InstructionsYour essay answer should be clear and succinct, amounting to perhaps 3-5 sentences totaling 50 to 80 words; longer essays are strongly discouraged. It is recommended that you prepare your answer in a separate document from which you copy it into Canvas.Question 1 5 ptsIs the temperature increase associated with increased concentrations of atmospheric CO2 globally uniform, or does it vary between continents and oceans, or show other spatial variations?A strong answer will describe the variations in temperature changes in different regions, ideally citing values for temperature anomalies in °C relative to the 1951-1980 baseline. It will compare the temperature changes for continents and oceans and identify regions where the changes are most extreme.Question 2 3 ptsMatch the three processes that are associated with climate change resulting from increasing CO2 with the specific feedbacks that they trigger.Loss of Arctic sea ice [ Choose ] Increased ocean productivity Increased albedo Increased calcification Sea level fall Increased dust fluxes Sea level rise Decreased albedo Coral bleaching and decreased calcification Ocean acidification [ Choose ] Increased ocean productivity Increased albedo Increased calcification Sea level fall Increased dust fluxes Sea level rise Decreased albedo Coral bleaching and decreased calcification Increasing ocean temperatures [ Choose ] Increased ocean productivity Increased albedo Increased calcification Sea level fall Increased dust fluxes Sea level rise Decreased albedo Coral bleaching and decreased calcification Question 3 2 ptsIce cores and/or marine sediments provide records of past glacial/interglacial cycles associated with major changes in ice volume. Select the two aspects of these climate cycles that are characteristic of these glacial/interglacial cycles.Stepwise cooling and rapid warmingRapid cooling and gradual warmingIncreased dust during glaciationsIncreased dust during interglacialsHigher levels of CO2 during glacialsHigher levels of CO2 associated with lower temperaturesDecreased 18O in forams during cold intervals
Oceans & Global Environment
Module 19: Global Climate Change
•Past and Future Climate:
• Records of paleoclimate, including ancient levels
of atmospheric CO2 from ice cores and ocean
temperatures from various climate proxies in
marine sediments – linking CO2 and temperature.
• Fe and ocean productivity – CO2 sequestration.
• Scenarios for future global temperature increase.
Key Concepts?
Annual layers
of ice core
•Understanding of Global Climate Change:
• Relating changes in atmospheric CO2 to global temperatures
based on paleoclimate records.
• Predicting future temperature rise based on CO2 emissions.
Glacial-Interglacial Cycles
Climate Records from Ice Cores
•Temporal trends in temperature (δH), in CO2
(air bubbles) & dust influx in ice layers
•Record shows stepwise cooling & rapid
warming. Vostock, Antarctica
4
MIS5e
0
-2
-4
280
-6
CO2 (ppmv)
z
Climatic Optimum)
2
260
ΔTemperature (°C)
Temperature trend
shows peaks during
the Eemian (MIS
5e; last
interglacial) & for
the HCO (Holocene
HCO
-8
240
220
200
Higher dust
during glacials
Air bubbles in ice
400
300
200
Age (kyr)
100
0
Dust (ppm)
1.5
1.2
0.9
0.6
0.3
Ice core
showing
annual
layers
Iron associated
with dust
Glacial-Interglacial Cycles
Climate Records from Sediments
18O in oceans & marine
Increased
•
fauna (forams) during cold intervals.
•Record of temperature & ice volume.
Warmer
17
15
13
11
9
7
Globigerinoides
sacculifer
-3
5
1
-1
0
1
Cooler
18
16
900
800
700
600
1-18 refer to globally correlated
marine isotopic stages (MIS)
14
12
500
10
400
Age (Kyr)
8
300
6
2
2
Oxygen isotope ratio
-2
3
200
100
0
MIS 2 is the last glacial
maximum (LGM)
Ocean Productivity & Iron
Iron Fertilization to Sequester Carbon
Ocean
productivity
is often Fe
limited
Concept: increase Fe, increase
productivity, increase carbon
assimilation & burial
Experiment
in progress
in S. Pacific
Future Global Temperatures
Measurements & Predictions
•Global climate models derive estimates from
scenarios with global vs. regional differences &
economic vs. environmental focus.
Average temperature increases
modeled for different
socioeconomic scenarios
dependent on political actions
4 scenarios used by IPCC
based on different
parameters characterized as:
A1, rapid economic growth;
B1, global environmental
sustainability;
A2, regionally oriented
economic development;
B2 local environmental
sustainability
All scenarios lead to predictions of
significant warming, although the
magnitude varies significantly
Oceans & Global Environment
Module 19: Global Climate Change
•Temperature Changes:
Arctic
meltwater
lakes
• Global temperature records show
spatial variations in progressive warming.
• Sea level rise reflects several factors.
• Evidence for glacial melting, changes in
Arctic sea ice, and feedback warming loop.
• Effect of meltwater on global circulation.
• Coastal impacts of sea level rise.
Key Concepts?
•Understanding of Global Climate Change:
Sea level
rise
• Increase in atmospheric CO2 increases temperatures leading
to glacial melting and sea level rise.
G131 Oceans & Global Environment
Evidence of Climate Change
Temperature Measurements
• What do these data reveal?
Global
compilation of
temperature
measurements
since records
began. The data
for all locations
are averaged for
each year and
plotted relative
to the average
values from
1961-1990.
Average Global Temperature (1861-2003)
Cooler 19th Century
last vestige of “Little
ice age”
Smoothed curve provides
10-year average
Progressive
increase
Reference line is
1961-1990
average values
Global Temperature Changes
Colors
reflect
annual
averaged
temperature
differences
relative to
the average
for the years
19511980.
Note
regional
variations &
magnitude of
change in
polar
regions.
Global Sea Level
Major Recent Rise
•Multiple factors operating
on different time scales:
Time/scale
effects of
controls on
sea level
• Ice melting (glaciers, Greenland).
• Thermal expansion.
• Tectonic uplift & subsidence.
Recent global
rise in sea level
Relative size of
contributions
to global rise in
sea level
Extreme Warming of Arctic
Melting of Greenland Ice Sheet
•Major increase in
melting in recent
years & rate of
increase in melting.
Warming in Arctic region exceeds
increases elsewhere on Earth
Jan 2010 vs. 1951-1980 ave.
Surface
ponds
Surface water descending
into a moulin, a shaft to
the base of the ice sheet
Area of
melting ice
increased
dramatically
from 1992
to 2002
Arctic Ice Sheet
Thinning ice opens
shipping routes
Progressive Decrease in Size
•Seasonal expansion & contraction
of ice sheet; ice sheet smaller
& thinner, no ice by 2055?
Water absorbs
more sunlight
than ice
Sea ice
thickness
Satellite image of Arctic ice
Climate Change in the Arctic
Glacial Retreat, Less Ice Cover
•Melting of glaciers in
Greenland.
•Reduced ice cover in
Arctic (lower albedo).
•Feedback warming loop.
Terminus of Jakobshavn
Isbrae has retreated
Greenland
glacier
Water absorbs more
sunlight than ice
Steadfast decrease
in Arctic ice cover
Modern Climate Trends
Decrease in Global Ice, Glacial Retreat
•Melting of ice sheets in Antarctica & Arctic.
•Widespread retreat & thinning
of glaciers on all continents.
Decrease in
Global
reduction
in
ice.
•
ice caps
1993
Examples of glacial retreat
1993
2001
2000
Nef, Chile
Triftgletscher, Switzerland
Mt Kilimanjaro
Fate of Greenland Meltwater
Potential Influence on Global Conveyor
•Meltwater affects deep water production.
Presence of
freshwater in
the N. Atlantic
restricts
northward flow
of surface
water and
results in
change in deep
water
production break in
conveyor belt
Ancient
precedents
for this
process
Increase in meltwater could
switch off global conveyor
Climate Change: Coastal Impacts
Direct & Indirect Effects
•Variety of Consequences
associated with climate
affect coastal environments.
Salt marshes
migrate inland
as sea level
rises
• For example, hurricanes.
Coastal systems are affected both directly & indirectly by
climate change manifest in marine & terrestrial
influences
Barrier islands: can be protected
from rising sea level by artificial
fill in backshore – but no
protection for hurricanes
Oceans & Global Environment
Module 19: Global Climate Change
•Atmospheric CO2:
• Progressive increase in atmospheric
Keeling Curve
levels of CO2 resulting from fossil
fuel combustion – Keeling Curve.
• Annual cycle of fluctuations in CO2
attributable to plants.
• Effects of increased CO2: warming, sea level rise &
coastal
flooding, severe storms, ocean acidification, coral
bleaching.
Key Concepts?
•Understanding of Global Climate Change:
• Increase in atmospheric levels of CO2 as a driver of
climate
change via temperature & feedback loops. G131 Oceans
& Global Environment
Atmospheric CO2 Levels
Modern Trend of Increasing CO2
•Historical records & Mauna Loa measurements.
Global CO2 levels
Pre-industrial level
~280 ppmv
CO2 Increase (ppmv)
~280 pre-industrial
~315 in 1958
~385 in 2008
~70 increase (>22%)over
50 yr
Keeling Curve
Monitoring began
in 1958
Atmospheric CO2
(Mauna Loa, HI)
Annual cycle associated
with carbon uptake &
release by plants
Effects of Increased CO2 Levels
The likely outcomes from
increased atmospheric CO2
concentrations include a
series of consequences for
the ocean & for coastal
regions
Direct (solid arrows) and indirect (dashed arrows)
consequences
of increased atmospheric CO2 concentrations
Ocean Acidification
Coral Bleaching
•Elevated CO2 reduces rates
of calcification.
•Challenge to reef
diversity.
Diversity of
coral species
off Australia
Bleached coral
Coral Bleaching in 1998
Characterized by
elevated sea surface
temperatures
…
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