Transcript Air Quality and Energy

Air Issues
Atmosphere basics
Air pollution
Climate change
Composition of atmosphere
78% nitrogen
21% oxygen
1% everything else
Structure of atmosphere
Mesosphere and thermosphere
52-120 km
Stratosphere
12-52 km
temperature increases upward
important ozone layer (19-26 km)
Troposphere
ground to 12 km
temperature decreases upward
Focus on troposphere
Our weather
Pollution that affects humans
Usual conditions vs. inversions
(change in temperature going upward)
Usual conditions
– pollution rises
Inversion
– pollution is trapped
Air pollution
Outdoor air pollution
Indoor air pollution
Criteria air pollutants
(Clean Air Act, EPA)
Carbon monoxide
NOx or nitrogen dioxide
SO2 (sulfur dioxide)
tropospheric ozone (O3)
particulate matter (PM)
lead (Pb)
Let’s look at sources of each of these.
Carbon monoxide (CO)
Incomplete combustion of
coal
gasoline (catalytic converters help here)
Why is it harmful to humans?
Nitrogen oxides (many forms)
NOx
Incomplete burning of gasoline
Contributes to acid rain
Part of ozone problem in summer in
cities
Tropospheric Ozone
Secondary pollutant
Monitor VOCs (volatile organic
compounds)
solvents and vehicle emissions
particularly important
Often a summer-time problem
Sulfur dioxide (SO2)
Burning of coal
Volcanic emissions (natural)
Effects: damages plant chlorophyll,
irritates throat and lungs; causes acid
rain
Particulate matter
Incomplete combustion of fossil fuels
Dust from fields, construction, etc.
Size of particles important
What ARE those particles?
Lead
Primary source from leaded gasoline
Metal processing industries
Effects central nervous system and
bioaccumulates
Criteria Air
pollutants
Carbon Monoxide
Sulfur Dioxide
Nitrogen Dioxide
Tropospheric
Ozone
Particulate
Matter
Lead
Primary sources to atmosphere
Secondary pollutants
Created by a reaction
Includes smog and tropospheric ozone
Smog
Photochemical smog (LA smog)
Industrial smog (London smog)
Photochemical smog (1)
Car exhaust
Hydrocarbons and NOx plus solar
radiation produces toxic chemicals,
particularly ozone
Higher ozone concentrations in late
summer afternoons
Photochemical smog (2)
Effects of ozone:
Solutions:
Ozone (O3)
Stratosphere = good; troposphere =
bad
Part of summertime smog
Charlotte area (and many other urban
areas) are in non-attainment for ozone
levels
Industrial smog
Older industrial cities
Often associated with coal burning
Particulates, sulfur dioxide and stagnant
air
Acid deposition
Sulfuric and nitric acids
Travel long distances
Some solutions: industrial scrubbers,
catalytic converters
Indoor air quality
Increasing awareness
Developing countries: particulate
matter and carbon monoxide
Industrialized nations: cigarette smoke,
radon, mold, VOCs
Solutions?
Global air issues
Stratospheric ozone depletion
Climate change
Stratospheric Ozone Depletion
What does stratospheric ozone do?
What is happening?
1970s
mid 1990s
Antarctic Researchers
Routinely monitor atmosphere above
Antarctica
Significant depletion started in 1980
Rowland and Molina
Predicted CFCs would destroy ozone
(1974)
CCl2F2 + UV
Cl + CClF2
Cl + O3
ClO + O
ClO + O2
O2 + Cl
What can we do?
Phase out manufacturing of CFCs –
done
Phase out use of CFCs – spray cans,
styrofoam products, refrigerants – done
Can this happen on a global basis?
Montreal Protocol (1987)
Major reduction in production of CFCs
and halons
Initially signed by 25 nations, eventually
ratified by over 150 nations
CFC production in industrial nations to
be cut by 50%
Halon production frozen at 1986 levels
SUCCESS
Climate Change
NATURAL TEMPERATURE VARIABILITY
INCLUDING GREEN HOUSE EFFECT
HUMAN IMPACT ON TEMPERATURES
ADAPTATION, MITIGATION, SUFFERING
Natural Temperature Variability
Seasons
Latitudes - altitudes
Milankovitch cycles
El Nino cycles
How do we know temperatures from long ago?
Human records: actual measurements
Proxies: ice cores, sediment cores for
example
Greenhouse effect
What is it?
Is it bad or good that Earth has a
greenhouse effect?
Greenhouse gases
Sources of greenhouse gases
 Carbon dioxide : burning fossil fuels and forests, making
cement
 Methane: decomposition of organic matter in swampy
environments; frozen in tundra and ocean floor;
stomachs of cows
 Nitrous oxides: bacterial decomposition of manure; soil
denitrification; some organic fertilizers
 Halocarbons (including CFCs): chemical cooling agent;
foaming agent; propellant (phased out by Montreal
Protocol)
Relative strength of GHG
(from IPCC, 2007)
Carbon Dioxide
1
Methane
25
Nitrous oxide
300
1 CFC replacement
15,000
Future of global warming?
Computer modeling
United Nations IPCC
Intergovernmental Panel on Climate Change
•Established in 1988
•2,000 scientists from many nations
•Four assessment reports (latest in 2007)
•Policy-relevant but policy neutral
•Won the Nobel Peace Prize (along with Al Gore)
IPCC Fourth Assessment Report Conclusions
Greenhouse gases
such as carbon
dioxide help trap
heat near Earth’s
surface.
IPCC Fourth Assessment Report Conclusions
“Global atmospheric concentrations of carbon
dioxide, methane, and nitrous oxide have
increased markedly as a result of human
activities since 1750 and now far exceed preindustrial values determined from ice cores
spanning many thousands of years.”
Today = 385 ppm
Preindustrial = 280 ppm
Highest in 650,000 years
Figure SPM.1
IPCC Fourth Assessment Report Conclusions
“Warming of the climate system is
unequivocal, as is now evident from
observations of increases in global
average air and ocean
temperatures, widespread melting
of snow and ice, and rising global
average sea level.”
Fi
Future?
Sea level change (3-20 ft rise)
Coral reef “bleaching”
Changes in locations of plants and animals
Melting of ice caps and glaciers
Sea Ice in Arctic Ocean
1979 and 2003
Alaskan glacier
1914 and 2004
Solutions?
Adaptation
Mitigation
Suffering is inevitable, but how much?
Evaluating Solutions
The Need for Adaptation
We are already committed to a certain amount of warming
Resources must be devoted to adapting to altered future
conditions
Sea level
Ecosystems
Focus on mitigation cannot ignore need for adaptation
Mitigation?
Limit dependence on fossils fuels
Plant trees
Kyoto Protocol and beyond