B.Y.A. = billions of years ago M.Y.A. = millions of years ago Y.A. = years ago
Paleoclimatology
T
he climate of the planet is constantly changing. In approximately two million
years, the Earth has gone through very cold periods, or glaciations, that lasted
thousands of years, alternating with warm periods. Today we live in aninterglacial period that began some 10,000 years ago with an increase in average
global temperature. These climatic changes can be analyzed over time periods
that exceed hundreds of thousands of years. Paleoclimatology uses records
derived from fossils, tree rings, corals, glaciers, and historical
documents to study the climates of the past.80 CLIMATE CHANGE WEATHER AND CLIMATE^81
Inhabitants
Year of founding
Temperature
SurfaceSurface area of the lakeOnly scientists
1957
-67° F (-55° C)
95% ice5,405 square miles
(14,000 sq km)VOSTOK
Latitude 77° S
Longitude 105° ESAMPLES
The zones marked on the
map are places where
scientists have gathered
samples of ice, which were
analyzed in the laboratories.Gas Measurement
Vertical ice cores (or samples) allow
scientists to study the climate of
the past. The nearly 12-foot-long (3.6-
m) ice sample taken at the Russian
Vostok station contains climatic
data going back 420,000 years,
including the concentration of
carbon dioxide, methane, and
other greenhouse gases in the
atmosphere.CLOTHES
protect the scientists from
the weather and prevent the
contamination of samples.Chronology
During the history of the
Earth, climate has changed
greatly, which has had a large effect
not only on the appearance of the
Earth's surface but also on animal
and plant life. This timeline shows the
planet's major climate changes and
their consequences.4.5 B.Y.A.
In the beginning,
there was heat. Life
produces oxygen and
cools the climate.
2.7-1.8 B.Y.A.
Ice covers very
extensive areas.544 M.Y.A.
Glacial climate in a
changing geography.
Extinction of 70 percent
of marine species.330 M.Y.A.
Beginning of a long
period of glaciation.
Ice covers different
geographic areas.245 M.Y.A.
Drought and heat at the
beginning. Abrupt
cooling at the end of the
period. Appearance of
the dinosaurs.65 M.Y.A.
Paleocene and
beginning Eocene: very
warm climate. Middle
Eocene: cooling begins.2 M.Y.A.
The cold continues;
glaciation occurs
every 100,000 years.18,000 Y.A.
begins the last
deglaciation.
Increase in temperature;
melting of ice.1,300-700 Y.A.
Medieval warm period;
in some places warmer
than today. Vikings
arrive in Greenland..550-150 Y.A.
Little Ice Age. Alpine
glaciers advance; more
severe winters.1.6 M.Y.A.
Interglacial. The
beginning of a two-
million-year period.Dronning Maud LandSouth PoleDominion RangeNewall glacierTalos DomeLaw DomeVOSTOKRIDSLittle
AmericaSiple StationKEY
Drillings
Ice sheetsEVALUATION OF GREENHOUSE GASES00.28 0.8 1.72803500.280.31Year 1990Year 17704003002001000Parts per
millionHalocarbons Methane Carbon
dioxideNitrous
oxideHuman Activity
Climate can be divided into before and after the Industrial
Revolution. This graphic shows the progressive increase of
halocarbon gases, methane, carbon dioxide, and nitrous oxide
between 1770 and 1990. It is clear that humans have contributed
to the contamination of the planet.Composition
The lower graphic shows the change in concentration of
methane in the atmosphere in the last 20,000 years until the
end of the preindustrial era. The information collected was estimated
on the basis of ice probes in Greenland and Antarctica.METHANE CONCENTRATIONAntarcticaGreenland0.8
0.7
0.6
0.5
0.4
0.3
0Parts per
millionTime in years before the present0 2.000 4.000 6.000 8.000 10.000 12.00014.000 16.000 18.000 20.000Holocene Glaciation174
(53 m)Feet 177
(54 m)6,024
(1,836 m)6,027
(1,837 m)10,007
(3,050 m)10,010
(3,051 m)ICE CORES
Samples are taken at different depths.
The surface snow becomes more
compact in the lower layers. In the
last layer, there are rocks and sand.280350