Earth 114 Lectures 6, 7 And 8

Front 1

the earth was _______ ________ 50 million years ago

Back 1

really warm
the cooling since then has been linked in reduction of atmospheric c02

Front 2

antarctic ice sheet starting developing about _____

Back 2

35 million years ago

Front 3

northern hemisphere ice sheets developed about -_____

Back 3

3 million years ago

Front 4

megafauna thrived in ______ climate

Back 4

pleistocene

Front 5

the pleistocene ice age (in the northern hemisphere) is the one we are currently in..started ____ years ago

Back 5

3 million years ago

marked by GLACIAL CYCLES of advancing and retreating ice sheets

Front 6

eccentricity

Back 6

shape of earth's orbit around the sun

Front 7

obliquity

Back 7

angle of Earth's axis from a line perpendicular to the orbital plane

Front 8

precession

Back 8

wobble of earth's rotational axis

Front 9

warmer northern hemisphere favored by

Back 9

greater tilt, summer at perihelion (closer to sun), less ice forming at 60 degrees latitude

Front 10

colder northern hemisphere favored by

Back 10

less tilt, summer at aphelion (farther from sun)

Front 11

ice cores

Back 11

CO2, CH4, O2 and other gases and dust trapped in layers of ice preserve a detailed record of ancient climates

Ice cores can provide annual (year-by-year) time resolution
Ice core records go back ~800,000 years in the Southern Hemisphere (Antarctica) and ~100,000 years in the Northern Hemisphere (Greenland)

Ice cores can provide information about temperature, atmospheric gas concentrations, dust, and other proxies for paleoclimate

Front 12

greenhouse gases ________ the natural glacial-interglacial cycles through _________

Back 12

amplify; feedback mechanisms

Front 13

glacial/interglacial C02 levels are a ____ feedback

Back 13

positive feedback

Front 14

positive feedback

Back 14

drives a system forward at ever increasing rates (amplifies an initially small effect into a much bigger one)

Example: Ice-albedo feedback is a positive feedback, because a small amount of atmospheric warming will cause more ice to melt, decreasing surface reflectivity, which causes more solar energy to be absorbed at the Earth’s surface, which warms the atmosphere more, melting more ice etc.

Front 15

negative feedback

Back 15

is a stabilizing effect (helps keep the system in check, or from veering too far off in one direction)

Front 16

C02 goes into the _______ during peak ice age periods

Back 16

the oceans probably

Front 17

more sun spots =

Back 17

higher solar irradiance

Front 18

extreme melting in _________ in mid july 2012

Back 18

Greenland

Front 19

holocene

Back 19

era of geology we currently live in?

Front 20

________ sources can explain some of the warming in the early 20th century

Back 20

natural (like volcanoes and solar activity)

Front 21

correlation between sunspots and Earth's temp ________ _________ after 1980

Back 21

falls apart

sunspot activity has weakened slightly, but temperature has increased

Front 22

the ________________________ is the fastest warming place on earth

Back 22

antarctic peninsula

Front 23

6 factors controlling Earth's surface temp and climate

Back 23

• Amount of incoming shortwave radiation from sun (varies with latitude)
• Ice-Albedo Feedback (variable reflectivity of Earth’s surface)
• Specific heat of water (4.18 Jg-1K-1) vs. soil (0.8 Jg-1K-1)
• Elevation (air temperature decreases with elevation)
• “Continentality” (distance from moderating effects of oceans)
• Greenhouse gas and dust levels in the troposphere

Front 24

cryosphere

Back 24

portion of the Earth where H20 is ice

Front 25

3 ice contributions to sea level

Back 25

continental ice sheets, alpine ice sheets, permafrost

snow and sea ice don't really contribute

Front 26

multi year sea ice = perennial sea ice

Back 26

sea ice that builds up over time that does not melt away completely during the summer season

supposed to disappear completely by 2100

Front 27

the arctic sea ice is

Back 27

thinning and shrinking

Front 28

antarctic sea ice

Back 28

no significant trends in antarctic sea ice loss since measurements began

Front 29

_______ antarctic ice loss appears to have accelerated in the past 10 years

Back 29

west

mass loss is through acceleration of ice sheets

Front 30

antarctic ice sheets

Back 30

Antarctic Ice Sheet
AntarcVc
climate
change
•
AntarcVc
temperatures
are
well
below
freezing
(ann.
avg
-­‐58F).
•
Some
regions
of
AntarcVca
have
been
warming
at
5x
global
average
(AntarcVc
Peninsula),
acceleraVng
summerVme
melVng.
•
Concern
here
is
the
acVve
breakup
of
large
ice
shelves
around
the
AntarcVc
Peninsula.
These
ice
shelves
are
floaVng
extensions
of
the
massive
West
AntarcVc
ice
sheet,
which
flows
out
to
sea
from
the
conVnent
via
glacial
ice
‘rivers’.
The
presence
of
ice
shelves
help
to
stabilize
the
ice
sheet
flow
behind
them.
AntarcAc
Peninsula

Front 31

______________ ice shelf has gotten much smaller

Back 31

Larsen B