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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 Mller, 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