Gas Hydrates- Climate and Hydrate Interactions Active
The USGS Gas Hydrates Project focuses on the study of natural gas hydrates in deepwater marine systems and permafrost areas. Breakdown of gas hydrates due to short- or long-term climate change may release methane to the ocean-atmosphere system. As a potent greenhouse gas, methane that reaches the atmosphere from degrading gas hydrate deposits could in turn exacerbate climate warming.
Over the past 15 years, hydrate-climate studies have taken on a central role in the USGS Gas Hydrates Project. Research focuses on the effects of Late Pleistocene to contemporary climate change on the stability of methane hydrate deposits. The goal is to determine how much, if any, methane hydrate is currently dissociating on Earth in response to global warming and to estimate the amount of methane that would directly reach the atmosphere from such degassing.
Methane is a strong greenhouse gas, and gas hydrates globally trap huge amounts of methane in a frozen form that is stable only a certain pressure and temperature conditions. If large amounts of methane were to reach the atmosphere from degassing gas hydrates, global warming might be exacerbated. In Earth's deep past, rapid warming may have led to widespread breakdown of methane hydrates, but there is as yet no strong evidence that methane release from dissociating gas hydrates triggered past greenhouse warming events.
A 2017 review paper coauthored by the USGS provides a modern perspective on the interaction of gas hydrates with the climate system, with a particular focus on warming ocean temperatures and changing sea levels. On contemporary Earth, some of the methane that might be released at the seafloor from gas hydrates dissociating within shallow marine sediments is injected into the deep oceans, where it dissolves and is usually oxidized to carbon dioxide. This carbon dioxide contributes to deep ocean acidification, and some of the carbon dioxide may reach the atmosphere in a few hundred years' time. For seeps at water depths greater than ~100 m, most of the methane likely never reaches the sea-air interface.
In contrast, a fraction of the methane emitted from shallow (< 100 m water depth) seafloor on continental shelves can reach the atmosphere directly. However, except at high latitudes, gas hydrate is not stable in such shallow seafloor, meaning that methane seeps on most continental shelves are not connected to gas hydrate dynamics. At high latitudes, remnant, now-inundated Pleistocene permafrost that lies beneath some continental shelves is thawing. Whether methane hydrates associated with such permafrost break down and release methane that reaches the seafloor and overlying ocean-atmosphere system remains the subject of active study.
The USGS Gas Hydrates Project primarily focuses its climate studies on areas where gas hydrates may actively be degrading due to warming climate. Onshore, investigations in areas of continuous permafrost on the Alaskan North Slope in 2010-2012 indicated that methane emissions were unlikely to be connected to degrading gas hydrates.
Marine study areas include (a) upper continental slopes, where the gas hydrate stability zone thins to zero thickness and is therefore highly susceptible to small perturbations in ocean temperature; and (b) continental shelves in the circum-Arctic Ocean, where subsea permafrost and associated gas hydrate continue to degrade. Upper continental slope studies have been conducted on the U.S. Atlantic, Cascadia, U.S. Beaufort Sea, and Svalbard margins, with additional investigations in the Baltic and North Seas and offshore Greenland. Continental shelf studies in areas with subsea permafrost have been carried out for the U.S. Beaufort Sea margin offshore the Atlantic North Slope, where the USGS has used seismic and borehole data to show that subsea permafrost extends a maximum distance of only a few tens of kilometers offshore. These findings have contributed to circum-Arctic studies documenting the contemporary state of subsea permafrost.
In addition to choosing study areas in geographic regions where key questions about climate-hydrate interactions can be addressed, the USGS Gas Hydrates Project also focuses on specific aspects of methane dynamics most critical for assessing the sources and sinks in natural systems. In the marine environment, one emphasis is the sediment-water interface. At this boundary, researchers study the transfer of methane into ocean waters at cold seeps, along with the underlying dynamics of the gas hydrate systems that may feed the seeps, seafloor chemosynthetic communities and authigenic carbonates around the cold seeps, and methane oxidation and the fate of methane bubbles in the water column.
Studies also focus on the shallow part of the ocean’s water column, where researchers map methane concentrations and undertake carbon isotopic analyses to determine the origin of the gas. Key findings are that elevated methane concentrations near the sea surface are generally not spatially coincident with deepwater methane seeps, nor does the methane at shallow depths in the water column have the characteristic signature of seep methane. In fact, methane hotspots near the sea-air interface are often related to plankton, not seepage of methane into the deep ocean from below the seafloor.
Research associated with the Gas Hydrates Climate and Hydrate Interactions Project
Data releases associated with the Gas Hydrates Climate and Hydrate Interactions Project
Below are publications associated with this project.
Minimum distribution of subsea ice-bearing permafrost on the US Beaufort Sea continental shelf
Observations of mass fractionation of noble gases in synthetic methane hydrate
Methane hydrates and contemporary climate change
Strong atmospheric chemistry feedback to climate warming from Arctic methane emissions
Permafrost gas hydrates and climate change: Lake-based seep studies on the Alaskan north slope
News associated with the Gas Hydrates Climate and Hydrate Interactions Project
- Overview
The USGS Gas Hydrates Project focuses on the study of natural gas hydrates in deepwater marine systems and permafrost areas. Breakdown of gas hydrates due to short- or long-term climate change may release methane to the ocean-atmosphere system. As a potent greenhouse gas, methane that reaches the atmosphere from degrading gas hydrate deposits could in turn exacerbate climate warming.
Over the past 15 years, hydrate-climate studies have taken on a central role in the USGS Gas Hydrates Project. Research focuses on the effects of Late Pleistocene to contemporary climate change on the stability of methane hydrate deposits. The goal is to determine how much, if any, methane hydrate is currently dissociating on Earth in response to global warming and to estimate the amount of methane that would directly reach the atmosphere from such degassing.
Methane is a strong greenhouse gas, and gas hydrates globally trap huge amounts of methane in a frozen form that is stable only a certain pressure and temperature conditions. If large amounts of methane were to reach the atmosphere from degassing gas hydrates, global warming might be exacerbated. In Earth's deep past, rapid warming may have led to widespread breakdown of methane hydrates, but there is as yet no strong evidence that methane release from dissociating gas hydrates triggered past greenhouse warming events.
A 2017 review paper coauthored by the USGS provides a modern perspective on the interaction of gas hydrates with the climate system, with a particular focus on warming ocean temperatures and changing sea levels. On contemporary Earth, some of the methane that might be released at the seafloor from gas hydrates dissociating within shallow marine sediments is injected into the deep oceans, where it dissolves and is usually oxidized to carbon dioxide. This carbon dioxide contributes to deep ocean acidification, and some of the carbon dioxide may reach the atmosphere in a few hundred years' time. For seeps at water depths greater than ~100 m, most of the methane likely never reaches the sea-air interface.
In contrast, a fraction of the methane emitted from shallow (< 100 m water depth) seafloor on continental shelves can reach the atmosphere directly. However, except at high latitudes, gas hydrate is not stable in such shallow seafloor, meaning that methane seeps on most continental shelves are not connected to gas hydrate dynamics. At high latitudes, remnant, now-inundated Pleistocene permafrost that lies beneath some continental shelves is thawing. Whether methane hydrates associated with such permafrost break down and release methane that reaches the seafloor and overlying ocean-atmosphere system remains the subject of active study.
The USGS Gas Hydrates Project primarily focuses its climate studies on areas where gas hydrates may actively be degrading due to warming climate. Onshore, investigations in areas of continuous permafrost on the Alaskan North Slope in 2010-2012 indicated that methane emissions were unlikely to be connected to degrading gas hydrates.
Marine study areas include (a) upper continental slopes, where the gas hydrate stability zone thins to zero thickness and is therefore highly susceptible to small perturbations in ocean temperature; and (b) continental shelves in the circum-Arctic Ocean, where subsea permafrost and associated gas hydrate continue to degrade. Upper continental slope studies have been conducted on the U.S. Atlantic, Cascadia, U.S. Beaufort Sea, and Svalbard margins, with additional investigations in the Baltic and North Seas and offshore Greenland. Continental shelf studies in areas with subsea permafrost have been carried out for the U.S. Beaufort Sea margin offshore the Atlantic North Slope, where the USGS has used seismic and borehole data to show that subsea permafrost extends a maximum distance of only a few tens of kilometers offshore. These findings have contributed to circum-Arctic studies documenting the contemporary state of subsea permafrost.
In addition to choosing study areas in geographic regions where key questions about climate-hydrate interactions can be addressed, the USGS Gas Hydrates Project also focuses on specific aspects of methane dynamics most critical for assessing the sources and sinks in natural systems. In the marine environment, one emphasis is the sediment-water interface. At this boundary, researchers study the transfer of methane into ocean waters at cold seeps, along with the underlying dynamics of the gas hydrate systems that may feed the seeps, seafloor chemosynthetic communities and authigenic carbonates around the cold seeps, and methane oxidation and the fate of methane bubbles in the water column.
Studies also focus on the shallow part of the ocean’s water column, where researchers map methane concentrations and undertake carbon isotopic analyses to determine the origin of the gas. Key findings are that elevated methane concentrations near the sea surface are generally not spatially coincident with deepwater methane seeps, nor does the methane at shallow depths in the water column have the characteristic signature of seep methane. In fact, methane hotspots near the sea-air interface are often related to plankton, not seepage of methane into the deep ocean from below the seafloor.
- Science
Research associated with the Gas Hydrates Climate and Hydrate Interactions Project
- Data
Data releases associated with the Gas Hydrates Climate and Hydrate Interactions Project
- Publications
Below are publications associated with this project.
Minimum distribution of subsea ice-bearing permafrost on the US Beaufort Sea continental shelf
Starting in Late Pleistocene time (~19 ka), sea level rise inundated coastal zones worldwide. On some parts of the present-day circum-Arctic continental shelf, this led to flooding and thawing of formerly subaerial permafrost and probable dissociation of associated gas hydrates. Relict permafrost has never been systematically mapped along the 700-km-long U.S. Beaufort Sea continental shelf and isAuthorsLaura L. Brothers, Patrick E. Hart, Carolyn D. RuppelFilter Total Items: 28Observations of mass fractionation of noble gases in synthetic methane hydrate
As a consequence of contemporary or longer term (since 15 ka) climate warming, gas hydrates in some settings are presently dissociating and releasing methane and other gases to the oceanatmosphere system. A key challenge in assessing the susceptibility of gas hydrates to warming climate is the lack of a technique able to distinguish between methane recently released from gas hydrates and methane eAuthorsAndrew G. Hunt, John W. Pohlman, Laura A. Stern, Carolyn D. Ruppel, Richard J. Moscati, Gary P. Landis, John C. PinkstonMethane hydrates and contemporary climate change
As the evidence for warming climate became better established in the latter part of the 20th century (IPCC 2001), some scientists raised the alarm that large quantities of methane (CH4) might be liberated by widespread destabilization of climate-sensitive gas hydrate deposits trapped in marine and permafrost-associated sediments (Bohannon 2008, Krey et al. 2009, Mascarelli 2009). Even if only a frAuthorsCarolyn D. RuppelStrong atmospheric chemistry feedback to climate warming from Arctic methane emissions
The magnitude and feedbacks of future methane release from the Arctic region are unknown. Despite limited documentation of potential future releases associated with thawing permafrost and degassing methane hydrates, the large potential for future methane releases calls for improved understanding of the interaction of a changing climate with processes in the Arctic and chemical feedbacks in the atmAuthorsIvar S.A. Isaksen, Michael Gauss, Gunnar Myhre, Katey M. Walter Anthony, Carolyn RuppelPermafrost gas hydrates and climate change: Lake-based seep studies on the Alaskan north slope
The potential interactions between climate change and methane hydrate destabilization are among the most societally-relevant aspects of gas hydrates research. Massive dissociation of deep marine methane hydrates following rapid Earth warming is the most plausible explanation for carbon isotopic data that imply widespread release of microbial methane during the Late Paleocene Thermal Maximum (~55 mAuthorsM.J. Wooller, Carolyn D. Ruppel, John W. Pohlman, M.B. Leigh, M. Heintz, K. Walter Anthony - News
News associated with the Gas Hydrates Climate and Hydrate Interactions Project