Chapter 16

1. Chapter 16 Climate Change and Ozone Loss

8. 16.3 Factors Affecting the Earth’s Temperature • Can the Oceans Store More CO2 and heat? • Unknown how much CO2 and heat the oceans can take out of the troposphere and how long long they’ll stay in the oceans. • Oceans remove about 48% of the excess CO2 we put in the atmosphere (part of global carbon cycle) • Oceans absorb heat from atmosphere and transfer some to the deep ocean. • Ocean currents on surface and deeper down are connected and move CO2 and heat. Store it and transfer hold and cold water from tropics to the poles. (like a conveyer belt, propelled by wind and density changes in water) • Changes in speed and its stopping and starting contribute to temperature changes. • Ocean currents greatly affect temperature. If the normal loop of currents were to stop, some areas would experience severe regional cooling, and others would get greater heat, floods, droughts, storms. Global warming can lead to significant global cooling in some parts of the world.

9. 16.3 Factors Affecting the Earth’s Temperature II. Science: Effects of Cloud Cover • Warmer temperatures increase evaporation of surface water  Creates more clouds. • Could have a warming effect, by absorbing and releasing heat. • Could have a cooling effect, by reflecting more sunlight into space. • Also depending on type and location of clouds. • An increase in thick and continuous clouds at low altitudes can decrease surface warming by reflecting sunlight. • An increase in thin and discontinuous cirrus (streaky) clouds at high can warm the lower troposphere and increase surface warming. • Trails left behind by jets (contrails) expand into large cirrus clouds that tend to release heat into the upper troposphere. (Could be responsible for ½ of the troposphere warming in northern hemisphere) • Summary: Warmer temperatures = more clouds. Could warm or cool troposphere, but we’re not sure which.

10. 16.3 Factors Affecting the Earth’s Temperature III. Science: Effects of Outdoor Air Pollution • Unknown how much CO2 and heat the oceans can take out of the troposphere and how long long they’ll stay in the oceans. • Oceans remove about 48% of the excess CO2 we put in the atmosphere (part of global carbon cycle) • Oceans absorb heat from atmosphere and transfer some to the deep ocean. • Ocean currents on surface and deeper down are connected and move CO2 and heat. Store it and transfer hold and cold water from tropics to the poles. (like a conveyer belt, propelled by wind and density changes in water) • Changes in speed and its stopping and starting contribute to temperature changes. • Ocean currents greatly affect temperature. If the normal loop of currents were to stop, some areas would experience severe regional cooling, and others would get greater heat, floods, droughts, storms. Global warming can lead to significant global cooling in some parts of the world.

11. 16.3 Factors Affecting the Earth’s Temperature IV. Science: Effects of Outdoor Air Pollution • Main idea: Aerosol pollutants and soot produced produced by human activities can warm or cool the atmosphere, but the effects will decrease w/ any decline in outdoor air pollution. • Aerosols: microscopic droplets and solid particles. • Formed and released in troposphere by volcanic eruptions and human activities. • May warm or cool air depending on factors ie. size and reflectivity of underlying surface. Most troposphere particles cool the atmosphere and temporarily slow global warming. • …BUT recent studies suggest that tiny particles of soot or black carbon aerosols (produced from diesel engines, open fires, ect) may be the second largest contributor to global warming after CO2. • Aerosol pollutants are not expected to counteract or enhance global warming very much in the next 50 yrs because they are washed out of the lower atmosphere in a few months and the number of aerosols are being reduced esp. in developed countries.

12. 16.3 Factors Affecting the Earth’s Temperature V. Effects of Higher CO2 levels on Photosynthesis • Main idea: Increased CO2 in the troposphere may increase plant photosynthesis, but there are factors that might limit/offset this effect. • The effect would be temporary for 2 reasons: (1) increase in photosynthesis would slow as the plant ages and (2) Carbon stored in plants would be returned when plants die/decompose/burn. VI. Effects of a Warmer Troposphere • Main idea: Warmer air can release methane gas stored in wetlands, bogs (marshes), and tundra soils and make the air warmer. • Global warming could be sped up w/ and increase in released methane. • Sources: bogs and other wetlands and ice-like compounds called methane hydrates trapped beneath arctic permafrost. Vicious cycle.

13. 16.4 Possible Effects of a Warmer World • Science: Projected Effects of a Warmer Troposphere • Main idea: A warmer climate would have beneficial and harmful effects, but poorer nation in the tropics would suffer the most. • Effects depend on location and the rate at which the climate changes. • Some areas will benefit bc of less severe winters, more precipitation in some dry areas, less precipitation in wet areas, and increased food production. • Benefits plant and animal species adapted to higher temperatures. • Some areas will suffer bc of excessive heat, lack of water, and decreased food production. More wildfires bc of drier conditions. May increase tree deaths bc disease and pest populations would thrive w/ warmer climate. Premature extinction. • Threaten biodiversity. Ecosystems most likely to be disrupted are lose species are coral reefs, polar seas, costal wetlands, arctic and alpine tundra, and high elevation.

14. 16.4 Possible Effects of a Warmer World II. Science: Sea Level Rise • Main idea: During this century, rising sea levels are projected to flood low-ling urban area, costal estuaries, wetlands, coral reefs, and barrier islands (long, narrow island that protect mainland from erosion) and beaches. • Average sea level expected to rise 9-88 cm during this century. • Large increase would threaten world’s costal estuaries, wetlands, and coral reefs, disrupt coastal fisheries, flood low-lying barrier islands causing coastlines to erode and retreat inland, flood agricultural lowlands and deltas in parts of Bangladesh, Indian, and China (where most of the world’s rice is grown), submerge low-lying islands, flood costal areas w/ large human populations/megacities. • Population growth in flood-prone areas. • Hurt poorer people and economies most.

15. 16.5 Dealing with the Threat of Global Warming I. Why is Climate Change Such a Hard Problem to Deal With? • Main Idea: Climate change is hard to deal with because it has many causes (many poorly understood), its effects are uneven and long-term, and there’s controversy about how it should be addressed. • Complex Causes: We don’t have the degree of scientific certainty that some decision makers want. • Global problem: Need unprecedented international corporation. • Long-term issue: chronic vs. catastrophic. Ethical question—how much are we willing to sacrifice now to benefit people in the future? • Uneven impacts: Some will benefit, some will suffer. BUT we won’t know which until it’s too late. • We can’t stop climate change, but we can help slow it and adapt to its effects. • Many actions to reduce climate change are controversial bc they disrupt economic and lifestyles

16. 16.5 Dealing with the Threat of Global Warming II. What Are Our Options? • Main Idea: Disagreement persists regarding what we should do about the threat of global warming. • Wait-and-see Strategy: More research now for a better understanding before we jump to changes. (US does this) • Act now to reduce the risks from climate change brought about by global warming: Proponents argue that the economic, ecological, and social consequences would be so bad that we need to act now. • Act now as part of a no-regrets strategy: We should take key actions to slow global warming because such actions lead to other important environmental, health, and economic benefits. • ie. reduction in the combustion of fossil fuels esp. coa. ,

17. 16.5 Dealing with the Threat of Global Warming III. Reducing the Threat • Main idea: We can improve energy efficiency, rely more on carbon-free renewable energy resources, and find ways to keep much of the CO2 we produce out of the troposphere. • Three major strategies: improve energy efficiency to reduce fossil fuel use, shift to carbon-free renewable energy resources, store as much CO2 as possible in soil, vegetation, the underground, and the deep ocean. IV. Science: Removing and Storing CO2 • Main idea: We can prevent some of the CO2 we produce from circulating in the troposphere, but the costs bay be high and the effectiveness of various approaches is unknown. • Smokestacks, soil sequestration, no-till cultivation, moving CO2.

18. 16.5 Dealing with the Threat of Global Warming V. Economics and Politics: The Role of the Government • Main idea: Government can tax greenhouse gas emissions and energy use, increase subsidies and tax breaks for saving energy and using renewable energy, and decrease subsidies and tax breaks for fossil fuels. • Governments could use three major methods to promote solutions to global warming • Carbon/Energy taxation: price on each unit of CO2 emitted by fossil fuels/on each unit of fossil fuel that is burned. • Level economic playing field: increase gov. subsidies for energy-efficient technologies/carbon free technologies. • Focus on technology transfer: fund the transfer of energy-efficient/sustainable agriculture technologies to developing countries.