Study Guide 14b
Chapter 47 Ecosystem Ecology – Global Warming
19. What is global warming? Increase in global average temperature near earth’s surface
20. What is the evidence the global warming is occurring, both physical and biological? Physical:
shrinking of glaciers, polar ice, melting of permafrost; Biological: changes in distribution, by latitude
and altitude; changes in times of migration
21. Thought question: How does the shrinking of the polar ice cap cause more warming to occur in the
Arctic? It creates more water (ice melting turns into water) which is darker and attracts more sunlight
which warms the water and then warms the polar ice caps and melts them
22. What else occurs in the Arctic and sub-Arctic that speeds up global warming? Melting of permafrost
How? If aerobic decomposition occurs  more carbon dioxide; if anaerobic decomposition occurs 
methane is produced (methane is 20x more potent a greenhouse gas than carbon dioxide)
23. How can we tell if the warming is the result of natural and/or human activities? Computer models
simulate sun’s radiation/movement of heat through world; models predict past 150 years with and
without human inputs What were the results? Humans are a major cause of global warming
24. What have humans done that causes warming? Added greenhouse gases to atmosphere What are
three of the main greenhouse gases? Carbon dioxide, methane, nitrous oxides What do humans do that
adds these greenhouse gases to the atmosphere? CO2: burning fossil fuels, cutting/burning forests; CH4:
increased number of cows, wet-rice paddies, landfills, pipeline leaks; N2O: burning fossil fuels,
fertilizer, livestock wastes
25. How do greenhouse gases cause a warming at the Earth’s surface and lower atmosphere? Heat
energy/infrared radiation tries to escape the atmosphere but the layer of greenhouse gases redirects it
back to the earth and warms the surface
26. What normally occurs in the carbon cycle? Carbon continually cycles between atmosphere and both
land- and ocean-based systems The amount of carbon dioxide we add to the atmosphere through burning
fossil fuels and the clearing/burning of forests is small compared to the total amount of carbon dioxide
released through respiration. So how can this be causing warming? We’re adding 6 gigatons C/year
27. What processes have been removing some of this carbon? Algae take in C near surface and C is
removed from cycle for long periods of time when algae sink into deep ocean; more C is removed when
coccolithophores and foraminifera sink to bottom of ocean and form sediments; on land, C stored in
plant tissues (especially xylem) and in soil Where does the carbon go? Bottom of ocean; undecayed
organic matter – out of cycle
28. What can we do regarding forests that would help reduce the amount of carbon that goes into the
atmosphere or removes some of the carbon that is there already? Reduce deforestation, plant trees in
deforested areas
29. World-wide, is there more carbon stored in vegetation (such as trees) or in the soil? soil What do
farmers typically do that leads to carbon going from the soil into the atmosphere? Deep plowing
Thought question: In what form? Carbon dioxide What are ways to reduce this loss? Using conservation
tillage such as contour plowing, chisel till, or no-till planting
30. Burning fossil fuels is the main source of human-produced carbon dioxide going into the
atmosphere. How could using biofuels reduce this addition of carbon dioxide, at least theoretically (i.e.
what can biofuels be used for and why would this count as reducing our emissions of carbon dioxide)?
Used for transportation fuels (ethanol, biodiesel, biogas and synfuels), heating fuels (wood, grass pellets,
biogas/methane); theoretically, biofuels are carbon-neutral so the amount of C given off equals the
amount taken in during photosynthesis
31. How does the production of biofuels relate to forest clearing? There are net emissions of carbon
dioxide if forests are cleared (to grow biofuel crops or to grow fuel crops because biofuel crops
displaced elsewhere) How does this impact the desirability to use biofuels to reduce carbon emissions?
Lowers desirability Understand the portion of Fig. 1 of Fargione et al. that is in the powerpoint – what is
the worst way to produce biofuels? Palm biodiesel What is the best way? Prairie biomass ethanol
Thought question: Compare the amount of emissions and the time to repay the carbon debt from
changing grassland in the central United States to corn fields to produce corn ethanol with changing
tropical rainforest in Indonesia/Malaysia to palm plantations to produce palm biodiesel. How can they
have about the same time to pay off the “carbon debt” even though there are fewer carbon emissions
from changing the habitat to grow corn rather than palm trees?
32. What are the pros and cons of using biofuels? Pros - can use in existing engines, farmers can make
more money, small farms can survive, rural communities can be self-sufficient, grow and process own
fuel, developing countries can earn money to repay loans; cons - may release more previously stored
carbon than save by switching from gasoline, if use food crops the price of food goes up, if water is
limited it adds to stress, if forests are cleared then people and wildlife may be displaced Thought
question: Do you think we and the farmers in the U.S. should do it? sure