Science 10 Notes Name: _____________________

11.1 Natural Climate Change

“Climate” describes the average ___________ of a ___________. Climate is usually measured over a minimum of ____ years or more. Climate = 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.

Climate and geography combine to allow specific ___________ to grow. Biogeoclimatic zones have distinct plants, soil, geography, and climate. British Columbia has 14 distinct biogeoclimatic zones.

Looking Forward by Studying the Past

Paleoclimatologists study long-term patterns in various regions. ___________ may show what kind of

environment was present. Tree ___________ show evidence of

growing seasons. (p. 466) River ________ can reveal types of rainfall. Glacier ice cores show air condition and

composition for thousands of years. Gases ___________ in the ice, specifically

CO2, reveal long-term atmospheric levels.

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Science 10 Notes Name: _____________________

Fossils and sediment evidence show Earth’s climate has drastically changed often in the past.

21 000 years ago, much of Canada and northern Europe was under ___________

Ice core data reveal CO2 levels for the past 650 000 years. Scientists have also tested the atmospheric air for CO2 for the past 50

years

Factors That Influence Climate: Composition of Earth’s Atmosphere

Earth is a ___________ system. A system is a group of parts that all function together as a whole. Very little energy (except radiant energy) enters or leaves the system. Earth’s atmosphere is the outer boundary.

A greenhouse is a closed system that absorbs thermal energy. The Earth’s “natural greenhouse effect” allows a narrow range of

temperatures. Solar radiation comes in, is absorbed, and is then emitted trapped

before being able to escape. Greenhouse gases in the atmosphere absorb thermal energy. This keeps Earth an average of 34ºC warmer than it would be otherwise. More greenhouse gases could make it too warm.

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Science 10 Notes Name: _____________________

Factors That Influence Climate: Earth’s Tilt, Rotation and Orbit

Earth’s tilt is responsible for ___________ in northern hemisphere. In summer, we are tilted toward the Sun, ___________ the angle of

incidence. In winter when we are tilted away from

the Sun, solar radiation has a ___________ angle of incidence.

Earth’s tilt varies between 22.3º and 24.5º (currently 23.5º) in 41 000 year cycles. (p. 469)

When tilt is largest, climate should experience the largest extremes.

Earth also “wobbles” as it rotates on its axis. Because the axis changes on a 23 000 year cycle, the angle of incidence

of solar radiation also changes. Earth’s revolution around the Sun is ___________, not circular.

On a 100 000 year cycle, Earth’s elliptical orbit becomes more ________. When the orbit is most elliptical, Earth is farther away from the Sun.

Factors That Influence Climate: The Water Cycle

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Science 10 Notes Name: _____________________

The water cycle describes the circulation of water on, above, and below Earth’s surface.

70 percent of all greenhouse gases in the atmosphere is ______ vapour. When temperature increases, ________ water evaporates. More water vapour in the atmosphere may have two effects.

• More solar energy may be absorbed by this greenhouse gas.• More solar energy may be reflected back out to space and never

reach Earth.

The water cycle stores and transfers large amounts of thermal energy.

Factors That Influence Climate: Ocean Currents

Convection currents in the oceans move large amounts of thermal energy all around Earth.

Deep ocean currents (200 m and deeper) flow based on ___________ differences. They behave like massive convection currents, with warm water rising in the ___________ and cold water from the higher latitudes ___________ it.

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Science 10 Notes Name: _____________________

Deep-ocean currents move cold, salty water below the surface and warm, less-salty water near the surface.

Salinity of water also changes density. Cold water (found at the poles) is ________ dense than warm water. Salty water (found at the poles) is ________ dense than fresh water. Large changes in ocean water density can ________ current direction.

Surface currents (0 - 200 m) are warmed by from ________ radiation. The thermocline is the region ___________ surface and deep ocean

currents. Upwelling occurs when cold, deep water rises into surface currents.

• La Niña is an example of upwelling.• When this occurs, cool water at the surface of the Pacific Ocean

causes warm winters in southeastern North America, and cool winters in the northwest.

• El Niño is the reverse: warmer water on the surface of the Pacific Ocean results in warm winters in the Pacific Northwest and in eastern Canada.

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Science 10 Notes Name: _____________________

Factors That Influence Climate: The Carbon Cycle

Carbon dioxide is a very important greenhouse gas. Even though each molecule absorbs only a ________ amount of thermal

energy, there are ________ CO2 molecules than any greenhouse gas other than H2O.

Without CO2 to trap infrared radiation from Earth’s surface, the average temperature of Earth would be below freezing.

The carbon cycle maintains a balance of CO2 in the atmosphere.• Deep oceans are carbon ________, as are forested areas.• CO2 in the ocean is converted to ___________ (CO3

2-), in shells.• Phytoplankton use CO2 for ___________ at the ocean’s surface.• Weathering of ________ releases carbon.• Carbonic acid (H2CO3) is formed when ________ reacts with CO2 in

the atmosphere.• Forests take in CO2 while ________ but release CO2 when ______

or when decaying.

Factors That Influence Climate: The Movement of Tectonic Plates, and Catastrophic Events

Large-scale disasters can quickly change atmospheric conditions.

Erupting volcanoes can release ash and molten rock that _________ radiation. Water vapour and sulfur dioxide (changed into sulfuric acid) can ______

solar radiation back into space. Meteorites and comets are thought to have caused dramatic changes.

These large masses strike Earth and the result is large quantities of dust, debris and gases in the atmosphere.

Solar radiation is affected so much that it is thought that these events are responsible for some of Earth’s largest ___________ events.

Large comet and meteor collisions with Earth can cause debris to ________ solar radiation and change all over the Earth.

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Science 10 Notes Name: _____________________

11.2 Human Activity and Climate Change

Climate change is the change in long-term weather patterns in certain regions. These changes can affect the flow of thermal energy over the entire

Earth. Several ice ages have occurred in the past million years. Global warming refers to a global increase in average temperature. Both the causes and effects of global warming are ___________ and

___________.

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Science 10 Notes Name: _____________________

The Enhanced Greenhouse Effect

The enhanced greenhouse effect increases thermal energy absorbed.

More greenhouse gases in the atmosphere = increase of natural greenhouse effect

Greenhouse gases include water vapour, CO2, methane, nitrous oxide, and CFCs.• Global warming potential (GWP) refers to the ability to trap

thermal energy.• CO2 is given a GWP of 1; CFCs are 4750-5310.

The Enhanced Greenhouse Effect: Carbon Dioxide and Methane

CO2 levels have increased greatly in the past ___________ years. Since the Industrial Revolution, humans have greatly increased their

overall use of __________ _________, which release CO2 when burned. Deforestation has changed carbon ___________, such as forests, into

carbon sources. Many people are attempting to reduce CO2 emissions by using

___________ energy sources or by reducing their energy use. Carbon offsets, such as wind farms, can be purchased to offset CO2

emissions.

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Science 10 Notes Name: _____________________

Methane is very efficient at ___________ thermal energy. 25X more efficient than CO2

Methane is produced by bacteria breaking down wastes in oxygen-free environments, animals digesting plant matter, rice paddies (and other natural wetlands), and the burning of fossil fuels.

___________ produce 18 percent of the total methane in the atmosphere.

The Enhanced Greenhouse Effect: Nitrous Oxide, Ozone, and Halocarbons

Nitrous oxide, N2O, is the ________ largest contributor to the enhanced greenhouse effect.

Even though there are only small amounts, it has ________ more GWP than CO2.

N2O comes from bacteria, fertilizers, and improper disposal of human and animal waste.

Ozone is an important UV radiation ___________ in the stratosphere. At _________ ________, however, it is a very powerful greenhouse gas. This ozone comes from solar radiation reacting with pollution from the

burning of fossil fuels, and is released from __________ and certain ___ ___________.

Halocarbons, used as refrigerants, are strong greenhouse gases. Chlorofluorocarbons (CFCs) are the best-known halocarbons. Halocarbons are also the main reason for ozone layer depletion.

Albedo and Climate, Making Predictions About Climate Change

The albedo at Earth’s surface affects the amount of solar radiation that region receives.

Changes in a region’s albedo - for example, snow cover melting earlier in the season than it did previously - Could result in _________ _________.

Forests have a low ___________. Deforestation ___________ albedo.• Forests also emit large amounts of water vapour, which reflects

solar radiation back into space.• Deforestation’s effects on climate change are unknown.

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Science 10 Notes Name: _____________________

The Role of Science in Understanding Climate Change

Scientists use ___________ 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. Global warming models use data from multiple _________ over long periods of _____. General circulation models (GCMs)

are computer models used to study climate.

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 are always trying to improve GCMs. GCMs predict the future and reveal the past.

The Role of International Cooperation in Climate Change

It is believed ________ -induced climate change is a recent occurrence. The United Nations and the World Meteorological Organization created

the Intergovernmental Panel on Climate Change (IPCC) to address global concerns about climate change and global warming.• The IPCC, formed in 1988, has members from 130 countries.• The IPCC examines possible climate change, highlights the causes,

and suggests solutions. The United Nations Framework Convention on Climate Change created a

voluntary treaty to encourage governments to __________ greenhouse gas emissions.

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Science 10 Notes Name: _____________________

Per capita emissions of greenhouse gases for various countries.

Global Impacts of Climate Change

Impacts of Climate Change on Canada

Being in the northern hemisphere, Canada could be strongly affected by global warming.

Parts of Canada have had average temperature increases of 0.5ºC to 1.5ºC.

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Science 10 Notes Name: _____________________

• Southern and western parts of the country have been most affected.

• The Arctic regions are losing ___________ and Arctic Ocean ice cover.

• Growing seasons are getting longer and more precipitation is falling.

• There could be heavier spring ________ and severe ___________ in the future.

• Fisheries could be very negatively affected.• Pollution concerns could lead to health issues.• Most regions of British Columbia will probably be warmer, sea

levels will _____, and fresh drinking water may be harder to find as glaciers ___________.

Impacts of Climate Change on BC

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Science 10 Notes Name: _____________________

Uncertainty and Decision, an Action Plan for the Global Community

Although climate change is a controversial issue, our actions now 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 precautionary principle, “better safe than sorry.”

Relatively small changes could have large positive impact on the climate in Canada.

Reduce vehicle greenhouse gas emissions.

Reduce industrial greenhouse gas emissions.

Increase use of energy-efficient products.

Improve indoor air quality.

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