THIS POST IS A LITERATURE REVIEW OF METHANE HYDRATE DISASSOCIATION EVENTS IN THE PALEO RECORD

RELATED POST ON PETM: LINK: https://tambonthongchai.com/2018/10/28/petm/

PART-1: WHAT THE PALEO RECORD TELL US ABOUT METHANE HYDRATE DISASSOCIATION

1. PETM: A significant source of paleo proxy data on oceanic methane hydrate disassociation is found in the Paleocine Eocine Thermal Maximum event about 60 million years ago. It is described in a relate post: LINK: https://tambonthongchai.com/2018/10/28/petm/ . The commonly held view of this incident is that an unspecified oceanic heat source of some kind, perhaps geothermal heat, caused deep ocean temperatures to rise by 4C from 11C to 15C and that the warming caused a large scale breakfown of methane hydrates and that is how the rise in atmospheric CO2 is explained. Other paleo proxy data are derived from the Cretacious and the Toarcian and Aptian oceanic anoxic events. In all of these data sources we find that the oceanic temperature at which hydrate released methane involved warming of 4C or more and a temperatiure of 15C or more.
2. THE CURRENT WARM PERIOD: The relevance of methane disassociation to the current warm period is that atmospheric temperatures have warmed by a little over 1C since pre-industrial and as it continues to warm unchecked by climate action, the effect on ocean temperature could eventually cause the breakdown of methane hydrates down there and the release of methane into the atmosphere could accelerate the rate of warming in a feedback system where the more methane it releases the more methane it can release.
3. WORLD OCEAN REVIEW: The World Ocean Review post on this issue {LINK: https://worldoceanreview.com/ summarizes this danger as follows: ” Huge amounts of methane are stored around the world in the sea floor in the form of solid methane hydrates. These hydrates represent a large energy reserve for humanity. Climate warming, however, could cause the hydrates to destabilize. The methane, a potent greenhouse gas, would escape unused into the atmosphere and could even accelerate climate change“. They go on to explain as follows:
4. “Methane hydrates represent a new and completely untapped reservoir of fossil fuel, because they contain immense amounts of methane, which is the main component of natural gas. Methane hydrates belong to a group of substances called clathrates – substances in which one molecule type forms a crystal-like cage structure and encloses another type of molecule. Methane hydrates form naturally in the ocean under high water pressure and low temperature. If the water is warm, however, the water pressure must be very high. In this case, the hydrate only forms at great depths. If the water is very cold, the methane hydrates could conceivably form in shallower water depths, or even at atmospheric pressure. In the open ocean, where the average bottom-water temperatures are around 2 to 4 degrees Celsius, methane hydrates occur starting at depths of around 500 metres. The deeper the sea floor is, the less organic matter settles on the bottom, so methane hydrates primarily occur on the continental slopes, those areas where the continental plates meet the deep-sea regions. Here there is sufficient organic matter accumulating on the bottom and the combination of temperature and pressure is favourable. In very cold regions like the Arctic, methane hydrates even occur on the shallow continental shelf (less than 200 metres of water depth) or on the land in permafrost, the deep-frozen Arctic soil.
5. OCEAN TEMPERATURE ; Deep ocean temperatures and warming rates are presented in a related post: LINK: https://tambonthongchai.com/2018/10/06/ohc/ . There we find that the deep ocean is warming but with certain oddities in the data. For example a pattern of higher temperatures in deeper water is inconsistent with an atmospheric source of heat. Typcal high temperatures at a depth of 700 meters are mostly in the range 4C to 5C but with a high value of 8C at the greater depth of 2000 meters, temperatures as high as 10C are seen but hydrate formation at these depths is sparse if at all. These temperatures are not sufficient to breakdown hydrates even with a strong upward temperature trend due to global warming if that were even possible given the data with higher temperatures at greater depth. For example, in the PETM, a warming from 11C to 15C is thought to have been the trigger for hydrate breakdown and methane release.
6. A HYDRATE BREAKDOWN EVENT IN ALASKA: In another related post LINK: https://tambonthongchai.com/2019/04/22/nox2013/ we show that though the release of greenhouse gases from thawing permafrost in the North Slope of Alaska was presented as evidence of catastrophic runaway positive feedback warming is not found in the data, no evidence of warming was found in the data.

7. OTHER FAILED PERMAFROST MELT ALARMS:

1997, THE BBC MAKES THE CASE FOR THE KYOTO PROTOCOL
Twenty years of hard data from meteorological stations and nature show a clear warming trend. Growth rings in Mongolian and Canadian trees are getting wider. Butterflies in California are moving to higher ground once too cold for butterflies. Stalactites in Britain are growing faster. The growing season for crops in Australia is getting longer. Permafrost in Siberia and Canada is melting. The evidence is there anywhere you look. A warming rate is one 1C per century is enough to wreak havoc. The cause is the greenhouse effect of CO2 emissions from fossil fuels as well as CFCs and HCFCs that trap heat. The effect is being compounded as deforestation simultaneously removes trees that absorb CO2. Some scientists are skeptical but the majority view is that the greenhouse effect is real and it requires urgent action. This conclusion rests on the results from sophisticated computer simulation models that give the best possible information on this topic even though they are not perfect. These models are giving us scary accounts of the future and we should be paying attention. The IPCC tell us that melting ice and thermal expansion of oceans will cause the sea level to rise one meter by 2037 and inundate low lying areas and island nations. Extreme weather events will become common. El Nino and La Nina cycles will become more extreme. There will be millions of climate refugees driven from their home by global warming. Some regions of the world will become hotter, others colder, some wetter, others drier. Entire weather systems will be dramatically altered. The Gulf Stream will switch off making Europe colder. Tropical diseases such as malaria will ravage the world as vectors migrate to higher latitudes and altitudes. Some wheat farmers may be able to grow more wheat but the net effect of global warming is overwhelmingly negative.

2004, RAPID ARCTIC WARMING BRINGS SEA LEVEL RISE
The Arctic Climate Impact Assessment (ACIA) report says: increasing greenhouse gases from human activities is causing the Arctic to warm twice as fast as the rest of the planet; in Alaska, western Canada, and eastern Russia winter temperatures have risen by 2C to 4C in the last 50 years; the Arctic will warm by 4C to 7C by 2100. A portion of Greenland’s ice sheet will melt; global sea levels will rise; global warming will intensify. Greenland contains enough melting ice to raise sea levels by 7 meters; Bangkok, Manila, Dhaka, Florida, Louisiana, and New Jersey are at risk of inundation; thawing permafrost and rising seas threaten Arctic coastal regions; climate change will accelerate and bring about profound ecological and social changes; the Arctic is experiencing the most rapid and severe climate change on earth and it’s going to get a lot worse; Arctic summer sea ice will decline by 50% to 100%; polar bears will be driven towards extinction; this report is an urgent SOS for the Arctic; forest fires and insect infestations will increase in frequency and intensity; changing vegetation and rising sea levels will shrink the tundra to its lowest level in 21000 years; vanishing breeding areas for birds and grazing areas for animals will cause extinctions of many species; “if we limit emission of heat trapping carbon dioxide we can still help protect the Arctic and slow global warming”.

2009: CATASTROPHIC ICE MELT NEEDS TREATY AT COPENHAGEN
Carbon dioxide emissions from fossil fuels have caused the following alarming changes to our planet: (1) ice covering the Arctic Ocean shrank in 2007 to its smallest since satellite records began, (2) In Antarctica, a section of the Wilkins Ice Shelf has broken up in recent days, (3) glaciers in the Himalayan mountains are shrinking and threatening to disrupt water supplies to hundreds of millions of people, (4) melting permafrost in Siberia will release large quantities of methane into the atmosphere and hasten global warming, and (5) if all of the land based ice in Antarctica melted it would raise the sea level by 80 meters. More info: http://chaamjamal.blogspot.com/2009/04/reference-melting-ice-to-spur-new.html

CONCLUSION: The fearful presentation of runaway global warming by way of melting permafrost and methane release from hydrates by climate science is not supported by the data.

PART-2: THE RELEVANT BIBLIOGRAPHY

Thomas, Deborah J., et al. “Warming the fuel for the fire: Evidence for the thermal dissociation of methane hydrate during the Paleocene-Eocene thermal maximum.” Geology 30.12 (2002): 1067-1070. Abstract: Dramatic warming and upheaval of the carbon system at the end of the Paleocene Epoch have been linked to massive dissociation of sedimentary methane hydrate. However, testing the Paleocene-Eocene thermal maximum hydrate dissociation hypothesis has been hindered by the inability of available proxy records to resolve the initial sequence of events. The cause of the Paleocene-Eocene thermal maximum carbon isotope excursion remains speculative, primarily due to uncertainties in the timing and duration of the Paleocene-Eocene thermal maximum. We present new high-resolution stable isotope records based on analyses of single planktonic and benthic foraminiferal shells from Ocean Drilling Program Site 690 (Weddell Sea, Southern Ocean), demonstrating that the initial carbon isotope excursion was geologically instantaneous and was preceded by a brief period of gradual surface-water warming. Both of these findings support the thermal dissociation of methane hydrate as the cause of the Paleocene-Eocene thermal maximum carbon isotope excursion. Furthermore, the data reveal that the methane-derived carbon was mixed from the surface ocean downward, suggesting that a significant fraction of the initial dissociated hydrate methane reached the atmosphere prior to oxidation.

Dickens, Gerald R., et al. “Dissociation of oceanic methane hydrate as a cause of the carbon isotope excursion at the end of the Paleocene.” Paleoceanography 10.6 (1995): 965-971. Abstract: Isotopic records across the “Latest Paleocene Thermal Maximum“ (LPTM) indicate that bottom water temperature increased by more than 4°C during a brief time interval (<10⁴ years) of the latest Paleocene (∼55.6 Ma). There also was a coeval −2 to −3‰ excursion in the δ¹³C of the ocean/atmosphere inorganic carbon reservoir. Given the large mass of this reservoir, a rapid δ¹³C shift of this magnitude is difficult to explain within the context of conventional hypotheses for changing the mean carbon isotope composition of the ocean and atmosphere. However, a direct consequence of warming bottom water temperature from 11 to 15°C over 10⁴ years would be a significant change in sediment thermal gradients and dissociation of oceanic CH₄ hydrate at locations with intermediate water depths. In terms of the present‐day oceanic CH₄ hydrate reservoir, thermal dissociation of oceanic CH₄ hydrate during the LPTM could have released greater than 1.1 to 2.1 × 10¹⁸ g of carbon with a δ¹³C of approximately −60‰. The release and subsequent oxidation of this amount of carbon is sufficient to explain a −2 to −3‰ excursion in δ¹³C across the LPTM. Fate of CH₄ in oceanic hydrates must be considered in developing models of the climatic and paleoceanographic regimes that operated during the LPTM.

Beerling, David J., M. R. Lomas, and Darren R. Gröcke. “On the nature of methane gas-hydrate dissociation during the Toarcian and Aptian oceanic anoxic events.” American Journal of Science 302.1 (2002): 28-49. ABSTRACT: The magnitude and timing of a major rapid negative carbon-isotope excursion recorded in marine and terrestrial matter through the Early Toarcian (Early Jurassic) and Early Aptian (Early Cretaceous) oceanic anoxic events (OAEs) have been proposed to be the result of large methane gas-hydrate dissociation events. Here, we develop and evaluate a global carbon-isotope mass-balance approach for determining the responses of each component of the exogenic carbon cycle (terrestrial biosphere, atmosphere and ocean). The approach includes a dynamic response of the terrestrial carbon cycle to methane-related CO₂ increases and climatic warming. Our analyses support the idea that both the Early Toarcian and Early Aptian isotopic curves were indicative of large episodic methane releases (∼5000 and ∼3000 Gt respectively) promoting warm ‘greenhouse’ conditions in the Mesozoic. These events are calculated to have increased the atmospheric CO₂ concentration by ∼900 and ∼600 ppmv respectively and land surface temperatures by 2.5° to 3.0°C. However, we show that much of the methane released from oceanic sediments is rapidly sequestered by terrestrial and marine components in the global carbon cycle, and this effect strongly attenuated the potential for ancient methane gas-hydrate dissociation events to act as major amplifiers in global warming. An increase in oceanic carbon sequestration is consistent with the deposition of globally distributed black shales during these OAEs. Our analyses point to the urgent need for high-resolution marine and terrestrial carbon-isotope records to better characterize the nature of the Toarcian and Aptian events and improve our interpretation of their consequences for the global carbon cycle.

Mienert, Jürgen, et al. “Ocean warming and gas hydrate stability on the mid-Norwegian margin at the Storegga Slide.” Ormen Lange–an Integrated Study for Safe Field Development in the Storegga Submarine Area. Elsevier, 2005. 233-244. ABSTRACT: The sensitivity of oceanic gas hydrates and submarine slope stability to the combined forcing of sea level changes and bottom water perturbation is a critical issue for risk assessment in the Storegga Slide area on the mid-Norwegian margin. Evidence for the existence of gas hydrates both inside and outside the Storegga Slide complex comes from reflection seismic profiles, where a bottom-simulating reflection marks today’s base of the gas hydrate stability zone. Paleo-bottom water temperatures show a relatively fast increase at approximately 12.5–10 ka (calendar years) following the Younger Dryas while stable warm water conditions have prevailed since then. Despite sea level rise, this warm-water inflow caused a major reduction in the thickness of the gas hydrate stability zone along the upper slope of the mid-Norwegian margin. Modelling results indicate that critical hydrate stability conditions and consequently the maximal potential pore pressure build-up occur at the location of the Storegga Slide headwall. Although the major phase of hydrate melting predates the Storegga slide event, dated at 8.2 ka (calendar years), reduced hydrate stability conditions could have facilitated or contributed to sub-marine slope failure. Additionally, the bottom-simulating reflections within the slide complex seem to have nearly adjusted to new equilibrium conditions, highlighting the dynamics of hydrate stability in continental margin sediments under environmental changes (climate change, geohazards).

Zeebe, Richard E. “What caused the long duration of the Paleocene‐Eocene Thermal Maximum?.” Paleoceanography 28.3 (2013): 440-452. ABSTRACT: Paleorecords show that the Paleocene‐Eocene Thermal Maximum (PETM, ∼56 Ma) was associated with a large carbon cycle anomaly and global warming >5 K, which persisted for at least 50 kyr. Conventional carbon cycle/climate models that include a single initial carbon input pulse over ∼10 kyr fail to reproduce the long duration of the PETM without invoking additional, slow carbon release over more than 50 kyr (hereafter referred to as bleeding). However, a potential carbon source for the bleeding, as well as its release mechanism, has hitherto remained elusive. Here I present first‐principle calculations of heat transfer in marine sediments which demonstrate that a bottom water temperature anomaly as generated during the PETM takes tens of thousands of years to penetrate the top few hundred meters of deep‐sea sediments. While the initial temperature rise has been suggested to cause dissociation of the majority of oceanic methane hydrate within ∼10 kyr, my calculations reveal a long tail of hydrate dissociation, causing smaller but continued carbon release substantially beyond 10 kyr. In addition, I suggest that temperature‐enhanced metabolic processes in marine sediments and the absence of methane hydrate deposition during the PETM contributed to prolonged carbon input during the event. Enhanced fluxes of methane over this time scale would have sustained the carbon isotope excursion and amplified long‐term greenhouse warming by elevating atmospheric concentrations of steady state CH₄, or in oxidized form, CO₂.

Panieri, Giuliana, Carolyn A. Graves, and Rachael H. James. “Paleo‐methane emissions recorded in foraminifera near the landward limit of the gas hydrate stability zone offshore western S valbard.” Geochemistry, Geophysics, Geosystems 17.2 (2016): 521-537. ABSTRACT: We present stable isotope and geochemical data from four sediment cores from west of Prins Karls Forland (ca. 340 m water depth), offshore western Svalbard, recovered from close to sites of active methane seepage, as well as from shallower water depths where methane seepage is not presently observed. Our analyses provide insight into the record of methane seepage in an area where ongoing ocean warming may be fueling the destabilization of shallow methane hydrate. The δ¹³C values of benthic and planktonic foraminifera at the methane seep sites show distinct intervals with negative values (as low as −27.8‰) that do not coincide with the present‐day depth of the sulfate methane transition zone (SMTZ). These intervals are interpreted to record long‐term fluctuations in methane release at the present‐day landward limit of the gas hydrate stability zone (GHSZ). Shifts in the radiocarbon ages obtained from planktonic foraminifera toward older values are related to methane‐derived authigenic carbonate overgrowths of the foraminiferal tests, and prevent us from establishing the chronology of seepage events. At shallower water depths, where seepage is not presently observed, no record of past methane seepage is recorded in foraminifera from sediments spanning the last 14 ka cal BP (¹⁴C‐AMS dating). δ¹³C values of foraminiferal carbonate tests appear to be much more sensitive to methane seepage than other sediment parameters. By providing nucleation sites for authigenic carbonate precipitation, foraminifera thus record the position of even a transiently stable SMTZ, which is likely to be a characteristic of temporally variable methane fluxes.

Méhay, Sabine, et al. “A volcanic CO2 pulse triggered the Cretaceous Oceanic Anoxic Event 1a and a biocalcification crisis.” Geology 37.9 (2009): 819-822. ABSTRACT; The Aptian Oceanic Anoxic Event 1a (OAE1a, ca.120 Ma ago) is one of the most prominent of a series of geologically brief intervals in the Cretaceous characterized by the deposition of organic carbon–rich sediments. OAEs reflect major perturbations in the global carbon cycle evidenced by sedimentary carbon isotope records. However, the triggering mechanisms for OAEs remain controversial. Here we present a bulk-rock and molecular (marine and terrestrial bio-markers) C isotope record at unprecedented time resolution, from the Cismon section of northern Italy, that shows that OAE1a conditions were reached over a period of several thousands of years through a stepwise perturbation of the carbon cycle. The documented sequence of events is most compatible with a trigger associated with increased CO₂ emissions, possibly leading to a doubling of pCO₂, which in turn caused larger C isotope fractionation in marine and terrestrial organisms and a major biotic crisis in the calcareous nannoplankton. Our data also show that a release of isotopically light carbon from partial methane hydrate dissociation probably played a minor role in the OAE1a carbon cycle perturbation.

PART-3: THE ARCTIC HOLOCENE PROXY CLIMATE DATABASE

1. A large database of paleo climate data for the Arctic over the entire time span of the Holocene has been constructed by climate scientists with significant roles played by Hanna Sundqvist, Darrell Kaufman, Nicholas McKay and 18 other authors. The database is available for download at this site. Here is the link: ARCTIC-DATABASE .  Warning, clicking on this link will cause a very large PDF file to be downloaded. This database contains only the data and not their interpretation. For that we refer to the published papers about these data in the literature provided below in the bibliography.
2. If you have a low opinion of climate scientists and their scientific integrity from your experience with things like the hockey stick, prepare to be surprised. The significant and chaotic cycles of warming and cooling in the Arctic for the whole of the Holocene in this database is consistent with the interpretation of these changes presented in a related post [LINK] such that periods with the Arctic warmer than AGW, colder than AGW, less ice than AGW, and more ice than AGW are all found in the database. In the context of the database, all we can say about the Arctic in the current warm period is that we are in the Holocene.