Transcript Powerpoint - G-WOW

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
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
Which is the most
abundant
greenhouse gas on
Earth?
National Center for Atmospheric Research
Primary greenhouse gases:
- Water vapor (#1) (<1 year)
- Carbon dioxide (100s years)
- Methane (10 years)
- Nitrous oxide (100 years)
- Ozone (<1 year)
- Hydrofluorocarbons (1000s years)
- Chlorofluorocarbons (100s years)
National Center for Atmospheric Research
Year
2000
#2
#1
#3
Global warming art
Atmospheric Levels of Carbon Dioxide
Atmospheric Levels of Methane
Concentrations are increasing
Pre-Industrial Era ≈ 280 ppm
June 2014 ≈ 400 ppm
(keelingcurve.ucsd.edu)
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
Absorption Spectrum: Amount of Radiation Absorbed at a Given
Wavelength
ULTRAVIOLET
(Shortwave)
Not absorbed
Fleagle & Businger
VISIBLE
Not
absorbe
d
INFRARED
(Longwave)
Absorbed
Greenhouse gases primarily absorb longwave (infrared)
radiation
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 Earth’s surface
and the lower atmosphere
(IPCC AR4 WG1).
Sun = hot =
emits
shortwave
(UV)
radiation
Earth = cool = emits
longwave (IR)
radiation
Wien’s Law:
Wavelength inversely
related to
temperature
Greenhouse
Effect
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.
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%.
National Climate Assessment; Global Carbon
Project; Boden et al. 2012
U.S.
17%
European
Union
13%
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.
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 Earth’s
surface than any preceding decade since 1850. In the Northern Hemisphere, 19832012 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 0.85°C over the period of 1880-2012.” – IPCC AR5
IPCC
Claim: But this last winter was brutally cold, so global warming is not happening.
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.
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.