Energy & Its Impact on Global Society Jerome K. Williams, Ph.D. Saint Leo University Dept. Mathematics & Sciences

Chapter 9: Global Warming & Thermal Pollution Overview Greenhouse Effect & Global Warming Possible Impacts: Global Warming Actions: What can be Done? Thermal Pollution

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Overview Evidence suggests that burning fossil fuels can raise Earth’s temperature and potentially change the climate of the entire planet. Global Warming (Greenhouse Effect)

Greenhouse Effect & Global Warming Greenhouse effect caused by gases in atmosphere that absorb infrared energy from the Earth that would otherwise escape into space. Earth’s temperature is a balance between the energy coming in from Sun and energy that is radiated from Earth back into space.

Greenhouse Effect & Global Warming Gases that are responsible for this effect: – Carbon dioxide (CO 2 ) – Methane(CH 4 ) – Nitrogen oxides (NO NO 2 ) – Chlorofluorocarbons (CFCs)

Table 9.1. Greenhouse Gases 2010 GasSources US Emissions (MT/yr) GWP Atmospheric Lifetime (years) 2010 Concentration (ppM) CO 2 Fossil Fuels, deforestation Methane Rice fields, cattle, landfills Nitrogen oxides Fertilizers, deforestation CFCsAerosol sprays, refrigerants , (Cl atoms) Source: Intergovernmental Panel on Climate Change

Greenhouse Effect & Global Warming GWP = Global Warming Potential (ability of greenhouse gas to trap heat). CO 2 levels are a Global Problem that can have devastating environmental consequences if not addressed soon.

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Possible Impacts: Global Warming Determining the impact of global warming in the 21 st century is very difficult Climate models about complex physical processes are based on assumptions and therefore contain many uncertainties

Possible Impacts: Global Warming Climate Sensitivity - defined as temperature rise that will occur when CO 2 concentrations double from pre-industrial levels Many scientists think that doubling will occur by middle of this century (assumes a 1-2% annual increase in CO 2 levels is maintained)

Possible Impacts: Global Warming Most scientists (but not all) agree that increasing CO 2 levels will affect the planet’s climate, the key questions are as follows: – How much of a change will be observed? – How fast will global temperatures rise?

Possible Impacts: Global Warming A key element in predicting the rise in global temperatures is to understand carbon cycle

Possible Impacts: Global Warming Much of uncertainty with predicting warming trends depends on understanding of sizes of various feedbacks that may occur in response to climate changes

Possible Impacts: Global Warming Effects of global warming will not be felt equally around the world. Poorer nations more susceptible to effects of global warming; widespread poverty across Africa makes it particularly vulnerable

Actions: What can be Done? What can be done to prevent greenhouse gas concentrations from rising to unacceptable levels? Energy Policy coupled with Political Leadership

Actions: What can be Done? Energy Policy: – Energy conservation – Economic incentives – Renewable energy technologies – Employ more natural gas & nuclear power US: 20 metric tons CO 2 /yr (6X greater than developing world)

Actions: What can be Done? Political Leadership (Legislative Action) – “Cap and Trade” Policy – Carbon Tax – Carbon Sequestration

Actions: What can be Done? Will Everyone Play in the same Sand Box? – International strategies must be developed and followed by everyone for this to work – Built-in-bias against solving long-term problems – Very expensive to fix problem; affects bottom line – Controversial (skeptics still out there)

Actions: What can be Done? Recent History: Do Nations Play well together? – 1992 Earth Summit (Rio de Janeiro) Countries must exercise “responsible stewardship” Compliance was voluntary – 1997 Kyoto Protocol on Global Climate Change

Thermal Pollution Thermal pollution is defined as addition of unwanted heat to environment, particularly natural waters Greatest source of heated water is from power-generating stations

Thermal Pollution Ecological Effects of Thermal Pollution – Decreased ability of water to hold oxygen – Increased rates of chemical reactions – Changes in food chain of ecosystem – Long-term damage (even death) to natural bodies of water

Thermal Pollution Current US laws dictate that one can not just “dump” waste heat directly into aquatic environments – Cooling Towers – Cooling Ponds

Thermal Pollution Using Waste Heat for other Benefits include – Hot water for industrial use – Aquaculture (increased fish growth) – Greenhouse heating – Desalination of sea water – Increased crop growth and frost protection

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