19) The use of tree rings to study past climates is known as dendroclimatology.
20) Speleothems, like trees, have growth rings whose size and property reflect the conditions
under which they formed.
21) The last glacial maximum (LGM) refers to the duration of the last period of glaciation.
22) The Younger Dryas, the Medieval Climate Anomaly, and the Little Ice Age demonstrate that
climates naturally fluctuate.
23) A lower 18O /16O ratio in ocean core sediments is indicative of warmer temperatures,
whereas a lower 18O /16O ratio in ice cores is indicative of cooler temperatures.
24) The Earth’s climate cycles between warmer and colder periods.
25) Recent temperature increases correspond to a period of increased sunspot activity.
26) Milankovitch cycles are currently accepted as a causal factor for long-term climatic
fluctuations.
27) The Earth’s elliptical orbit around the sun (eccentricity) is mostly constant, only changing
negligibly over a 100,000 year period.
28) The Earth’s axial tilt varies from 21.5° to 24.5° during a 41,000 year period.
29) As ocean temperatures increase, the ability of oceans to dissolve CO2 is diminished.
30) Increased atmospheric CO2 may lead to plants in some regions of the world producing more
leaves.
31) Carbon dioxide (CO2) is the most abundant natural greenhouse gas.
32) Clouds can create both positive and negative feedback loops in relationship to warming
climates.
33) Some climate feedback loops, such as CO2 weathering feedback, occur over very long time
scales.
34) The world’s highest rates of deforestation (based on the Deforestation Index), a significant
factor in global warming, is occurring in Brazil.
35) Thawing of tundra due to warming temperatures results in more carbon released from tundra
soils than is absorbed.
36) Over the last two decades, the Antarctic ice sheet has lost mass. However, the Greenland ice
sheet has actually gained mass due to increased winter precipitation.
37) According to the Intergovernmental Panel on Climate Change (IPCC), warming of the
climate system is unequivocal.
38) Sea surface temperatures increased at an average annual rate of 0.07 C° (0.13 F°) from 1901
to 2012.
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39) Ice shelves and icebergs are an example of sea ice.
40) There has been a decrease in multi-year ice., that is, sea ice that survives through two or
more summers.
41) A definitive link between climate change and extreme weather events has been established.
42) The current data indicate that the record high global temperatures of the past two decades
correspond to record high atmospheric CO2.
43) All greenhouse gases contribute equally to global climate change.
44) Water vapor (H2O) has a longer residence time in the atmosphere than carbon dioxide
(CO2).
45) Carbon dioxide (CO2) residence time in the atmosphere is 7 to 10 years.
46) Carbon dioxide (CO2)has a longer residence time in the atmosphere than methane (CH4).
47) Methane(CH4) is the second most prevalent anthropogenic greenhouse gas.
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48) Currently, atmospheric methane(CH4) concentrations are increasing at a rate faster than
carbon dioxide (CO2).
49) The United States leads the world in total carbon dioxide (CO2) emissions.
50) The United States leads the world in per capita carbon dioxide (CO2) emissions.
51) Methane(CH4) has a higher global warming potential than carbon dioxide (CO2).
52) Halogenated gases are purely anthropogenic and have no natural sources.
53) Natural climate forcing is greater than anthropogenic climate forcing.
54) While GCMs are useful for visualization the complex global oceanic-atmosphere circulation,
they have had little utility in the study of climate change.
55) According to climate simulations using GCMs, natural climate forcing, alone, cannot
account for the increases in global temperature trends.
56) GCMs are used to predict specific temperatures in the near and long-term future.
57) Sea level is rising more quickly on the east coast of the United States than on the west coast.
58) Vulnerability to sea level rise is not uniformly distributed across the world.
59) Though the U.S. is a signatory to the Kyoto Protocol, the U.S. Congress never ratified it.
60) Delaying action on climate change may be dangerous and more costly in the long run.
61) The average individual is helpless to do anything about climate change.
11.3 Essay Questions
1) What methods do scientists use to reconstruct both long-term and shorter term climate
histories?
2) Based on climate reconstructions, there is ample evidence that climates have fluctuated
throughout Earth’s long history. Describe some of the mechanisms of this climate fluctuations.
3) What are some examples of positive and negative climate feedback loops?
4) What is some of the evidence establishing that climate change is currently occurring?
5) Describe the properties, current atmospheric concentrations, and sources the primary
greenhouse gases contributing to climate change?
6) What is radiative forcing? List gases and aerosols that have positive or negative radiative
forcing. What is the primary source of each.
7) Describe the functioning of a general circulation model. What are some of the predictions for
the 21st Century based on GCMs?
8) What steps can you take to help reduce climate change?
9) Describe methods that individuals and communities are taking to mitigate against climate
change.