Transcript Air pollution, climate change, and ozone depletion

AIR POLLUTION, CLIMATE
CHANGE, AND OZONE
DEPLETION
WHAT IS THE NATURE OF THE ATMOSPHERE
• We live at the bottom of a thin layer of gases surrounding the
earth called the atmosphere, which is divided into smaller
spherical layers
• In the troposphere, the layer closest to earth, about 75-80% of
the earths air mass is found here.
• About 99% of the air you inhale everyday consists of two gases:
nitrogen (78%) and oxygen (21%)
• The second layer of the atmosphere is the stratosphere
• The composition is the similar to that of the troposphere, but its
concentration of ozone (O3) is much higher
• Much of the atmosphere’s small amount of ozone is found in a
concentrated portion of the stratosphere called the ozone layer
• Thanks to the ozone layer, about 95% of the suns harmful UV
radiation is kept from reaching the earths surface
WHAT ARE THE MAJOR AIR POLLUTION PROBLEMS?
• Air pollution is the presence of chemicals in the atmosphere in
concentrations high enough to harm organisms, ecosystems, or
human made materials, or to alter climate.
• Air pollutants can come from natural and human sources.
• Natural sources include pollutants from wildfires and volcanic
eruptions, dust blown by wind, and volatile organic chemicals
released by some plants.
• Most natural air pollutants and spread out, throughout the earth, or
are removed by precipitation or gravity.
HUMAN SOURCES OF AIR POLLUTANTS
•
Occur in industrialized and urban
areas
•
Majority of these pollutants are
caused by the burning of fossil fuels
in power generation, industrialized
plants, and automobiles
•
Primary pollutants - harmful
chemicals emitted directly into the air
from natural processes and human
activities
•
Secondary pollutants - formed when
primary pollutants react with one
another and with other normal
components of air in the atmosphere
to form new harmful chemicals.
MAJOR OUTDOOR AIR POLLUTANTS
Carbon monoxide
• Colorless, odorless, and highly toxic gas that forms during an
incomplete combustion of carbon-containing materials.
• Major sources - exhaust from vehicles, burning of forests,
tobacco smoke, and open fires.
• Carbon monoxide reacts with hemoglobin in red blood cells,
which reduces the bloods ability to transport oxygen to body cells
and tissue
• At high levels, it can cause headache, nausea, drowsiness,
mental impairment, collapse, coma and even death.
Carbon dioxide
• Colorless, odorless gas
• 93% of the CO2 in the atmosphere is from the natural carbon
cycle. The other 7% comes from human activities, mainly the
burning of fossil fuels and clearing forests
• Suspended particulate matter (SPM) consists of a variety of solid
particles and liquid droplets small and light enough to remain
suspended in the air for long periods of time
• 62% of SPM comes from natural sources such as dust and
wildfires while the other 38% comes from human activities
• These particles can irritate the nose and throat, damage the
lungs, aggravate asthma and bronchitis, shorten life and cause
cancer
SMOG
• Industrial smog consists mostly of an unhealthy mix of sulfur dioxide,
suspended droplets of sulfuric acid, and a variety of other SPM’s.
• Today in the US, industrial smog is no longer a big problem, but in urban
areas of China, India and Eastern European Countries, still burn coal in
houses, power plants and factories with bad pollution controls
• This problem can be fixed by setting standards for coal burning
industries. China and India are only just beginning to take such steps
• Photochemical smog is a mixture of primary and secondary pollutants
formed under the influence of UV radiation from the sun.
• All modern cities have photochemical smog, but it is much more common
in cities with sunny, warm, and dry climates and a massive number of
automobiles
PRESENT DAY CHINA
DECREASING OUTDOOR AIR POLLUTION
Five natural factors help reduce outdoor air pollution
1. Particles heavier than air settle out as a result of
gravitational attraction
2. Rain and snow help remove pollutants from the air
3. Salty sea spray from the oceans washes out many
pollutants from the air that flows from land over the oceans
4. Winds sweep pollutants away and mix them with cleaner air
5. Some pollutants are removed by chemical reactions
INCREASING OUTDOOR AIR POLLUTION
Six other factors can increase outdoor air pollution
1. Urban buildings slow wind speed and reduce dilution and removal of
pollutants
2. Hills and mountains reduce the flow of air in valleys below them and allow
pollutant levels to build up at ground level
3. High temperatures promote the chemical reactions leading to the
formation of photochemical smog
4. Emissions of volatile organic compounds from certain trees and plants in
heavily wooded urban areas can play a large role in the formation of PS
5. Grasshopper effect occurs when air pollutants are transported by
evaporation and winds from tropical areas where they are deposited
6. Temperature inversions can cause pollutants to build to high levels
ACID DEPOSITION
• Acidic substances from coal-burning power plants produce air
pollutants such as Sulfur dioxide and Nitrogen oxides mix and form a
mixture called Acid Deposition or Acid Rain
• This is a major problem for places that lie downwind of these power
plants that burn coal
• Many acid-producing chemicals generated in one country are
exported to other countries by prevailing winds
• Acid Deposition is harmful to human respiratory diseases, harms
aquatic ecosystems and can also affect forests by leaching essential
plant nutrients and by releasing ions of aluminum, lead, cadmium,
and mercury
INDOOR AIR POLLUTION
• In developing countries, the indoor burning of wood, charcoal,
dung, crop residues, coal, and other cooking and heating fuels
exposes people to dangerous levels of particulate air pollution
• Indoor air pollution is also a problem in developed countries due
to chemicals used in building materials and products
• EPA studies have revealed some alarming facts about indoor air pollution
1. Levels of 11 common pollutants generally are 2-5 times higher inside US
homes than outside
2. Pollution levels inside cars in traffic-clogged urban areas can be up to 18
times higher than outside levels
3. The health risks from exposure to such chemicals are magnified because
most people in developed urban areas spend 70-98% of their time indoors
• Indoor air pollutants cause about 1.6 million deaths per year, or 1 every 20
seconds
• The four most dangerous indoor pollutants are, tobacco smoke,
formaldehyde, radioactive radon -222 gas, and very small (ultrafine) particles
YOUR BODY’S DEFENSE AGAINST AIR POLLUTION
• Your respiratory system has a number of ways to help protect you
from air pollution.
• Hair in your nose filter out large particles. Hundreds of thousands
of tiny mucus-coated, hair like structures called cilia, line you
upper respiratory tract.
• The cilia transport mucus and the pollutants they trap to your
throat where they are either swallowed or expelled
• Fine and ultrafine particles get lodged deep in the lungs,
resulting in lung cancer, asthma attacks, heart attacks, and
stroke.
AIR POLLUTION IS A BIG KILLER
• At least 2.4 million people worldwide die prematurely each year
from the effects of air pollution.
• Most of these deaths occur in Asia, with China having 656,000
deaths per year
• In the US, deaths range from 150,000 to 350,000 people, which
is like 2-5 fully loaded, 200-passenger airliners crashing each
day with no survivors
• The EPA says that each year, more than 125,000 Americans get
cancer from breathing soot-laden diesel fumes emitted by buses
and trucks.
HOW SHOULD WE DEAL WITH AIR POLLUTION? LAWS/REGULATIONS
Clean Air Acts (1970, 1977, 1990) Federal governments established air pollution
regulations for key pollutants to be enforced by states and major cities.
EPA was directed to establish air quality standards for six major pollutants:
• Carbon monoxide (CO)
• Nitrogen Dioxide (NO2)
• Sulfur Dioxide (SO2)
• Suspended particulate matter (SPM)
• Ozone (O3)
• Lead
According to the 2009 EPA report, the combined emissions of these pollutants decreased
significantly between 1980 and 2008, despite an increase in gross domestic product,
population, transportation lengths and energy consumption.
HOW CAN WE IMPROVE?
• US relies heavily on cleanup rather than prevention in regards to air pollution
• Improve fuel efficiency for vehicles
• Machine such as lawn mowers and motorcycles are inadequate. The
emissions from a gas powered lawn mower for an hour = 34 cars for an hour.
• “ultra fine particles”, the main contributors to premature deaths as a result of
air pollution are not adequately regulated
• Airports are exempt from many air pollution laws
HOW CAN WE IMPROVE?
• Urban ozone levels are still far too high in many areas
• Laws have not yet begun seriously dealing with indoor air pollution and
quality
• There is a general need for enforcement of our Clean Air Acts.
• Many companies that are being urge to develop environmental policies are
claiming that implementing new regulations would cost too much money
and hinder economic growth. Supporters say that, historically, the estimates
of costs are much higher than their actual numbers, and that new
regulations would stimulate the economy by providing new jobs.
USING THE MARKETPLACE
• Allow air pollutant producers to buy and sell government air
pollution allotments in the marketplace.
• (Act of 1990): emissions trading (cap-and-trade program)
enables 110 of the most pollutant coal-burning power plants
in 21 states to buy and sell Sulfur Dioxide pollution rights.
Businesses are given pollution credit, which allows them to
emit a certain amount of pollutants. A utility that falls below
their given credits then has a surplus that can either be
sold/traded or kept as a buffer for future pollution.
USING THE MARKETPLACE, CONT’D
• The problem with this idea is that it’s based on selfreporting and there is a constant risk of a company
lying about it’s emissions.
• This method also allows for certain power plants to
buy themselves out of irresponsible pollution.
• But, the strategy is deemed cheaper in the long run
and between 1990 and 2006 was found to reduce
pollutant emissions from electric power plants by
53%.
REDUCING OUTDOOR POLLUTION
About 20,00 old coal-burning plants, industrial plants and oil refineries in the United
States have not been required to meet the air pollution standards for new facilities
under the Clean Air Acts.
Ways that industries are able to reduce environmental harm from pollutants are split
between “prevention” and “dispersion/cleanup. The former prevents the pollution
emission (obviously), while the latter attempts to reduce the harm of pollutants
already sent into the atmosphere.
Prevention:
 Burn Low-sulfur coal
 Remove sulfur from coal before burning
 Convert coal to a liquid or gaseous fuel
 Just shift to a generally less harmful process of extracting energy (less pollutants)
MOTOR VEHICLE AIR POLLUTION
Prevention:
Cleanup:
•
Use mass transit, ex: busses,
trains, etc
•
Walk or bike
•
Use less polluting fuels
•Inspect car exhaust systems
twice a year
•
Get older cars off the road
(more pollution)
•Set strict emissions
standards
•
Give large tax write-offs or
rebates for buying lowpolluting, energy efficient
vehicles
•Require emission control
devices
REDUCING INDOOR POLLUTION
•
Little has been done to reduce indoor pollution, which is bad seeing as indoor
pollution poses a much greater threat to our health than does outdoor pollution.
•
Indoor pollutions comes as a result from leaky systems, inside burning fires and
general mismanagement of materials within enclosed spaces.
•
Prevention: clean ceiling tiles and line AC ducts to prevent release of fibers, ban
smoking or limit it to well-ventilated areas, set stricter formaldehyde emissions
standards for carpets, furniture and building materials, prevent radon infiltration, use
office machines in well-ventilated areas and use less harmful substitutes for cleaning
materials.
•
Cleanup/dilution: Use adjustable fresh air vents for work spaces, increase intake of
outside air, change air more frequently, circulate a building’s air through rooftop
greenhouses, use efficient venting systems for wood-burning stoves and use exhaust
hoods for stoves and appliances burning natural gas.
GENERAL SOLUTIONS
Outdoor:
•
Improve energy efficiency to reduce fossil fuel use
•
Rely on low polluting gas
•
Rely more on renewable energy
•
Transfer energy efficiency, renewable energy and pollution prevention technology
must be given to less developed countries.
Indoor:
•
Reduce poverty
•
Distribute cheap and efficient cookstoves or solar cookers to poor families in
developing countries
•
Develop simple and cheap tests for indoor pollutants such as particulates, radon and
formaldehyde
HOW MIGHT THE EARTHS CLIMATE CHANGE IN
THE FUTURE
Climate change is not new; the climate has been changing over the past 3.5 billion years
due to volcanic emissions and changes in solar input as well as continents slowly
moving atop shifting tectonic plates, along with changes made by the impact of
meteors.
Over the past 900,000 years, the planet has been experiencing prolonged periods of
global cooling as well as global warming. These periods of freezing and thawing are
known as glacial and interglacial periods.
We are lucky enough to be living within an interglacial period characterized by temperate
weather that remained stable enough for the human population to thrive via
advancements in agriculture that was made possible by the kind weather. But since
about 1975, temperatures have begun to rise as they historically have during
glacial/interglacial periods.
HUMAN CONTRIBUTION
•
Life on earth depends on the natural greenhouse effect thanks to the presence of four natural
greenhouse gases: water vapor (H20), carbon dioxide (C02), methane (CH4), and nitrous oxide
(N20), all of which help to warm the atmosphere and keep it hospitable.
•
Evidence of human impact on greenhouse gas emission/global warming:
•
Between 1906 and 2005, the average global surface temp has risen by about .74 ºC. Most of
this has taken place since 1980.
•
Annual greenhouse gas emissions from human activities rose 70% between 1970 and 2008,
which all correlate closely with the rising temperatures
•
In certain part of the world, glaciers are shattering and sea ice is drifting apart, as evidence of
slowly warming waters and general temperatures.
•
During the last century, the sea level rose about 10-20 centimeters primarily due to run off from
melting land based ice and the expansion of ocean water as its temperature increased.
•
The 10 warmest years have been occurred since 1997.
http://www.youtube.com/watch?v=hC3VTgIPoGU
C02
•
CO2 emissions are being produced at the exponential rate of 3.3% per years, with levels in the
atmosphere likely to rise about 560 ppm by 2050 and get up to 1390 ppm by 2100. Carbon
dioxide would be introduced to the environment faster than it would be taken out, resulting in
extreme changes in the global temperature and climate.
•
The problems cause by this would change our sights on “climate change” to “climate disruption”.
•
We must keep carbon emission levels from reaching 450 ppm (an irreversible tipping point, at
which our planet will begin to free fall into a mess of climate-induced destruction over the course
of thousands of years)
•
In 2008, the largest C02 emitters were China, the United States, the European Union (27
countries) Indonesia, Russia, Japan and India. The US is responsible for 25% of world cumulative
C02 emissions.
•
US: emits 5x more per person than China and 200x more than people in the “poorest countries”.
OCEANS
•
Help to moderate the earths average temperature of the atmosphere and thus it’s
climate by removing 25-30% of the C02 pumped into the lower atmosphere by what
we humans do.
•
The solubility of C02 in ocean water decreases with increasing temperature, thus the
increasing temperature of the globe will result in an inability to efficiently absorb C0 2
into the oceans, which just becomes one big giant ugly cycle.
•
The higher levels of C02 in the ocean have increased the acidity of the ocean surface
by 30% from preindustrial times and the ocean acidity could reach dangerous levels
before 2050.
•
The water is becoming acidic because the C02 is reacting with the water to produce
carbonic acid (H2C03). The increasing acid level is further weakening the oceans
ability to absorb C02 and safely store it in bottom sediments.
EFFECTS OF PROJECTED CLIMATE CHANGE
Increased chance of drought and flooding
Rising sea levels
Spreading Deserts
Larger Forest Fires
Decrease in crop yields
Fragmentation of ecosystems
RISING SEA LEVEL
• Dependent on the expansion of seawater as it warms and the
melting of land-based ice.
• Predicted rise of at least 1m by 2100
• Would erode coast lines, flood barrier islands, threaten coastal
ecosystems and cause trillions of dollars of damage to costal
cities.
EXTREME WEATHER
Projected climate change will increase the incidence of heat waves and severe
drought in some regions, while the warmer atmosphere holding more water will
cause flooding in other regions.
Debate over if the the size and strength of tropical storms will be increased or not.
AGRICULTURE
• Crop productivity could increase slightly in middle to high latitudes at 2 o
warming but worsen as a whole. Worst effect is projected to be in Africa and
areas of South America.
• Northward shift in the production of some agriculture.
• Soil in these regions is not as suitable for large scale crop production.
• IPCC scientists warn that by 2050, 200-600 million of the worlds poorest and
most vulnerable people could face malnutrition and starvation due to the
effects of climate change on agricultural systems.
CAN WE STOP IT?
• A warming of 2o C and the effects that follow are inevitable according to the
IPCC
• Even if greenhouse gas emissions are completely stopped, some effects will
be felt for at least the next 1,000 years.
• Effects become much more severe with 3o and 4o C global climate warming.
WHAT WE CAN DO TO SLOW PROJECTED CLIMATE CHANGE?
2 basic approaches
• Drastically reduce greenhouse gas emissions and shift to a mix of non carbonbased energy options
• Recognize climate change is unavoidable and devise strategies to reduce its
harmful effects
• Most scientist agree we need a mix of both approaches.
Prevention
Cleanup
Cut Fossil Fuel use
Filter CO2 from smokestacks and vehicle
emissions
Shift from coal to natural gas
Store CO2 by planting trees
Improve energy efficiency
Store CO2 by practicing no-till cultivation
Shift to renewables
Store CO2 underground
Increase 3rd world energy technology
Store CO2 in the deep ocean
Reduce deforestation
Repair leaky natural gas pipelines
Sustainable agriculture and forestry
practices
Use animal feeds that reduce methane
emissions from cows
Limit urban sprawl
Reduce poverty
Slow population growth
GOVERNMENT’S ROLE
Government can regulate pollution by installing a carbon and methane tax
• Currently emissions are free and this has led to a Tragedy of the commons.
• Incentive for corporations to move towards cleaner practices
International Negotiations
• Kyoto Protocol involving 161 nations agreeing to a multiple phase plan requiring
participating nations to cut greenhouse gas emissions to 5.6% under their 1990
levels.
• US Withdrew in 2001 because the agreement did not require rapidly developing
countries like China to meet the 1st phase and it could hurt our economy
OZONE IN THE STRATOSPHERE
• Ozone layer keeps about 95% of harmful UV rays from reaching the
earths surface
• Chlorofluorocarbons (CFCs) are manufactured chemicals discovered in
the 1930’s which were used in many products including aerosol spray
cans and air conditioner because they were so cheap and versatile.
• In 1974 Sherwood Rowland and Mario Molina discovered the harmful
effects of these persistent chemicals on the ozone layer of our
atmosphere.
REVERSING OZONE DEPLETION
• Experts recommend we should immediately stop producing all ozone
depleting chemicals.
• Even with immediate and sustained action it will take 60 years for ozone
to recover to 1980’s levels and 100 years to recover to pre 1950’s levels.