Ch 1, Purves

1
Weather Condition of the atmosphere at any
particular time and place Air temperature, air
pressure, humidity, clouds, precipitation,
visibility, wind Climate Accumulation of
daily and seasonal weather events over a long
period of time Average weather
Wisconsin Initiative on Climate Change Impacts
2011
2
What is the Greenhouse Effect?
Both Good and Bad
Earth 400 ppm CO2 Venus 965,000 ppm CO2 Venus
460?C, hotter than Mercury, despite 1/4 of
solar irradiance
3
Which is the most abundant greenhouse gas on
Earth?
National Center for Atmospheric Research
4

• Primary greenhouse gases
• Water vapor (1) (lt1 year)
• Carbon dioxide (100s years)
• Methane (10 years)
• Nitrous oxide (100 years)
• Ozone (lt1 year)
• Hydrofluorocarbons (1000s years)
• Chlorofluorocarbons (100s years)

National Center for Atmospheric Research
5
Year 2000
2
1
3
Global warming art
6
Atmospheric Levels of Methane
Atmospheric Levels of Carbon Dioxide
Concentrations are increasing Pre-Industrial Era
280 ppm June 2014 400 ppm (keelingcurve.ucsd.e
du)
Accelerated trend 1959-1963 0.76
ppm/year 2009-2013 2.18 ppm/year
Note the distinct seasonal cycle Breath of the
biosphere
Fifth Assessment Report of the Intergovernmental
Panel on Climate Change (IPCC AR5) NOAA Florida
Center for Environmental Studies
7
Absorption Spectrum Amount of Radiation Absorbed
at a Given Wavelength
ULTRAVIOLET (Shortwave)
INFRARED (Longwave)
VISIBLE
Not absorbed
Absorbed
Not absorbed
Greenhouse gases primarily absorb longwave
(infrared) radiation
Fleagle Businger
8
Some of the infrared radiation passes through
the atmosphere but most is absorbed and
re-emitted in all directions by greenhouse gas
molecules and clouds. The effect of this is to
warm the Earths surface and the lower
atmosphere (IPCC AR4 WG1).
Greenhouse Effect
Sun hot emits shortwave (UV) radiation
Shortwave
Longwave
Greenhouse gases
Earth cool emits longwave (IR)
radiation Wiens Law Wavelength inversely
related to temperature
9
Global carbon emissions from burning coal, oil,
and gas and producing cement during 1850-2009.
These emissions account for about 80 of the
total emissions of carbon from human activities,
with land-use changes accounting for the other
20.
Human-induced changes in the global carbon budget
since the beginning of the Industrial Revolution.
Emissions from fossil fuel burning are the
dominant cause of the steep rise from 1850 to
2012.
National Climate Assessment Global Carbon
Project Boden et al. 2012
10
European Union 13
U.S. 17
Carbon dioxide emissions
China 26
China 26 U.S. 17 European Union 13
Climate change is an ethics issue
Predicted mortality for 2000-2030 due to
malaria, malnutrition, diarrhea, flooding
related to climate change
Patz et al. 2007
11
Note the distinct interannual and decadal
variability, in addition to the long-term trend
Each decade is subsequently warmer
Each of the last three decades has been
successively warmer at the Earths surface than
any preceding decade since 1850. In the Northern
Hemisphere, 1983-2012 was likely the warmest
30-year period of the last 1400 years. IPCC
AR5 The globally averaged combined land and
ocean surface temperature data.show a warming of
0.85C over the period of 1880-2012. IPCC AR5
IPCC AR5
12
Claim But this last winter was brutally cold, so
global warming is not happening.
Histogram of surface air temperature anomalies
(C) during December 2013 April 2014 for all
global grid cells During those 5 months, 66 of
the world was warmer than normal and only 34 was
colder than normal.
Surface air temperature anomalies (C) during
December 2013 April 2014 Only cold over central
North America.most other places in the world
were warm, especially the Arctic.