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Transcript
CLIMATE CHANGE
CURWOOD: Welcome to Living on Earth. I’m Steve Curwood.
[THUNDER, FALLING RAIN]
CURWOOD: It’s another rainy day in New York City. Another
rainy day in what’s been a very wet year.
[THUNDER AND RAIN]
CURWOOD: During one intense downpour in early August, New
York set a record for the most rainfall in a 24-hour period. Just one
year earlier, the city was in the midst of a drought. These days, we
live in a time of extreme weather. The 1990’s were the warmest
decade of the 20th century, and, by some estimates, the warmest
decade of the past 1,000 years. Many scientists say/believe the
human impact on the world’s climate is promoting dramatic
swings in the weather – more droughts and heat waves but also
more storms and floods. Cities like New York will be affected by
these events and will have to adapt to them.
But, how much and how soon? That’s the central question for the
next hour as Living on Earth and WNYC present a special report, “Degrees of Concern: Climate Change and New York City’s
Future.”
[TRAFFIC, STREET SOUNDS]
CURWOOD: New York is certainly the ultimate man-made
environment. A place where weather can seem almost irrelevant. It
can be raining or snowing, freezing-cold or hot and humid, but
most of the city’s business goes on, unimpeded by the forces of
nature. If it's pouring, hop in a cab, or jump on the subway. If it's
hot, turn up the AC. Everyone has a quick fix for the weather. But
in the future, quick fixes may be harder to come by. Producer John
Rudolph has been traveling around New York investigating how
the city is responding to the early signs of global warming. He’s
found that in an urban environment, disruption in the climate as
we’ve come to know it presents unique challenges.
RUDOLPH: On a hazy afternoon Dan Mundy guides his boat
through Jamaica Bay, a huge salt-water estuary on the western end
of Long Island. If you’ve ever taken off or landed at Kennedy
Airport, you’ve probably seen Jamaica Bay from the air. Dan
Mundy has lived near the bay all his life.
MUNDY: And we’re now approaching what is known as Black
Wall Marsh, on a navigational chart.
RUDOLPH: Mundy is a retired New York City firefighter. Since
he left the Fire Department, Mundy’s been on a different kind of
rescue mission. He’s trying to save Jamaica Bay from an
environmental disaster – the sudden disappearance of the bay’s salt
marshes.
MUNDY: We’ve lost over 50 percent of this marsh in a short
period of time. Now, the ironic thing about this is that these
marshes are a thousand years old. Now, you’re looking at one of
the oldest, largest, living organisms around the New York area!
And in the last 15 to 20 years – and even less than that – it’s dying.
Everyplace you see water out there is where a marsh used to be.
The experts tell us that by the year 2022, all of these will be gone.
So, we’re in a situation where we’re running against time here.
Vocabulary
unimpeded  impede (vt) : to interfere with or slow the progress of;
synonym see HINDER
estuary (n) : a water passage where the tide meets a river current; especially :
an arm of the sea at the lower end of a river(有潮汐的)河口三角洲,入海口
marsh (n): 沼澤;濕地 a tract of soft wet land usually characterized by
monocotyledons 單子葉植物 (as grasses or cattails)
monocotyledon
(n): any of a class or subclass (Liliopsida or
Monocotyledoneae) of chiefly herbaceous seedplants having an embryo
with a single cotyledon, usually parallel-veined leaves, and floral organs
arranged in cycles of three  monocotyledonous (adj) /-d&n-&s/
dicotyledon
"dI-"kä-t&l-'E-d&n (n): any of a class or subclass
(Magnoliopsida or Dicotyledoneae) of angiospermous plants that produce
an embryo with two cotyledons and usually have floral organs arranged in
cycles of four or five and leaves with reticulate venation 
dicotyledonous (adj) /-d&n-&s/
cotyledon "kä-t&-'lE-d&n (n)1 : a lobule of the mammalian placenta
【動】 胎盤葉,分葉 2 : the first leaf or one of the first pair or whorl of
leaves developed by the embryo of a seed plant or of some lower plants (as
ferns) 【植】 子葉 ( 胚的第一片葉 )
plumule of morning glory seedling: 1 hypocotyl 下胚軸, 2 plumule
【植】 胚芽, 3 cotyledons 子葉
cattail (n) any of a genus (Typha of the family Typhaceae, the cattail
family) of tall reedy marsh plants with brown furry fruiting spikes;
especially : a plant (Typha latifolia) with long flat leaves used especially
for making mats and chair seats 香蒲 ( 生長於沼澤地 )
Discussions
1. Do you think that Taipei is getting warmer and warmer
every year? Tell us why you think so. Do you have any
evidence? Can you live without an AC during summer time?
2. Do you believe that the droughts and flood that Taipei had
in the past few years was just part of the natural process in
a millennium or was due to the greenhouse effect/global
warming made by human after industrial revolution?
3. What do you think as a single person can do in reducing the
global warming? What do you think you can do if you were
to become the next Taipei Mayor? Is the amount of the CO2
emissions be one of the priority items on your desk?
4. Do you know that there is a salt marsh in Taipei suburban
area near where Dang-Suei River 淡水河 meets the ocean?
Such as 關渡, 竹圍, 社 子. Trees there, like Ceriops tagal(細蕊
紅樹) and bruguiera gymnorrhiza(紅茄苳), are of red wood,
barks, and flowers, and therefore, named “Red Forest” 紅
樹林 by Taiwanese. Talk about what you know about this?
5. Salt marsh forests are protected. But, the global warming
will change the sea level, the marsh and the ecosystem. We
can leave the area untouched, but we can not reduce the
CO2 production in our daily life. Are you worried?
Reference:
The Salt Marsh: A Valued and Protected, Marine Ecosystem
Within the marine environment, some of the Earth 掇 most productive ecosystems are
formed when streams and rivers merge with ocean water in areas known as estuaries.
Organisms found within these estuaries experience strong changes in temperature and salt
concentration as the fresh water and salt-water mix. The nutrient rich soil that is carried
into these areas by rivers, supports a vast diversity of life both in the water and on
surrounding lands. Estuaries not only serve as breeding grounds for many invertebrate
and fish species, but as nesting and feeding areas for a wide range of birds (Campbell et.
al., 2004). The wetlands formed by these estuaries are typically classified into several
environments depending on there physical characteristics. The different types of
vegetation, which grow in these areas, flood frequency, and fluvial and tidal processes all
give a wetland a unique characteristic. For example, shallow subaqueous flats are areas
which are more frequently submerged than not. Mud and sand flats are slightly higher in
elevation than subaqueous flats and can be characterized by having blue-green algae and
moist or wet surfaces. Salt water marshes are more defined based on vegetation, soil
moisture, and the proximity of the land area to bay, lagoon, or estuary waters. Brackish
marshes experience more of an effect from flooding of estuary waters, and freshwater
precipitation.
These wetlands serve as a transition between salt and fresh marshes. Finally, fresh water
marshes are located more inland along river or fluvial systems and are typically found
beyond the point of salt water flooding (University of Texas, 2003).
Not only do these coastal wetlands experience a variety of physical characteristics, but
also offer significant ecological benefits. In addition to providing grounds for breeding
and habitats to a wide variety of wildlife, they maintain coastal water quality by acting as
a filter to sediments and excess nutrients and provide a region for the dilution of
pollutants. Coastal wetlands also slow the flow of water and protect shorelines from
erosion and damage during storms; this aids and maintains the integrity of surrounding
property. Additionally, two-thirds of the U.S. fishing industry relies heavily on the
characteristics of coastal estuaries and marshes for nursery and spawnin grounds (Miller,
1996).
Along most of the east coast of the U.S., the major ecosystems found in estuaries are salt
marshes. Within these regions of low shore energy, there are usually distinct tidal
fluctuations and the vegetation in these areas displays various tolerances to salt water
concentration (EPA, 2003). Generally, salt marshes are recognized by their characteristic
grassy vegetation: cordgrass in lower regions of the marsh and salt hay in the high marsh.
These plant species are able to thrive in marsh soils, which are commonly anaerobic and
concentrate salt through seawater evaporation (University of Georgia, 2003). Often times,
these salt concentrations depend on the frequency of flooding. Flood frequency also plays
a major role in the types of animals and plant species that may be found in a particular
area. Low marsh zones, typically flood twice on a daily basis. This creates areas of highly
saturated, anaerobic soil with very high salt concentrations producing very harsh
conditions for plant and animal species in these lower zones. In contrast, high marsh
zones are defined as areas, which only flood during storms or unusually high tides
(SCDNR, 2003).
More specifically, salt marshes can be divided into seven different ecological zones; these
zones are based on the time and depth of the tidal flood and include the following: tidal
creek, levee, low marsh, high marsh, marsh border, transition communities, and maritime
climax forest. Tidal creeks are units of flowing water through the marsh, and levees are
the habitats located on the banks of these creeks. These two zones, in addition to the low
marsh, are typified by constant sea water flooding and little change in salinity and
temperature levels. At a slightly higher elevation are the high marsh zones, which are
characterized by very little flooding throughout the day. Because of this longer exposure
to air and continued evaporation, these zones experience very high concentrations of salt
and low amounts of plant growth. Surrounding these high marsh zones are marsh borders.
These regions experience tidal flooding solely on a seasonal scale, and because of this,
runoff from fresh water is more prominent and there is strong differentiation in the
number of plant species. Transitional communities allow for more woody vegetation to
become established and lead to maritime forests and mature tree species (University of
Georgia, 2003).
Despite the seemingly simple appearance of a salt marsh ecosystem, these areas are
actually quite complex and play a very valuable role in the health and integrity of all
coastal ecosystems. A major function of salt marshes is that they greatly aid in the control
of flooding and improve coastal water quality. Because of their buffer-like qualities,
marshes add nutrients and microorganisms, greatly contributing to coastal food webs.
These areas also function as a safe habitat for a wide variety of birds, fish and other
species of wildlife. Salt marshes also provide people with attractive natural areas,
allowing for opportunities of education, recreation, and tourism (Ecology Action
Centre?EAC, 2003).
Salt marshes are ordered among the top ecosystems in the world; in terms of production
and the organisms that inhabit these areas, they play a large part in productivity.
Beginning at the microscopic level, decaying marsh plants provide nutrients in the form
of detritus for a large variety of bacteria, fungi, and small algae species. These organisms
take part in an important role by breaking down certain portions of detritus, which cannot
be digested by larger animals, at the same time providing valuable fertilizer for future
seasonal marsh plants. These microorganisms also provide a food source for large
numbers of primary and secondary consumers, mainly invertebrates. Although drastic
changes in salinity and temperature may limit the number of invertebrates inhabiting
these areas, those that can withstand these factors make a valuable link in the food chain.
Marsh snails, fiddler crabs and marsh mussels are among the more typical invertebrates
that may be found in these ecosystems, additionally, highly valued oysters inhabit the
borders of salt marshes (SCDNR, 2003).
Other abundant types of invertebrates in the marsh food web are insects. Similar to all
other organisms, insects rely heavily on plant detritus; however, insects largest role is the
primary source of food they provide for the abundant number of bird species (including
herons, egrets, and red-winged blackbirds) and fish for much of the year. Additionally, as
mentioned, marshes provide safe dwellings for a variety of fish species and shrimp. Each
type of organism within a salt marsh plays a fundamental role in maintaining the delicate
food chain and overall integrity of these wetland ecosystems (SCDNR, 2003).
The component of salt marshes that is most important for productivity and function
comes from various species of vegetation. One particular plant species, which dominates
the heavily flooded low marsh zones, is cordgrass (Spartina alterniflora). Cordgrass is
able to withstand high salt concentrations using special glands that secrete excess salt;
additionally their strong root systems and narrow blades enable them to withstand
frequent flooding and temperature fluctuations. In addition, Cordgrass protects marsh
surfaces and soils as well as provide detritus and nutrients for organisms in the food web.
Higher marsh zones display different types of grass species due to the differences in flood
frequency and salt concentrations; in these areas Saltgrass (Distichlis spicata) and Black
needle rush (Juncus roemerianus) are the dominant species of plants (EPA, 2003).
Although grasses are the most dominant forms of plant life inhabiting salt marshes, many
other types of species are also present and provide unique characteristics to these
wetlands. Glasswort (Salicornia virginica) and saltwort (Batis maritima) are two common
succulent species that are capable of water storage and provide organisms with a valuable
food source (EPA, 2003). These species are typically found in higher marsh zones and
transitional communities where environmental factors such as salinity levels and
temperatures are less extreme. However, despite their difference in appearance and
locality from grass species, these plants play a similar role in providing organisms in
these wetlands with an abundant food source, maintaining the health of salt marshes.
Although the benefits of a healthy salt marsh may be quite apparent, there are unfortunate
and common instances of these valuable wetlands becoming degraded or 烞 ick.? Many
factors may affect the health of a marsh; these factors can be natural, but oftentimes are
caused by human populations. A common occurrence is the blockage of tidal flow from
structures such as roads, railroads, even bridges and culverts that may restrict the flow of
tidal flooding. By restricting the flood frequency of an area, the environmental conditions
created are no longer suitable for naturally occurring grass species and other organisms
(NRCS, 2003).
Another common problem occurs when people attempt to reduce mosquito populations
by digging ditches and draining these areas. Many times, this results in the increase in the
number of mosquitoes due to standing water and greatly degrades the amount of
vegetation within the marsh. This drainage, in turn, may lead to natural invasion of
nonnative species such as common reed (Phragmites australis) and purple loosestrife
(Lythrum salicaria). These plant species typically invade unhealthy salt marshes and
crowd out native grasses and other beneficial species, while providing very little value to
wildlife (NRCS, 2003). It is extremely important to maintain the integrity and health of
these wetland ecosystems and the species within these areas. Accomplishing this ensures
water quality safety for all species and protects valuable shoreline lands and habitats.
What is being done to secure salt marsh health? There are two areas which may be
approached in order to achieve salt marsh health security, from both regulatory and
restoration processes. Point and nonpoint source pollution are common factors in
negatively affecting salt marsh health, however regulatory permits provided by state level
EPA greatly diminish, if not alleviate point source pollutions from discharge pipes and
single sources. Nonpoint source pollution is much more difficult to provide protection
against due to often unknown origin and multiple sources. However, monitoring and
regulation of local land use practices (i.e. installing buffer strips, detention basins, and
porous pavement) can greatly reduce the affect of nonpoint pollutants on local salt marsh
areas (SCDNR, 2003).
Regulations offer solutions in preventing damage to these valuable wetlands; however, if
damage has already occurred, or the health of an area has been greatly diminished, then
restoration projects provide an answer. One of the most frequent problems with the
installation of structures such as culverts in salt marshes is improper placement, thereby
reducing tidal flow. Correcting the placement of these culverts is one of the more
common restoration projects in these types of areas. Simply lowering a culvert below
creek bed elevation or replacing an existing culvert with a larger one can directly
reinstate tidal flooding to a particular area (EAC, 2003). Other restoration projects may
involve replacement of native plants and grasses or rerouting or redesigning roads and
bridges. In any case, ensuring and protecting the safety of these valuable salt marsh
ecosystems and the organisms found within, plays an important role in protecting all
aquatic and coastal habitats and ecosystems.