11.1 natural causes of climate change · pdf file11.05.2011 · 11.1 natural causes...
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11.1 NATURAL CAUSES OF CLIMATE CHANGE
Name: Date:
Block: (Reference: pp. 464 - 481 of BC Science 10)
• Climate change is not new on Earth.
Earth has undergone periods of freezing followed by periods
of warming throughout its history.
DESCRIBING CLIMATE
• climate: ___________________________________________
___________________________________________________________________
Climate includes clouds, precipitation, average
temperature, humidity, atmospheric pressure, solar
radiation, and wind.
The size of the region can range from an island to the
entire planet.
BC has a range of climates due to its varied ___________.
• Climate and geography combine to allow specific organisms to grow.
Biogeoclimatic zones: ____________________________
____________________________
____________________________
____________________________
British Columbia has ____ distinct
biogeoclimatic zones.
LOOKING FORWARD BY STUDYING THE PAST
• Paleoclimatologists study:
__________ ___________- they may show if the
environment was cold and dry or warm and wet.
________ ________- show evidence of growing seasons
(yearly changes in the weather).
__________ _________________- can reveal types of
precipitation a region received in the past
• Fossils and sediments evidence from around the world indicate
that Earth’s climate has drastically changed _______ in the past.
• Ice ages and periods of warming have occurred _________ times.
21 000 years ago much of Canada and northern Europe was
under _____________.
• Ice core data show the composition of ________ in the
atmosphere when the ice formed.
gases can be trapped in the ice for thousands of years.
reveal CO2 levels for the past __________ years.
• Scientists have also tested the atmospheric air for CO2 for the
past _____ years
• Several factors that influence climate include:
1. Composition of Earth’s Atmosphere
• The Earth’s “natural greenhouse effect” is a closed system
that allows a narrow range of ___________________.
Some of the solar radiation that reaches the Earth’s
surface is reflected into the atmosphere.
Greenhouse gases in the atmosphere ___________ and
_______ thermal energy.
This keeps Earth an average of ____ºC warmer
than it would be otherwise.
More greenhouse gases could make it too warm.
2. Earth’s Tilt, Rotation and Orbit
• Earth’s ______ and _______ is responsible for seasons at
higher latitudes.
In the northern hemisphere…
in the summer, we are tilted ___________ the
Sun, _______________ the angle of incidence.
in the winter when we are tilted _______ from
the Sun, solar radiation has a _________ angle
of incidence.
Earth’s tilt _______ between 22.3º and 24.5º (currently
______º) in 41 000 year cycles.
Scientists believe when the tilt is the greatest
the seasonal changes would be the most ______.
• Earth “wobbles” as it ____________ on its axis.
The axis changes on a 23 000 year cycle
In about 12 000 years, the North Pole won’t point to
Polaris, it will point to ________.
• This will __________ the angle of incidence of
solar radiation.
• Earth’s _______________ around the Sun is elliptical, not
circular.
On a 100 000 year cycle, Earth’s elliptical orbit becomes
_______ circular.
When the orbit is most elliptical, Earth is farther away
from the Sun, so _______ solar radiation reaches
Earth’s surface.
• Scientists believe the combination of Earth’s tilt, wobble, and
shape of orbit have caused past ______ _________.
3. The Water Cycle
• The water cycle describes the circulation of water ___,
_____________, and _________ Earth’s surface.
water vapour is the most _________________
greenhouse gas in the atmosphere (70%).
When temperature increases, evaporation of water
and the capacity of air to hold water vapour _______.
More thermal energy is trapped in the
atmosphere, temperatures increase even more
at the Earth’s surface, and even more water
evaporates, etc.
4. Ocean Currents
• ________________ ______________ in the oceans move
large amounts of thermal energy all around Earth.
• Two types of currents that affect climate:
1. _________ ocean currents (below 500 m deep)
2. ______________ currents (up to 500 m deep)
• Deep ocean currents are driven by ___________ differences.
They behave like massive convection currents, with
_______ water rising in the tropics and ______
water from the higher latitudes replacing it.
Two factors that affect the density of water:
_______________________
• Cold water (found at the poles) is
more dense than warm water.
_____________ (salt content).
• Salty water (found at the poles) is
more dense than fresh water.
Cold, salty water will _____ below warmer, less salty water
• Large changes in ocean water density can _____________
current direction.
Create saltier water -> _______________ of
surface water or the formation of ______ .
Dilute salt water -> __________________ or the
___________ of glaciers.
• Surface currents are warmed by ________ radiation.
• Three factors that influence surface currents:
1. ____________
• drag surface water
2. ___________________________ (Coriolis effect)
• deflects the path of moving water to the right in
the northern hemisphere and left in the southern
hemisphere
3. __________________________________________
• affect the direction of surface currents
• thermocline: ______________________________________
_______________________________________________
________________ occurs when cold, deep water
rises above the thermocline, into surface currents.
Ex. ____ _________
Cool water at the surface of the eastern
Pacific Ocean causes warm winters in
southeastern North America, and cool
winters in the northwest.
____ _______ is the reverse: warmer water on the
surface of the Pacific Ocean results in warm winters
in the Pacific Northwest and in eastern Canada.
5. The Carbon Cycle
• Carbon dioxide is a very important _______________ gas.
Even though each molecule absorbs only a small
amount of thermal energy, there are more CO2
molecules than any greenhouse gas other than _____.
Without CO2 to trap ___________ radiation from
Earth’s surface, the average temperature of Earth
would be below freezing.
• The carbon cycle maintains a ______________ of CO2 in
the atmosphere.
Deep oceans and forested areas are ______
_______ (remove carbon from the atmosphere)
• CO2 dissolved in the ocean is converted to
_______________ ions (HCO32-), in
shells.
• Phytoplankton use CO2 for
___________________ at the ocean’s
surface.
_________________ of rocks is a carbon
_________ (release carbon into the cycle).
• __________ ______ (H2CO3) is formed
when water reacts with CO2 in the
atmosphere.
____________ are carbon sinks when growing and a
carbon source of CO2 when burned or when decaying.
6. Catastrophic Events
• Large-scale disasters quickly change atmospheric conditions.
Large ____________ ______________ can release
molten rock, ash, water vapour and sulphur dioxide, which
have cause temperatures on Earth to ______.
Ash __________ out sunlight.
Sulphur dioxide reacts with water vapour to
produce sulfuric acid, which can ___________
solar radiation back into space.
_________________ and other large pieces of rock
from space are thought to have caused even more
dramatic cooling.
Resulted in large quantities of dust, debris and
gases shot up into the atmosphere.
Believed to be responsible for some of Earth’s
largest _________ ____________________.
• 65 million years ago ->the extinction of many
____________________.
11.2 HUMAN ACTIVITY AND CLIMATE CHANGE
Name: Date:
Block: (Reference: pp. 482 - 501 of BC Science 10)
• Climate change: ___________________________________
_______________________________________________
_______________________________________________
These changes can affect the flow of ____________
energy over the entire Earth.
Several ice ages have occurred in the past million years.
Global warming: ______________________________
___________________________________________
___________________________________________
Both the causes and effects of global warming are
unknown and controversial.
THE ENHANCED GREENHOUSE EFFECT
The enhanced greenhouse effect: _________________
____________________________________________
____________________________________________
More greenhouse gases in the atmosphere =
________________ of natural greenhouse effect
5 examples of greenhouse gases include: ________
__________, _____, ________________, _________
________, and _____.
Global warming potential (GWP): __________________
____________________________________________
____________________________________________
CO2 is given a GWP of _____; methane is ______, nitrous
oxide is _______ and CFCs are __________________.
Carbon Dioxide and Methane
• CO2 levels have _____________ greatly in the past 200 years.
Since the _______________ _________________,
humans have greatly increased their overall use of
________ fuels, which release CO2 when burned.
Deforestation has changed carbon sinks, such as forests,
into carbon sources.
Many people are attempting to reduce CO2 emissions by
using _______________ energy sources or by
___________ their energy use.
Carbon offsets, such as wind farms, can be purchased to
offset CO2 emissions.
• Methane is very efficient at trapping thermal energy.
_____X more efficient than CO2
Methane is produced by _____________ breaking down
wastes in oxygen-free environments, ___________
digesting plant matter, rice paddies (and other natural
_____________ ), and the burning of ________ fuels.
Nitrous Oxide, Ozone, and Halocarbons
• Nitrous oxide, ______, is the ________ largest contributor to
the enhanced greenhouse effect.
Even though there are only small amounts, it has _____X
more GWP than CO2.
N2O comes from _____________, _____________,
and improper ____________ of human and animal waste.
• Ozone is an important ____ radiation blocker in the
stratosphere.
At _________ altitudes, however, it is a very powerful
greenhouse gas.
This ozone comes from ________ radiation
reacting with pollution from the burning of
_________ fuels, and is released from
photocopiers and certain ______ conditioners.
• Chlorofluorocarbons (CFCs) are the ________ reason for ozone
layer depletion.
They are ________-made greenhouse gases.
They are made up of ___________, ____________ and
___________.
Their main use is as coolants in ___________________
and _____ ________________ systems.
The _____________ atoms break apart ozone (O3) in
the atmosphere.
ALBEDO AND CLIMATE,
MAKING PREDICTIONS ABOUT CLIMATE CHANGE
• The albedo at Earth’s surface affects the amount of ________
radiation that region receives.
Changes in a region’s albedo could result in climate change
For example, large areas of Arctic sea ice
__________ would cause albedo in the Arctic to
_______, and _________ more solar radiation.
Some forests have _____ albedo which is believed
to play an important role in regulating climate.
THE ROLE OF SCIENCE IN UNDERSTANDING CLIMATE
CHANGE
• To increase the reliability of conclusions about climate change,
____________ measurements must be taken over ______
from around the ____________.
From these measurements, scientists have noticed
____________.
• Scientists use computers to model what Earth’s climate might
be like.
Although models differ, most indicate that a decrease in
the production of greenhouse gases is necessary to stop
the apparent global warming trend.
General circulation models (GCMs): _______________
__________________________________________
GCMs take into account changes in greenhouse
gases, albedo, ocean currents, winds and surface
temperatures.
GCMs are also used for weather forecasting,
climate analysis, and climate change predictions.
Scientists who use GCMs are always trying to
improve their understanding of climate and the
effects of human activities on it.
GCMs provide the best predictions of the future
conditions of our atmosphere and global climate.
THE ROLE OF INTERNATIONAL COOPERATION IN
CLIMATE CHANGE
• It is believed human-induced climate change is a ___________
occurrence.
The United Nations Environmental Programme (______)
and the World Meteorological Organization (______)
created the Intergovernmental Panel on Climate Change
(______) to address global concerns about climate
change and global warming.
The IPCC, formed in _______, has members from
____ countries.
The IPCC examines possible climate change,
highlights the causes, and suggests ___________.
The United Nations Framework Convention on Climate
Change (___________) created a voluntary treaty to
encourage governments to ___________ greenhouse gas
emissions.
GLOBAL IMPACTS OF CLIMATE CHANGE
• The IPCC suggests that lifestyle _________ and the use of
energy-_____________ technologies can reduce greenhouse
emissions.
Evidence shows that this will improve _____ _________.
IMPACTS OF CLIMATE CHANGE ON CANADA
• Being in the northern hemisphere, Canada could be strongly
affected by global warming.
Parts of southern Canada have had average
temperature increases of ____ºC to ____ºC, with
the greatest warming in the _______.
Temperatures are also increasing in the north.
• The Arctic regions are losing
___________ and Arctic Ocean ____
cover.
Growing seasons are getting ___________ and
______ precipitation is falling.
• There could be _________ spring rains
and severe ___________ in the future.
• __________ could be very negatively
affected.
• Pollution concerns could lead to
__________ issues.
IMPACTS OF CLIMATE CHANGE ON BC
• Most regions of British Columbia will probably be __________,
sea levels will ______, and fresh drinking water may be harder
to find as glaciers _______.
UNCERTAINTY AND DECISION, AN ACTION PLAN FOR THE
GLOBAL COMMUNITY
• Although climate change is a _________________ issue, our
actions _____ are important.
Improving our environmental approach will help, no matter
how dramatic climate change actually is.
Not acting could result in huge problems.
The United Nations suggests the ________________
______________, “better safe than sorry.”
CANADA’S RESPONSE TO CLIMATE CHANGE
• Relatively small changes could have large positive impact on the
climate in Canada.
_______ vehicle greenhouse gas emissions.
_______ industrial greenhouse gas emissions.
_________ use of energy-efficient products.
__________ indoor air quality.