Page 390 - Earth's Climate Past and Future

366 GLOSSARY

correlated with historical observations of temperature and closed system A system that does not exchange matter
precipitation change. across its boundaries.
calorie The amount of energy required to raise the tempera- coccoliths Tiny disklike plates of CaCO produced by algae
3
ture of 1 gram of water by 1°C. living in ocean surface waters.
calving The process by which a large block of ice breaks off COHMAP (Cooperative Holocene Mapping Project) A
from the margin of a glacier and forms an iceberg that floats cooperative research effort in the 1980s and 1990s that
in the ocean or in a lake. evaluated the causes of climate change during the most recent
deglaciation by comparing geologic data with climate model
carbon isotopes Isotopes of the element carbon with differ-
ent atomic masses, used to trace the movement of different simulations.
kinds of carbon through Earth’s climate system (12C and conifer forest Forest comprising evergreen, needle-bearing
13C) or to measure elapsed time indicated by radioactive trees.
decay (14C and 12C). continental collision The occasional result of plate tectonic
cardinal points The two equinoxes (spring and autumn) and processes in which two continents are carried into each other
the two solstices (summer and winter) in Earth’s annual revo- by plate movements, creating high plateaus.
lution around the Sun. continental crust A layer of rock averaging 30 km thick,
Celsius A temperature scale on which water freezes at 0° and having the composition of granite, and comprising the conti-
boils at 100°. nents.
channeled scablands A region in Idaho and eastern Wash- continental ice sheet A mass of ice kilometers thick covering
ington State in which water impounded in glacial lakes a continent or a large portion of a continent and moving inde-
suddenly rushed out and reshaped the landscape, perhaps pendently of the underlying bedrock topography.
repeatedly. continental shelf A shallowly submerged extension of a con-
tinent beneath the ocean.
chemical weathering Dissolving or other alteration of min-
erals to a different form by chemical reactions in the presence continental slope A ramplike structural edge of a continent
of water. that slopes into the deep ocean.
chlorofluorocarbons (CFCs) Synthetic chemical com- control case A model simulation run to reproduce Earth’s
pounds generated by human activity and containing chlorine present-day climate from its present-day boundary conditions.
or fluorine that can destroy ozone in the stratosphere. convection The rising motion of a fluid (air or water) pro-
CLIMAP (Climatic Mapping and Prediction Project) A large duced when its bottom layer is heated, accompanied by sink-
cooperative research group during the 1970s and 1980s that ing of cooler, denser fluid elsewhere.
first mapped the surface of the ice-age Earth. convergent margin A boundary between two lithospheric
climate Fluctuations in Earth’s air, water, ice, vegetation, and plates that move toward each other and cause a collision of
other properties on time scales longer than one year. continents or subduction of one plate beneath the other.
climate data output The climatic properties (such as tem- coral bands Annual banding in the structure of corals caused
perature, precipitation, and winds) that are produced by simu- by seasonal changes in sunlight, water temperature, and nutri-
lations with climate models. ent content.
Cordilleran ice sheet A small ice sheet that covered western
climate point The point where the equilibrium line that
separates net ice melting from net ice accumulation intercepts Canada and the far northwestern United States during
sea level. orbital-scale glaciation cycles.
Coriolis effect The apparent deflection of a fluid (air or
climate proxy A quantifiable indicator of climate change
contained in a climate archive and covering an interval that water) from a straight-line path because of Earth’s rotation.
precedes direct instrument measurements of climate. The deflection is to the right in the northern hemisphere and
to the left in the southern hemisphere.
climate science The study of climate changes and their CO fertilization effect The increased growth rate of plants
causes. 2
caused by adding CO to the atmosphere.
2
climate simulation The use of a numerical model to repro- CO saturation The point at which the concentration of
duce climate for a specified set of boundary conditions. 2
CO in the atmosphere reaches so high a level that additional
2
climate system The components of Earth (air, water, ice, amounts do not increase the greenhouse effect.
vegetation, and land surfaces) that participate in climate Cretaceous An interval of warmer climates and higher sea
change.
level between 135 and 65 Myr ago.
climatic hypothesis of human evolution The hypothesis
that a trend toward drier climates in Africa changed forest to Dansgaard-Oeschger cycles Oscillations in various proper-
savanna or grasslands and accelerated human evolution.
ties (including dust and isotopes of oxygen) recorded in
clipped responses Climatic responses that are truncated (cut Greenland ice at intervals of 2000 to 7000 years during glacial
off) in one direction. intervals.