met 112 global climate change - lecture 8
DESCRIPTION
MET 112 Global Climate Change - Lecture 8. The Carbon Cycle Dr. Craig Clements San Jos é State University. Outline Earth system perspective Carbon: what’s the big deal? Carbon: exchanges Long term carbon exchanges. Goals. - PowerPoint PPT PresentationTRANSCRIPT
1 MET 112 Global Climate MET 112 Global Climate ChangeChange
MET 112 Global Climate Change - Lecture 8
The Carbon CycleDr. Craig Clements
San José State University
Outline Earth system perspective Carbon: what’s the big deal? Carbon: exchanges Long term carbon exchanges
2 MET 112 Global Climate MET 112 Global Climate ChangeChange
Goals
We want to understand the difference between short term and long term carbon cycle
We want to understand the main components of the long term carbon cycle
3 MET 112 Global Climate MET 112 Global Climate ChangeChange
4 MET 112 Global Climate MET 112 Global Climate ChangeChange
An Earth System Perspective
Earth composed of:– Atmosphere– Hydrosphere– Cryosphere– Land Surfaces– Biosphere
These ‘Machines’ run the Earth
5 MET 112 Global Climate MET 112 Global Climate ChangeChange
The Earth’s history can be characterized by different geologic events or eras.
6 MET 112 Global Climate MET 112 Global Climate ChangeChange
Hydrosphere
Component comprising all liquid water– Surface and subterranean (ground water)
Fresh/Salt water Thus…lakes, streams, rivers, oceans…
Oceans:– Oceans currently cover ~ 70% of earth– Average depth of oceans: 3.5 km– Oceans store large amount of energy– Oceans dissolve carbon dioxide (more later)– Circulation driven by wind systems– Sea Level has varied significantly over Earth’s history– Slow to heat up and cool down
7 MET 112 Global Climate MET 112 Global Climate ChangeChange
Cryosphere
Component comprising all ice– Glaciers– Ice sheets:
Antarctica, Greenland, Patagonia– Sea Ice– Snow Fields
Climate:– Typically high albedo surface– Positive feedback possibility Store large amounts of
water; sea level variations.
9 MET 112 Global Climate MET 112 Global Climate ChangeChange
10 MET 112 Global Climate MET 112 Global Climate ChangeChange
Land Surfaces
Continents Soils surfaces and vegetation Volcanoes
Climate:– Location of continents controls
ocean/atmosphere circulations– Volcanoes return CO2 to atmosphere– Volcanic aerosols affect climate
11 MET 112 Global Climate MET 112 Global Climate ChangeChange
Biosphere
All living organisms; (Biota) Biota- "The living plants and animals of a
region.“ or "The sum total of all organisms alive today”– Marine– Terrestrial
Climate: Photosynthetic process store significant amount
of carbon (from CO2)
12 MET 112 Global Climate MET 112 Global Climate ChangeChange
Interactions Between Components of Earth System
Hydrologic Cycle (Hydrosphere, Surface,and Atmosphere)– Evaporation from surface puts water vapor into
atmosphere– Precipitation transfers water from atmosphere to
surface Cryosphere-Hydrosphere
– When glaciers and ice sheets shrink, sea level rises– When glaciers and ice sheets grow, sea level falls
When ice sheets melt and thus sea levels rise, which components of the earth system are interacting? 1. Atmosphere-Cryosphere2. Atmosphere-Hydropshere3. Hydrosphere-Cryosphere4. Atmosphere-Biosphere5. Hydrosphere-Biosphere
When water from lakes and the ocean evaporates, which components of the earth system are interacting?
1. Land Surface – atmosphere2. Hydrosphere-atmosphere3. Hydrosphere-land surface4. Crysophere-Atmosphere5. Biosphere-Atmosphere
The Earth’s history can be characterized by different geologic events or eras.
16 MET 112 Global Climate MET 112 Global Climate ChangeChange
Interactions
Components of the Earth System are linked by various exchanges including
Energy Water (previous example) Carbon
In this lecture, we are going to focus on the exchange of Carbon within the Earth System
17 MET 112 Global Climate MET 112 Global Climate ChangeChange
Carbon: what is it? Carbon (C), the fourth most abundant element
in the Universe, Building block of life.
– from fossil fuels and DNA – Carbon cycles through the land (bioshpere),
ocean, atmosphere, and the Earth’s interior Carbon found
– in all living things – in the atmosphere – in the layers of limestone sediment on the
ocean floor– in fossil fuels like coal
18 MET 112 Global Climate MET 112 Global Climate ChangeChange
Carbon: where is it?
Exists:– Atmosphere:
–CO2 and CH4 (to lesser extent)– Living biota (plants/animals)
–Carbon– Soils and Detritus
–Carbon–Methane
– Oceans–Dissolved CO2
–Most carbon in the deep ocean
19 MET 112 Global Climate MET 112 Global Climate ChangeChange
Carbon conservation
Initial carbon present during Earth’s formation
Carbon doesn’t increase or decrease globally
Carbon is exchanged between different components of Earth System.
20 MET 112 Global Climate MET 112 Global Climate ChangeChange
The Carbon Cycle
The complex series of reactions by which carbon passes through the Earth's
– Atmosphere – Land (biosphere and Earth’s crust)– Oceans
Carbon is exchanged in the earth system at all time scales
- Long term cycle (hundreds to millions of years)- Short term cycle (from seconds to a few years)
21 MET 112 Global Climate MET 112 Global Climate ChangeChange
22 MET 112 Global Climate MET 112 Global Climate ChangeChange
The carbon cycle has different speeds
Short Term Carbon Cycle
Long Term Carbon Cycle
23 MET 112 Global Climate MET 112 Global Climate ChangeChange
Short Term Carbon Cycle
One example of the short term carbon cycle involves plants Photosynthesis: is the conversion of carbon dioxide and
water into a sugar called glucose (carbohydrate) using sunlight energy. Oxygen is produced as a waste product.
Plants require Sunlight, water and carbon, (from CO2 in atmosphere or
ocean) to produce carbohydrates (food) to grow. When plants decay, carbon is mostly returned to the
atmosphere (respiration)
Global CO2
24 MET 112 Global Climate MET 112 Global Climate ChangeChange
25 MET 112 Global Climate MET 112 Global Climate ChangeChange
Short Term Carbon Cycle
One example of the short term carbon cycle involves plants Photosynthesis: is the conversion of carbon dioxide and
water into a sugar called glucose (carbohydrate) using sunlight energy. Oxygen is produced as a waste product.
Plants require Sunlight, water and carbon, (from CO2 in atmosphere or
ocean) to produce carbohydrates (food) to grow. When plants decay, carbon is mostly returned to the
atmosphere (respiration)
During spring: (more photosynthesis) atmospheric CO2 levels go down (slightly)
During fall: (more respiration) atmospheric CO2 levels go up (slightly)
26 MET 112 Global Climate MET 112 Global Climate ChangeChange
Carbon exchange (short term)
Other examples of short term carbon exchanges include:
Soils and Detritus: - organic matter decays and releases carbon
Surface Oceans– absorb CO2 via photosynthesis– also release CO2
27 MET 112 Global Climate MET 112 Global Climate ChangeChange
Short Term Carbon Exchanges
28 MET 112 Global Climate MET 112 Global Climate ChangeChange
Long Term Carbon Cycle
Carbon is slowly and continuously being transported around our earth system.– Between atmosphere/ocean/biosphere – And the Earth’s crust (rocks like limestone)
The main components to the long term carbon cycle:
29 MET 112 Global Climate MET 112 Global Climate ChangeChange
Long Term Carbon Cycle
Carbon is slowly and continuously being transported around our earth system.– Between atmosphere/ocean/biosphere – And the Earth’s crust (rocks like limestone)
The main components to the long term carbon cycle:1. Chemical weathering (or called: “silicate to
carbonate conversion process”)2. Volcanism/Subduction3. Organic carbon burial4. Oxidation of organic carbon
30 MET 112 Global Climate MET 112 Global Climate ChangeChange
The Long-Term Carbon Cycle (Diagram)
Atmosphere (CO2)
Ocean (Dissolved CO2)
Biosphere (Organic Carbon)
Carbonates Buried Organic Carbon
Subduction/Volcanism
Silicate-to-Carbonate Conversion
Organic Carbon Burial
Oxidation of Buried Organic Carbon
31 MET 112 Global Climate MET 112 Global Climate ChangeChange
Where is most of the carbon today?
Most Carbon is ‘locked’ away in the earth’s crust (i.e. rocks) as – Carbonates (containing carbon)
Limestone is mainly made of calcium carbonate (CaCO3)
Carbonates are formed by a complex geochemical process called:– Silicate-to-Carbonate Conversion (long term carbon
cycle)
32 MET 112 Global Climate MET 112 Global Climate ChangeChange
Silicate to carbonate conversion – chemical
weathering
One component of the long term carbon cycle
33 MET 112 Global Climate MET 112 Global Climate ChangeChange
Granite (A Silicate Rock)
34 MET 112 Global Climate MET 112 Global Climate ChangeChange
Limestone (A Carbonate Rock)
35 MET 112 Global Climate MET 112 Global Climate ChangeChange
Silicate-to-Carbonate Conversion
1. Chemical Weathering Phase• CO2 + rainwater carbonic acid• Carbonic acid dissolves silicate rock
2. Transport Phase• Solution products transported to ocean by
rivers3. Formation Phase
• In oceans, calcium carbonate precipitates out of solution and settles to the bottom
36 MET 112 Global Climate MET 112 Global Climate ChangeChange
Silicate-to-Carbonate Conversion
Rain1. CO2 Dissolves in Rainwater2. Acid
Dissolves Silicates (carbonic acid)
3. Dissolved Material Transported to Oceans
4. CaCO3 Forms in Ocean and Settles to the Bottom
Calcium carbonate
Land
37 MET 112 Global Climate MET 112 Global Climate ChangeChange
Changes in chemical weathering
The process is temperature dependant: – rate of evaporation of water is temperature
dependant– so, increasing temperature increases weathering
(more water vapor, more clouds, more rain)
Thus as CO2 in the atmosphere rises, the planet warms. Evaporation increases, thus the flow of carbon into the rock cycle increases removing CO2 from the atmosphere and lowering the planet’s temperature– Negative feedback
38 MET 112 Global Climate MET 112 Global Climate ChangeChange
Earth vs. Venus
The amount of carbon in carbonate minerals (e.g., limestone) is approximately– the same as the amount of carbon in Venus’
atmosphere
On Earth, most of the CO2 produced is – now “locked up” in the carbonates
On Venus, the silicate-to-carbonate conversion process apparently never took place
Subjuction/Volcanism
Another Component of the Long-Term Carbon Cycle
40 MET 112 Global Climate MET 112 Global Climate ChangeChange
Subduction
Definition: The process of the ocean plate descending beneath the continental plate.
During this processes, extreme heat and pressure convert carbonate rocks eventually into CO2
41 MET 112 Global Climate MET 112 Global Climate ChangeChange
Volcanic Eruption
Mt. Pinatubo (June 15, 1991)
Eruption injected (Mt – megatons)
17 Mt SO2, 42 Mt CO2,
3 Mt Cl, 491 Mt H2O
Can inject large amounts of CO2 into the atmosphere
Organic Carbon Burial/Oxidation of Buried Carbon
Another Component of the Long-Term Carbon Cycle
43 MET 112 Global Climate MET 112 Global Climate ChangeChange
Buried organic carbon (1)
Living plants remove CO2 from the atmosphere by the process of – photosynthesis
When dead plants decay, the CO2 is put back into the atmosphere – fairly quickly when the carbon in the plants is
oxidized However, some carbon escapes oxidation
when it is covered up by sediments
44 MET 112 Global Climate MET 112 Global Climate ChangeChange
Organic Carbon Burial Process
CO2 Removed by Photo-Synthesis
CO2 Put Into Atmosphere by Decay
CC
O2
Some Carbon escapes oxidation
CResult: Carbon into land
45 MET 112 Global Climate MET 112 Global Climate ChangeChange
Oxidation of Buried Organic Carbon
Eventually, buried organic carbon may be exposed by erosion
The carbon is then oxidized to CO2
46 MET 112 Global Climate MET 112 Global Climate ChangeChange
Oxidation of Buried Organic Carbon
Atmosphere
Buried Carbon (e.g., coal)
47 MET 112 Global Climate MET 112 Global Climate ChangeChange
Oxidation of Buried Organic Carbon
Atmosphere
Buried Carbon (e.g., coal)
Erosion
48 MET 112 Global Climate MET 112 Global Climate ChangeChange
Oxidation of Buried Organic Carbon
Atmosphere
Buried Carbon
O2
CO2
C
Result: Carbon into atmosphere (CO2)
49 MET 112 Global Climate MET 112 Global Climate ChangeChange
The (Almost) Complete Long-Term Carbon Cycle
Inorganic Component– Silicate-to-Carbonate Conversion – Subduction/Volcanism
Organic Component– Organic Carbon Burial– Oxidation of Buried Organic Carbon
51 MET 112 Global Climate MET 112 Global Climate ChangeChange
The Long-Term Carbon Cycle (Diagram)
Atmosphere (CO2)
Ocean (Dissolved CO2)
Biosphere (Organic Carbon)
Carbonates Buried Organic Carbon
Subduction/Volcanism
Silicate-to-Carbonate Conversion
Organic Carbon Burial
Oxidation of Buried Organic Carbon
52 MET 112 Global Climate MET 112 Global Climate ChangeChange
53 MET 112 Global Climate MET 112 Global Climate ChangeChange
54 MET 112 Global Climate MET 112 Global Climate ChangeChange
Review of Long Term Carbon Cycle
55 MET 112 Global Climate MET 112 Global Climate ChangeChange
If volcanism was to increase over a period of thousands of years, how would this affect atmospheric CO2 levels?
Atmospheric CO2 levels would
Increas
e
Decrea
se
Stay th
e sam
e
Are not re
lated
to vo
l...
92%
0%0%8%
1. Increase2. Decrease3. Stay the same4. Are not related to
volcanism
56 MET 112 Global Climate MET 112 Global Climate ChangeChange
If the silicate to carbonate conversion process was to increase over a period of millions of years, how would this affect volcanism?
Volcanism would
Increas
e
Decrea
se
Stay th
e sam
e
Not be a
ffecte
d by t
he ...
43%35%
14%8%
1. Increase2. Decrease3. Stay the same4. Not be affected by
the silicate to carbonate conversion process
57 MET 112 Global Climate MET 112 Global Climate ChangeChange
If the oxidation of organic carbon was to increase, how would global temperatures respond?
Global temperatures
Would incr
ease
Would decrea
se
Would stay
the s
ame
Are not a
ffecte
d by th...
86%
8%4%2%
1. Would increase2. Would decrease3. Would stay the same4. Are not affected by
the oxidation of organic carbon
58 MET 112 Global Climate MET 112 Global Climate ChangeChange
If there was a decline in the silicate to carbonate conversion process, how would global temperatures respond?
Global temperatures
Would incr
ease
Would decrea
se
Would stay
the s
ame
Are not a
ffecte
d by the..
.
42%
15%8%
35%1. Would increase2. Would decrease3. Would stay the same4. Are not affected by
the silicate to carbonate conversion process
59 MET 112 Global Climate MET 112 Global Climate ChangeChange
Activity (groups of two)Imagine that the global temperature were to
increase significantly for some reason.
1. How would the silicate-to-carbonate conversion process change during this warming period. Explain.
2. How would this affect atmospheric CO2 levels and as a result, global temperature?
3. What type of feedback process would this be and why (positive or negative)?
60 MET 112 Global Climate MET 112 Global Climate ChangeChange
The silicate to carbonate conversion processes would
Increas
e
Decrea
se
Remain
unchan
ged
Impo
ssible
to tell
82%
0%0%
18%
1. Increase2. Decrease3. Remain unchanged4. Impossible to tell
Imagine that the global temperature were to increase significantly for some reason.
61 MET 112 Global Climate MET 112 Global Climate ChangeChange
How would atmospheric CO2 levels change?
Increas
e
Decrea
se
Stay th
e sam
e
Impo
ssible
to tell
30%
0%6%
64%1. Increase2. Decrease3. Stay the same4. Impossible to tell
62 MET 112 Global Climate MET 112 Global Climate ChangeChange
How would this affect global temps?
Increas
e
Decrea
se
Stay th
e sam
e
Impo
ssible
to tell
2% 0%0%
98%1. Increase2. Decrease3. Stay the same4. Impossible to tell
63 MET 112 Global Climate MET 112 Global Climate ChangeChange
What type of feedback process would this be
Positiv
e
Negati
ve
Neither
Both
12%2%0%
86%1. Positive2. Negative3. Neither4. Both
64 MET 112 Global Climate MET 112 Global Climate ChangeChange
End
65 MET 112 Global Climate MET 112 Global Climate ChangeChange
Effect of Imbalances
Atmosphere-Ocean-Biosphere
Earth’s Crust
What would happen?
Imbalances in the long-term carbon cycle can cause slow, but sizeable changes in atmospheric
CO2
66 MET 112 Global Climate MET 112 Global Climate ChangeChange
Atmosphere-Ocean-Biosphere
Earth’s Crust
Consider the long term carbon cycle as seen below Suppose the Atmosphere-Ocean-Biosphere has 40,000 Gt* of
carbon and the earth’s crust has 40,000,000 Gt of carbon
*1 Gt = 1015 grams
67 MET 112 Global Climate MET 112 Global Climate ChangeChange
Atmosphere-Ocean-Biosphere40,000 Gt
Earth’s Crust40,000,000 Gt
Suppose that an imbalance developed in which the amount leaving the Atm/Ocean/Biosphere was to decrease by 1%.
If the arrows represent flux (carbon moving), and flux from the Earth’s crust to the atm/ocean/bio (labeled B) is 0.03Gt/year, what would the flux be for arrow A?
*1 Gt = 1015 grams
A B 0.0300 Gt./yr
68 MET 112 Global Climate MET 112 Global Climate ChangeChange
Arrow A would be
0 of 5 0.03
Gt/y
r
0.3 G
t/yr
0.02
97 G
t/yr
0.03
03 G
t/yr
0% 0%0%0%
1. 0.03 Gt/yr2. 0.3 Gt/yr3. 0.0297 Gt/yr4. 0.0303 Gt/yr
69 MET 112 Global Climate MET 112 Global Climate ChangeChange
Atmosphere-Ocean-Biosphere40,000 Gt
Earth’s Crust 40,000,000 Gt
For such an imbalance as shown below, what is the net carbon flux and in what direction?
*1 Gt = 1015 grams
A B 0.0300 Gt./yr
0.0297 Gt./yr
70 MET 112 Global Climate MET 112 Global Climate ChangeChange
For such an imbalance as shown below, what is the net carbon flux and in what direction?
0 of 5 0.03
3 - up
0.033
down
0.000
3 up
0.000
3 down
0% 0%0%0%
1. 0.033 - up2. 0.033 down3. 0.0003 up4. 0.0003 down
71 MET 112 Global Climate MET 112 Global Climate ChangeChange
Atmosphere-Ocean-Biosphere40,000 Gt
Earth’s Crust40,000,000 Gt
Based on the below Carbon Flux information, how many years will it take for the carbon in the atm/ocean/bio to double?
*1 Gt = 1015 grams
A B 0.0300 Gt./yr
0.0297 Gt./yr
Net Carbon Flux
0.0003 Gt./yr
72 MET 112 Global Climate MET 112 Global Climate ChangeChange
How many years will it take for the carbon in the atm/ocean/bio to double?
0 of 50.0
3 yea
rs
12 ye
ars
100,0
00 ye
ars
133 m
illion ye
ars
0% 0%0%0%
1. 0.03 years2. 12 years3. 100,000 years4. 133 million years
73 MET 112 Global Climate MET 112 Global Climate ChangeChange
Atmosphere-Ocean-Biosphere
Earth’s Crust
Based on the below Carbon Flux information, how many years will it take for the carbon in the atm/ocean/bio to double?
*1 Gt = 1015 grams
A B 0.0300 Gt./yr
0.0297 Gt./yr
Net Carbon Flux
0.0003 Gt./yr
Answer: 40, 000/.0003 years = 133 million years
74 MET 112 Global Climate MET 112 Global Climate ChangeChange
Long-Term CO2 Changes
Source: Berner, R. A., The rise of plants and their effect on weathering and atmospheric CO2. Science, 276, 544-546.
75 MET 112 Global Climate MET 112 Global Climate ChangeChange
Time Scale (Continued)
The preceding operation would remove 40, 000 Gt. of carbon from the crust;
This is only 0.1% of the carbon in the crust Thus, it is perfectly plausible that such an
imbalance could be sustained
76 MET 112 Global Climate MET 112 Global Climate ChangeChange
77 MET 112 Global Climate MET 112 Global Climate ChangeChange
Long-Term Carbon Cycle (Quantitative Assessment)
Atmosphere-Ocean-Biosphere
Earth’s Crust
Carbon Content: 40, 000 Gt*.
Carbon Content: 40, 000, 000 Gt.
Carbon Flux: 0.03 Gt/yr
*1 Gt = 1015 grams
Carbon Flux: 0.03 Gt/yr