Greenhouse Effect and Global Warming
Greenhouse Effect
• Key FactorsEarth-Sun Temperature
DifferencesGreenhouse Gas Concentrations
• The atmosphere is transparent to incoming solar radiation (short wave, high energy), outgoing terrestrial radiation (longer waves, lower energy) is absorbed by GHGs. (also relates to Black body radiation)
→WIEN’S LAW !!!
Energy Balance
Greenhouse Gases
• Carbon dioxide – CO2
• Methane – CH4
• Nitrous oxide – N2O• Freons – CFCs (totally
anthropogenic)What makes it a GHG???
• Water vapor – H2O
GHG Concentration Changes Years 1000-2000
Global Warming• An increase in global temperatures
due to increases in the concentrations of greenhouse gases
• Increased CO2 concentrations exerts largest radiative forcing (i.e., explains bulk of temperature increase)
• NOT CAUSED BY STRATOSPHERIC OZONE DEPLETION
GHG Sources
• Combustion of fossil fuels • Deforestation (loss of sink)
– Slash and burn techniques release CO2
– Fewer trees, less photosynthesis• Fertilizers• CFCs• Methane
Data Source: C.D. Keeling and T.P. Whorf, Atmospheric CO2 Concentrations (ppmv) derived from in situ air samples collected at Mauna Loa Observatory, Hawaii, Scripps Institute of Oceanography, August 1998. A. Neftel et al, Historical CO2 Record from the Siple Station Ice Core, Physics Institute, University of Bern, Switzerland, September 1994. See http://cdiac.esd.ornl.gov/trends/co2/contents.htm
Atmospheric carbon dioxide (CO2) concentrations (1750 to present)
270
280
290
300
310
320
330
340
350
360
370
1750 1800 1850 1900 1950 2000
part
s pe
r m
illio
n vo
lum
e
Mauna Loa (1958-present)
Siple Station (1750-)
Data Source: Marland et al, 1999. Carbon Dioxide Information Analysis Center.
Cumulative carbon emissions, 1950-1996
7,415
8,504
11,651
15,715
4,235
4,054
2,331
1,361
966
50,795
1,557
2,080
2,118
0 10,000 20,000 30,000 40,000 50,000 60,000
United States
Indonesia
Korea, Rep.
Brazil
Australia
Mexico
South Africa
Canada
India
United Kingdom
Japan
Germany
China
Million tons of carbon
Variations in the Earth’s surface temperature
Impacts
• Rise in sea level– Thermal expansion of the oceans– Melting ice caps and glaciers
• Climatic shifts• Shifts in agriculture• Increase in disease• Declines in biodiversity• Coral bleaching
Reducing GH Emissions
Solutions
Global Agreements
• IPCC – Intergovernmental Panel on Climate Change 1988 UNEP
• Rio de Janeiro 1992• Kyoto Protocol 1997
– Ratified Nov. 2006– U.S. and Australia have not signed the treaty
U.S. Position
Bush Sr. (1988 – 1992)
Clinton (1992 – 2000)
Bush Jr. (2000 – 2008)
Obama (2008 - )