprobabilityofmoreor
of more severe hurricanes in the
setting of climate change, and P0 is
the probability associated with the
counterfactual scenario.

ATTRIBUTION AND
LIABILITY

In public health, attribution
and liability are closely linked and
form a basis for policy action and,
in some instances, compensation.
In some legal settings, proof of
causation is judged on the basis of
“more likely than not,” meaning
that the outcome rests on estab-
lishing the presence of exposure
because of a relative risk greater
than 2. Climate scientists have
put their toes into the same water,
for example, in exploring the
issue of responsibility for extreme
events such as the 2003 European
heatwave.1

The attribution of events such
as Harvey and Irma is more dif-
ficult than is attribution in the
lung cancer example because of
the difference between climate
and weather. Exposure estimates
(analogous to the presence or

absence of smoking) relate to
climate—what prevails in the
long run—but the outcomes are
acute weather events, and these
are qualitatively different phe-
nomena. The relation between
weather and climate is complex,
and modeling different counter-
factuals (e.g., storm frequency
in a world without human-
induced climate change) is not
straightforward.

Precipitation is especially dif-
ficult to simulate, because it de-
pends on much tighter space and
time scales than apply to tem-
perature and is heavily influenced
by local physical processes such as
convection.4 Nonetheless, such
modeling is difficult but not
impossible; climate models are
now capable of simulating the
incidence and intensity of tropi-
cal cyclones, with and without
greenhouse loading, and dis-
tinguishing to some extent the
influences of natural variability
(such as the occurrence of El
Nino events) from anthropo-
genic forcing.

A recent modeling study of
this kind examined cyclone ac-
tivity in the western north Paci-
fic area in 2015 and linked the
extreme energy levels that were
observed to human-induced cli-
mate change. This and other
studies have concluded that
climate change makes high-
intensity storms more likely, but
it is less certain that the overall
frequency of storms is affected.5

ATTRIBUTING HEALTH
IMPACTS

Attributing health impacts is
even more complex than is at-
tributing weather events, because
many variables are relevant aside
from the meteorological condi-
tions.6 There is no single method
for this task. If there were

sufficient data, it might be pos-
sible to proceed in steps, de-
termining first, for example,
whether a rise in greenhouse gas
emissions increased the proba-
bility of very high temperatures
and, second, to what extent ex-
cess mortality may be attributed
to observed high temperatures.
Other health outcomes, such as
geographic spread of vector-
borne disease and water-borne
infections in warming seas, may
require different analytic ap-
proaches, including pattern
matching and argument from
understanding disease
mechanisms.7

For hurricanes, modeling
health impacts is challenging
because the impacts of storms are
modified strongly by local cir-
cumstances. The health losses
that result from the storms can be
attributed, in part, to the lack of
effective and general adaptation
to extreme weather. In Houston,
Texas, for instance, there were
features of the city, such as urban
expansion over wetlands and
a landscape dominated by im-
pervious surfaces, that made the
flooding worse than it would
have been otherwise.

Despite these complexities,
the recent storms provide
a powerful reminder, absent
modeling, that hurricanes di-
rectly and indirectly increase
mortality and lead to long-term
increases in morbidity. Media
accounts document many deaths
from physical injury and
drowning: access to clean water
has been interrupted for millions
as has the availability of electric
power; elderly nursing home
residents died in Florida from
heat exposure; and needed and
life-sustaining medical services
were lost by many because hos-
pitals closed and dialysis units
could not operate. For the longer
term, people face loss of property,
water-damaged homes, and loss

AJPH HURRICANES

34 Editorial Woodward and Samet AJPH January 2018, Vol 108, No. 1

of livelihood, and there may be
persisting economic and psy-
chosocial consequences. Puerto
Rico seems at particular risk in
this regard.

The hurricanes of 2017 are
consistent with model-based
projections of more severe
weather associated with climate
change. Theresulting devastation
has reached broadly; Puerto Rico
and other Caribbean islands will
need years to recover. These
storms offer another moment to
begin to address climate change
and its implications, yet the En-
vironmental Protection Agency
administrator Scott Pruitt has said
that it would be “too insensitive”
to have that discussion now. The
storms’ victims may wish that
action had been taken decades
ago.

Alistair J. Woodward,
MMedSci, PhD, MB

Jonathan M. Samet, MD, MS

CONTRIBUTORS
The authors contributed equally to this
editorial.

ACKNOWLEDGMENTS
This editorial was supported by the
GEOHealth Hub for research and training
inEasternAfricaandfundedbytheFogarty
International Center, National Institutes
of Health (grant U2RTW010125).

REFERENCES
1. Otto FEL. Extreme events: the art of
attribution. Nat Clim Chang. 2016;6(4):
342–343.

2. Glass TA, Goodman SN, Hernán MA,
Samet JM. Causal inference in public
health. Annu Rev Public Health. 2013;34:
61–75.

3. National Academies of Sciences, En-
gineering, and Medicine. Attribution of
Extreme Weather Events in the Context of
Climate Change. Washington, DC: Na-
tional Academies Press; 2016.

4. Stott PA, Stone DA, Allen MR. Human
contribution to the European heatwave of
2003. Nature. 2004;432(7017):610–614.

5. Herring SC, Hoell A, Hoerling MP,
Kossin JP, Schreck CJ III, Stott PA.
Explaining extremes of 2015 from a cli-
mate perspective. Bull Am Meteorol Soc.
2016;97(12):S1–S3.

6. Zhang W, Vecchi GA, Murakami H,
et al. Influences of natural variability and
anthropogenic forcing on the extreme
2015 accumulated cyclone energy in the
western north Pacific. Bull Am Meteorol
Soc. 2016;97(12):S131–S135.

7. Mitchell D, Heaviside C, Vardoulakis S,
et al. Attributing human mortality during
extreme heat waves to anthropogenic
climate change. Environ Res Lett. 2016;
11(7):074006.

AJPH HURRICANES

January 2018, Vol 108, No. 1 AJPH Woodward and Samet Editorial 35

Reproduced with permission of copyright owner. Further reproduction
prohibited without permission.