The topic of climate change is like a puzzle with many different pieces—oceans, the atmosphere, ecosystems, polar ice, natural and human influences. Scientists have been working on this puzzle for more than a century, and while there are still gaps in our knowledge, most experts feel we have the puzzle is complete enough to show that human activities are having an adverse effect on our planet. This talks looks at many of those puzzle pieces, the evidence behind them, and the conclusions we can draw from them.
Scientists have a good understanding of what has changed earth’s climate in the past: Incoming solar radiation is the main climate driver. Its energy output increased about 0.1% from 1750 to 1950, increasing temperatures by 0.2°F (0.1°C) in the first part of the 20 th century. But since 1979, when we began taking measurements from space, the data show no long-term change in total solar energy, even though Earth has been warming. Repetitive cycles in Earth’s orbit that occur over tens of thousands of years can influence the angle and timing of sunlight. In the distant past, drifting continents make a big difference in climate over millions of years by changing ice caps at the poles and by altering ocean currents, which transport heat and cold throughout the ocean depths. Huge volcanic eruptions can cool Earth by injecting ash and tiny particles into the stratosphere. Changes in the concentration of greenhouse gases, which occur both naturally and as a result of human activities, also influence Earth’s climate.
[Image 1] Earth’s surface absorbs heat from the sun and then re-radiates it back into the atmosphere and to space. [click, Image 2] Much of this heat is absorbed by greenhouse gases, which then send the heat back to the surface, to other greenhouse gas molecules, or out to space. Though only 1% of atmospheric gases are greenhouse gases, they are extremely powerful heat trappers. By burning fossil fuels faster and faster, humans are effectively piling on more blankets, heating the planet so much and so quickly that it’s hard for Mother Nature and human societies to adapt.
Global average temperatures are expected to increase by about 2-13°F (1-7°C) by the end of the century. That may not sound like a lot, so what’s the big deal? The problem is that small changes in global average temperature can lead to really large changes in the environment. Let’s look at some of the expected changes.
The oceans will continue their rise in the coming century. The IPCC’s best estimates range from a few inches to a few feet by 2100. If the rise is 2 feet, the US could lose 10,000 square miles, If they rise three, they will inundate Miami and most of coastal Florida. Sea-level rise also increases coastal erosion and the loss of coastal wetlands, and saltwater spoils freshwater drinking supplies. Coastal populations become even more vulnerable to storm surge and flooding. Considering that half of the world’s population lives near coasts, sea-level rise is a serious concern. The big unknown in all this is how much the planet’s ice sheets will melt.
Based on the evidence accumulated over the last 40 years, these are some of their main conclusions. The words in red were very carefully chosen to reflect quantifiable estimates. So Very High Confidence and means the statement has at least a 9 out of 10 chance of being correct, Very Likely means the scientists are more than 90% sure, and Likely means they are more than 66% sure.
Here are examples of 8 technologies that could save 8 billion tons, or 8 wedges, of carbon. Some of these we could do right away, while others are based on technologies still being studied, such as capturing and storing carbon. [Details on strategies: Efficient vehicles: Double car fuel efficiency in 2055 from 30 miles per gallon (mpg) to 60 mpg Reduced vehicle use: Halve the miles traveled by the world’s cars in 2055 Efficient buildings: Cut emissions by 25% in all buildings CCS electricity: Capture and store carbon from 800 large coal power plants or 1600 large natural gas power plants Triple the world’s current nuclear capacity Solar electricity: Increase solar capacity 700 times Forest storage: Halve global deforestation and double forest planting in 50 years Soil storage: Apply carbon management strategies to all of the world’s farm fields] This list represents only some of the possible strategies, but choosing strategies will not be easy. However, the longer we wait to reduce emissions, the higher the target will need to be, and the more adaptation will be necessary. In 2004, when the wedges concept was first introduced, the target was only 7 billion tons.
Scientists are still working on the puzzle. The IPCC’s 5 th Assessment Report is planned for 2013-2014. Climate models are being improved, more data is being collected. However, the puzzle is already complete enough to know we need to take action.
review again the sequence of events leading the the formation of the ozone hole
[Image 1] A survey conducted in 2007 by George Mason University of U.S. scientists who have expertise in climate science (not just a scientific background) what they think. 97% of the 489 respondents agreed that “global average temperatures have increased” during the past century. That’s up from 60% in 1991. [click, Image 2] 84% believe human activities are causing the warming, and only 5% disagree. So the survey does indicate the bulk of climate scientists—those most knowledgeable about the field—now agree that human activity contributes to global warming.
Climate Change, Global
Warming & Ozone Layer
St. Vincent Pallotti College
of Engineering and
What is Climate?
• Climate is the pattern of variation in
temperature, humidity, atmospheric
pressure, wind, precipitation,
atmospheric particle count and other
meteorological variables in a given
region over long periods.
• Climate can be contrasted to weather,
which is the present condition of these
variables over shorter periods.
What is Climate Change?
• Climate is the average weather at a given point and time
of year, over a long period (typically 30 years).
• Climate change is the greatest threat facing our planet
• A warming planet alters weather patterns, water
supplies, seasonal growth for plants and a sustainable
way of life for us and the world’s wildlife.
• Climate change has already started, but it’s not too late
to take action. There’s still time for us all to be part of the
What Changes Climate?
• A continuous flow of energy from the sun heats
the Earth. Naturally occurring gases in the
atmosphere, known as greenhouse gases – this
includes carbon dioxide (CO2) - , trap this heat
like a blanket, keeping the Earth at an average of
15 degrees Celsius – warm enough to sustain life.
• The overuse of fossil fuels is increasing CO2 in
the atmosphere, trapping more and more heat
and warming the Earth.
Sea-level rise projections : a few inches to a few feet
•2 ft: U.S. would lose 10,000 square miles
•3 ft: Would inundate Miami
•Affects erosion, loss of wetlands, freshwater supplies
•Half of the world’s population lives along coasts
•Big question: Ice sheets
• Warming of the climate system is unequivocal
• Very high confidence that global average net
effect of human activities since 1750 one of
• Human-caused warming over last 30 years has
likely had a visible influence on many physical
and biological systems
• Continued GHG emissions at or above current
rates would cause further warming and induce
many changes in the global climate system during
century that would very likely be larger
than those observed during the 20th
• Produce more fuel-efficient vehicles
• Reduce vehicle use
• Improve energy-efficiency in buildings
• Develop carbon capture and storage
• Triple nuclear power
• Increase solar power
• Decrease deforestation/plant forests
• Improve soil carbon management
What WE can do?
Ozone DepletionOzone Depletion
Significant concentrations of ozone (OSignificant concentrations of ozone (O33) exist in the) exist in the
lower elevations of the stratosphere.lower elevations of the stratosphere.
Ozone in the stratosphereOzone in the stratosphere
absorbs UV B radiation fromabsorbs UV B radiation from
UV B radiation damagesUV B radiation damages
DNA molecules and canDNA molecules and can
cause genetic defects oncause genetic defects on
the outer surfaces ofthe outer surfaces of
plants and animals,plants and animals,
including human skin (skinincluding human skin (skin
• Ozone depletion is the seasonal loss of
a large swath of our stratospheric ozone
above Antartica, as well as the general
degradation of this protective layer
around the globe.
• With less ozone in the atmosphere,
more ultraviolet radiation strikes Earth,
causing more skin cancer, eye damage,
and possible harm to crops.
Ozone Layer Depletion
Ozone Layer: Function
• What does the ozone layer
do for us?
• Ozone is the only major
atmospheric constituent that
between 210 and 290 nm.
• Without it life would have
• The ozone layer is a
consequence of oxygen-only
chemistry. It formed once
began “polluting” the
atmosphere with oxygen.
Ozone Depletion ResultsOzone Depletion Results
Each 1% loss of ozone leads to a 2% increaseEach 1% loss of ozone leads to a 2% increase
in UV radiation striking the earth.in UV radiation striking the earth.
A 2% increase in UV radiation results in a 5% toA 2% increase in UV radiation results in a 5% to
7% increase in skin cancer, including a 1%7% increase in skin cancer, including a 1%
increase in deadly malignant melanomaincrease in deadly malignant melanoma
A 5% Ozone Depletion would cause:A 5% Ozone Depletion would cause:
• An additional 940,000 cases annually of basal-cell andAn additional 940,000 cases annually of basal-cell and
squamous-cell skin cancer (disfiguring, but not usually deadly)squamous-cell skin cancer (disfiguring, but not usually deadly)
• An additional 30,000 cases annually of melanoma skin cancerAn additional 30,000 cases annually of melanoma skin cancer
(often fatal). There are 9,000 American deaths per year from(often fatal). There are 9,000 American deaths per year from
this now.this now.
• A sharp increase in eye cataracts and severe sunburn inA sharp increase in eye cataracts and severe sunburn in
people, cataracts in cattle.people, cataracts in cattle.
• Suppression of the human immune systemSuppression of the human immune system
• An increase in smog. The EPA estimates a 1% decrease inAn increase in smog. The EPA estimates a 1% decrease in
stratospheric ozone causes a 2% increase in ozone near thestratospheric ozone causes a 2% increase in ozone near the
• Reduced yields from crops like corn, rice, beans, and wheatReduced yields from crops like corn, rice, beans, and wheat
• Reduction in ocean phytoplankton growthReduction in ocean phytoplankton growth
• Loss of $2 billion per year from materials degradationLoss of $2 billion per year from materials degradation
• Increased global warmingIncreased global warming
Causes of DepletionCauses of Depletion
• Chlorine and Bromine in the StratosphereChlorine and Bromine in the Stratosphere
• CFC-11 (chlorofluoromethane) andCFC-11 (chlorofluoromethane) and
CFC-12 (dichlorofluoromethane) areCFC-12 (dichlorofluoromethane) are
the most widely used as coolants forthe most widely used as coolants for
refrigerators and air conditionersrefrigerators and air conditioners
• CFC-11 (chlorofluoromethane) and CFC-12CFC-11 (chlorofluoromethane) and CFC-12
(dichlorofluoromethane) are the most widely used(dichlorofluoromethane) are the most widely used
as coolants for refrigerators and air conditionersas coolants for refrigerators and air conditioners
SourcesSources Chlorofluorocarbons (CFC’s)Chlorofluorocarbons (CFC’s)
• Commonly called Freons (a Du Pont ChemicalCommonly called Freons (a Du Pont Chemical
• Also used as propellant in aerosol cans, industrial cleaner,Also used as propellant in aerosol cans, industrial cleaner,
hospital sterilant, fumigant, and to create bubbles inhospital sterilant, fumigant, and to create bubbles in
polystyrene plastic foam used for insulation and packaging.polystyrene plastic foam used for insulation and packaging.
• Bromine containing compounds used in fireBromine containing compounds used in fire
Carbon TetrachlorideCarbon Tetrachloride
• An industrial solventAn industrial solvent
United States accounts for largest part of world-wideUnited States accounts for largest part of world-wide
consumption o CFC’sconsumption o CFC’s
29% of global consumption is from US29% of global consumption is from US
Americans use six times more CFC’s than globalAmericans use six times more CFC’s than global
Vehicle air conditioners accounted for about 75%Vehicle air conditioners accounted for about 75%
of annual CFC emissions in the US in 1990of annual CFC emissions in the US in 1990
Since 1978 the use of CFC’s in aerosol cans hasSince 1978 the use of CFC’s in aerosol cans has
been banned in many countries; however,been banned in many countries; however,
worldwide, aerosol cans still account of 25% ofworldwide, aerosol cans still account of 25% of
CFC emissionsCFC emissions
What do these compounds do?What do these compounds do?
Spray cans, discarded and/or leaking refrigeration and airSpray cans, discarded and/or leaking refrigeration and air
conditioning units, the production and burning of plastic foamconditioning units, the production and burning of plastic foam
products, and the use of solvents result in the release of theseproducts, and the use of solvents result in the release of these
compounds into the environment.compounds into the environment.
Most of these compounds are non-reactive and have lives of 22 toMost of these compounds are non-reactive and have lives of 22 to
111 years in the atmosphere111 years in the atmosphere..
They circulate in the atmosphere until they reach the stratosphere.They circulate in the atmosphere until they reach the stratosphere.
In the stratosphere they are broken down by UV radiation toIn the stratosphere they are broken down by UV radiation to
release chlorine and bromine atomsrelease chlorine and bromine atoms
Chemical reactions between chlorine or bromine and ozone causeChemical reactions between chlorine or bromine and ozone cause
ozone to degrade to Oozone to degrade to O22 and O.and O.
Over time a single chlorine atom can cause the breakdown of asOver time a single chlorine atom can cause the breakdown of as
many as 100,000 molecules of ozone.many as 100,000 molecules of ozone.
The Ozone HoleThe Ozone Hole
In the 1980’s researchers discovered that up to 50% of theIn the 1980’s researchers discovered that up to 50% of the
ozone in the stratosphere over Antartica is destroyed betweenozone in the stratosphere over Antartica is destroyed between
September and October (Arctic Spring). An area larger thanSeptember and October (Arctic Spring). An area larger than
the USthe US
Vortexing winds with ice crystals that have absorbed CFC’s on theVortexing winds with ice crystals that have absorbed CFC’s on the
surface that lift CFC’s into the stratosphere and destroy the ozone atsurface that lift CFC’s into the stratosphere and destroy the ozone at
a fast rate.a fast rate.
The vortex breaks up in a couple of months and large masses of ozoneThe vortex breaks up in a couple of months and large masses of ozone
depleted air flow northward over parts of Australia, New Zealand anddepleted air flow northward over parts of Australia, New Zealand and
southern South America. During this time UV levels increase by as muchsouthern South America. During this time UV levels increase by as much
as 20% there.as 20% there.
A similar phenomenon has recently been observed in the ArcticA similar phenomenon has recently been observed in the Arctic
Satellite photo of south pole. Purple shade shows the extent of the ozoneSatellite photo of south pole. Purple shade shows the extent of the ozone
Protecting the Ozone LayerProtecting the Ozone Layer
Ban the use of CFC’sBan the use of CFC’s
Have to replace with somethingHave to replace with something
Current replacements are greenhouse gasesCurrent replacements are greenhouse gases
and do not eliminate ozone depletion, justand do not eliminate ozone depletion, just
slow it downslow it down
Air Quality StandardsAir Quality Standards
Emission StandardsEmission Standards
Limit amounts of pollutants that can beLimit amounts of pollutants that can be
emitted by pollution sourcesemitted by pollution sources
Generally set by State Air Quality OfficesGenerally set by State Air Quality Offices
Ambient Air QualityAmbient Air Quality
StandardsStandards• The Clean Air Act, which was last amended in 1990, requiresThe Clean Air Act, which was last amended in 1990, requires
EPA to set National Ambient Air Quality Standards for pollutantsEPA to set National Ambient Air Quality Standards for pollutants
considered harmful to public health and the environment. Theconsidered harmful to public health and the environment. The
Clean Air Act established two types of national air qualityClean Air Act established two types of national air quality
standards. Primary standards set limits to protect public health,standards. Primary standards set limits to protect public health,
including the health of "sensitive" populations such as asthmatics,including the health of "sensitive" populations such as asthmatics,
children, and the elderly. Secondary standards set limits tochildren, and the elderly. Secondary standards set limits to
protect public welfare, including protection against decreasedprotect public welfare, including protection against decreased
visibility, damage to animals, crops, vegetation, and buildings.visibility, damage to animals, crops, vegetation, and buildings.
• The EPA Office of Air Quality Planning and Standards (OAQPS)The EPA Office of Air Quality Planning and Standards (OAQPS)
has set National Ambient Air Quality Standards for six principalhas set National Ambient Air Quality Standards for six principal
pollutants, which are called "criteria" pollutants. They are listedpollutants, which are called "criteria" pollutants. They are listed
below. Units of measure for the standards are parts per millionbelow. Units of measure for the standards are parts per million
(ppm) by volume, milligrams per cubic meter of air (mg/m3), and(ppm) by volume, milligrams per cubic meter of air (mg/m3), and
micrograms per cubic meter of air (µg/m3).micrograms per cubic meter of air (µg/m3).
• Global surface temperatures have risen by about 0.6°C
• It is likely that this warming is larger than for any century
since 200AD, and that the 1990s were the warmest
decade in the last millennium.
• The warming differs in different parts of the world, but over
the last 25 years, almost everywhere has warmed, and
very few places have cooled.
• Other changes have occurred, e.g.:
– Sea level has risen by about 20 cm,
– Ocean heat content has increased,
– Almost all mountain glaciers have retreated
• Coincident with this global warming, levels of CO2 (and
other ‘greenhouse’ gases) have dramatically increased, to
levels higher than those experienced for maybe millions of
• Global warming is a Global
• It refers to a gradual increase in the
temperature of the Earth due to
trapping of green house gases.
Green House gases
• Gases such as CO2, SO2, NO2,CH4, etc.
Are the green house gases.
• Most of these are the polluting gases
that are produced by the industries.
• These gases trap the heat from the
sunrays that are reflected from the sun.
Why Global Warming
It is the effect of the process of trapping of
Heat due to CO2 which has been going
on since times unknown.
• But due to rapid rise in population over the
last few decades, the CO2 emission has
increased whereas due to deforestation,
the rate of CO2 absorption has gone down
thus disturbing the balance of Nature.
Why Global Warming Occurs?
• Also due to Globalization, various
industries started to grow.
• This also led to the problems of
various types of pollutions including
• Most of the gases that pollute the
environment are Green house gases.
• This leads to Global warming.
Effects of Global Warming
• It has been reported that the temperature of
Earth is increasing each day by few degrees.
• As a result of this, the snow in various
regions of Earth is rapidly melting.
• This may add more water to fresh water
reserves like lakes and rivers in the
beginning but when the “meltdown” is
completed, there would be no fresh water
• Also it destroys the ecosystem in the Polar
Prevention Of Global Warming
• The various ways to control Global
1.Control of population. But, since it is not
possible to control population, the best
way to control Global warming is by
2.Use of ecofriendly and biodegradable
3.Avoid using vehicles when not necessary.