Snowball Earth" refers to
an extreme icehouse climate from 600 to 700 million years ago with ice sheets extending to the tropics.
Which of the following is incorrect?
Scientists can say with 100% certainty that current climate change can be solely attributed to anthropogenic causes.
Scientists use ________ to study past climates, using ________ to reconstruct climates that extend back further than our present instrumentation allows.
proxy methods; climate proxies
As of 2014, which country led the world in CO2 emissions?
china
In which of the following ways is the study of tree rings, speleothems, and corals for understanding past climatic conditions similar?
Each have growth bands, yielding evidence of the conditions under which they formed and grew.
Since the Industrial Revolution,
global temperatures have continued to warm at accelerating rates.
The Little Ice Age likely resulted from
solar activity, volcanic activity and/or multiyear changes in global circulation.
Scientists attribute the recent rise in atmospheric concentrations of nitrous oxide (N2O) primarily to
agricultural activity.
Milankovitch cycles refer to
changes in Earth-Sun relationships, namely the Earth's orbit around the sun, the Earth's axial rotation, and the Earth's axial tilt.
The ________ is a graph which plots monthly averages of CO2 concentrations since 1958.
keeling curve
Radiocarbon dating of organic material may provide a climate record for up to ________ years before present.
50,000
Approximately ________ of total atmospheric methane comes from anthropogenic sources.
two-thirds
Over the span of 70 million years, the Earth's climate
was much warmer 70 m.y.a. compared to the present.
Ice cores provide a climate record for the past ________ years.
800,000
Which of the following accurately describes 18O/16O ratios of ice sheets?
A higher ratio of oceanic 18O to 16O indicates a warmer period during which more 18O evaporates and precipitates onto ice sheets.
According to readings from the Mauna Loa Observatory, CO2 concentrations currently exceed ________.
400-ppm
Since 1880, the years with the highest land surface temperature were
2010, 2014, and 2015.
The Maunder minimum during the Little Ice Age has been linked to
a period of low sunspot activity from 1645 to 1715.
Which of the following gases accounts for the largest amount of radiative forcing?
carbon dioxide (CO2)
The residence time of carbon dioxide (CO2) in the atmosphere is
50 to 200 years.
Ocean sediment cores provide a climate record for the past ________ years.
70 million
The 16O evaporates ________ than 18O, and condenses ________.
more easily; less easily
A lower 18O/16O ratio in ocean sediment cores indicates a(n) ________ climate, whereas a higher 18O/16O ratio indicates a(n) ________ climate.
warmer; cooler
In the case of radiocarbon dating of organic material, the half-life of 14C is
5,730 years.
Annual mass balance of glaciers worldwide from 1980 to 2012
shows a negative cumulative annual mass balance.
Obliquity, i.e. variations in the Earth's axial tilt, range from ________ to ________ over a 41,000-year cycle.
21.5� to 24.5�
The primary factors contributing to present sea-level rise are
melting of land ice and thermal expansion of seawater.
The key elements of climate change science include which of the following?
study of past climates, measurement of current climatic change, and projection of future climate scenarios
General circulation models (GCMs) of the atmosphere
are based on statistical three-dimensional grids that characterize portions of the atmosphere and ocean in terms of climate-related variables.
How have scientists used isotopic analysis to determine the rise of atmospheric CO2 is mostly from the burning of fossil fuels?
The low proportions of 13C and 14C within atmospheric CO2 indicates the source is fossil carbon.
Why is the thawing of permafrost in the Arctic of special concern?
Permafrost thawing releases massive amounts of methane into the atmosphere, which could further amplify warming.
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
permafrost-carbon feedback.
Which of the following is correct regarding Arctic sea ice?
Since 1979, summer sea ice minimum extent and winter sea ice maximum extent have declined.
Which of the following is not considered an important carbon sink?
farmlands
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
water-vapor feedback.
The residence time of methane (CH4) in the atmosphere is
12 years.
The last interglacial period with temperatures similar to the present interglacial period was the
125,000 years ago (Eemian interglacial).
Changes in Earth's elliptical orbit around the Sun (eccentricity) varies over a ________ year cycle.
100,000
Which climate reconstruction methods provides the longest record of Earth's climate history?
ocean sediment cores
The rate of sea-level rise
is higher than predicted by most climate models, and appears to be accelerating.
The last glacial maximum (LGM) occurred approximately ________ years ago.
20,000
The Medieval Climate Anomaly was
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).
Which of the following has a negative radiative forcing (i.e. cools the planet)?
stratospheric ozone (O3)
Mineral deposits within caves and caverns are known as
speleothems.
The Younger Dryas refers to
a brief return to near-glacial conditions during the transition period from the last glacial period to the present interglacial period.
Which of the following is not a key indicator of present climate change?
decreasing atmospheric water vapor
The graph shows that from 1850 to 2000, five large volcanic eruptions have
resulted in lowered global temperatures for several years.
How do scientists use lake sediments to study past climates?
Lake sediments contain organic materials that can be identified and radiocarbon dated, giving insight into past plant communities and climatic conditions.
Which of the following is true of 16O and 18O?
Both the 16O and 18O isotopes occur in water molecules.
During the last century, sea level
rose 17 to 21 cm (6.7 to 8.3 in.).
Which of the following is not considered a mechanism of natural climate change?
the burning of fossil fuels
Changes in the orientation of the Earth's axis over a 26,000-year cycle is known as
precession
Which of the following accurately describes the use of tree rings for studying past climates (dendroclimatology)?
The width of annual tree rings indicates the climatic conditions; wider rings suggest favorable conditions, whereas narrower rings suggest harsher conditions.