The Rising Tide -
Cause, Effects and Planning
for Rising Sea Level
 Introduction
Most people, standing at the edge of a tidal wetland and gazing
across the water, think of sea level as fixed and constant,
as unwavering as the height of the mountains. And over a few
years, and even a decade or two, changes are usually so small
you might feel justified believing in that constancy. However,
like so many things in nature, time-scale is important, and
over the longer term – even just a century - sea level
changes. And this change has serious consequences for ecosystems
at the water’s edge, such as tidal wetlands.
Wetlands Watch has been working for years to protect and conserve
wetlands in Virginia. When we started looking at the most conservative
estimates of relative sea level rise in the Chesapeake Bay
region over the next century – 1.5 – 2 feet by
2100 – we realized that could eliminate nearly all of
the vegetated tidal wetlands in the Bay. This led us to begin
a campaign in Virginia to identify and mitigate the impacts
of sea level rise on coastal ecosystems (wetlands, shoreline
buffers, and primary dunes)
Why is Sea Level Rising?
Read how glaciers, comets and more
tell the story of sea level rise in the Chesapeake Bay.
There are two factors that determine “relative” sea
level in the mid-Atlantic region and Chesapeake Bay. First,
global sea level is rising and, second, the land around the
Chesapeake Bay is slowly “sinking.” Together, these
two factors determine the rate at which “relative” sea
level changes. Measurements show that over the past few centuries
the rate of sea level rise in our area has been about 1 foot
(0.3 Meters) per century, or about 3 millimeters a year – the
height of this capital “S.” However, direct measurements
over the past eighty years around the Bay indicate a recent
increase in the rate of sea level rise, ranging from 1 ½ to
as much as 3 feet per century.
More on sea level - the science,
measurements and predictions.
How will Wetlands be affected?
Wetlands in the Chesapeake Bay and its tributaries are at
risk due to this increased rate of sea level rise. Research
has shown that vegetated tidal marshes can naturally build
upward at a rate of 2-3 millimeters per year, meaning that
they have been able to maintain their elevation in step with
sea level rising at a similar rate. Once sea level begins
to rise at a rate over 3-4 mm per year evidence indicates that
vegetated wetlands will not be able to build up fast enough
to keep from "drowning"
in place.
What has happened in the past with gradual sea level rise
is wetlands have migrated inland, taking over areas behind
the vegetated marshes that have become flooded by higher tides. However,
because so much of our coastline is developed
today, there is no “inland” for
the wetlands to migrate to. The land behind the tidal marshes
is increasingly armored by bulkheads, riprap, impervious surfaces,
roads, and buildings. As a result, most of our marshes will
drown in place.
Why should you care?
How will sea level
rise affect you - economically and environmentally?
While protecting our natural environment
is in itself a good reason, wetlands mean money - something
more people can relate to. We often talk about the value of
wetland “functions” - what they do to create environmental
value - but few people take the next step to recognize that
these wetlands functions produce economic value.
How is Virginia addressing the impacts
of sea level rise?
Unfortunately, we are well behind our mid-Atlantic neighbors..
While North Carolina, Maryland, Delaware, New Jersey and Maine
have each undertaken major studies and produced reports addressing
the economic and environmental impacts of coming sea level
rise, Virginia has made no similar progress and there are few
signs that plans have been made to begin the necessary work.
What are governments' responses
to the sea level rise threat?
What can you, Virginia, and the localities do?
Sea level rise action plan |
