17 MARCH 2017 • VOL 355 ISSUE 6330 1139 SCIENCE sciencemag.org
science festivals and other outreach activi-
ties, and organizing extended visits for U.S.
students to Latin American universities.
As demonstrated by the success of the
European Erasmus program (5), exposing
future researchers to different cultures and
lifestyles can substantially improve international academic networks.
Antonio Lazcano,1 Adriana Ortiz
Ortega,2 Saúl Armendariz3
1The National College and Faculty of Science, National
Autonomous University of Mexico (UNAM), Mexico
City, Mexico. 2Center of Sociological Studies, Faculty
of Political and Social Sciences, UNAM, Mexico City,
Mexico. 3Biblioteca Conjunta de Ciencias de la Tierra,
UNAM, Mexico City, Mexico.
*Corresponding author. Email: firstname.lastname@example.org
1. J. Berger-Sweeney etal ., “A message to the president,” The
New York Revie w of Books (9 March 2017).
2. J.G.Merino,A.Jha,E.Loder,K.Abbasi,Brit.Med.J. 356,
3. Government of Mexico, Conacyt, Sistema Nacional de
Investigadores ( http://conacyt.gob.mx/index.php/
4. O. Ortega Adriana, S. Armendáriz, “Miradas multidisci-plinarias a la producción científica mexicana con
perspectiva de género: el caso de la UNAM” (UNAM,
México, 2017) [in Spanish].
5. E. Pain, “25 years of Erasmus,”Science Careers
blog (2012); http://blogs.sciencemag.org/
Lessons from the
CALIFORNIA HAS EXPERIENCED tremendous amounts of precipitation in the
past few months, leading to the wettest
year on record (as of mid-rainy season)
immediately after a 5-year record-setting
drought over the region. On 7 February
2017, the Oroville dam, the tallest dam in
North America (1), suffered damage when
extreme water flows created a massive hole
in the primary spillway and then excessive
erosion in the emergency spillway. The
rapidly developing situation prompted an
emergency evacuation of about 190,000
people living downstream of the dam. A
few days later, a levee breach occurred near
Manteca, leading to evacuation of about
500 people. These incidents clearly demonstrate how extreme events, land-cover
and land-use changes, and the emerging
climatic changes can threaten the integrity
of our aging dams and levees (2).
Structural repairs to the Oroville dam and
the Manteca levee are in progress. There
are, however, still active threats to dams
and levees due to excessive sediment and
debris flow, exacerbated by wildfires during
the drought. The large swaths of flood-induced flowing sediments are observable
even from space (3). Such a large volume of
unexpected sediments, intensified by floods
in a drought-stricken area, can substantially
affect the operation of hundreds of dams
and levees in California. Large volumes
of sediment and debris can shorten the
service life of these dams, which are already
not far from the end of their design life.
Furthermore, a wet year leads to a lot of
fuel for future fires. If a dry year follows
a wet year, the fire risk (and hence debris
flow) will be higher than average. A classic
example is the infamous Devil’s Gate dam in
southern California, which has turned into a
large debris basin because of a series of post-fire flood events (4).
Compounding effects of a number of fac-
tors unfolded in the Oroville dam incident.
We need to reevaluate failure probability
of all major dams and levees under multi-hazard scenarios. Ignoring the underlying
relationships between multiple events can
lead to underestimation of extreme events
and their impacts. We need a new paradigm
for describing extreme events based on their
impacts and not just occurrence probability
of climatic conditions. The Oroville experience showed that even a moderate extreme
precipitation event (a 7-day event likely to
happen about once every 2 years) (5) could
lead to a potentially hazardous situation
given the antecedent conditions [i.e., the
second-most-extreme runoff observed in the
Oroville basin since 1995 (6)]. Furthermore,
the majority of critical infrastructure
elements are interdependent. Resilience
dependency between flood protection
systems (such as levees and dams) and other
critical infrastructures (such as energy infrastructures) needs to be better understood.
The average age of the dams and levees
in the United States is well above 50 years.
Nearly 15,500 dams were classified as “high
hazard” in 2016, and the number continues
Mexican and U.S.
SOME OF THE staunchest challenges to
President Trump’s new immigration policies have come from U.S. researchers and
academic organizations determined to
ensure unfettered scientific pursuit [e.g.,
(1, 2)]. Given the administration’s negative
portrayal of Mexicans, we appreciate the
commitment of our American colleagues
to defend academic freedom in the United
States and beyond.
Mexican scientists value the opportuni-
ties for education and collaboration with
scientists in the United States. Of the
27,286 Mexican scholars registered in the
National System of Researchers (SNI), 2218
of them obtained their Ph.D. from U.S.
universities (3). Judging by collaborative
work, many of these U.S.-trained scholars
continue to reinforce their academic bonds
with U.S. universities after they return
home. Since the 1940s, Mexican researchers have published 104,664 papers with
foreign colleagues, and of these, more than
one-third (36,057 articles) have been co-authored with U.S. scientists (4).
The long-term social and academic
consequences of the current political
climate could be dire. Ethnic, religious,
and racial profiling are unacceptable, and
Mexicans are not unwanted enemy aliens.
Rather than deportations and travel bans,
which only promote anti-Americanism, we
require constructive solutions to protect
our joint scientific efforts. Part of the
answer may lie in developing an extended
binational community of science students,
researchers, and teachers on both sides of
the border by reinforcing and diversifying
existing exchange programs, setting up
Edited by Jennifer Sills
People cross an international border
bridge from Mexico to the United States.