Deck 10: Climate Change

Question 1

A lower 18O/16O ratio in ocean sediment cores indicates a(n)_ climate,whereas a higher 18O/16O ratio indicates a(n)climate.

A)cooler;warmer
B)warmer;cooler
C)cooler;cold
D)imbalanced;balanced
E)stable;unstable

Answer 1

B

Question 2

"Snowball Earth" refers to

A)an extreme icehouse climate from 600 to 700 million years ago with ice sheets extending to the tropics.
B)a climate model that predicts large expanses of ice sheets due to negative feedback loops triggered by climate change.
C)the Pleistocene glaciation ending 12,000 years ago when the Laurentide Ice Sheet covered large portions of North America.
D)a hypothesized model of climate change based on massive volcanic eruptions and/or nuclear fallout creating a global winter.
E)a supercontinent that existed during the late Paleozoic and early Mesozoic eras.

Answer 2

A

Question 3

16O makes up approximately percent of all oxygen atoms.

A)0.05
B)0.2
C)20.21
D)50.33
E)99.76

Answer 3

E

Question 4

The interdisciplinary study of the causes and consequences of changing climate for all Earth systems and the sustainability of human societies is

A)climate change science.
B)meteorology.
C)paleoclimatology.
D)climate policy.
E)microclimatology.

Question 5

The rapid warming associated with the Paleocene-Eocene Thermal Maximum (PETM)likely resulted from

A)several massive volcanic eruptions.
B)the sudden die off of photosynthetic organisms and associated increase in atmospheric CO2.
C)a sudden (geologically speaking)increase in atmospheric carbon.
D)decreased surface albedo brought about by Paleocene afforestation.
E)absorption of CO2 by the recently uplifted Himalayas.

Question 6

So-called climates are periods with relatively warmer temperatures.

A)greenhouse
B)coolhouse
C)glasshouse
D)conservatory
E)hothouse

Question 7

Scientists use to study past climates,using to reconstruct climates that extend back further than our present instrumentation allows.

A)proxy methods;climate proxies
B)direct measurements;historical records
C)indirect evidence;conjecture
D)computer models;algorithms
E)inference;supposition

Question 8

The science that studies Earth's past climates is

A)climate change science.
B)meteorology.
C)paleoclimatology.
D)dendrochronology.
E)limnology

Question 9

The 16O evaporates _ than 18O,and condenses .

A)less easily;more easily
B)less easily;less easily
C)more easily;less easily
D)more easily;more easily
E)more rapidly;more slowly

Question 10

Which of the following is true of 16O and 18O?

A)Both the 16O and 18O isotopes occur in water molecules.
B)Only the 16O isotope occurs in water molecules.
C)Only the 18O isotope occurs in water molecules.
D)Neither the 16O nor 18O isotopes occur in water molecules.
E)The 16O and 18O isotopes are so radically different they are not used in paleoclimate reconstructions.

Question 11

The last interglacial period with temperatures similar to the present interglacial period was the

A)385,00 years ago (Holstein interglacial).
B)781,000 years ago (Pastonian Stage).
C)125,000 years ago (Eemian interglacial).
D)500,000 years ago (Günz-Mindel interglacial).
E)12,000 years ago (Flandrian interglacial).

Question 12

Ice cores provide a climate record for the past years.
A)2 million

A)50,000
B)10 million
B)800,000
C)70 million

Question 13

Ocean sediment cores provide a climate record for the past years.
A)2 million

A)50,000
B)10 million
B)800,000
C)70 million

Question 14

Which of the following is not an example of methods used for short-term climate reconstructions?

A)dendrochronology
B)ocean sediment core analysis
C)carbon isotope analysis
D)speleothems analysis
E)lake core analysis

Question 15

Which of the following accurately describes 18O/16O ratios of ice sheets?

A)The higher the ratio of oceanic 18O to 16O,the cooler the temperature is because 18O will be locked up in ice sheets.
B)A higher ratio of oceanic 18O to 16O indicates a warmer period during which more 18O evaporates and precipitates onto ice sheets.
C)During periods of colder temperatures,the 18O/16O ratio is higher because only the 18O isotope is being evaporated.
D)During warmer periods,16O evaporates more readily and,therefore,the 18O/16O ratio is significantly lower than cooler periods.
E)During cooler periods,18O evaporates more readily and,therefore,the amount of 16O in glaciers is negligible.

Question 16

A lower 18O/16O ratio in ice core indicates a(n)climate,whereas a higher 18O/16O ratio indicates a(n)climate.

A)cooler;warmer
B)warmer;cooler
C)cooler;cold
D)imbalanced;balanced
E)stable;unstable

Question 17

Which of the following accurately describes 18O/16O ratios of the world's oceans?

A)A higher ratio of oceanic 16O to 18O,the colder the temperatures because 18O will have been mostly evaporated from the oceans.
B)Because 18O evaporates more readily than 16O,the oceans have a higher relative abundance of 16O during warm periods and a more balanced ration when evaporation is less.
C)Neither the 16O nor 18O isotopes are common in water,so when either is present,it shows a disequilibrium in normal climatic conditions.
D)During periods of colder temperatures,16O is locked up in snow and ice and 18O concentrations are highest in the oceans.
E)The 16O/18O ratio is low during colder temperatures because temperatures are too low for evaporation to be effective and both isotopes remain in the ocean.

Question 18

Climate reconstructions using oxygen isotopes (^{18O)over two timescales} Over the span of 70 million years,the Earth's climate

A)was much warmer 70 m.y.a.compared to the present.
B)was warmest approximately 10 million years ago and coolest about 56 million years ago.
C)has remained fairly constant,only showing a warming trend during the past 200 years.
D)was much cooler 70 m.y.a.compared to the present.
E)did not fluctuate greatly from approximately 500 m.y.a.to 65 m.y.a. ,then widely fluctuated until the current stable period.

Question 19

Which of the following accurately describes 13C/12C ratios of plant materials and their use in climate reconstructions?

A)Carbon is such a rare element on Earth that the 13C/12C ratios help scientists deduce glacial and interglacial cycles.
B)13C is an unstable isotope,which decays at a constant rate.This is used to date plant material,which can then be used as a proxy for temperature and climate conditions at that time.
C)12C is very rare in nature.When it does appear in plant material,it is indicative of climate anomalies.By measuring the 13C/12C ratios,scientists can determine whether the plants were alive during normal or anomalous conditions.
D)Scientists can determine if conditions were wetter or drier,warmer or cooler,but analyzing the ratio of 12C to 13C.
E)By analyzing the ratio of 13C/12C in marine phytoplankton,the source of the water in which the organisms resided can be determined.

Question 20

The key elements of climate change science include which of the following?

A)study of past climates,only
B)measurement of current climatic change,only
C)projection of future climate scenarios,only
D)establishing policy on CO2 emissions
E)study of past climates,measurement of current climatic change,and projection of future climate scenarios

Question 21

Changes in the Earth's elliptical orbit around the Sun is called

A)eccentricity.
B)obliquity.
C)precession.
D)inclination.
E)declination.

Question 22

Changes in Earth's elliptical orbit around the Sun (eccentricity)varies over a year cycle.

A)12.000
B)175,000
C)41,000
D)100,000
E)26,000

Question 23

Obliquity,i.e.variations in the Earth's axial tilt,range from to over a 41,000-year cycle.

A)11.5° to 15.5°
B)20.5° to 23.5°
C)21.5° to 24.5°
D)23.5° to 27.5°
E)10.5° to 24.5°

Question 24

Radiocarbon dating of organic material may provide a climate record for up to years before present.

A)10,000
B)25,000
C)50,000
D)75,000
E)150,000

Question 25

Which of the following accurately describes the use of tree rings for studying past climates (dendroclimatology)?

A)The width of annual tree rings indicates the climatic conditions;wider rings suggest favorable conditions,whereas narrower rings suggest harsher conditions.
B)Because most trees only live 60 to 100 years,dendrochronology can only serve as a climate record for recent history and are primarily used to supplement instrument data.
C)Tree ring analysis is best suited for short-lived species because it enables scientists to quickly and easily correlate tree ring growth to documented climatic conditions.
D)Dendrochronology is primarily used in the tropical regions,where one can easily correlate a tree species' age with the climatic conditions there.
E)The age of trees can be determined by tree ring analysis.By establishing the age of long-lived trees,one can determine the climate conditions of the area the year the tree sprouted.

Question 26

How do scientists use lake sediments to study past climates?

A)Isotopic analysis of the relative proportions of 18O to 16O enable determination of evaporation rates from ancient lakes.
B)Lake sediments contain organic materials that can be identified and radiocarbon dated,giving insight into past plant communities and climatic conditions.
C)During warmer conditions,lake sediments form wider rings,whereas in cooler conditions,these rings are narrower.
D)The amount and type of pollen in lake sediments is an indication of the macrovertebrate assemblages that dominated an area.
E)Lake sediment analysis is used to determine which fish species have persisted in a particular lake over long periods of time.

Question 27

The Medieval Climate Anomaly was

A)a mild climate episode that lasted from 800 to 1200 and involved warmer than normal conditions in the North Atlantic region (e.g.Greenland and Iceland).
B)the current period of unprecedented warming that has occurred since 1980.
C)a warming trend that occurred from the Last Glacial Maximum until the Little Ice Age (1250).
D)a global cooling trend that lasted from approximately 1250 to 1850.
E)higher than average temperatures throughout Asia,but mostly affecting China,that occurred during the Classical Chinese Medieval Period.

Question 28

In the case of radiocarbon dating of organic material,the half-life of 14C is

A)1,255 years.
B)5,730 years.
C)15,397 years.
D)75,000 years.
E)113,257 years.

Question 29

In which of the following ways is the study of tree rings,speleothems,and corals for understanding past climatic conditions similar?

A)The chronology each can provide only dates back to a maximum of 1,000 years and are,therefore,only useful for relatively recent climatic trends.
B)Each have growth bands,yielding evidence of the conditions under which they formed and grew.
C)The fossilized form of each is used for understanding past climatic conditions.
D)Each are composed of organic materials and are therefore used solely for radiocarbon dating.
E)Both are examples of macrofossils and can be used to determine plant and animal assemblages of bygone times.

Question 30

Which climate reconstruction methods provides the longest record of Earth's climate history?

A)carbon isotope analysis
B)dendrochronology
C)speleothem analysis
D)ice cores
E)ocean sediment cores

Question 31

The Maunder minimum during the Little Ice Age has been linked to

A)a period of low sunspot activity from 1645 to 1715.
B)changes in Earth's axial tilt (obliquity).
C)a cooling of the Gulf Stream from rapid glacial melt in Greenland.
D)volcanic activity and multiyear changes in global circulation.
E)changes in Earth's orbital shape (eccentricity).

Question 32

Since the Industrial Revolution,

A)human population growth rates have decreased with a subsequent decrease in the warming trend that characterized pre-Industrial Revolution times.
B)global temperatures rapidly increased,then steadied out over the past 25 to 30 years.
C)global temperatures have continued to warm at accelerating rates.
D)no observable warming or cooling trends have occurred,rather temperatures have oscillated between warm and cold periods.
E)sun spot activity has accelerated,resulting in an apparent warming that will subside when this activity ceases.

Question 33

The is the most recent epoch of repeated glaciation on the Earth.

A)Holocene
B)Pleistocene
C)Pliocene
D)Miocene
E)Oligocene

Question 34

Milankovitch cycles refer to

A)changes in Earth-Sun relationships,namely the Earth's orbit around the sun,the Earth's axial rotation,and the Earth's axial tilt.
B)cyclical changes in solar irradiance caused by increases and decreases in sunspot activity.
C)increases and decreases in atmospheric gases and aerosols,primarily caused by natural activity such as volcanic activity and changes in net primary productivity.
D)tectonic changes in continental positions.
E)topographic changes from orogeny,erosion,and mass wasting.

Question 35

Changes in the orientation of the Earth's axis over a 26,000-year cycle is known as

A)eccentricity.
B)obliquity.
C)precession.
D)inclination.
E)declination.

Question 36

The Younger Dryas refers to

A)an interglacial period,characterized by a general warming trend,lasting since the last glacial maximum (LGM)to the present.
B)a global cooling episode,lasting from approximately A.D.1250 to 1850.
C)a brief return to near-glacial conditions during the transition period from the last glacial period to the present interglacial period.
D)a 400-year period,from A.D.800 to 1200,characterized by warmer than normal conditions in the North Atlantic region (e.g.Greenland and Iceland).
E)any interglacial period lasting more the 100 years.

Question 37

Temperature impacts of aerosols from volcanic eruptions The graph shows that from 1850 to 2000,five large volcanic eruptions have

A)caused a sudden rise in global temperatures,often lasting a decade or more.
B)led to dramatic increases in regional temperatures over the past century.
C)increased the amount of acid deposition in areas surrounding the eruptions.
D)had no noticeable effects on global temperatures,only local and regional temperatures.
E)resulted in lowered global temperatures for several years.

Question 38

Mineral deposits within caves and caverns are known as

A)earlywood.
B)latewood.
C)varves.
D)speleothems.
E)foraminifera

Question 39

The Little Ice Age likely resulted from

A)changes in Earth's orbital shape (eccentricity).
B)changes in Earth's axial tilt (obliquity).
C)a cooling of the Gulf Stream from rapid glacial melt in Greenland.
D)solar activity,volcanic activity and/or multiyear changes in global circulation.
E)the Pleistocene megafauna extinction.

Question 40

The last glacial maximum (LGM)occurred approximately years ago.

A)10,000
B)20,000
C)50,000
D)110,000
E)150,000

Question 41

As air temperatures increase,evaporation increases.Warmer temperatures also increase the capacity to absorb water vapor.More water vapor in the atmosphere accelerates the greenhouse effect.As temperatures increase further,more water vapor can enter the atmosphere,causing temperatures to increase even more.This is an example of a(n)

A)positive feedback loop.
B)negative feedback loop.
C)threshold.
D)static state.
E)equilibrium state.

Question 42

Since 1880,the years with the highest land surface temperature were

A)1990 and 2000.
B)2010,2014,and 2015.
C)1985 and 1992.
D)1900,1940,and 1962.
E)1910,1940,and 1950.

Question 43

Seasonal fluctuations in CO2 emissions reflect

A)summer melting in the tundra.
B)geothermal activity,which is highest in the fall.
C)increased fuel use for home and building heat in winter months.
D)reduction of sea ice cover and associated decrease in albedo in the summer.
E)seasonal changes in vegetation cover.

Question 44

As permafrost thaws,increased microbial activity in the soils results in the release of more carbon to the atmosphere.More carbon in the atmosphere accelerated the greenhouse effect.This is known as the

A)ice-albedo feedback.
B)water-vapor feedback.
C)permafrost-carbon feedback.
D)wildfire-carbon feedback.
E)CO2-weathering feedback.

Question 45

Which of the following is not considered a mechanism of natural climate change?

A)changes in Earth-Sun relationships
B)movement of continents via plate tectonics
C)volcanic eruptions
D)solar variability
E)the burning of fossil fuels

Question 46

The rate of sea-level rise

A)is higher than predicted by most climate models,though appears to be decreasing.
B)is lower than predicted by most climate models,and appears to be decreasing.
C)is lower than predicted by most climate models,though appear to be accelerating.
D)has remained constant throughout the past century,though appears to be accelerating.
E)is higher than predicted by most climate models,and appears to be accelerating.

Question 47

The 650,000-year record for carbon dioxide (CO2)Climate reconstructions indicate that carbon dioxide (CO₂)levels

A)are at the highest levels now of any time during the past 650,000 years.
B)have consistently decreased over the past 650,000 years.
C)were highest approximately 350,000 years ago and have decreased since.
D)have fluctuated over the past 650,000 years,so recent upward trends are not a concern.
E)have steadily increased (with some minor fluctuations)over the past 350,000 years.

Question 48

As permafrost thaws,increased microbial activity in the soils results in the release of more carbon to the atmosphere.More carbon in the atmosphere accelerated the greenhouse effect.As temperatures increase further,more carbon can enter the atmosphere,causing temperatures to increase even more.This is an example of a(n)

A)positive feedback loop.
B)negative feedback loop.
C)threshold.
D)static state.
E)equilibrium state.

Question 49

Which of the following is correct regarding Arctic sea ice?

A)Until recently,seasonal variations in sea ice extent were rare.
B)Summer sea ice reached its minimum extent in 2001 and has gradually increased since then.
C)Since 1979,summer sea ice minimum extent and winter sea ice maximum extent have declined.
D)In the summer,most to all sea ice melts,only to refreeze in the winter.However,less water has been refreezing over the past decade.
E)Because of high latitudes,sea ice remains throughout the year.However,for the past 30 years,the extent of sea ice has diminished.

Question 50

Which of the following is not considered an important carbon sink?

A)oceans
B)rocks
C)forests
D)farmlands
E)soils

Question 51

Global land-ocean temperature trends,1880-2015.The graph shows change in global surface temperatures relative to the 1951-1980 global average.The gray bars represent uncertainty in the measurements.Note the inclusion of both annual average temperature anomalies and 5-year mean temperature anomalies;together,they give a sense of overall trends.[Based on data from NASA/GISS;available at http:// climate.nasa.gov/vital-signs/global-temperature/.] Since 1880,global land-ocean temperatures have shown

A)a warming trend.
B)a cooling trend.
C)an oscillation between warming and cooling.
D)a cooling trend until 1950,then a rapid warming trend.
E)no trend.

Question 52

As air temperatures increase,evaporation increases.Warmer temperatures also increase the capacity to absorb water vapor.More water vapor in the atmosphere accelerates the greenhouse effect.This is known as the

A)ice-albedo feedback.
B)water-vapor feedback.
C)permafrost-carbon feedback.
D)wildfire-carbon feedback.
E)CO2-weathering feedback.

Question 53

Worldwide annual glacial mass balance Annual mass balance of glaciers worldwide from 1980 to 2012

A)indicates a positive cumulative annual mass balance.
B)shows a negative cumulative annual mass balance.
C)has fluctuated greatly,with some positive and some negative years.
D)trends near zero,indicating snowfall and melting are mostly equal.
E)was positive through 1995 and has been slightly negative since.

Question 54

The process of chemical weathering transfers CO2 from the atmosphere to the lithosphere and hydrosphere,thereby providing a natural buffer to climatic change over long time scales.This is an example of a(n)

A)positive feedback loop.
B)negative feedback loop.
C)threshold.
D)static state.
E)equilibrium state.

Question 55

Key Indicators of climatic warming Which of the following is not a key indicator of present climate change?

A)increasing sea-surface temperatures
B)decreasing mass of glaciers and ice sheets
C)decreasing extent of sea ice
D)rising sea level
E)decreasing atmospheric water vapor

Question 56

The primary factors contributing to present sea-level rise are

A)melting of land ice and thermal expansion of seawater.
B)melting of land ice and melting of sea ice.
C)melting of sea ice and thermal expansion of seawater.
D)thermal expansion of seawater,only.
E)melting of land ice,only.

Question 57

According to readings from the Mauna Loa Observatory,CO2 concentrations currently exceed .

A)100-ppm
B)200-ppm
C)300-ppm
D)400-ppm
E)500-ppm

Question 58

During the last century,sea level

A)dropped 3 to 5 cm (1.18 to 3.15 in. ).
B)remained fairly constant,though some areas (such at the Atlantic coast)experienced moderate rises.
C)rose 30 to 46 cm (11.8 to 18 in. ).
D)rose 17 to 21 cm (6.7 to 8.3 in. ).
E)dropped 10 to 13 cm (3.93 to 5.12 in. ).

Question 59

The is a graph which plots monthly averages of CO2 concentrations since 1958.

A)Keeling Curve
B)PETM
C)Maunder minimum
D)Younger Dryas
E)MCA

Question 60

Since 1973,global average specific humidity has

A)increased by about 0.5 g/kg.
B)increased by about 1.0 g/kg.
C)decreased by about 0.1g/kg.
D)decreased by about 0.5 g/kg.
E)increased by about 0.1g/kg.

Question 61

General Circulation Models (GCMs)

A)are primarily two dimensional models for several weather forecasting.
B)predict specific future temperatures based on various scenarios.
C)can currently only represent atmospheric conditions,though future models will incorporate ocean circulation.
D)typically have very fine resolution (e.g. ,30 m).
E)offer scenarios of future global warming based on societal choices.

Question 62

As of 2014,which country led the world in CO2 emissions?

A)the United States
B)Germany
C)Canada
D)France
E)China

Question 63

Which of the following is incorrect?

A)Carbon dioxide (CO2)concentrations are growing more quickly today than is seen throughout most of the long-term climate record.
B)Scientists can say with 100% certainty that current climate change can be solely attributed to anthropogenic causes.
C)Increased atmospheric carbon dioxide (CO2)causes warming temperatures.
D)Human activities have increased the amount of greenhouse gases in the atmosphere.
E)The rise of global temperatures causes global climate change.

Question 64

The most abundant greenhouse gas in the Earth's atmosphere is

A)carbon dioxide (CO2).
B)methane (CH4).
C)water vapor (H2O).
D)nitrous oxide (N2O).
E)sulfur dioxide (SO2).

Question 65

Of the following greenhouse gases,which have actually decreased in atmospheric concentrations during the past 30 years?

A)methane (CH4)
B)carbon dioxide (CO2)
C)chlorofluorocarbons (CFCs)
D)nitrous oxides (NO)
E)hydrofluorocarbons (HFCs)

Question 66

Radiative forcing (climate forcing)refers to

A)the power of electromagnetic radiation per unit area.
B)the amount by which some perturbation causes Earth's energy balance to deviate from zero.
C)a measurement of solar radiation energy received on a given surface area.
D)the contribution of each greenhouse gas to global warming.
E)the amount of time,on average,a greenhouse gas resides in the atmosphere.

Question 67

Scientists attribute the recent rise in atmospheric concentrations of nitrous oxide (N2O)primarily to

A)automobile combustion.
B)agricultural activity.
C)wastewater management.
D)industrial practices.
E)drainage of wetlands.

Question 68

Approximately of total atmospheric methane comes from anthropogenic sources.

A)half
B)two-thirds
C)one-eighth
D)one-third
E)25%

Question 69

According to the IPCC Fifth Assessment Report,which of the following is virtually certain to occur?

A)The frequency of heavy precipitation events will decrease.
B)Extreme high sea-level events will decrease due to increase evaporation.
C)The ocean's conveyer built will strengthen.
D)The extent of permafrost will increase.
E)Ocean acidification will increase as the atmosphere accumulates more CO2.

Question 70

General circulation models (GCMs)of the atmosphere

A)are pre-computer based models that estimated atmospheric and oceanic circulation and are now being used to study climate change.
B)are highly simplistic models that use one or two variables to test the veracity of climate proxies,such as ice core and ocean sediment core samples.
C)are based on statistical three-dimensional grids that characterize portions of the atmosphere and ocean in terms of climate-related variables.
D)calculate the concentrations of greenhouse gases in the atmosphere based on data from weather stations located around the globe.
E)are a combined GIS and remote sensing technique to monitor atmospheric and ocean currents.

Question 71

Concentrations of methane gas since 1985 Present atmospheric methane (CH₄)concentrations are at approximately_ ppb.

A)250
B)750
C)1000
D)1500
E)1800

Question 72

According to models developed by NOAA,given the extreme,global sea level may rise as high as

A)0.2 m (0.7 ft).
B)0.5 m (1.6 ft).
C)1.2 m (3.9 ft).
D)2.0 m (6.6 ft).
E)3.2 m (10.5 m).

Question 73

Why is the thawing of permafrost in the Arctic of special concern?

A)Thawing permafrost will lead to increased solifluction.
B)Most permafrost is in the Southern Hemisphere where the thawing is contributing to a decline in global biodiversity.
C)Wet peatland forests will be further drained and logged as the conditions are conducive for such activity.
D)Permafrost thawing releases massive amounts of methane into the atmosphere,which could further amplify warming.
E)As permafrost thaws,it will contribute to global sea level rise.

Question 74

How have scientists used isotopic analysis to determine the rise of atmospheric CO2 is mostly from the burning of fossil fuels?

A)Since 14C is an unstable isotope,scientists have dated the atmospheric carbon to the period since the Industrial Revolution.
B)Both coal and oil contain a high proportion of 14C.By analyzing,14C /12C ratios,scientists have been able to determine the source based on this fact.
C)The low proportions of 13C and 14C within atmospheric CO2 indicates the source is fossil carbon.
D)14C concentrations are much higher in urban areas than in rural areas,indicating fossil fuels must have a higher 14C /12C ratio than carbon from other sources.
E)The relative low amount of 12C in atmospheric carbon demonstrates that the carbon dates from about the 1800s or later.

Question 75

The residence time of methane (CH4)in the atmosphere is

A)50 to 200 years.
B)45 days.
C)approximately 90 days.
D)12 years.
E)500 years.

Question 76

Greenhouse gases: Relative percentages of radiative forcing Which of the following gases accounts for the largest amount of radiative forcing?

A)carbon dioxide (CO2)
B)nitrous oxides (N2O)
C)chlorofluorocarbons (CFCs)
D)methane (CH4)
E)hydrofluorocarbons (HFCs)

Question 77

Which of the following has a negative radiative forcing (i.e.cools the planet)?

A)carbon dioxide (CO2)
B)nitrous oxides (N2O)
C)stratospheric ozone (O3)
D)methane (CH4)
E)chlorofluorocarbons (CFCs)

Question 78

The residence time of carbon dioxide (CO2)in the atmosphere is

A)50 to 200 years.
B)45 days.
C)approximately 90 days.
D)12 years.
E)500 years.

Question 79

The IPCC Fifth Assessment Report concludes

A)that while climate change is occurring,it is largely natural climate fluctuations.
B)much uncertainty still remains related to the warming of the climate.
C)scientists are 95 to 100% certain that human activities are the primary cause of present climate change.
D)no consensus exists on whether current climate change is natural or anthropogenic.
E)the observed climatic changes of the past half century are similar to changes that have occurred throughout the past couple hundreds of years.

Question 80

Fossil fuel burning accounts for over percent of CO2 emissions.

A)10
B)20
C)50
D)70
E)85