Climate Change and Ozone Loss

Key Concepts  Changes in Earth’s climate over time  Factors affecting climate  Possible effects of global warming  Adapting to climate change  Human impacts on the ozone layer  Protecting and restoring the ozone layer

Past Climate Changes  Past global temperatures  Recent trends in global temperatures

Temperature change over past 22,000 years Years ago Temperature change (°C) 20,00010,0002,0001, Now End of last ice age Agriculture established Average temperature over past 10,000 years = 15°C (59°F)

Temperature change over past 1,000 years Year Temperature change (°C)

Average temperature over past 130 years Year Average surface temperature (°C)

The Greenhouse Effect  Greenhouse effect  Greenhouse gases

Table 21-1 Major Greenhouse Gases from Human Activities Greenhouse Gas Carbon dioxide (CO2) Methane (CH4) Nitrous oxide (N2O) Chlorofluorocarbons (CFCs)* Hydrochloro- fluorocarbons (HCFCs) Hydrofluorocarbons (HFCs) Halons Carbon tetrachloride Average Time in the Troposphere 100–120 years 12–18 years 114–120 years 11–20 years (65–110 years in stratosphere) 9–390 15– Human Sources Fossil fuel burning, especially coal (70– 75%), deforestation, and plant burning Rice paddies, guts of cattle and termites, landfills, coal production, coal seams, and natural gas leaks from oil and gas production and pipelines Fossil fuel burning, fertilizers, livestock wastes, and nylon production Air conditioners, refrigerators, plastic foams Fire extinguishers Cleaning solvent Relative Warming Potential (compared to CO 2 ) –8, –2, –12,700 5,500 1,400

Carbon dioxide Temperature change End of last ice age Thousands of years before present Concentration of carbon dioxide in the atmosphere (ppm) –10.0 –7.5 –5.0 – Variation of temperature (˚C) from current level

Carbon dioxide (CO 2 ) Year Parts per million

Methane (CH 4 ) Year Parts per million

Year Parts per million Nitrous oxide (N 2 O)

Climate Change and Human Activities  Increased use of fossil fuels  Deforestation  Global warming  Melting icecaps and glaciers  Rising sea level

Table 21-2 Major Characteristics of Global Warming and Ozone Depletion Characteristic Region of atmosphere involved Major substances involved Interaction with radiation Nature of problem Possible consequences Possible responses Ozone Depletion Stratosphere. O 3, O 2, chlorofluorocarbons (CFCs). About 95% of incoming ultraviolet (UV) radiation from the sun is absorbed by O3 molecules in the stratosphere and does not reach the earth’s surface. CFCs and other ozone-depleting chemicals released into the troposphere by human activities have made their way to the stratosphere, where they decrease O3 concentration. This can allow more harmful UV radiation to reach the earth’s surface. Increased incidence of skin cancer, eye cataracts, and immune system suppression and damage to crops and phytoplankton. Eliminate or find acceptable substitutes for CFCs and other ozone-depleting chemicals. Global Warming Troposphere. CO 2, CH 4, N 2 O (greenhouse gases). Molecules of greenhouse gases absorb infrared (IR) radiation from the earth’s surface, vibrate, and release longer-wavelength IR radiation (heat) into the lower troposphere. This natural greenhouse effect helps warm the lower troposphere. There is a high (90–99%) probability that increasing concentrations of greenhouse gases in the troposphere from burning fossil fuels,deforestation, and agriculture are enhancing the natural greenhouse effect and raising the earth’s average surface temperature (Figure 21-2, bottom right, and Figure 21-11, p. 471). Changes in climate, agricultural productivity, water supplies, and sea level. Decrease fossil fuel use and deforestation; prepare for climate change.

Greenland

Oceans 5% Bare sand 30–60% Grass 15–25% Clouds 50–55% Snow 80–90% City 10–15% Forest 5%

Today’s sea level Years before presentPresent 250,000200,000150,000100,00050,0000 –130 0 –426 0 Height above or below present sea level (meters) Height above or below present sea level (feet)

Projecting Future Changes in Earth’s Climate  Climate models  Apparent influence of human activities  Could be natural changes

Troposphere Aerosols Greenhouse gases Warming from decrease Cooling from increase CO 2 removal by plants and soil organisms CO 2 emissions from land cleaning, fires, and decay Heat and CO 2 removal Heat and CO 2 emissions Ice and snow cover Natural and human emissions Land and soil biota Shallow ocean Long-term storage Deep ocean

Cell Clouds Ocean Land

Year Change in temperature (ºC)

Factors Affecting the Earth’s Temperature  Changes in solar output  Changes in Earth’s albedo  Moderating effect of oceans  Clouds and water vapor  Air pollution

Antarctica Greenland

Some Possible Effects of a Warmer World

Possible Benefits from a Warmer Atmosphere  Less severe winters  More precipitation in some dry areas  Less precipitation in some wet areas  Increased food production in some areas  Expanded population and ranges of some species  Less severe winters  More precipitation in some dry areas  Less precipitation in some wet areas  Increased food production in some areas  Expanded population and ranges of some species

Present range Future range Overlap

Year Mean Sea-Level Rises (centimeters) High Projection Shanghai, New Orleans, and other low-lying cities largely underwater Medium Projection More than a third of U.S. wetlands underwater Low Projection

Tree plantation Coal power plant Tanker delivers CO 2 from plant to rig Oil rig Crop field Switchgrass Spent oil reservoir is used for CO 2 deposit CO 2 is pumped down to reservoir through abandoned oil field Abandoned oil field CO 2 is pumped down from rig for deep ocean disposal = CO 2 deposit = CO 2 pumping

Reducing CO 2 Emissions What Can You Do? Drive a fuel-efficient car, walk, bike, carpool, and use mass transit Use energy-efficient windows Use energy-efficient appliances and lights Heavily insulate your house and seal all drafts Reduce garbage by recycling and reuse Insulate hot water heater Use compact fluorescent bulbs Plant trees to shade your house during summer Set water heater no higher than 49°C (120°F) Wash laundry in warm or cold water Use low-flow shower head

Solutions: Dealing with the Threat of Climate Change Options  Do nothing  Do more research  Act now to reduce risks  Precautionary principle

Global Warming Solutions PreventionCleanup Cut fossil fuel use (especially coal) Shift from coal to natural gas Improve energy efficiency Shift to renewable energy resources Transfer energy efficiency and renewable energy technologies to developing countries Reduce deforestation Use more sustainable agriculture Limit urban sprawl Reduce poverty Slow population growth Store (sequester) CO 2 by planting trees Sequester CO 2 deep underground Sequester CO 2 in soil by using no-till cultivation and taking crop land out of production Sequester CO 2 in the deep ocean Repair leaky natural gas pipelines and facilities Use feeds that reduce CH 4 emissions by belching cows Remove CO 2 from smokestack and vehicle emissions

Reducing Greenhouse Gas Emissions  Kyoto Treaty (1997)  Other reductions in CO 2  U.S. withdraws from Kyoto Treaty (2001)

Loss of the Ozone Layer: Reasons for Concern  Increased incidence and severity of sunburn  Increase in eye cataracts  Increased incidence of skin cancer  Immune system suppression  Increase in acid deposition  Lower crop yields and decline in productivity

When did it all begin? Dramatic loss of ozone in the lower stratosphere over Antarctica was first noticed in the 1970s by a research group. They were monitoring the atmosphere above Antarctica from a research station

Research Station in Antarctica

The Atmosphere

Where and how ozone is formed? Ozone (O 3 ) forms a layer in the stratosphere, thinnest in the tropics (around the equator) and denser towards the poles. It is created when ultraviolet radiation (sunlight) strikes the stratosphere, dissociating (or "splitting") oxygen molecules (O 2 ) to atomic oxygen (O). The atomic oxygen quickly combines with further oxygen molecules to form ozone (O 3 )

Where is the Ozone “hole” ? Over Antarctica (and recently over the Arctic), stratospheric ozone has been depleted at certain times of the year. This is mainly due to the release of man-made chemicals containing chlorine such as CFC's (Chlorofluorocarbons), but also compounds containing bromine, other related halogen compounds and also nitrogen oxides (NO x ).

Ozone Depleting Chemicals  Chlorofluorocarbons (CFCs)  Halons  Methyl bromide  Carbon tetrachloride  Methyl chloroform  Hydrogen chloride

Former Uses of CFCs  Air Conditioners  Refrigerators  Spray cans  Cleaners for electronic parts  Sterilizing medical instruments  Fumigants for granaries and cargo ships  Air Conditioners  Refrigerators  Spray cans  Cleaners for electronic parts  Sterilizing medical instruments  Fumigants for granaries and cargo ships

CFC’s in the air

Ozone Depletion in the Stratosphere

Ultraviolet light hits a chlorofluorocarbon (CFC) molecule, such as CFCl 3, breaking off a chlorine atom and leaving CFCl 2. UV radiation Sun Once free, the chlorine atom is off to attack another ozone molecule and begin the cycle again. A free oxygen atom pulls the oxygen atom off the chlorine monoxide molecule to form O 2. The chlorine atom and the oxygen atom join to form a chlorine monoxide molecule (ClO). The chlorine atom attacks an ozone (O 3 ) molecule, pulling an oxygen atom off it and leaving an oxygen molecule (O 2 ). Cl C F O O O O O O O O O O Summary of Reactions CCl 3 F + UV Cl + CCl 2 F Cl + O 3 ClO + O 2 Cl + O Cl + O 2 Repeated many times

Seasonal Ozone Layer Thinning at the Poles  Ozone thinning (hole)  Polar vortex

January 1995 October 1995

It’s getting bigger…….. Satellite measurements in September 2000 revealed that the stratospheric ozone “hole” over the Antarctic had a reached a record 28.3 million square kilometers (some one million sq. km more than the previous record, in 1998).

October October 2002

Year Total ozone (Dobson units) October monthly means

August 6, 2003 October 11, Ozone partial pressure (milipascals) Altitude (kilometers)

Effects of Ozone Depletion Natural Capital Degradation Human Health Worse sunburn More eye cataracts More skin cancers Immune system suppression Food and Forests Reduced yields for some crops Reduced seafood supplies from reduced phytoplankton Decreased forest productivity for UV-sensitive tree species Wildlife Increased eye cataracts in some species Decreased population of aquatic species sensitive to UV radiation Reduced population of surface phytoplankton Disrupted aquatic food webs from reduced phytoplankton Air Pollution and Materials Increased acid deposition Increased photochemical smog Degradation of outdoor paints and plastics Global Warming Accelerated warming because of decreased ocean uptake of CO2 from atmosphere by phytoplankton and CFCs acting as greenhouse gases

What are some of the dangers associated with the ozone hole? Experts predict that an estimated 10 % reduction in the ozone layer will result in a 25% increase in non-melanoma skin cancer rates for temperate latitudes by the year 2050.

Skin Cancers Squamous Cell Carcinoma Melanoma Basal Cell Carcinoma

Ultraviolet A Ultraviolet B Thin layer of dead cells Squamous cells Basal layer Melanocyte cells Basal cell Blood vessels Hair Epidermis Sweat gland Dermis Squamous Cell CarcinomaBasal Cell CarcinomaMelanoma

Reducing Exposure to UV-Radiation What Can You Do? Stay out of the sun, especially between 10 A.M. and 3 P.M. Do not use tanning parlors or sunlamps. When in the sun, wear protective clothing and sun– glasses that protect against UV-A and UV-B radiation. Be aware that overcast skies do not protect you. Do not expose yourself to the sun if you are taking antibiotics or birth control pills. Use a sunscreen with a protection factor of 15 or 25 if you have light skin. Examine your skin and scalp at least once a month for moles or warts that change in size, shape, or color or sores that keep oozing, bleeding, and crusting over. If you observe any of these signs, consult a doctor immediately.

Skin Cancer Fact Sheet Over half of all new cancers are skin cancers. More than 1 million new cases of skin cancer will be diagnosed in the United States this year. An estimated 10,250 people will die of skin cancer this year. One person dies of melanoma every hour. An estimated 10,250 people will die of skin cancer this year. One person dies of melanoma every hour.

More Facts At current rates one in 37 Americans have a lifetime risk of developing melanoma and one in 65 Americans have a lifetime risk of developing invasive melanoma. The incidence of melanoma more than tripled among Caucasians between 1980 and More than 77 percent of skin cancer deaths are from melanoma. The incidence of melanoma more than tripled among Caucasians between 1980 and More than 77 percent of skin cancer deaths are from melanoma.

Solutions: Protecting the Ozone Layer  CFC substitutes  Montreal Protocol  Copenhagen Protocol

Year , ,000 9,000 12,000 15,000 Abundance (parts per trillion) No protocol 1987 Montreal Protocol 1992 Copenhagen Protocol