Transcript Climate change is due to human activities. or

Nominated for 4 PPTA awards including:
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What is Carbon?
• Carbon is an element that is in all living things.
• Molecules containing carbon are called Organic.
Carbon Cycle
• The movement of carbon
from the environment into
living things and then back
again is the Carbon Cycle.
• You already know how
carbon dioxide cycles
between photosynthesis
and cellular respiration.
Carbon Cycle
• Carbon dioxide in the air
enters into living things
through photosynthesis.
• Oxygen and glucose
produced from
photosynthesis are then used
by plants and animals for
cellular respiration.
• Cellular respiration produces
carbon dioxide to be released
again.
Carbon Cycle
• Keep in mind all living things have carbon in
them, so when they die, decomposers help
return that carbon to the environment and
soil.
Carbon Cycle
• That carbon makes up coal,
oil, and natural gas (fossil
fuels).
• Fossil fuels are burned in a
process called Combustion.
• Combustion releases carbon
dioxide back into the air.
• What do you think the
largest natural release of
carbon stored in the ground
is?
How many of you have heard that…
• Climate change is due to human activities.
or…
Climate change is due to human and natural causes.
• Nearly all climate scientists agree on causes of
climate change.
or…
Many scientists do not agree on causes of climate
change.
Science
• Science is a way of knowing about the natural and
material world.
–Hypothesis
–Data
–Evidence
–Conclusions
Research
• Thousands of studies
dealing with different
aspects of climate change
have been conducted and
published
• So… how do we make
sense of all this?
Intergovernmental Panel on Climate Change
(IPCC)
• Who is it?
– Governments
• Members of the UN
• Participate by naming experts and
reviewing the reports before they’re
published
– Scientists
• Close to 1000 scientists
• Climatologists, ecologists,
atmospheric physicists, and others
Dr. Susan Solomon, a NOAA atmospheric chemist,
an IPCC member and one author of IPCC summary
Intergovernmental Panel on Climate Change
(IPCC)
• What do they do?
– Review current scientific and technical literature
relevant to global climate change
– Provide reports on their findings at regular
intervals
– Reports are designed to be politically neutral and
of high scientific and technical standards
Weather vs. Climate
• Weather describes the atmospheric conditions at a
specific place at a specific point in time.
• Climate is determined by long term trends in weather.
Evidence of Climate Change
• Will not be the same everywhere
• Evidence found in:
1.
2.
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6.
7.
Ice core sampling
Tree rings
Earth’s average temperature
Patterns and amounts of precipitation
Ice and snow cover
Sea level
Extreme weather events
1. Ice Core Sampling
• Direct atmosphere
measurements
date back to the
1950’s
• The oldest
continuous ice core
dates back 800,000
years in Antarctica
• The ice encloses
bubbles of air that
contain a sample
of the atmosphere
2. Tree Rings
(Dendrochronology)
• Tree ring data lets
us look as far back
as 2,000 years
• Tree rings provide
direct evidence of
droughts, heavy
precipitation, and
length of the
growing season.
3. Temperature (1880-2010)
Image Credit: http://www.nasa.gov/pdf/509983main_adjusted_annual_temperature_anomalies%20_final.pdf
3. Temperature (1000-2000)
Image Credit: IPCC. http://www.ipcc.ch/ipccreports/tar/wg1/figspm-1.htm
4. Precipitation
Observed Precipitation Changes: 1901-2007
Statistically Significant Trends in
Precipitation Anomaly (inches/decade):
1895-2011
Southeast
Winter
Spring
Summer
Fall
Annual
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-0.10
+0.27
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Data Source: Regional Climate Trends and Scenarios for the U.S.
National Climate Assessment
Image Credit: http://nca2009.globalchange.gov/sites/default/files/11-Southeast-pg-111%20top.jpg
5. Sea Ice Coverage
Image Credit: National Snow and Ice Data Center. 2013. http://nsidc.org/arcticseaicenews/
6. Sea Level
Data source: Coastal tide gauge records. Credit: CSIRO. 2012.
Data source: Satellite sea level observations. Credit: CLS/Cnes/Legos. 2012
7. Extreme Weather Events
Image Credit: http://www.grida.no/graphic.aspx?f=series/et-common/trends_L.gif
Climate is Affected by Several Factors
Historical (Natural) Changes
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Milankovitch Cycles
Solar fluctuations
Plate Tectonics
Volcanic eruptions
Greenhouse effect
Recent (Human) Changes
• Greenhouse effect
• Fossil fuel combustion
• Land-use change from human
activities
Natural Factors
Affecting Earth’s
Climate
Milankovitch Cycles
• Named after a Serbain mathematician, Milutin
Milankovitch
• EXTREMELY long term
effects that scientists think
may be the cause of the
ice ages.
• These are movements of
the Earth that affect the
amount of solar radiation
that it gets.
Milankovitch Cycles
Earth’s
wobble, tilt,
and orbit
Precession
Obliquity
Eccentricity
Milankovitch Cycles
Precession
Direction of the Earth’s
axis changes over time
The Earth wobbles like a
top on its axis
26,000 year cycle
Milankovitch Cycles
Obliquity
The tilt angle of the
Earth’s axis changes
over time
The greater the tilt
the greater the
differences in the
seasons.
40,000 year cycle
Milankovitch Cycles
Eccentricity
Varying shape of
Earth’s orbit, e.g. how
elliptical it is
100,000 year long cycle
Animation
Solar Cycles
Sunspots are storms on the surface of the sun and are
associated with
extremely strong magnetic activity,
solar flares
hot gaseous emissions
These follow an 11 year cycle.
Scientific research estimates that normal fluctuations
due to Solar Cycles increase or decrease solar
radiation reaching Earth by only 0.1% - 0.2%.
400 Years of Sunspot Activity
Plate Tectonics
Plate Tectonics and associated
Continental drift
• Have been exerting their effect on the Earth’s
geography over billions of years
• Have shaped the continents as we know them
• The impact on climate (very long term, and in the
past) was:
– by changing land mass and ice caps (size & location) and
– changing ocean circulation patterns which transport heat around the
Earth and in turn
– influences atmospheric circulation processes.
Volcanic Eruptions /
Albedo
Volcanic eruptions of ash and gases
into the troposphere and above cause SHORT TERM cooling
(few years).
The gases released are mainly water (H2O), carbon dioxide
(CO2) and sulfur dioxide (SO2). The 1st 2 do not change
ambient levels by much. But the SO2 reacts with H2O to form
sulfates. Sulfates increase the brightness (albedo) of clouds,
reducing the solar radiation reaching Earth.
The large volumes of ash also block some incoming solar
radiation but the effect is less significant and more short lived.
Volcanic Eruptions
Do Volcanic eruptions cause long term climate change?
Apparently not.
There is evidence of slight warming at some times, and
slight cooling at other times. In these cases any
temperature changes are minimal and short lived.
Interesting point:
During the time before and at the beginning of the Little
Ice Age, there was an increased incidence of volcanic
activity – enhancing the effect of the Sun Spot minimum.
Forest Fires
• Forest fires produce a lot of smoke – made up of
particulates and gases.
• Based on what you learned about volcanic activity,
what impact could large forest fires have on climate?
– Will this impact be local? Global?
Greenhouse Effect
Solar Radiation – What does
this data tell you?
Image Credit: http://www.skepticalscience.com/solar-activity-sunspots-global-warming.htm
Anthropogenic Factors
Affecting Earth’s
Climate
Land-Use Change
In the Southeast U.S., land use changes from bare soil in cotton and other row
crops to forests (currently 70 percent of the region) may have contributed to the
negative trend in temperature over the past 100 years.
We Have Altered the Atmosphere
Greenhouse Gas
Pre-1750
Tropospheric
Concentration
Recent Tropospheric
Concentration
Change in
Tropospheric
Concentration
Carbon dioxide (CO2)
280 ppm
400 ppm
43%
Methane (CH4)
700 ppb
1874 ppb
168%
Nitrous oxide (N2O)
270 ppb
324 ppb
20%
Chlorofluorocarbons
(CFCs)
0
21-529 ppb
NA
Ozone (O3)
(different for each CFC)
25 ppb
Data Source: http://cdiac.ornl.gov/pns/current_ghg.html
34 ppb
36%
Atmosphere Gases
Image Credit: http://www.ipcc.ch/publications_and_data/ar4/wg1/en/figure-ts-2.html
Focus on CO2
• It has changed a lot
• It stays in the atmosphere a long
time
• The US emits more CO2 than other
greenhouse gases
• We can do something about it
Image Credits: http://www.epa.gov/climatechange/images/ghgemissions/GlobalGHGEmissionsByGas.png
http://www.edf.org/climate/human-activity-causes-warming
Global and Continental Temperature
Change
Natural forces alone do not explain the changes in temperature
What does all this mean?
• 97% of climate scientists combine this and other
evidence to draw conclusions:
– Earth’s climate is currently changing.
– Changes are not the same at all locations on Earth.
– Future changes may be more rapid than historical
changes.
– Human activities are responsible for most of the climate
change being observed.
What will happen in the future?
Scientists use models to project temperature changes with
different assumptions for emissions.
Image Credit: http://www.cara.psu.edu/climate/emissionscenarios3.asp.
Forest Habitat Changing
Future Model – High Emissions
Current
Modeled
Forest
Future
Model
– Low Emissions
Sea Level Rise
1-5 meters in Bangladesh
PCC slide no.
7-8 meters in Florida
It’s a Challenge
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A very complex system
Regional variation
Changes are hard to see
No firm predictions; models have limitations
Not just about the science
-
Political, Ethical, Economic
- As policies are made concerning climate change, what are some
economic sectors that would be affected?
- What are some ethical factors involved?
The US Public Has Many Beliefs about
Climate Change
But why disagreement?
• People see and remember information that
matches what they know
– So it is hard to change someone’s mind
• People have partial information and leap to
conclusions
– And then when presented with complete information, it
doesn’t match
• People listen to influential leaders
– Rather than figuring it out for themselves
Solutions to Climate Change
• Lots of options; no single
solution
– Adaptation
– Mitigation
• Policies and actions
implemented by
– Governments: international,
national, state, local
– Industry and business
– Individuals – all of us!
Air Pollution: Other Human
Impacts on the Atmosphere
• Photochemical Smog
– Air pollution caused by automobile exhaust in the presence
of sunlight.
– Solar radiation turns the nitrogen and carbon compounds
into ozone.
Ozone Depletion
• CFCs
(chlorofluorocarbons) –
Gas released by cleaning
agents, old refrigerators,
and aerosol cans.
• Ozone Hole – Seasonal
decrease in ozone over
Earth’s polar regions.
Acid Precipitation
• Occurs when sulfur
dioxide and nitrogen
oxides act as
condensation nuclei,
making precipitation
acidic
– 90% of sulfur emissions
in the US are human
caused