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Oxford College
D1090
Diploma in Oceanography
Level 3
SAP: Module 7
The Oceans and Climate
Student No:
PD16-31465-OCQ
Student Name:
Heather Hoyle
Date:
23rd March 2017
D1090 - Diploma in Oceanography (L3)
Student No: PD16-31465-OCQ Heather Hoyle
Part 1
1. State the three main properties of water.
The structure of the water molecule accounts for its unique properties and
anomalous behaviour. The three main properties are:
i.
Specific heat: At 1 calorie/gram °C, which is higher than any other common
substance, water can absorb or lose a large amount of heat before changing
temperature. As a consequence, oceans can be maintained at relatively
constant temperatures, and absorbed heat can be transported around the
globe, thereby playing a major role in thermoregulation and moderation of the
Earth’s climate (Franzese and Stanley, 2010; Finney, 2015).√ Good
ii.
Density: Density is strongly related to temperature, with density generally
increasing
as
temperature
decreases.
Of
particular
importance,
for
freshwater, 4°C is the point of maximum density of 1,000 kg/m 3, after which
volume starts to increase and density decreases. Seawater, however,
continues to increase in density with decreasing temperature until it reaches
actual freezing point, after which the volume expands (Finney, 2015; Law and
Rennie, 2015). Significantly, this increase in volume allows ice to float on the
top of water: otherwise, it would sink to the seabed, thus exposing and
allowing further water to freeze above it. With sunlight only penetrating to a
depth of around 200 metres, the lack of heat to thaw ice on the seabed would
result in total ocean freezing (Garrison and Ellis, 2016).√
iii.
Solvent: Water is known as the “universal solvent”, and can dissolve more
substances in greater quantities than any other commonly found liquid (Ball,
2010; Morris and Louis, 2010; Finney, 2015). For example, water absorbs
atmospheric carbon dioxide at the air-sea interface, as well as that excreted
by marine organisms. The ocean, therefore, acts as a vast carbon sink,
serving both as a vast reservoir and regulator of carbon dioxide (Trujillo and
Thurman, 2014; Garrison and Ellis, 2016). √ Superb answer.
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D1090 - Diploma in Oceanography (L3)
Student No: PD16-31465-OCQ Heather Hoyle
2. At what point in the Earth’s history was the ocean a source of carbon
dioxide?
Research would suggest that the oceans have acted as a source of carbon dioxide
at the end of ice ages, when rising temperatures caused a release of carbon dioxide
from the oceans, with a subsequent dramatic increase in atmospheric levels.
Supporting evidence shows levels of atmospheric carbon dioxide have been
consistently low during the glacial periods (ice ages), and consistently high during
the interglacial periods (Riebeek, 2011; EPA, 2016).√
3. Name the three types of atmospheric cells.
Global wind circulation comprises of three convection loops within each of Earth’s
hemispheres, known as atmospheric cells. The three types of atmospheric cells are:
i.
Hadley cells: Hadley cells involve the rising of warm air near the equator,
cooling in the upper atmosphere, descent at the subtropical latitudes of 30°N
and 30°S, and return of air to the equator.√
ii.
Ferrel cells: Ferrel cells occur in the middle latitudes, with air rising in the
subpolar latitudes of 60°N and 60°S, cooling, descending in the subtropics at
30°N and 30°S, and then moving towards the poles.√
iii.
Polar cells: Polar cells involve the descent of air at the poles, movement
towards the equator, the rising of air in the subtropical latitudes of 60°N and
60°S, followed by return to the poles.
(Allaby, 2013; Lutgens et al., 2014)√
A well presented answer, well done Heather, great referencing too.
Atmospheric cells are shown in Figure 1 below.
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D1090 - Diploma in Oceanography (L3)
Student No: PD16-31465-OCQ Heather Hoyle
Figure 1: Atmospheric cells (Lutgens et al., 2014)√ A superb image to support
your answers above.
4. What is an anticyclone?
An anticyclone is an area of high atmospheric pressure, typically occurring at
subtropical latitudes, where air sinks and diverges horizontally near the surface. In
the northern hemisphere, air moves around the anticyclone in a clockwise direction;
whereas in the southern hemisphere, movement is counter-clockwise (Allaby, 2013;
Lutgens et al., 2014). Figure 2 below shows an anticyclone in comparison to a
cyclone.√
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D1090 - Diploma in Oceanography (L3)
Student No: PD16-31465-OCQ Heather Hoyle
Figure 2: Anticyclone vs. cyclone (Indiana University, 2007)√ A great choice of
image
5. What causes onshore breezes?
Onshore breezes, also known as sea breezes, are generated near the coasts,
particularly in sunny conditions. They develop during the day as solar energy is
absorbed by both the land and the sea. However, due to the high specific heat of
water, and the fact that the same amount of heat energy causes a greater rise in
temperature of the land than of the sea, the differential results in warm air rising from
the land, cooling, and sinking over the sea. Low pressure develops on the shore, and
high pressure develops over the sea. As air moves from an area of high pressure to
an area of low pressure, air moves from the sea towards the land, causing in an
onshore breeze (NOAA, 2017) (see Figure 3 below).√ Superb description of onshore
breezes
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D1090 - Diploma in Oceanography (L3)
Student No: PD16-31465-OCQ Heather Hoyle
Figure 3: Formation of onshore breeze (sea breeze) (NOAA, 2017)√
6. What is the Saffir-Simpson scale used for?
The Saffir-Simpson scale is an internationally accepted scale used to measure and
classify the intensity of tropical cyclones (hurricanes). It is based on wind speed and
potential damage, ranging from minimal to catastrophic. It was first introduced by
meteorologists of the US weather bureau in 1955, adding an additional five
categories to the Beaufort wind scale, along with the potential damage expected at
each level (Allaby, 2013; Trujillo and Thurman, 2014). Figure 4 below details the
scale, and identifies a hurricane in each category.√
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D1090 - Diploma in Oceanography (L3)
Student No: PD16-31465-OCQ Heather Hoyle
Figure 4: Saffir-Simpson Hurricane Scale (Eastern PA Weather Authority,
2015)√ An excellent answer Heather
7. Explain what is meant by the term typhoon.
Typhoon is the term applied to a mature tropical cyclone which forms specifically
over the region known as the north-west Pacific basin, ie. between 180°E and 100°E
(Lutgens et al., 2014). The term originates from the Chinese “tai-fung”, which means
great wind (Garrison and Ellis, 2016). Figure 5 below shows the area associated with
typhoons, as well as areas where the same weather feature is termed differently, ie.
cyclone or hurricane.√ Good understanding shown here.
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D1090 - Diploma in Oceanography (L3)
Student No: PD16-31465-OCQ Heather Hoyle
Figure 5: Distribution of typhoons, cyclones, and hurricanes (NASA, 2017)
8. Why is it believed that the Earth’s climate was warmer when the continents
were arranged in a ring close to the equator?
The distribution of continental landmasses has a major influence on ocean
circulation: currents can be permitted to flow freely, or they can be blocked or
redirected. As a process, continental drift causes seaways to open up or close, thus
altering ocean circulation and the subsequent transfer of heat around the globe over
time. When the continents were arranged in a ring close to the equator, warm
equatorial currents were allowed to circulate, so heat could be transported around
the globe. Cooling and subsequent glaciation were prevented, and levels of
atmospheric carbon dioxide remained stable, retaining Earth’s heat. The climate,
therefore, remained warm (Carlowicz,
2004; Rogers and Santosh, 2004;
Enviropedia, 2017).√
This warming effect becomes more apparent when contrasted with the climate
changes brought about by the formation of the supercontinent Pangea. Pangea
stretched from pole to pole, blocking the flow of warm equatorial currents. The
resultant cooling brought about glaciation, which in turn caused a lowering of sea
levels. When sea levels drop, the erosion of silicate minerals is increased. These are
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Student No: PD16-31465-OCQ Heather Hoyle
ultimately transported to the ocean and deposited, where they combine with carbon
dioxide to form solid precipitates. To fuel this process, carbon dioxide is drawn from
the atmosphere, causing a fall in atmospheric levels. As atmospheric carbon dioxide
plays a major role in retaining the Earth’s heat, this mass depletion had an overall
cooling effect on the Earth’s climate. Continental drift and ocean circulation clearly
play an important role in relation to Earth’s climate and climate change (Kaczor,
2008).√ Excellent description here, you have great knowledge of the Earth’s climate
and why this changes.
9. Why does advection fog form?
Fog is classed as a low cloud, comprising of water droplets suspended in air. It
occurs at, or near to, the surface of the Earth: however, unlike cloud, fog obtains its
water vapour from nearby sources, such as a large body of water. Advection fog
forms because of the condensation of over-saturated air as it moves from a warm
surface over a cooler surface. It typically occurs at sea, when warmer air moves over
cooler waters. When air lies over a warm surface, such as land or warmer ocean
waters, evaporation causes the air to become saturated with water vapour. As it
subsequently moves over cooler waters, the air undergoes rapid cooling, and
becomes over-saturated. Some of the water vapour condenses into liquid and
attaches to particles held in the air, such as dust or salt, thus forming fog (see Figure
6 below). Of note, advection fog is a frequent occurrence in areas of upwelling,
where colder water is brought to the ocean surface, and differences in surface
temperature of adjacent waters are created (ECCC, 2017).Velde-Laudama.
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D1090 - Diploma in Oceanography (L3)
Student No: PD16-31465-OCQ Heather Hoyle
Figure 6: Formation of advection fog (ECCC, 2017)
10. List five of the major greenhouse gases.
A greenhouse gas is a gas with the molecular construction capable of absorbing and
re-radiating infra-red electromagnetic radiation (Allaby, 2013). The five major
greenhouses gases are:
i.
Water vapour
ii.
Carbon dioxide
iii.
Methane
iv.
Ozone
v.
Nitrous oxide
Of note, these gases constitute a natural greenhouse effect, which, in the absence of
compounding human activities, is crucial for maintaining Earth as a habitable planet
(Lutgens et al., 2014; Garrison and Ellis, 2016).√ Good effort here, well done.
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Student No: PD16-31465-OCQ Heather Hoyle
11. Why does sea fog form in Japan in the summer months?
Sea fog forms off the coast of Japan as a result of the collision of the warm Kuroshio
Current with the cold Oyashio Current. The Kuroshio Current moves warm water
from the equator northwards past the east coast of Japan, while the Oyashio Current
brings colder water from the Arctic to the surface as it moves southwards along
Japan’s north and east coasts (see Figure 7 below). During the summer months,
temperatures are higher and winds blow in a northerly direction. This brings about
increased evaporation as winds blow over the warm Kuroshio waters, and the air
becomes saturated with water vapour. As winds continue to blow, this warm air
moves horizontally over the colder waters of the Oyashio and undergoes rapid
cooling. Air subsequently becomes over-saturated, and therefore condenses and
forms sea fog (Qiu, 2001; Tokinaga et al., 2009).
Figure 7: Meeting of the warm Kuroshio Current and the cold Oyashio Current
in the formation of sea fog (University of Washington, 2011)
12. State the two ways that sea level rises may occur?
Global sea levels continue to rise, with a noted increased rate in recent years.
Compared to the1993 average, the global sea level of 2014 was some 2.6 inches
higher (NOAA, 2016). The two main reasons for a rise in global sea levels are:
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D1090 - Diploma in Oceanography (L3)
i.
Student No: PD16-31465-OCQ Heather Hoyle
Thermal expansion: As temperature increases, water increases in volume.
Due to the large amount of water contained within the oceanic basins, only a
small rise in temperature would be required to bring about a significant rise in
sea levels.√
ii.
Melting of land ice: Increased temperatures also cause the melting of land
ice, which, in its liquid state, subsequently flows into the ocean, adding to the
overall volume of water. Of note, the melting of ice already present in the
oceans would not cause a rise in sea levels, as the ice would have a lower
volume when melted than in its solid state.
(NOAA, 2016)√ Good knowledgeable information.
13. Why is carbon dioxide released from the ocean if it warms up?
In terms of solubility, gases, including carbon dioxide, behave differently from solids.
Gases are more soluble in oceans with lower temperatures, and less soluble in
oceans with higher temperatures. Higher temperatures are associated with higher
kinetic energy, which causes the mobility of gas molecules to increase as the
temperature increases. As a consequence, intermolecular bonds break, thus
facilitating the release of gas, in this case carbon dioxide, from warmer ocean
waters. Of note, carbon dioxide becomes 40% - 50% less soluble with an increase of
25°C (Pilson, 2013; Mitra and Zaman, 2015).√
14. What is meant by the term ‘positive feedback mechanism’?
Earth’s climate system involves many feedback mechanisms. These are processes
which modify initial changes, and can be either positive or negative. A positive
feedback mechanism is an effect that reinforces and amplifies the initial change, ie. it
increases the amount or rate of the initial change, thus causing even further
increase. The water vapour cycle in terms of the greenhouse effect provides a good
example. In this feedback loop, increased surface temperatures lead to greater
evaporation, which increases levels of water vapour in the atmosphere. Water
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Student No: PD16-31465-OCQ Heather Hoyle
vapour is a powerful absorber of radiation emitted by the Earth – much more so than
carbon dioxide – with the result that more heat is trapped and retained, temperatures
rise, thus reinforcing and amplifying the initial effect, and so the cycle continues
(Naik, 2010; Lutgens et al., 2014; Trujillo and Thurman, 2014) (see Figure 8 below).√
An excellent explanation here of positive feedback mechanisms.
Figure 8: Positive feedback mechanism in relation to water vapour (Naik, 2010)
15. Why might global warming cause more iron dust to settle in the ocean?
Windblown dust from soil and desert sand has a rich iron content. Current estimates
suggest that, on a daily basis, approximately 1010 kilograms of this dust is
transported to and deposited in the oceans, where it is used as a nutrient by
phytoplankton. With global warming and rising temperatures, it is predicted that
continental interiors will become hotter and drier, thus producing more iron dust. In
turn, this increased amount of dust will be deposited in the oceans, where iron levels
will rise and phytoplankton productivity will be increased. Importantly, as a result of
increased iron dust deposits and increased phytoplankton productivity, the rate of
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increase of atmospheric carbon dioxide would be slowed, suggesting the deposition
of iron dust could offer a negative feedback mechanism (Herring, 1999; Totterdell et
al., 2005; Trujillo and Thurman, 2014).√
16. What was the main aim of the Kyoto Protocol?
The Kyoto Protocol was agreed in Japan in 1997, and came into force in 2005. It
was a legally binding mandate, aimed at lowering overall emissions of six
greenhouses gases; namely,

Carbon dioxide

Methane

Nitrous oxide

Sulphur hexafluoride

HFCs

PFCs
whereby more economically developed countries were committed to reduce
collective emissions of greenhouse gases by 5.2% below 1990 levels. This equates
to a 29% decrease in values which would have occurred otherwise. Whilst
reductions of 8% were recommended for the European Union, 7% for the United
States, and 6% for Japan, for example, there were also permitted increases for
Australia (8%) and Iceland (10%). Developing countries such as China and India
were considered to be relatively small contributors of increased CO 2 emissions, so
were excluded from the mandate. Countries failing to meet their targets were to be
sanctioned with further cuts to permitted emissions. There was also a system of
financial penalties, as well as the facility to purchase extra allowances. Most notably,
whilst ratified by most countries, the Kyoto Protocol was not ratified by the United
States (UNFCCC, 2014; Garrison and Ellis, 2016). Overall, the effectiveness of the
mandate has been compromised by increased emissions from some nations,
predominantly the United States and China, such that, rather than CO 2 emissions
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decreasing, they rocketed by approximately 45% between 1990 and 2010 (NEAA,
2011).√
17. State two ways that carbon dioxide emissions could be reduced?
As carbon dioxide is the main greenhouse gas emitted as a result of human
activities, behaviours can be modified such that carbon dioxide emissions are
reduced. Two methods are:
i.
Reduced use of fossil fuels: The burning of fossil fuels (coal,
petroleum, gas, oil) is the predominant human activity associated with carbon
dioxide emissions. These fuels are used for energy and transportation, both
domestically and industrially. The ideal solution is to replace fossil fuels with
renewable energy sources; however, where they continue to be used,
switching to a fossil fuel with a lower carbon content can have a positive
impact on emissions. For example, burning oil or gas can produce less
carbon dioxide than burning coal (EPA, 2017).√
ii.
Carbon sequestration: This method involves the removal and
storage of atmospheric carbon dioxide. A predominant feature of this method
is forest restoration and the mass planting of trees, which promotes the
natural removal of carbon dioxide from the atmosphere via the biological
process of photosynthesis. In this instance, the biomass acts as a carbon
sink. A major concern, however, is the potential effect this may have on
existing ecosystems (Sundquist et al., 2009).√ Well done.
Part 2
Explain how the oceans are involved in the formation of hurricanes.
Hurricanes are dependent on current circulation and ocean temperature, and only
form over water with a surface ocean temperature above 27°C, as lower
temperatures are insufficient to fuel the weather disturbance. A hurricane therefore
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Student No: PD16-31465-OCQ Heather Hoyle
begins life as a low pressure area over tropical waters, where warm seawater is able
to interact with warm air (Lutgens et al., 2014).
As ocean waters move from east to west, seawater gains heat and evaporates,
increasing the amount of water vapour in the lower atmosphere. When winds
converge, collide, and turn upwards, this humid air near the ocean surface is also
drawn upwards. With altitude, water vapour condenses into storm clouds, releasing
vast amounts of heat, and causing the surrounding air to warm and rise also. This
upward flow of air facilitates even more warm, moist air moving in from the ocean
surface, with winds spiralling in towards the centre (eye) of the storm (NOAA, 2013).
As winds increase in speed, evaporation from the ocean also increases, creating a
positive feedback mechanism fundamental to the fuelling of the hurricane, which will
continue for as long as the waters remain sufficiently warm and there is ample
supply of hot humid air. Equally, however, the ocean also serves as a negative
feedback mechanism which has a major role in weakening the hurricane. Surface
sea temperatures undergo substantial cooling as a result of the winds of the
hurricane bringing about the mixing of deeper, colder waters with warm surface
waters. This ocean-hurricane interaction results in a decrease in surface
temperatures, which subsequently cause a decrease in evaporation and a reduction
in storm intensity (Ginis, 2000). Consequently, the light winds outside the hurricane
are also of significance in causing the storm to thrive or weaken, by steering it either
over further warm waters or cooler waters (NOAA, 2013; Storm Chaser, 2017). Of
note, hurricanes do not form between latitudes 5°N and 5°S, as, although the waters
are warm enough, the Coriolis effect is insufficient to generate enough wind spin
(Garrison and Ellis, 2016). The steps involved in hurricane formation are itemized in
Figure 9 below.√ An excellent effort here, Heather you have excellent understanding
of warm waters and how water moves.
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Student No: PD16-31465-OCQ Heather Hoyle
Figure 9: Hurricane formation (Storm Chaser, 2017)
Part 3
Select two marine species that may be at risk through future climate change,
and explain why the changes might affect them, and the prognosis for their
survival.
Future climate change is predicted to impact significantly on the distribution of
marine species (ZSL, 2010). Two such examples are sea turtles and Mediterranean
monk seals.√
Sea turtles are well recognized as creatures whose life at sea and on land is closely
synchronized with environmental conditions, so they are at particular risk from
climate change (Warne, 2014). Most especially, rising temperatures will impact on
population sex ratios. Like alligators and crocodiles, for example, the sex of turtle
hatchlings is determined by the temperature of the nest in which they develop. For
turtles, 30°C is a pivotal temperature, with temperatures < 30°C favouring males,
and temperatures > 30°C favouring females. An increase of as little as 2°C is
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considered sufficient to skew the sex ratio, whilst 4°C is equated with the potential
elimination of male turtle offspring (ZSL, 2010; GGW, 2017). Turtles currently
synchronize breeding to the time of the year best suited to a balanced sex ratio, and
whilst there is opportunity in the Indian Ocean, for example, for green turtles to shift
their breeding from warmer to cooler islands, this change of breeding habitat is not
open to other populations which are already breeding in the coolest nesting sites
available to them. These turtle populations are at especial risk, as the lack of males
and the excess of females could lead to extinction. Breeding encounters further
potential risk from rising sea levels and storm surges, as increased inundation would
destroy nesting beaches, with the expected increase in humidity also rendering eggs
more susceptible to disease and increased mortality (ZSL, 2010). Further difficulties
would be encountered if ocean circulation was substantially altered by rising
temperatures. Hatchlings rely on ocean circulation to steer them through their
migratory corridors, and any changed pattern could carry them away from traditional
feeding and breeding sites (ZSL, 2010; Warne, 2014). Turtles have adapted and
survived many climate changes in the past. Nonetheless, Leatherback turtles, for
example, are declining rapidly, with only 1500 females nesting around the Pacific
rim. For these turtles, extinction could occur within the next 10 – 20 years (GGW,
2017). Currently, approximately only 0.1% of all turtle hatchlings survive to sexual
maturity, suggesting protective measures are crucial to prevent extinction (Garrison
and Ellis, 2016). One strategy for turtle survival is to maximize their adaptive abilities
by protecting them from known threats such as high mortality rates caused by the
fishing industry (Warne, 2014).√ Excellent answer very knowledgeable
Destruction of habitat as a result of rising sea levels also poses a serious threat to
Mediterranean monk seals, a reclusive species now only numbering between 600
and 700 animals, and found exclusively in four isolated populations; namely, the
north-eastern Mediterranean, Mauritania, Madeira archipelago, and the southwestern Mediterranean (MMC, 2017). By 2030, sea levels in their habitats are
predicted to rise by approximately 18cm as a direct result of increasing temperatures
and water expansion. This will cause increased inundation, reducing the area of
beaches where seals can raise their pups. The breeding caves, such as at Cabo
Blanco, are considered particularly at risk (MSCP, 2015). Unlike their Hawaiian
counterparts, Mediterranean monk seal mothers do not fast and nurse their pups
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intensively for 6 weeks. Instead, lactation and nursing are spread over 5 months, and
while mothers search for food, pups are left unattended in the maternal caves, where
inundation could exacerbate the already high pup mortality rate reported as between
25% and 40%, which is currently brought about by existing bad weather and Spring
tides (MOm, 2012). Further difficulties are foreseen in relation to the food web. With
atmospheric levels increasing, additional carbon dioxide is already being absorbed
by the ocean, causing acidification and changes in upper ocean chemistry which are
rapid in comparison to variations in the geological past. Such acidification will impact
directly on phytoplankton, and introduce a bottom-up effect on ocean food webs,
which will be felt throughout the entire trophic chain (Doney, 2013). Monk seals are
positioned at the top of the food web, so are susceptible to the cumulative effect of
lower trophic levels (MSCP, 2015). Whilst organism response to acidification may
vary, juveniles are considered especially sensitive (Doney, 2013), putting the survival
of Mediterranean monk seals even more at risk. Whilst prognosis might not be
considered initially bright, research indicates survival is very dependent on suitable
pupping caves, suggesting any survival strategy should focus on the preservation of
these caves (MOm, 2012).
Part 4
Explain why certain parts of the world experience a monsoon season.
A monsoon is a pattern of wind circulation characterized by seasonal reversal.
Although strictly a wind, it is typically used to refer to the rainy phase in regions
characterized by the monsoon wind pattern (Garrison and Ellis, 2016). Monsoons
are a result of the different specific heats of land and water, and the seasonal
changes in the Hadley circulation and the Intertropical Convergence Zone (ITCZ).
The ITCZ is the area near the equator where the two Hadley cells converge (see
Figure 10a below), and where air rises, water vapour cools and condenses to form
clouds, and then falls as rain. During December and January, when the southern
hemisphere receives more solar heat than the northern hemisphere, the hottest air,
and hence the ITCZ, lies south of the equator; whereas during June and July, the
process is reversed (UCAR, 2017).√ Well done.
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Figure 10a: Hadley circulation (UCAR, 2017)
A monsoon climate is typically characterized by a wet summer and a dry winter, with
the different specific heats of land and water responsible for the direction of the
monsoon wind. In summer, overland air warms more rapidly than air over the sea.
This air rises, creating an area of low pressure over the land. Cooler moist air
subsequently moves in from the sea to take its place, and, as this air is subjected to
continued warming, it rises and condenses, forming clouds and rain. A steady wind
develops from the sea towards the land, bringing a constant supply of moisture
which leads to heavy clouds and heavy rainfall overland. This is illustrated in the
upper diagram of Figure 10b below. In winter, the process is reversed. Land cools
more rapidly than the sea, with the result that cooler air sinks, creating an area of
high pressure overland. Dry surface winds subsequently move from the land towards
the sea, creating arid conditions overland and rain clouds over the sea (see the
lower diagram of Figure 10b). Summer monsoons are, therefore associated with
heavy rains, whereas winter monsoons are associated with arid conditions, and even
drought (North Carolina State University, 2012; Garrison and Ellis, 2016).
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Figure 10b: Monsoon formation: summer vs. winter
(North Carolina State University, 2012)
Importantly, the different specific heats of land and water mean the ITCZ shifts more
towards landmasses (see Figure 10c below). This accounts for why certain areas,
such as Asia, experience a monsoon season, whereas other areas remain monsoon
free. Asia is the world’s largest landmass, and, for this reason, draws vast amounts
of warm, moist air from the Indian Ocean during the summer. This air is driven by
winds from the south, carrying an enormous volume of water vapour inland.
Overland, this air warms, rises, and condenses, bringing the very heavy rains which
characterize the region, with the south and the east of the continent experiencing the
most powerful and most intense monsoons (Garrison and Ellis, 2016; Central
Weather Bureau, 2017; UCAR, 2017). This is apparent from Figure 10d below, which
highlights the distribution of summer and winter monsoons for both northern and
southern hemispheres.√
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Figure 10c: The changing position of the ITCZ (UCAR, 2017)
Figure 10d: Map showing the distribution of summer and winter monsoons in
the northern and southern hemispheres (CLIVAR, 2017)
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Part 5
Explain why scientists disagree about the predictions for future climate
change. Include within the answer the reasons why it is difficult to predict the
changes accurately.
Whilst there is general consensus that Earth’s climate is changing, disagreement
continues amongst scientists regarding the future environmental impact (Oreskes,
2007). Three areas of note are:
i.
Complexity: Climate is a complex phenomenon, and, as with all predictions,
climate prediction carries a level of uncertainty. Climate modelling is
becoming more sophisticated, but still remains dependent on climate data
from limited historical sources (Knutti, 2008; Idso et al., 2015). In addition to
missing data, measurements may lack consistency, validity, and reliability,
which possibly skews interpretation and leads to several conflicting
predictions (Knutti, 2008; Milroy, 2016). Moreover, there are many interrelated positive and negative feedback mechanisms which make it difficult for
models to describe the climate system fully, as well as deficits in knowledge,
such as regarding cloud formation, which make simulation via computer
modelling particularly difficult (Knutti, 2008). As such, the predictions obtained
from models sometimes disagree with actual observations, as exemplified by
temperature changes in the middle troposphere, which have not increased as
much as predicted. Furthermore, differences in programming can cause
computer models to generate very different results, leading to conflict and
dissension regarding future predictions (Knutti, 2008; Idso et al., 2015).
Predictions of rising sea levels, floods, storms, and drought, could, therefore,
be considered more in keeping with informed judgments based on personal
opinion and probability, rather than scientific evidence per se: consequently it
is only to be expected that opinions will vary (Oreskes, 2007; Knutti, 2008).√
Superb referencing here.
ii.
Natural variation: Throughout geological time, Earth’s climate has been
characterized by natural variability, including changes in solar radiation and
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Student No: PD16-31465-OCQ Heather Hoyle
ocean circulation. Temperatures, for example, have shown wide fluctuation,
which some interpret as an indicator that global warming is neither
anthropogenic nor harmful to the planet. Similarly, some scientists interpret
increased levels of carbon dioxide as a natural fluctuation which is of benefit
rather than a threat to life on Earth, equating higher levels to increased plant
life, longer growing seasons, increased crop production, and more food for all
other life forms. Nonetheless, this still leaves the question of how much is too
much (Oreskes, 2007; Idso et al., 2015).
iii.
Bias: Scientists are just as susceptible to human weaknesses as anyone
else, so bias cannot be discounted. Climate, as a subject, requires insight
from many disciplines. However, scientists typically specialize in only one or
possibly two areas of knowledge, which inevitably leads to subject bias. Of
note, scientists are frequently observed to be optimistic about environmental
safety when it relates to their own area of expertise, but pessimistic about
risks in areas where they lack academic familiarity (Idso et al., 2015).
Predictions on future climate change will, therefore, vary, as findings are
interpreted differently and emphasis is placed on personal areas of interest
(Oreskes, 2008; Idso et al., 2015). Importantly, much research receives
funding from various interested parties, and this can lead to conflicts of
interest, with the conclusions and predictions of some scientists wittingly or
unwittingly influenced by financial and/or career gain. The politicization of
science presents an additional threat to consensus, as scientists can also
become allied to governmental agendas which use scientific findings out of
context and in isolation. Ultimately, the above biases lead to distortion of the
evidence, strong opinion, disagreement, and division amongst the scientific
community (Oreskes, 2008; Idso et al., 2015).√
Consideration of potential factors underlying disagreement in the scientific
community serves to highlight why predictions on future climate change are
especially difficult. Overall, prediction does not constitute an exact science, and even
science itself is fallible. However, predictions about future climate change are
confounded by several factors specific to climate processes which make accuracy
very difficult to achieve (Knutti, 2008). The following factors have emerged:
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D1090 - Diploma in Oceanography (L3)
Student No: PD16-31465-OCQ Heather Hoyle
i.
Earth’s climate is characterized by naturally occurring fluctuations;
ii.
Earth’s climate is complex, and involves multiple causes and multiple
processes;
iii.
The inter-relationship between positive and negative feedback mechanisms is
complex and not fully understood;
iv.
Climate change occurs slowly, requiring long periods of consistent
measurement;
v.
Climate change sometimes varies by geographic region;
vi.
Historical records are limited, and potentially inconsistent;
vii.
Deficits in human knowledge compromise understanding of some climate
processes;
viii.
Climate models cannot fully describe Earth’s climate system.√
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D1090 - Diploma in Oceanography (L3)
Student No: PD16-31465-OCQ Heather Hoyle
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Student No: PD16-31465-OCQ Heather Hoyle
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Accessed 21st March 2017.√ Excellent list of bibliography used here, well done.
Well done this is an excellent piece, you have gone into detail throughout the
assignment. You have presented well and included in- text referencing to support
your answers. I found your written work to be very informative and highlights your
complete understanding of weather changes, sea breeze, direction and weather
changes including climate change and waters. A great piece, well done!
Tutor- Lucy O’Donoghue
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