Transcript Geological and Man-Made Climate and Sea Level Changes

Geological and Man-Made Climate and
Sea Level Changes
Presented at the
Global Warming Study Group
January 13, 2009
By
Dag Nummedal
Colorado Energy Research Institute
Colorado School of Mines, Golden, CO 80401
CERI
Global Warming – the Ultimate(?) – Major –
Multidisciplinary Challenge of Our Time
• Geologists: we understand a bit about the climate in the past
• Climate scientists: understand something about earth-oceanatmosphere interactions
• Physicists: understand something about the interaction of
molecules and radiation
• Chemists: understand something about the fate of CO2, in
oceans and on land
Of all disciplines, geologists should appreciate the causes,
magnitudes, and effects of climate change the most and play a
leadership role in making the lay public understand what is at
stake in global warming. Yet, we are perceived by our science
colleagues as “climate challenged”. Why?
Recognition of the Greenhouse Effect
Jean Baptiste Joseph Fourier (mathematician) in 1827 recognized that gases
in the atmosphere that absorb IR radiation could warm up the earth’s surface
Earth without atmosphere: 3 oF or -16 oC
Earth with atmosphere (which absorbs and reemits IR): 15 °C (59 °F, 288 °K).
In the 1860's, John Tyndall (scientist) noted:
“Waves of heat speed from our earth through our atmosphere
towards space. These waves dash in their passage against the
atoms of oxygen and nitrogen, and against molecules of
aqueous vapour. Thinly scattered as these latter are, we might
naturally think of them mainly as barriers to the waves of heat”.
Svante Arrhenius (chemist) defined and estimated “Climate Sensitivity”, DT2x.
Data from S.P. Langley, who wanted to know the temperature of the moon.
Arrhenius use Langley’s data to see how the intensity of the IR light from the moon
varied by the angle of moon (length of path through earth’s atmosphere) and humidity.
Concluded that doubling the CO2 concentration lead to 4 to 6 oC warming.
Today, the best estimate is about 2.5 to 4 oC warming.
Solar irradiance: 680 W/m2
Wikikpedia
Long wave radiation from earth
See site: earth’s energy budget: http://en.wikipedia.org/wiki/Earth's_energy_budget
Conclusions - 1
Greenhouse effect – physics simple and well-understood. The
greenhouse works. A good thing!
The Many Time Scales of Climate Change
• Daily to several years: Weather – not Climate
• Century: the climate change the IPCC and people everywhere are worried
about, because it affects the economy of society, and tracks man’s direct impact
• Centuries to millennia – Dansgaard-Oeschger cycles; Heinrich events
• 20 to 400 thousand years (perhaps more) – Milankovitch cycles in
insolation due to earth’s orbital changes
• 100s of millions years – Pennsylvanian ‘ice house’ and Cretaceous
‘greenhouse’ due to plate tectonic cycles of continental assembly and break-up
and vertical movements. Cycling of CO2 into and out of earth
Unique events:
“Snowball earth” in late Proterozoic (and more?)
Large volcanic eruptions (OAE-2 at C/T boundary)
PETM – major heat spike due to?
Message: Don’t confuse the causes of climate change at one time scale with
the drivers of change at another. Example: CO2 vs. temperature “leads and
lags”.
Phanerozoic Climate Patterns
Relative changes in oxygen isotope ratios can be interpreted as rough changes in climate.
Quantitative conversion between this data and direct temperature changes is a complicated
process subject to many systematic uncertainties, however it is estimated that each 1 part per
thousand change in δ18O represents roughly a 1.5-2 °C change in tropical sea surface
temperatures (Veizer et al. 2000).
Conclusions - 2
Greenhouse effect – physics simple and well-understood. The
greenhouse works. A good thing!
Long-term (100 ma scale) climate change are due to CO2 imbalance
between emissions rates and geological storage (weathering, ocean
carbonates).
Cretaceous and Cenozoic Sea Level Histories
Authors:
Pitman, 1976
Watts and Steckler, 1979
Watts and Thorne, 1984
Kominz, 1984
Haq et al., 1986
Gordon and Jurdy, 1986
Miller et al., 2005
Haq and Al-Qahtani, 2006
Xu et al., 2006
Compiled by
Muller et al., 2008
Age-Area Distribution
of the Ocean Floor
140 Ma
50 Ma
100 Ma
0 Ma
R. D. Muller et al., 2008
Changes in Ocean Depth
70
60
All oceans
50
40
30
5000
All oceans
4800
4600
4400
140
120
100
80
60
40
20
0
Reconstruction age (Ma)
(from
MŸller,
etal.,
al.,2008
2008)
From
Muller et
Cenozoic Climate Record
Wikipedia
Milankovitch
Cycles
Climate Changes from Ocean Sediment
Cores, since 5 Ma. Milankovitch Cycles
Wikipedia
Seismically Defined Sequences – in Depth
Abreu and Nummedal, 2007
Late Miocene Sequences in Kirmaky Valley,
Baku, Azerbaijan
Outcrop Gamma Log at Kirmaky Valley
Insolation Index from 6 to 4 Ma
Berger and Loutre, 1992
Cycle Tuning, Kirmaky Suite
Conclusions - 3
Greenhouse effect – physics simple and well-understood. The
greenhouse works. A good thing!
Long-term (100 ma scale) climate change are due to CO2 imbalance
between emissions rates and geological storage (weathering, ocean
carbonates).
Climate changes in the Milankovitch frequency band (20 ka to ~
400,000 ka (or more?) are expressed in nearly all sedimentary
systems on Earth. The 400,000 year cycles are particularly ‘robust’.
Milankovitch Cycles the Past 1 Million Years
Berger and Loutre, 1992
400,000 Year Climate Records
NOAA data base archives
CO2 vs. Temperature Leads and Lags
Mann et al., 1999 – ‘hockey stick’ diagram for past 1000-yr temperature.
Temperature and CO2 ‘correlative’ trends. Correlation does not prove causation –
correct. CO2 should ‘lead’ temperature changes. In many cycles is does, but not
always because of feed-back mechanisms due to role of vegetation.
Other papers revealed that a rapid rise in sea level, caused by the melting of landbased ice that began approximately 19,000 years ago, preceded the post-glacial
rise in atmospheric CO2 concentration by about 3,000 years. Then, when the CO2
finally began to rise, it had to race to make up the difference; but it still took it a
couple more thousand years to catch up with the sea level rise.
Explanation: emerging from the Ice age is a function of increasing solar insolation an expression of the precessional (20-ky) Milankovitch cycle. This will cause
temperature increase, more growth of plants, decay, methane production, oxidation
to CO2, increased atmospheric CO2 and an amplification of temperature increase.
There are other data that show that during glacial inceptions of the past half million
years, temperature always dropped before the air's CO2 concentration declined.
“Clearly, therefore, changes in the air's CO2 content cannot be responsible for these
major climate changes, for it would be a strange cause indeed that followed its
effect!” CORRECT: nobody has argued that ice ages were driven by CO2 – they
were driven by changes in solar insolation.
Conclusions - 4
Greenhouse effect – physics simple and well-understood. The
greenhouse works. A good thing!
Long-term (100 ma scale) climate change are due to CO2 imbalance
between emissions rates and geological storage (weathering, ocean
carbonates).
Climate changes in the Milankovitch frequency band (20 ka to ~
400,000 ka (or more?) are expressed in nearly all sedimentary
systems on Earth.
Both Milankovitch insolation cycles and feed-back mechanisms with
vegetation drove Pleistocene-Holocene temperature patterns. Leads
and lags are consistent with the physical causes.
Unique Events 1 –
Permian-Triassic
Extinction at
251.4 Ma
% genera extinction
Combination of causes – a series of catastrophes, one worse
than the previous: Major volcanic induced global warming
• The Siberian Traps eruptions were bad enough in their own right (huge CO2 burp)
• They occurred near coal beds and the continental shelf, they also triggered very
large releases of carbon dioxide and methane (perhaps from hydrates)
•Most likely driven by massive degassing of methane hydrates to CH4, oxidized to
CO2
• The oceans may have became so anoxic that anaerobic sulfur-reducing organisms
dominated the chemistry of the oceans and caused massive emissions of toxic
hydrogen sulfide
Unique Events – Example 2:
The PETM Climate Event
Plants preferentially ‘eat’ 12C. So, when 13C/12C goes down, there is a ‘burst’ of
CO2 much more than plants can absorb.
The more ocean water is stored as ice on land, the heavier the remaining water.
So, when 18O goes down, it is high sea level, little global ice, warm climate.
Conclusion: 13C concentrations decay over a few 100,000s years.
What about the present CO2 burst?
J. C. Zachos et al., Science 302, 1551 -1554 (2003)
Colorado’s
Oil Shale a
Product
of the
PETM?
Pica
• Organic rich sedimentary rock formed in lake or marine environments
• Commonly carbonate rich; most not true shale
• Kerogen-rich, primarily algal and bacterial
• Immature precursor to oil & gas
• Produces oil upon heating
Boak
Piceance Creek Seqs. Greater Green River
(400k)
48
Ages
9
7
6
Parachute Creek
10
8
51
48.8
12
11
50
49.6 Sixth
50 Main 49.8 Layered
50.6 Boar
50.8 Firehole
Garden Gulch
5
52
PC GGR
Mbr.
14
13
49
Lake Type
Laney
Age (Ma)
I
F or D
H
A
H
T
N
T
50.4 Grey
51.3 Rife
51.8 Scheggs
Tipton
N
N
4
3
53
2
1
54
PETM event
Wasatch
H – halite
N - nahcolite
T - trona
Overfilled
Balanced Fill
Under Filled
13 Green River Sequences Represent
400 ka Milankovitch Cycles
S
N
R-7
R-6
R-5
R-2
R-3
Mahogany Zone
Upper salt
R-4
Lower salt
R-1
R-0
Colors represent a total of 13 sequences
Bartov et al.
Conclusions - 5
Greenhouse effect – physics simple and well-understood. The
greenhouse works. A good thing!
Long-term (100 ma scale) climate change are due to CO2 imbalance
between emissions rates and geological storage (weathering, ocean
carbonates).
Climate changes in the Milankovitch frequency band (20 ka to ~ 400,000
ka (or more?) are expressed in nearly all sedimentary systems on Earth.
Both Milankovitch insolation and feed-back mechanisms with vegetation
drove Pleistocene Holocene temperature patterns. Leads and lags are
consistent with the physical causes.
Unique events have long-lived consequences (‘forever’ in the case of the
P/T extinction event, 100,000 s of years recovery from massive CO2 spike
at the PETM. Natural events can be bad for life (including man).
Today’s Unique Event:
Anthropogenic Global Warming
Today
CO2 for the
past 400 ky
The State of Affairs
NOAA web site archives & Peter Tans
Distribution of Warming: Polar/Cold Regions
Wikipedia
Arctic Sea Ice Extent
Satellite imagery of sea ice extent in September
1979, and at a record low in September 2007. Source: NASA
If sea-ice continues to contract rapidly over the next several years, Arctic land
warming and permafrost thaw are likely to accelerate.
David Lawrence, NCAR
Larsen Ice Shelf Collapse 2002
ice-shelf break up is not controlled simply by climate. A
number of other atmospheric, oceanic and glaciological
factors are involved. For example, the location and
spacing of fractures on the ice shelf such as crevasses
and rifts are very important too because they determine
how strong or weak the ice shelf is”.
The study is important because ice shelf collapse
contributes to global sea level rise, albeit indirectly. “Ice
shelves themselves do not contribute directly to sea
level rise because they are floating on the ocean and
they already displace the same volume of water. But
when the ice shelves collapse the glaciers that feed
them speed up and get thinner, so they supply more ice
to the oceans,” Prof. Glasser explained.
Professor Glasser acknowledges that global warming
had a major part to play in the collapse, but emphasises
that it is only one in a number of contributory factors,
and despite the dramatic nature of the break-up in 2002,
both observations by glaciologists and numerical
modeling by other scientists at NASA and CPOM
(Centre of Polar Observation and Modeling) had pointed
to an ice shelf in distress for decades previously. “It's
likely that melting from higher ocean temperatures, or
even a gradual decline in the ice mass of the Peninsula
over the centuries, was pushing the Larsen to the
brink”,.
Neil Glasser, Aberystwyth University
Ted Scambos, University of Colorado's National Snow and Ice Data Centre
Future Arctic Temperature Trends
Regional heating of the Arctic following rapid sea ice loss events. Following
such events, heating extends up to 1500km inland from the sea
An early arctic melt will cause additional
heating, additional greenhouse gas
emissions and additional sea level rise,
over and above those foreseen by
existing climate models
Source: Steve Deyo, ©University
Corporation of Atmospheric
Research
Permafrost extent in the northern hemisphere
Climate Safety, 2008 from UNEP
Carbon Content by Source
Volumes of total carbon content estimated in billion tonnes
Climatesafety.org
First Published in the United Kingdom 2008 by the Public Interest
Research Centre. Sources: Schuur et al., UNEP, CDIAC
U.S. Energy Policy
• “We have only two modes—complacency
and panic.”
• —James R. Schlesinger, the first energy
secretary, in 1977, on the country's
approach to energy
What to Do About It?
Reduce emissions and increase sinks for GHGs –
fast, very fast!
Conclusions
• Greenhouse effect – physics simple and well-understood. The
greenhouse works. A good thing!
• Long-term (100 ma scale) climate change are due to CO2 imbalance
between emissions rates and geological storage (weathering, ocean
carbonates).
• Climate changes in the Milankovitch frequency band (20 ka to ~ 400,000
ka (or more?) are expressed in nearly all sedimentary systems on Earth.
• Both Milankovitch insolation and feed-back mechanisms with vegetation
drove Pleistocene Holocene temperature patterns. Leads and lags are
consistent with the physical causes.
• Unique events have long-lived consequences (‘forever’ in the case of the
P/T extinction event, 100,000 years recovery from massive CO2 spike at
the PETM
• Decrease emissions, increase storage of CO2 - NOW