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Geography AS - World at Risk (Global Hazards) (Hazard Distribution…
Geography AS - World at Risk (Global Hazards)
Global Hazards
Global Warming
arguably the
Greatest Current Global Hazard
Global Warming Overview (GW)
:
Global warming
describes *recent increase in average global temperature.
It's a type of
Climate change (CC)
.
Causes other types of
CC
.
Scientific consensus
that
GW
due to
human activity
.
GW
is a
context hazard
(
global
in scale). Potential to
trigger other hazards
/make them
worse
.
GW
is a
chronic
hazard (
constant threat
, can't be solved quickly/easily).
GW
highlights
issues of injustice
(not necessarily the people causing the problem
most affected
).
GW
solution will be
complex
as the
causes
and
effects
not fully understood. Requires
international cooperation
between
governments
,
businesses
and
individuals
.
Hydro-meteorological Hazards
becoming more
frequent
Number of
Hydro-meteorological hazards (HMH)
increasing in recent years.
Number of
Geophysical hazards (GH)
hasn't changed much.
Thought that the increase in
HMH
due to increasing
GW
effects (thought to be largely due to
human activity
).
Number of disasters increased may be due to
greater media coverage
.
Number of
disasters
increasing due to:
Human factors
:
⇨ Rapid
population growth
and
urbanisation
.
⇨ Increasing
world poverty
.
⇨
Exploitation of resources
.
Physical factors
:
⇨ Increasing
GW
effects.
⇨
El Niño
events (oceanic current and temperature fluctuations).
Disaster Risk Equation
Disaster risk increases as:
⇨ The
frequency/severity
of hazards increase.
⇨ People's
vulnerability
increases.
⇨ People's
capacity to cope
decreases.
Risk (R)
=
Hazards (H)
x
Vulnerability (V)
/
Capacity to cope (C)
Deaths
decreasing but
Economic Losses
increasing
Number of deaths decreasing due to improvements in
risk management strategies
:
Prediction
- Improved technology (Allows hazard prediction and advance warning/evacuation).
Prevention
- Prevent natural hazards becoming disasters.
Preparedness
- Educating people (helps reduce number of deaths).
Trend of decreasing deaths
levelling off
recently due to increasing number of
vulnerable people
in poorer countries (more affected by disasters leads to more death).
Global economic losses
due to rapidly increasing disasters:
Actual financial cost
- the amount of money lost (greatest in
richer countries
).
Relative financial cost
- the amount of money lost relative to how much people had to start with (greatest in
poorer countries
).
Different Types
of
Hazard
Hazard
- Something that's a
potential threat
to
human life
or
property
.
Natural Hazards
are caused by
natural processes
, there are two types:
⇨
Hydro-meteorological hazards
(caused by
climatic
processes)
⇨
Geophysical hazards
(caused by
land
processes)
Disaster
- when a hazard
actually seriously affects
humans.
Risk
- the
likelihood
that humans will be seriously affected by a hazard.
Vulnerability
- how
susceptible
a
population
is to damage caused by a hazard
Hazard Distribution
Volcanoes
and
Earthquakes
Also Occur at
Destructive Boundaries
Destructive boundary
- where two plates are moving
towards each other
.
Continental crust
and
Oceanic crust
more towards each other and
subduction
occurs.
Oceanic crust
heated
by
friction
and contact
with the upper mantle, melting into
magma
(can form
volcanoes
). (e.g.
Japanese island arc
)
Same process for two plates of oceanic crust but the denser of the two subducts. (e.g.
Formed the volcanic islands of Indonesia
)
Subducted plate can
get stuck
causing a
pressure build up
until it becomes
too much
and the plates
jerk
past each other, causing an
earthquake
.
Where two plates of continental crust move towards each other,
neither
subducts (so no
volcanoes
) but pressure builds up and can cause
earthquakes
. (e.g.
Kashmir earthquake in 2005
)
Earthquakes
Also Occur at
Conservative Boundaries
Conservative boundary
- where two plates are moving
past each other
.
Two plates
lock together
in place and
pressure builds up
causing plates to jerk past each other (or to
crack
forming
fault lines
), releasing energy as an
earthquake
. (e.g.
San Andreas fault
)
Volcanoes
and
Earthquakes
Occur at
Constructive Boundaries
Constructive boundary
- where two plates are moving
apart
.
Mantle under
pressure
from plates above. When they move apart, pressure is
released
at the
boundary
.
The pressure release causes the mantle to
melt
(producing
magma
).
Magma is
less dense
than the plate above, so it
rises
and can
erupt
to form a
volcano
(e.g.
Iceland
).
Plates don't move apart in a
uniform way
. Parts move faster than others
building up pressure
until it's
too much
and the plate
cracks
creating a
fault line
and causing an
earthquake
(
further earthquakes
can occur later).
Some
Volcanoes
Occur
Away
from
Plate Boundaries
Volcanoes can occur
far away
from any
plate boundaries
such as
volcanic hotspots
. (e.g.
Hawaii
)
Geophysical Hazards
Usually Occur
Near Plate Boundaries
The
Earth's crust
is made up of
Tectonic plates
that sit on top of the
Mantle
.
Plates are made of two types of crust:
⇨ The
Continental crust
- It is
thicker
,
less dense
and is mostly
above
sea level.
⇨ The
Oceanic crust
- It is
thinner
,
more dense
and is mostly
below
sea level.
Plates move due to
convection currents
in the
mantle
(caused by
temperature differences
within).
Volcanoes
and
earthquakes
most commonly occur at
plate boundaries
.
Three types of plate boundary:
⇨
Constructive
⇨
Destructive
⇨
Conservative
Tropical Cyclones
Occur over
Warm Water
Tropical Cyclones
- huge
storms
with
strong winds
and
torrential rain
.
Develop over
26.5°C or higher sea water
. As warm, moist air
rises
and
condenses
, it releases energy which
increases wind speed
.
Energy supply
cut off over land (lack of
warm water
).
Cyclones spin because of the
Coriolis effect
(force that deflects wind paths due to Earth's rotation).
Coriolis effect
also reason why they move away from the equator.
Occur
between 5° and 30°
north/south.
More than 30°
, too cold.
Between 0-5°
,
Coriolis effect
not strong enough.
TC
move westwards due to
east-west winds
in the tropics.
Known as
Hurricanes
(If in the
Atlantic Ocean
/
Caribbean Sea
) or
Typhoons
(If in the
Pacific Ocean
).
Global Hazards - The Future
Global Warming
may be the
Greatest Hazard
to
Life
and
Property
Global warming one of the world's biggest challenges:
Massive effects
- Potential to cause massive
loss of life
and
property damage
.
Context Hazard
- can cause other global problems/hazards and
worsen
their effects.
Long-term hazard
- Impacts may be permanent and irreversible.
Global effect
- Affects the entire planet (unlike other problems which are more local).
Strategies proposed and used to cope with Global Warming impacts:
Increasing energy efficiency
- Making produced energy do more.
Energy conservation*
- using less energy.
Decreasing carbon emissions
- Directly slowing global warming rate.
Increasing alternative energy use
- Using sustainable energy sources.
Reafforestation
- replant trees to increase CO2 uptake.
Difficulty and cost to manage Global Warming:
Stern Review (2006)
- Looked at climate change economies.
Cost
- Concluded an investment of
1%
of the world's
GDP
needed to prevent
worst effects
.
If investment not made, could reduce
GDP
by up to
20%
in the future.
Refer to Strategies for Coping with Climate Change
Impacts of
Climate Change
may lead to
Conflict
Conflict caused by Climate Change
Water shortage and food security problems caused
political disputes
between countries (could lead to
armed conflict
).
Conflicts can escalate as risk/uncertainty increases. (e.g.
The Nile
)
Conflict can occur
within
and
between
countries if a resource cannot support the population (will only get worse).
Solutions
to Hazards should
Focus
on
Risk
and
Vulnerability
Solutions should focus on
assessing
and
altering
the hazard risk and the populations vulnerability.
The
United Nations (UN)
set up a programme in
1992
called
Agenda 21
.
Outlined actions to help
sustainable development
(global and local scale).
First section
- reducing
vulnerability
- combats poverty, changes consumption and promotes better health.
Second section
- reducing
risk
- changes emissions, stops deforestation and protects environments.
Both should reduce risk and vulnerability.
The
World
is Becoming
Increasingly Hazardous
Future issues with Global Hazards:
Global risk and uncertainty increasing as hazards increase in magnitude/frequency.
Threatens
major disruption
to people and the environment.
Could cause
water shortages
leading to reduced
food security
.
With rapidly increasing populations, vulnerability increases so disaster risk much higher.
Other
Global Problems
make
Managing Hazards Difficult
Global warming makes other problems more difficult:
Increase vulnerability of populations.
Risk increases if population is vulnerable.
Some countries won't have resources to manage impacts.
Downward cycle
can occur (one hazard increases risk of more hazards).