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Global Climate Change:
Evidence and Causes
Maureen Knabb1, Tim Lutz2, and Win Fairchild1
Department of Biology1 and Department of Geology2
West Chester University
What is climate?
Climate refers to time and space patterns of precipitation,
temperature, and wind. For example, temperature and
precipitation differ across the United States.
2
What is climate change?
Climate change occurs when the patterns change in time (e.g.,
winter months get warmer) and space (e.g., monsoon rains
occur further south).
Suppose winter in Pennsylvania began to look like winter in
Florida?
3
Why is studying climate change a
scientific challenge?
• Climate changes naturally on a range of timescales, from
decadal (10’s of years), centennial (100’s of years),
millennial (1000’s of years), and longer (glacial cycles, e.g.
Ice Ages).
• Climate changes naturally on a range of spatial scales,
from local and regional to global.
4
Why should we be interested in
climate change?
• Climate determines the type and location of humanmanaged ecosystems, such as agricultural farmlands.
• Climate affects the weathering of rock, the type of soil that
forms, and the rate of soil formation.
5
Why should we be interested in
climate change?
• Climate helps to determine the quantity and quality of water
available for human use.
• Climate determines the severity of droughts, storms, and
floods.
6
Why should we be
interested in climate
change?
Climate largely determines the
nature and locations of biomes
(major terrestrial ecosystems,
defined based on their plant
communities).
Example: A prediction of climate
change for eastern PA. By the
end of this century Philadelphia,
PA, could have the climate that
Savanna, GA, has now.
7
A shift in climate from the south,
could result in Reno having
temperatures that Las Vegas
currently has. On average, 5-7
degrees higher than now.
A shift from the north could result
in rains that are common in
Oregon. *
How do we study climate?
Air bubbles in ice cores retain atmospheric
gases present when the ice was formed.
Annual tree rings
not only indicate
tree age, the ring
width indicates
growth spurts
due to warmer
temperature.
CO2 measured continuously
at Mauna Loa Observatory
since 1958 has provided
strong evidence for
atmospheric change.
9
At what rate have global surface temperatures
changed over the last 30 years?
B
A→B: 0.6 °C/30 years= 0.02
°C/yr
A
10
CO2 and energy in the atmosphere
• The Earth’s surface
absorbs solar radiation,
and reradiates it as
heat.
• CO2 and other
greenhouse gases
(GHG) reduce the rate
at which this heat can
escape into space.
• The more GHG, the
higher the global
temperature.
• This role of CO2 and other GHG has been understood for over
a century.
11
CO2 and other GHG vary naturally. Why are
humans thought to affect GHG, and thus climate?
Human activities
including land use
change (agriculture,
deforestation), fossil
fuel use (coal, oil,
natural gas), and
cement production
are known to release
CO2 and other GHG.
12
Why do we think that CO2 released by human
activities is causing the increase in the atmosphere?
• Seasonal cycles
in CO2 result from
photosynthesis
and respiration.
• Such short-term
flows of carbon
cannot explain the
upward trend
• The trend has to result from carbon that has been stored for
long periods of time, such as in fossil fuels and soils.
13
Is all of the human-caused CO2 in the atmosphere?
• Only about 50% of the increased CO2 stays in the
atmosphere.
• The rest is absorbed by the oceans and other sinks.
14
Do the models prove that humans are causing
climate change?
• Models cannot prove that humans are involved; however,
they show that the changes observed so far are consistent
with human causes.
• Models do not account for some complexities of climate, such
as the feedback effects of water vapor and cloud formation.
• Scientists consider the models sufficient to say that it is very
likely (>90% probability) that the climate change observed in
the last 50 years is not a result of natural effects alone.
15
Slide Credits
Slide 4
Description: The United States Capitol Building in Washington DC, framed with the Supreme Court columns.
Author: ©Michael Shake
Source: Dreamstime.com, ID: 11882582
Clearance: Licensed royalty free.
Slide 6
Description: Climate map for the U.S.
Source: Natural Resources Conservation Service (NRCS), United States Department of Agriculture.
Link: http://www.nrcs.usda.gov/news/thisweek/2006/071906/techtip07-19-06.html
Clearance: As a work of the U.S. federal government, the image is in the public domain (17 U.S.C. § 101 and § 105).
Slide 7—Left
Description: Pennsylvania in winter.
Author: User:Ruhrfisch
Source: Modified from Wikimedia Commons, http://commons.wikimedia.org/wiki/File:Plunketts_Creek_Winter_Panorama.JPG
Clearance: Licensed in accordance with Creative Commons Attribution-Share Alike 3.0 Unported.
Slide 7—Right
Description: Florida in winter.
Author: WV-Mike www.EpicRoadTrips.us
Source: Modified from Wikimedia Commons,
http://commons.wikimedia.org/wiki/File:Saw_palmetto_Serenoa_repens_and_Oak_Forest_at_Edward_Ball_Wakulla_Springs_State_Park
_in_Florida.jpg
Clearance: Licensed in accordance with Creative Commons Attribution 3.0 Unported.
Slide 9—Left
Description: Farmland in Niger river delta region.
Author: ‫ازرق‬, Radosław Botev
Source: Modified from Wikimedia Commons, http://commons.wikimedia.org/wiki/File:Macina.jpg
Clearance: Licensed in accordance with Creative Commons Attribution-Share Alike 2.0 Generic.
Slide 9—Right
Description: Terraced rice paddy in Vietnam.
Author: AJ Oswald
Source: Modified from Wikimedia Commons, http://commons.wikimedia.org/wiki/File:Sapa,_terraced_rice_paddy.jpg
Clearance: Licensed in accordance with Creative Commons Attribution-Share Alike 2.0 Generic.
Slide 10—Left
Description: Drought scene in Australia.
Author: Peripitus
Source: Modified from Wikimedia Commons, http://commons.wikimedia.org/wiki/File:Drought_Swimming_Hole.JPG
Clearance: Licensed in accordance with Creative Commons Attribution-Share Alike 3.0 Unported.
Slide 10—Right
Description: Flood on the Stillaguamish River, Washington, U.S.
Author: Walter Siegmund
Source: Modified from Wikimedia Commons, http://commons.wikimedia.org/wiki/File:Granite_Falls_26455.JPG
Clearance: Licensed in accordance with Creative Commons Attribution-Share Alike 3.0 Unported.
Slide 11
Description: Climate change for Eastern PA
Source: Right panel (Eastern Pennsylvania) of Figure 2 (Migrating Climates) in “Climate Change Impacts and Solutions for Pennsylvania:
How Today’s Actions Shape the State’s Future,” Union of Concerned Scientists, 2008, available at
http://www.climatechoices.org/assets/documents/climatechoices/exec-summary_climate-change-in-pennsylvania.pdf.
Clearance: Used with permission from Union of Concerned Scientists.
Slide 12 and Slide 13
Description: Temperature, precipitation and terrestrial biomes.
Source: Originally from R.H. Whitaker Communities and Ecosystems, 1975; redrawn and modified after R.E. Ricklefs The Economy of
Nature, 2000.
Clearance: NCCSTS
Slide 14—Left top
Description: Deep ice core sheathed in protective netting at WAIS (West Antarctic Ice sheet) Divide field camp.
Author: Chad Naughton (National Science Foundation)
Source: http://www.usap.gov/; exact source
Clearance: This image is a work of a National Science Foundation employee, taken or made during the course of the person’s official duties.
As a work of the U.S. federal government, the image is in the public domain.
Clearance: Used in accordance with terms of use on http://www.ipcc.ch/home_copyright.htm.
Slide 14—Right
Description: The Scripps Institution of Oceanography (Keeling) carbon dioxide analyzer at NOAA’s Mauna Loa Observatory.
Source: NOAA Celebrates 200 Years of Science, Service, and Stewardship; http://www.usap.gov/; exact source
Clearance: This image is a work of the National Oceanic and Atmospheric Administration (NOAA). As a work of the U.S. federal government,
the image is in the public domain.
Slide 14—Left bottom
Description: Tree rings seen in a cross section of a trunk of a tree.
Author: Arnoldius
Source: http://www.usap.gov/; exact source
Clearance: Licensed in accordance with Creative Commons Attribution-Share Alike 2.5 Generic.
Slide 15
Description: Graph of annual temperature change.
Author: Graph prepared by case author, Timothy Lutz.
Source: Data from Jones, P.D., D.E. Parker, T.J. Osborn, and K.R. Briffa. 2008. Global and hemispheric temperature anomalies—land and
marine instrumental records. In Trends: A Compendium of Data on Global Change. Carbon Dioxide Information Analysis Center, Oak
Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., U.S.A.
Link: http://cdiac.ornl.gov/trends/temp/jonescru/data.html
Clearance: Graph used with permission.
Slide 16
Description: Long-term changes in temperature derived from isotopes in the Vostok ice core.
Author: Graph prepared by case author, Timothy Lutz.
Source: Temperature data from: Petit, J.R., D. Raynaud, C. Lorius, J. Jouzel, G. Delaygue, N.I. Barkov, and V.M. Kotlyakov. 2000. Historical
isotopic temperature record from the Vostok ice core. In Trends: A Compendium of Data on Global Change. Carbon Dioxide Information
Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., U.S.A.
Clearance: Graph used with permission.
Slide 17
Description: Milankovitch cycles, the pace makers of ice ages.
Author: Hannes Grobe, Alfred Wegener Institute for Polar and Marine Research.
Source: Wikimedia Commons, http://commons.wikimedia.org/wiki/File:Milankovitch-cycles_hg.png
Clearance: Licensed in accordance with Creative Commons Attribution-Share Alike 2.5 Generic.
Slide 19
Description: Long-term variation of temperature and of CO2 in air bubbles preserved in the Vostok ice core.
Author: Graph prepared by case author, Timothy Lutz.
Source: CO2 data from Barnola, J.-M., D. Raynaud, C. Lorius, and N.I. Barkov. 2003. Historical CO2 record from the Vostok ice core. In
Trends: A Compendium of Data on Global Change. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S.
Department of Energy, Oak Ridge, Tenn., U.S.A. Concentrations are in parts per million by volume (ppmv).
Clearance: Graph used with permission.
Slide 20
Description: Temperature and CO2 correlation in the ice core.
Author: Graph prepared by case author, Timothy Lutz.
Source: CO2 data from Barnola, J.-M., D. Raynaud, C. Lorius, and N.I. Barkov. 2003. Historical CO2 record from the Vostok ice core. In
Trends: A Compendium of Data on Global Change. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S.
Department of Energy, Oak Ridge, Tenn., U.S.A.
Clearance: Graph used with permission.
Slide 21
Description: Greenhouse gas effects.
Author: Figure created by Robert A. Rohde from published data and is part of the Global Warming Art project.
Source: Wikimedia Commons, http://commons.wikimedia.org/wiki/File:Greenhouse_Effect.png
Clearance: Licensed in accordance with Creative Commons Attribution-Noncommercial-Share Alike 2.5 Generic.
Slide 23
Description: CO2 levels from 450,000 year ago to the present.
Author: Graph prepared by case author, Timothy Lutz.
Source: Measurements (1958 through 2008) are from Mauna Loa as reported by Pieter Tans of NOAA
(http://www.esrl.noaa.gov/gmd/ccgg/trends/). Other ice core data from: (1) Neftel, A., H. Friedli, E. Moor, H. Lötscher, H. Oeschger, U.
Siegenthaler, and B. Stauffer. 1994. Historical CO2 record from the Siple Station ice core. In Trends: A Compendium of Data on Global
Change. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn.,
U.S.A. (2) D.M. Etheridge, L.P. Steele, R.L. Langenfelds, R.J. Francey, J.-M. Barnola and V.I. Morgan. 1998. Historical CO2 records from
the Law Dome DE08, DE08-2, and DSS ice cores. In Trends: A Compendium of Data on Global Change. Carbon Dioxide Information
Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., U.S.A.
Clearance: Graph used with permission.
Slide 24
Description: Increase in CO2 and other GHG over the last 2000 years.
Source: FAQ 2.1, Figure 1 in: Forster, P., V. Ramaswamy, P. Artaxo, T. Berntsen, R. Betts, D.W. Fahey, J. Haywood, J. Lean, D.C. Lowe, G.
Myhre, J. Nganga, R. Prinn, G. Raga, M. Schulz and R. Van Dorland, 2007: Changes in Atmospheric Constituents and in Radiative
Forcing. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the
Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L.
Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
Link: http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter2.pdf
Clearance: Used in accordance with terms of use on http://www.ipcc.ch/home_copyright.htm.
Slide 25
Description: Contribution of GHG to climate change.
Author: Graph prepared by case author, Timothy Lutz.
Source: Diagram constructed from data in: Forster, P., V. Ramaswamy, P. Artaxo, T. Berntsen, R. Betts, D.W. Fahey, J. Haywood, J. Lean,
D.C. Lowe, G. Myhre, J. Nganga, R. Prinn, G. Raga, M. Schulz and R. Van Dorland, 2007: Changes in Atmospheric Constituents and in
Radiative Forcing. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment
Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor
and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
Link: http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter2.pdf
Clearance: Graph used with permission.
Slide 27
Description: Human activities and carbon emissions worldwide.
Author: Graph prepared by case author, Timothy Lutz.
Source: Fossil fuel-related emissions + cement production from: (1) Marland, G., T.A. Boden, and R.J. Andres. 2008. Global, Regional, and
National Fossil-Fuel CO2 Emissions. In Trends: A Compendium of Data on Global Change. Carbon Dioxide Information Analysis Center,
Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., U.S.A. (2) Land use-related emissions from: Houghton,
R.A. 2008. Carbon Flux to the Atmosphere from Land-Use Changes: 1850-2005. In Trends: A Compendium of Data on Global Change.
Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., U.S.A.
Links: (1) http://cdiac.ornl.gov/trends/emis/overview.html; (2) http://cdiac.ornl.gov/trends/landuse/houghton/houghton.html
Clearance: Graph used with permission.
Slide 28
Description: Yearly fluctuations in CO2 over the last 10 years.
Author: Graph prepared by case author, Timothy Lutz.
Source: Measurements are from Mauna Loa as reported by Pieter Tans of NOAA.
Link: http://www.esrl.noaa.gov/gmd/ccgg/trends/
Clearance: Graph used with permission.
Slide 29
Description: Carbon sources and sinks
Source: NOAA Earth System Research Laboratory
Link: http://www.esrl.noaa.gov/research/themes/carbon/
Slide 30
Description: Carbon sources and sinks
Source: Modified from a figure at NOAA/PMEL Ocean Acidification Home Page, http://www.pmel.noaa.gov/co2/OA/background.html
Clearance: A figure of DOC / NOAA / OAR / PMEL
Slide 33
Description: Graphs from IPCC report.
Source: Bottom panels of Figure SPM.4, p. 11. IPCC, 2007: Summary for Policymakers. In: Climate Change 2007: The Physical Science
Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon,
S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge,
United Kingdom and New York, NY, USA.
Link: http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-spm.pdf