structure, the safety and health of the American peo-
ple,” President Barack Obama said during a May 20
speech at the U.S. Coast Guard Academy graduation.
Some cities flood “at high tide. Along our coasts, thou-
sands of miles of highways and roads, railways, energy
facilities are all vulnerable. It’s estimated that a further
increase in sea level of just 1 foot by the end of this
century could cost our nation $200 billion.”
Scientists say the breakup of sea ice around
Antarctica is happening “even faster than expected,”
Obama noted. “The world’s glaciers are melting, pour-
ing new water into the ocean. Over the past century,
the world sea level rose by about 8 inches. That was in
the last century. By the end of this century, it’s project-
Several factors account for rising seas, said Dan
Cayan, a climate researcher and director of the Climate
Change Center at Scripps Institution of Oceanography
and University of California-San Diego.
“As the oceans warm up, they become less dense,
and they occupy more volume in unit mass,” Cayan
said. “They’re like air in a balloon.”
Not all melting ice adds to the problem. Floating sea
ice in the Arctic Sea does not, but glaciers melting in
Greenland and in Antarctica “are major contributors to
sea level rise,” he said. These “add up” over time and,
particularly during storms and king tides, will cause
more serious and expansive flooding and erosion of
coastal and low-lying areas. Continued higher temper-
atures will accelerate ice melt.
Overall, Cayan said, the pace of
increases is particularly worrisome.
“We are really seeing the development of the new sort of ocean-land interface, and it will continue
to evolve as long as our planet is
out of whack,” he said.
Coastal installations already see
the effects of storms generated by
events like El Niño on the West
Coast. Higher seas “can overlap
existing structures, which are generally built to withstand storms that are
rare,” said Cayan, who has participated in numerous studies and assessments of coastal areas including
The ocean floor is not uniform,
he said, so sea level rise varies. For
example, seas have not risen as high
along the West Coast as in the western Pacific. And even along the West
Coast, the amount varies because of
tectonic plate shifts as well as winds.
But sea levels along California will rise at least 1 foot
by 2050, from levels in 2000, and by 3 to 5 feet by 2100,
according to a 2012 white paper he coauthored looking
at the state’s coastal vulnerabilities to rising seas.
Dire warnings from scientists, climatologists and others
over the last decade have prompted governments and
agencies, including the Navy and the Defense Department
(DoD), to collect the data and assess the risks, dangers and
vulnerabilities of rising sea levels. These are necessary to
determine how to mitigate the effects, perhaps with hardened seawalls, taller piers and cranes, or by relocating
buildings, training areas or utilities.
The military and federal government’s efforts come
amid political debates questioning whether climate
change is real or whether humans are to blame, and
previously conflicting conclusions from some scientists. Bonelli, a Unified Port of San Diego commissioner representing the city of Coronado, and others say
the issue is apolitical.
“We’re not debating whether climate change or sea
level rise is real or not,” he said. “We worry about the
cycles of good weather and bad weather. The cycles of
good and bad weather — especially the bad weather —
are becoming more frequent, and, too, the severity.”
Before he left office, Defense Secretary Chuck Hagel
signed off on the fiscal 2014 Climate Change Adapta-
tion Roadmap, which spells out the department’s
vision for maintaining military readiness while adapt-
ing to the changing environment. He called climate
change a “threat multiplier.”
43 WWW.SEAPOWERMAGAZINE.ORG SEAPOWER / JULY/AUGUST 2015
The west gate to Naval Air Station Pensacola, Fla., was closed due to flooding
from a storm starting April 29, 2014. Many areas of the base were inaccessible with water measured in excess of 3. 5 feet in low-lying areas.