Climate Change and Ozone Loss G. Tyler Miller’s Living in the Environment 15 th Edition Chapter 20 G. Tyler Miller’s Living in the Environment 15 th Edition Chapter 20

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

How Do We Know What Temperatures Were in the Past? Scientists analyze tiny air bubbles trapped in ice cores learn about past: –troposphere composition. –temperature trends. –greenhouse gas concentrations. –solar, snowfall, and forest fire activity. Figure 20-3

How Do We Know What Temperatures Were in the Past? In 2005, an ice core showed that CO 2 levels in the troposphere are the highest they have been in 650,000 years. Figure 20-4

Past Climate Changes  Past global temperatures: _____ and _____.  Past global temperatures: _____ and _____.  Recent trends in global temperatures… _________ ________.  Recent trends in global temperatures… _________ ________.

The Greenhouse Effect  Greenhouse gases: _______________  Greenhouse gases: _______________ Fig p. 110

Animation: Greenhouse Effect PLAY ANIMATION

Global Warming Potential Describes Impact of Each Gas Carbon dioxide (CO 2 ) has a GWP of 1 and serves as a baseline for other GWP values. CO 2 remains in the atmosphere for a very long time - changes in atmospheric CO 2 concentrations persist for thousands of years. Methane (CH 4 ) has a GWP more than 20 times higher than CO 2 for a 100-year time scale. CH 4 emitted today lasts for only about a decade in the atmosphere, on average. [3] However, on a pound-for-pound basis, CH 4 absorbs more energy than CO 2, making its GWP higher. Nitrous Oxide (N2O) has a GWP 300 times that of CO 2 for a 100-year timescale. N2O emitted today remains in the atmosphere for more than 100 years, on average. [3] Chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs), hydrochlorofluorocarbons (HCFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6) are sometimes called high-GWP gases because, for a given amount of mass, they trap substantially more heat than CO 2. (EPA.gov)

Table 21-1 Page 464 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

Fig. 20-5c, p. 467

Climate Change and Human Activities  Increased use of ____________ (CO 2 )  _________________ (CO 2 )  Increased number of _________ that release _____________  Cultivation of _______ in _________ (_________ from anaerobic microbes)

Increasing greenhouse gases play

IPCC findings that support the consensus that the troposphere is getting warmer: 20 th century was the ____________ century in the past 1000 years since 1861 the average global temperature near earth’s surface has __________ 0.6 degrees C 16 warmest years on record since _________ ________________ are melting during the last century average sea level rose by ___________ from melting ice and water volume expanding with temperature increase

IPCC

Arctic sea ice 1979 (left) 2003 (right)

Factors Affecting the Earth’s Temperature  ___________ store CO 2 and heat  __________ cover  ___________ (microscopic droplets and particles)  Plant ____________________  Bogs, wetlands and ____________ store or release methane

Fig. 20-6, p. 469 Troposphere Cooling from increase Aerosols Warming from decrease Green- house gases CO2 removal by plants and soil organisms CO2 emissions from land clearing, fires, and decay Heat and CO2 emissions Heat and CO2 removal Deep ocean Long-term storage Land and soil biota Natural and human emissions Shallow ocean Sun Ice and snow cover

Some Possible Effects of a Warmer World

Effects of a Warmer Atmosphere  Change in _____________ and ______________ size of species  ___________________ shifts  Rising _________ _________  Change in _____________ and ______________ size of species  ___________________ shifts  Rising _________ _________

Rising Sea Levels During this century rising seas levels are projected to flood low- lying urban areas, coastal estuaries, wetlands, coral reefs, and barrier islands and beaches. Figure 20-10

Fig , p. 475 High Projection New Orleans, Shanghai, and other low-lying cities largely underwater Year Low Projection Medium Projection More than a third of U.S. wetlands underwater Mean Sea-Level Rises (centimeters)

Changing Ocean Currents Global warming could alter ocean currents and cause both excessive warming and severe cooling. Figure 20-12

Solutions: Dealing with the Threat of Climate Change Options  Do ____________  Do more __________ – wait and see  Act now to reduce risks - ___________ ______________  No _______ strategy  Act now to reduce risks - ___________ ______________  No _______ strategy Fig p. 479

Reducing the Threat Reduce fossil fuel use through ___________ _____________ Shift to renewable _________-____ energy Sequester (store) CO2 in _______, __________, ___________, _______ _________

Removing CO 2 from the Atmosphere Fig p. 480

Reducing Greenhouse Gas Emissions  _______________ Protocol (Treaty) (1997)  _____________ withdraws from Kyoto Treaty (2001)

International Climate Negotiations: The Kyoto Protocol –Treaty on global warming which first phase went into effect January, 2005 with 189 countries participating. –It requires 38 participating developed countries to cut their emissions of CO 2, CH 4, and N 2 O to 5.2% below their 1990 levels by –Developing countries were excluded. The U.S. did not sign, but California and Maine are participating. U.S. did not sign because developing countries such as China, India and Brazil were excluded.

The Ozone Shield The ozone layer is in the stratosphere at an altitude of 15 to 40 km. Ozone absorbs ultraviolet solar radiation. Ozone is a molecule made of three oxygen atoms. Too much UV light is harmful to organisms because it can damage the genetic material in living cells. Ozone in the stratosphere acts like a sunscreen for the Earth’s inhabitants by shielding the Earth’s surface from most of the sun’s UV light

OZONE DEPLETION IN THE STRATOSPHERE Since 1976, in Antarctica, ozone levels have markedly decreased during October and November. Figure 20-20

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

Former Uses of CFCs  _________ _____________  _____________  _________ cans  Cleaners for ___________ parts  Sterilizing medical instruments  Fumigants for granaries and cargo ships  _________ _____________  _____________  _________ cans  Cleaners for ___________ parts  Sterilizing medical instruments  Fumigants for granaries and cargo ships

Chemicals That Cause Ozone Depletion Each CFC molecule contains from one to four chlorine atoms, and scientists have estimated that a single chlorine atom in the CFC structure can destroy 100,000 ozone molecules.

Ozone Depletion in the Stratosphere Fig p. 484

Animation: How CFCs Destroy Ozone PLAY ANIMATION

The Ozone Hole In 1985, studies by scientists working in Antarctica revealed that the ozone layer above the South Pole had thinned by 50 to 98 percent. The ozone hole is a thinning of stratospheric ozone that occurs over the poles during the spring. This was the first news of the hole, and was published in an article in the scientific journal Nature in 1985.

The Ozone Hole After the results were published, NASA scientists reviewed data that had been sent to Earth by the Nimbus 7 weather satellite. They were able to see the first signs of ozone thinning in the data from Although the concentration of ozone fluctuated during the year, the data showed a growing hole. Ozone levels over the Arctic have decreased as well. In March 1997, ozone levels over part of Canada were 45 percent below normal. Nimbus 7

The Ozone Hole NASA Ozone Hole Watch

Seasonal Ozone Layer Thinning at the Poles  Ozone thinning (hole):  Greatest over______________  Causes increased _________ and ____________ radiation  Greatest over______________  Causes increased _________ and ____________ radiation

OZONE DEPLETION IN THE STRATOSPHERE During four months of each year up to half of the ozone in the stratosphere over Antarctica and a smaller amount over the Arctic is depleted. Figure 20-19

How Does the Ozone Hole Form? You may be thinking, “If ozone is also being produced as air pollution, why does this ozone not repair the ozone hole in the stratosphere?” The answer is that ozone is very chemically reactive. Ozone produced by pollution breaks down or combines with other substances in the troposphere long before it can reach the stratosphere to replace ozone that is being destroyed.

Loss of the Ozone Layer: Reasons for Concern  Increased incidence and severity of ___________  Increase in _____ _____________  Increased incidence of ________ cancer  __________ system suppression  Increase in _______ ____________  Lower _____ _______ and reduced ___________ Refer to Fig p. 486 Refer to Fig p. 486

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 Effects of Ozone Depletion Natural Capital Degradation Fig , p. 488

Skin Cancers Fig p. 487

Effects of Ozone Thinning on Humans

Protecting the Ozone Layer In 1987, a group of nations made an agreement, called the Montreal Protocol, to sharply limit their production of CFCs. At a second conference in Copenhagen, Denmark in 1992, developed countries agreed to eliminate most CFCs by The United States pledged to ban all substances that pose a significant danger to the ozone layer by the year 2000.

Solutions: Protecting the Ozone Layer  CFC substitutes  _______________ Protocol (1987)  _______________ Protocol (1992) Fig p. 489