A sophisticated analysis of sea-level rise in Puget Sound and
along the Washington Coast offers shoreline residents and land-use
planners a new map-based tool to assess potential flood hazards for
the coming years.
Click on map to access online
interactive map
Map: Washington Coastal Hazards Resilience
Network
Sea-level rise depends on two factors: how fast the oceans rise
and the rate of vertical land shifts. Uplift, such as what occurs
along the Washington Coast, slows the rate of sea-level rise
relative to waterfront property. Subsidence, which occurs in
Central Puget Sound, results in elevated tides sooner than in
stable or uplifting areas. One map on this page shows the measured
uplift and subsidence and another shows the uncertainty in that
measurement.
Ian Miller, a coastal hazards specialist at Washington Sea
Grant, has worked on studies that describe sea-level rise in Island
County and on the Olympic Peninsula. The new report, titled
“Projected Sea Level Rise for Washington State” (PDF 10.4 mb)
goes well beyond what he and his colleagues have done before. It
takes a more detailed look at where the land is uplifting and
subsiding, according to Miller, the lead author on the new report
that involves work by scientists at Sea Grant and the University of
Washington’s Climate Impacts Group.
Rising sea levels and isolated floods will be an increasing
challenge for waterfront property owners, according to experts I
interviewed for a story published this week in the Encyclopedia of
Puget Sound.
The Vechey home and bulkhead
before the big move. // Photo: John
Vechey
Changing conditions call for property owners to consider their
options with regard to their shoreline — not just for today but for
the long run. What I learned while researching this story is that
every waterfront site will respond differently as the highest tides
go higher and higher.
Before I started my inquiry, I thought the obvious answer would
be for people to build taller and stronger bulkheads — despite
well-known environmental damage. And that may be the only answer
for some. But for others, that approach could be a waste of money,
as bigger walls degrade the owners’ enjoyment of the beach as well
disrupting natural systems. Alternatives include moving or raising
a house or even replacing a bulkhead with “soft shore”
protections.
After the home was moved back
from shore and the bulkhead removed. // Photo: John
Vechey
Sea levels in Puget Sound are rising slowly at this time, with
the actual rate dependent on location. We live in a tectonically
active area, with major movements along continental plates. As a
result, the ground is sinking in most areas around Puget Sound,
adding to the relative rise in sea level.
In Seattle, the sea level has risen about 9 inches since 1900
and is expected to rise an additional 4 to 56 inches (4.75 feet) by
2100. The uncertainty reflected in that range relates to whether
greenhouse gases continue to increase, thus accelerating the rate
of melting of land-based ice in the polar regions.
Some changes can be expected regardless of the human response
over the next 80 years. For example, one analysis looking at
Whidbey Island suggests that there is a 99 percent chance that by
2040 — just 13 23 years from now — sea level will
be at least 2.4 inches higher than today with a 50 percent chance
that it will be 7.2 inches higher. After 2040, the tides will keep
rising even faster. Take a look at the related story “Average high
tides are creeping higher in Puget Sound.”
John Vechey of Orcas Island, who I featured in my story, took
sea level into account when deciding whether to remove his bulkhead
while seeking to improve the beach for family activities and for
the environment. His solution was to move his house and give the
beach more room to function naturally.
Moving a house will not be the answer for everyone, but I can
safely say that everyone should consider their long-term picture
before making any investments that will last a lifetime — and that
includes changes to the shoreline.
I believe it is generally possible, certainly with professional
help, to calculate elevations for the house and any low spots on
the property, add one to four feet above the current high-tide
mark, and then consider tidal surge, which is the wave height
caused by weather conditions. In some counties, professional help
is available if you are considering whether to remove a bulkhead.
Check out the “Shore
Friendly” website and “Resources
in Your Area.”
At this time, future sea levels do not enter into regulatory
considerations about where a person can build a house. One problem
is the uncertainty surrounding the amount that sea levels will
actually rise. But some environmental advocates say it is time to
require additional setbacks, not only to protect the environment as
tides push back the natural beach but also to protect homeowners
from future losses.
For some people, sea-level rise is a distant worry, but for
others the threat is just around the corner. I was reading this
morning about how high tides are already affecting Naval Station
Norfolk. Check out
“Rising Seas Are Flooding Virginia’s Naval Base, and There’s No
Plan to Fix It” by Nicholas Kusnetz of Inside Climate News.
A new Government Accountability
Office report, released yesterday, cites estimates of future
property damage totaling between $4 billion and $6 billion per year
in the U.S. as a result of sea-level rise and more frequent and
intense storms. The report outlines the need for a coordinated
federal response.
Sen. Maria Cantwell discusses the new GAO report and calls for
better planning in the video below.
It goes without saying that wood, rock or concrete bulkheads
built along the shoreline are not natural. They certainly don’t
look like any structure formed by nature. And when the water is
pushing up against them, waves bounce around and splash back
instead of rolling up on shore.
I have never had any trouble understanding some of the problems
caused by bulkheads. I imagine little juvenile salmon swimming
along the shoreline, working their way toward the ocean. In shallow
water, these little fish can stay away from the bigger fish that
want to eat them. But bulkheads create a stretch of deeper water,
where predatory fish can swim in close and devour the little
ones.
I’ve been told that bulkheads cause other problems as well, such
as blocking shoreline erosion. But isn’t that what they are
designed to do? What’s the problem? As I’ve learned — especially
over the past few months — natural erosion provides the sands and
gravels needed for healthy beaches. Natural beaches also collect
driftwood, which provides additional habitat for a variety of
creatures.
As many readers know, I now work half-time for the Puget Sound
Institute, a University of Washington affiliate that publishes the
Encyclopedia of Puget Sound. We’ve been working on a series of
articles about bulkheads — formally known as shoreline armoring —
and I’m more convinced than ever that bulkheads really do cause
problems.
Surf smelt // Photo:
Wikimedia commons
The first story in the series, released this week, describes the
effects of bulkheads on spawning habitat for surf smelt and sand
lance, two kinds of small fish that are an important food source
for salmon, birds and marine mammals. Check out my story, “Spawning
habitat for forage fish being lost to rising tides.”
As sea levels continue to rise, the high-tide and low-tide lines
move to higher elevations on the beach — until the high-tide line
reaches the bulkhead. For many bulkheads, the high-tide line is
already there. At that point, the rising sea level continues to
push the low-tide line to higher and higher elevations, reducing
the spawning habitat for fish that lay their eggs in the intertidal
area.
This shrinking habitat is known as “coastal squeeze” or “beach
squeeze.” Recent studies suggest that where bulkheads are located,
Puget Sound could lose 80 percent of this spawning habitat by the
turn of the century, based on average predictions of sea-level
rise.
On beaches without bulkheads, the high-tide line would move
steadily inland, helping to maintain the critical habitat for
forage fish, according to Timothy Quinn, chief scientist for the
Washington Department of Fish and Wildlife.
“Everywhere in Puget Sound, there will be beach squeeze when you
don’t allow things to equilibrate on the land side,” he told me.
“What used to be exposed beach (during the tidal cycle) will no
longer be exposed.”
It turns out that many bulkheads constructed through the years
were never needed to prevent erosion, because they were built to
protect homes in areas where erosion is minimal. Future stories in
our series will cover this issue, including the prospect of
removing existing bulkheads to improve shoreline habitats.
Unfortunately, sea level rise adds a new twist to the discussion.
Still, the best advice when building a new house is to keep the
structure back from the water’s edge.
In addition to the general story about beach squeeze, I wrote a
sidebar about a study that looked at the effects of this phenomenon
on 15 different beaches in the San Juan Islands. See “Forage
fish are losing places to lay their eggs.”
Meanwhile, this initial installment of the Shoreline Armoring
Series includes a nice piece by science writer Eric Scigliano
called “Shoreline
armoring’s effect on the food web.” In this story, Eric looks
at a broad spectrum of effects caused by bulkheads. He reports on
an involved study that focused on a series of paired beaches — one
with a bulkhead and one without — located in various parts of Puget
Sound.
Most of the studies that we will report on during this series
were funded by the Environmental Protection Agency through grants
coordinated by the Washington Department of Fish and Wildlife. The
plan is to release about two additional stories each week over the
next two weeks.
Surf smelt spawning zone below
high tide mark
Illustration: Dan Penttila, Washington Department of Fish
and Wildlife
A new worldwide map of sea level rise, plotted with precision
satellite instruments, shows that the Earth’s oceans are rising
faster with no end in sight.
Sea levels have gone up an average of 3 inches since 1992, with
some locations rising as much as 9 inches. Meanwhile, some limited
areas — including the West Coast — have experienced declining sea
levels for various reasons.
Sea level change over 22 years.
(Click to enlarge) // Map: NASA
Two years ago, climatologists released an international
consensus, which predicted a sea-level rise of between 1 and 3 feet
by the end of this century. It was a conservative estimate, and new
evidence suggests that ocean waters are likely to meet or exceed
the top of that range, possibly going much higher, according to
four leading researchers speaking at a news conference
yesterday.
The implications are huge and growing more important all the
time. At a minimum, waterfront property owners and shoreline
planners need to begin taking this into consideration. It doesn’t
make sense to build close to the shoreline if extreme high tides
will bring seawater to one’s doorstep.
If we hope to avoid local extinctions of key intertidal species,
we must start thinking about how high the waters will be in 50 to
100 years.
For clues to the future, we can watch Florida, where vast areas
stand at low elevations. Even now, during high tides, Miami is
beginning to see regular flooding in areas that never got wet
before. This is the future of low-lying areas in Puget Sound, such
as estuaries. In the Pacific ocean, the threat of inundating
complete islands is becoming very real.
Along the West Coast, sea levels have actually declined over the
past 20 years, largely because of the cooling effect of the Pacific
Decadal Oscillation, a warming/cooling cycle that can remain in one
phase for decades. The cycle appears to be shifting, with the
likely effect that sea levels on the West Coast will soon rise as
fast or faster than the worldwide average, according to Josh
Willis, an oceanographer at NASA’s Jet Propulsion Laboratory in
Pasadena, Calif.
Global sea level has been
measured accurately and continuously by satellites since 1993.
Graphic: Steve Nerem, University of
Colorado
The cause of sea level rise is attributed to three factors.
Scientists estimate that roughly one-third of the rise is caused by
thermal expansion of ocean waters, which absorb much of the energy
from global warming. Another third comes from the melting of the
massive Greenland and Antarctic ice sheets. The remaining third
comes from the melting of mountain glaciers throughout the world.
Researchers at yesterday’s news conference said they expect the
melting to accelerate.
Measuring the change in sea-level rise has become possible
thanks to advanced technology built into altimeters carried aboard
satellites. The instruments can distinguish changes in elevation as
small as one part in 100 million.
“The instruments are so sensitive that if they were mounted on a
commercial jetliner flying at 40,000 feet, they could detect the
bump caused by a dime lying flat on the ground,” said Michael
Freilich, director of NASA’s Earth Science Division.
While sea level rise can now be measured, predicting the rate of
future rise is difficult, because much of the melting by ice sheets
occurs out of sight under the water.
The Greenland ice sheet covers 660,000 miles — nearly the size
of Alaska. Satellite measurements have shown that an average of 303
gigatons of ice have melted each year over the past decade. The
Antarctic ice sheet has lost an average of 118 gigatons per year,
but some new studies suggest it could begin to melt much
faster.
In Greenland, researchers are reporting that one of the largest
chunks of ice ever to break away from land cleaved from the
Jakobshavn glacier in a “calving” event that left researchers
awestruck. More than 4 cubic miles of ice was loosed quickly into
the sea. Check out the news release by the
European Space Agency.
“This is a continuing and evolving story,” glaciologist Eric
Rignot said during yesterday’s news conference. “We are moving into
a set of processes where we have very tall calving cliffs that are
unstable and start fracturing and break up into icebergs …
“We have never seen something like this on that scale before,”
said Rignot, associated with JPL and the University of California
at Irvine. “Personally, I am in awe at seeing how fast the icefall,
the calving part of the glacier, is retreating inland year by
year.”
Other new information from NASA, including lots of graphics:
The world’s fish populations are already being affected by
global warming, and the human population faces long-term
consequences with respect to seafood supplies and local economies
that depend on them, according to a statement from the United
Nations Food and Agriculture Organization.
These conclusions are coming out of a four-day conference of 200
experts and policymakers focused on the marine fisheries issue. The
conference, in Rome, Italy, comes to a close today.
Oceans are warming, while currents, such as those affected by
El Nino, seem to be changing. This could have implications for the
West Coast.
Salinity is changing in surface waters, with warming areas of
Earth growing more salty from evaporation, while more northern and
southern areas grow less salty from increased rain along with ice
and snow melt.
Global sea level has been rising since 1961 with an accelerated
rate since 1993.
Fish distribution has been changing, generally with both warm-
and cold-water species moving closer to the poles.
Predictions for the future:
Changes in fish availability will change at the local and
regional levels.
Markets for various seafoods could grow unstable, as
distribution systems try to respond to shifts in supply at various
locations.
Prices for various seafoods could fluctuate with uncertain
supplies, and those in the industry could see their jobs
disrupted.
Countries where people eat a lot of seafood may face changes in
nutrition with related health implications.
The technical summary also includes this statement:
At both the local and global levels, fisheries and aquaculture
play important roles in providing food and generating income. Some
42 million people work directly in the sector, the great majority
in developing countries. Adding those who work in associated
processing, marketing, distribution and supply industries, the
sector supports several hundred million livelihoods.
Aquatic foods have high nutritional quality, contributing 20
percent or more of average per capita animal protein intake for
more than 2.8 billion people, again mostly in developing
countries.
Fish is also the world’s most widely traded foodstuff and a key
source of export earnings for many poorer countries. The sector has
particular significance for small island states.
