Chapter 19 Global Change 1

o Global change- any chemical, biological or physical property change of the planet. o Global climate change- changes in the climate of the Earth. o Global warming- the warming of the oceans, land masses and atmosphere of the Earth. Global Change 2

The Sun-Earth Heating System The Greenhouse Effect 1. Incoming solar energy = 100% - Radiation is absorbed by the clouds and the surface of Earth thus becoming warmer. 2. I/3 of all solar energy is reflected. 3. Most of the infrared radiation from Earth is absorbed by greenhouse gases in the atmosphere. - The rest is emitted back into space. - Known as the greenhouse effect. 3

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o Water vapor o Absorbs and releases energy o Carbon dioxide o Methane o Nitrous oxide o Ozone o CFCs Greenhouse Gases 5

Greenhouse warming potential —ratio of how much a molecule of a compound can contribute to global warming over 100 years compared to 1 molecule of CO 2 6

1. Volcanic eruptions o CO 2 —long term effects o Particulate Matter — (ash) shorter term o Ash reflects incoming solar radiation back to space, causes Earth’s temperature to decrease. 4 Natural Greenhouse Gases 7

2. Methane – is created when there is not enough oxygen available to produce carbon dioxide during decomposition. o Occurs at the bottom of wetlands – largest natural source of methane (anaerobic decomposition) o Organism digestion, gut of a termite, no oxygen is present methane given off. Second largest source. 4 Natural Greenhouse Gases 8

3. Nitrous oxide o Produced during denitrification o NO 3 -  N 2 O o Occurs in a low oxygen environment such as soils at the bottom of wetlands, lakes, and oceans. 4 Natural Greenhouse Gases 9

4. Water vapor o Most abundant o Greatest contributor 4 Natural Greenhouse Gases 10

5 Anthropogenic Sources of Greenhouse Gases 11

1. Burning of fossil fuels o Trapped reserves of CO 2 plants don’t take in as much as we are contributing during burning. o Coal v. Petroleum v. Natural gas o Particulate Matter 5 Anthropogenic Sources of Greenhouse Gases 12

2. Agricultural practices o Anaerobic conditions (CH 4 and N 2 O) o Irrigation and flooding for cultivating crops create low oxygen environments for bacteria. o Fertilizers o Excess Nitrates are added  denitrification = N 2 O o Livestock o Digestion – sheep and cows rely on gut bacteria to break down cellulose which produces a lot of CH 4 o Manure lagoons – not aerated, decompose and release CH 4 5 Anthropogenic Sources of Greenhouse Gases 13

3. Deforestation…without replacement o Plants remove CO 2 o Slash-and-burn method (shifting agriculture) releases CO 2, CH 4, and N 2 O 5 Anthropogenic Sources of Greenhouse Gases 14

4. Landfills o Anaerobic methane generation from low oxygen due to poor aeration. 5 Anthropogenic Sources of Greenhouse Gases 15

5. Industrial production o CFCs replaced by HCFCs 5 Anthropogenic Sources of Greenhouse Gases 16

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o David Keeling began measuring CO 2 in Increasing CO 2 Concentrations 18

Emissions from the Developed and Developing World 19

o Indirect measurements—lack of records o Changes in species compositions o Foraminifera o Chemical analyses of ice Temperatures and Greenhouse Gas Concentrations in Past 400,000 Years 20

Historic CO 2 Concentrations 21

Historic CO 2 Concentrations 22

- We know that an increase in CO 2 in the atmosphere causes a greater capacity for warming through the greenhouse effect. - When the Earth experiences higher temperatures, the oceans warm and cannot contain as much CO 2 gas and, as a result, they release CO 2 into the atmosphere. Putting It Together 23

Evidence of Global Climate Change 1. Global sea level rose about 17 centimeters (6.7 inches) in the last century. The rate in the last decade, however, is nearly double that of the last century. 2. Average Arctic temperatures increased at almost twice the global average rate in the past 100 years. Shrinking glaciers and ice caps. 3.Most of this warming has occurred since the 1970s, with the 20 warmest years having occurred since 1981 and with all 10 of the warmest years occurring in the past 12 years. 4.Seasonal events starting earlier and ending later 5.The top 700 meters (about 2,300 feet) of ocean showing warming of degrees Fahrenheit since The number of record high temperature events in the United States has been increasing, while the number of record low temperature events has been decreasing, since The U.S. has also witnessed increasing numbers of intense rainfall events. 24

Feedbacks 25

Feedbacks  POSITIVE  High C in soil  High temperatures   decomposition   CO 2 in atmosphere  Tundra warms  Anaerobic decomposition  CH 4  NEGATIVE  High CO 2   plant growth  Removes CO 2 26

1. Melting of polar ice caps, Greenland and Antarctica 2. Melting of many glaciers around the world 3. Melting of permafrost 4. Rising of sea levels due to the melting of glaciers and ice sheets and as water warms it expands 5. Heat waves 6. Cold spells 7. Change in precipitation patterns 8. Increase in storm intensity 9. Shift in ocean currents Consequences to the Environment From Global Warming 27

North Pole is currently 39% smaller than it was in

1.Thermal expansion 2.Additions of water from melting ice 29

o Wild plants and animals can be affected. The growing season for plants has changed and animals have the potential to be harmed if they can’t move to better climates. o Humans may have to relocate, some diseases like those carried by mosquitoes could increase and there could be economic consequences. Consequences to Living Organisms 30

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o The fundamental basis of climate change- that greenhouse gas concentrations are increasing and that this will lead to global warming is not in dispute among the vast majority of scientists. o What is unclear is how much world temperatures will increase for a given change in greenhouse gases, because that depends on the different feedback loops. The Controversy of Climate ChangeControversy 32

o 1997, Japan--discuss how best to control emissions contributing to global warming. o Green house gas emissions from all industrialized countries will be reduced to 5.2% below their 1990 levels by o Developing nations did not have emission limits imposed by the protocol. The Kyoto Protocol 33