Global Climate Change

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Transcript Global Climate Change

Think-Pair-Share
 Complete
the 4 questions on your
handout using the accompanying
graphs
 Check
your answers with a partner.
Elaborate upon your answers as
much as possible
Homework
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Tonight: Read your briefing and answer the
accompanying questions. Be prepared for our
climate summit tomorrow!
Global Climate Change
Global Climate Change
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Changes in Earth’s climate, including
aspects such as temperature, precipitation,
and storm frequency and intensity
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Our climate has never been stable (ex) ice
ages)
3 main factors affect the Earth’s climate
1.
The sun
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2.
The atmosphere
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3.
Warms the Earth
warms Earth and decreases temperature
differences during night/day
Oceans
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store and transport heat and moisture
Greenhouse Gases
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Atmospheric gases
that absorb infrared
radiation released
from Earth’s surface
Water vapor,
ozone,
carbon dioxide,
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nitrous oxide,
methane,
halocarons (includes
CFCs)
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Futurama video
Greenhouse Effect/Global warming
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The greenhouse gases that surround the
Earth absorb infrared radiation from the sun
They then re-emit energy that slightly
warms the troposphere
This is a natural phenomenon
EARTH
Recent Global Warming
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In the past 250-300 years, human activities
have increased the concentrations of many
greenhouse gases, thereby enhancing the
greenhouse effect
Carbon Dioxide (CO2)
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Carbon dioxide is not the most
powerful greenhouse gas, but its
abundance in the atmosphere means
that it contributes more to the
greenhouse effect
 Atmospheric
400,000 years
CO2 is at its highest levels in
CO2 and temperature
Carbon Dioxide (CO2)
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Carbon is stored for long periods in the
upper layers of the lithosphere and forms
fossil fuels
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Human activities have released these stores of
carbon into the atmosphere
Deforestation has also reduced the
biosphere’s ability to absorb CO2
Other greenhouse gases
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Methane is released from fossil fuels, from
livestock, from crops, and from landfills
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Since 1750, methane has increased 151%
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Nitrous oxide has increased as a byproduct
of feedlots and fertilizers, as well as fossil
fuel burning
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Ozone concentrations have increased as a
secondary pollutant
Water vapor
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The strongest greenhouse gas
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As temperatures increase, bodies of water
evaporate, increasing water vapor
concentrations
This causes an increase in temperature, and
a subsequent positive feedback loop
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Alternatively, it could cause increased
cloudiness and thus decrease temperatures
Proxy Indicators of climate change
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Things such as ice cores and pollen are used
as indirect evidence that serve as proxies for
direct measurement and that indicate the
nature of past climate
Other examples are coral reefs and tree rings
of long-lived trees
Using Ice to Study Climate Change
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As glaciers form throughout time, bubbles of
atmospheric gases are trapped
We can examine these bubbles by drilling
cores into the ice
This was used to
show how CO2
has increased
over long periods
of time
Using pollen to study climate change
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Pg 538
Plants usually live in very
specific climates
By looking at pollen that is
trapped in sediment,
scientists can determine what
type of plants lived in a
geographic area during a
relative time period
Effects of Climate Change
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Average surface temperatures have risen by
0.6˚C (1.0˚F) during the 20th century (90-99%
certainty)
 By this, we can infer that glaciers, snow cover, and
ice caps were melting worldwide
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Droughts increased in frequency and severity
Hot days and heat index increased
Effects of Climate Change
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Average sea level increased 10-20 cm
Arctic sea ice thinned by 10-40%
Mountaintop glaciers retreated widely during the
century
Permafrost thawed in many regions
El Nino events became more frequent,
persistent, and intense
Growing seasons lengthened by 1-4 days per
decade
Effects of Climate Change
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Geographic ranges of many plants, insects,
birds, and fish shifted toward the poles and
upward in elevation
Coral reefs are experiencing bleaching more
frequently
Global economic losses due to weather events
rose 10-fold over the past 40 years
Many changes are interconnected
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Warming temperatures are causing glaciers to
shrink and disappear and ice shelves to melt
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This causes sea levels to rise
Sea level is also rising because ocean water
expands as its temperature increases
Higher sea levels lead to beach erosion, coastal
flooding, intrusion of saltwater into aquifers, etc
Local impacts
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Maldives pg 529, 541-542
New Orleans pg 542-543
Impacts of Climate Change in the US
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Pg 543
Average temperatures will increase 3-5˚C in the
next 100 years
Drought and other factors will decrease crop
yield
Water shortages will worsen
Alpine ecosystems and barrier islands will
disappear
Loss of coastal wetlands
Impacts on Agriculture
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Drought and temperature change can impact
farms already struggling
Warmer temperatures and longer growing
seasons at higher latitudes could increase
agricultural productivity
Some areas will be hurt while others will benefit,
making overall production stable
Impacts on Forestry
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Productivity will increase due to the increased
levels of CO2
Frequency and intensity of forest fires will
increase by 10% or more
Forests will more upward in elevation and
northward
Mountaintop communities will decline
Impacts on freshwater systems
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With increased precipitation and stream flow,
erosion and flooding will change ecosystems
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Near agricultural areas, pollution may increase
With decreased precipitation, lakes, ponds, and
wetlands will shrink
Marine ecosystems such as coral reefs will
decrease
Impacts on Human Health
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Heat stress from high temps and humidity
Respiratory ailments from air pollution and
increased smog
Expansion of tropical diseases such as malaria
Disease and sanitation problems from floods
Hunger-related ailments if agriculture is affected
Debate over Climate Change
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Scientists agree that climate change is occurring,
but some disagree on the details (pg 546-547)
For example, some people argue that the current
climate change is not accelerated due to human
impacts
 Many scientists are uncertain what the extent of
future impacts will be
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Kyoto Protocol
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1997 treaty that mandates signatory nations to
reduce emissions of 6 greenhouse gases to levels
equal to or lower than those of 1990
Only came into effect after countries responsible
for 55% of global greenhouse levels signed it
(2005)
Kyoto Protocol
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The United States, the world’s largest emitter of
greenhouse gases has refused to ratify the treaty
Our leaders say that it is unfair because it requires
industrialized nations to reduce emissions but does
not require the same of developing nations
 This refusal has alienated the US from many other
countries
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Other climate summit
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There are now 191 Parties to the Kyoto
Protocol
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Copenhagen (2009) non-binding agreements
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Cancun (2010)