2001 David Packard Distinguished Lecturer

James P. Kennett, Ph.D.

University of California, Santa Barbara

Methane hydrate reservoir instability: Implications for marine geology and climate change

Thursday, July 21, 2001
Pacific Forum—3:00 p.m.

Episodes of methane hydrate instability in the oceans have induced rapid climatic warmings in the past through greenhouse forcing by atmospheric methane (CH4). We suggest that the last 800,000 years of the Quaternary was a time of major, but episodic instability of the gas hydrate reservoir. Critical ice sheet expansion and instability created significant changes in sea level and bottom water temperatures on the upper continental slope—the zone of potential gas hydrate instability. Episodic instability in the gas hydrate reservoir contributed significantly to the distinctive behavior of late Quaternary climatic change on orbital (Milankovitch) and millennial time scales. Upper intermediate water oscillations produced fluctuating temperature and episodic hydrate reservoir dissociation. Methane releases into the atmosphere triggered warmings that were significantly reinforced by other greenhouse gases, especially water vapor, thus contributing to the large magnitude of late Quaternary climate change. This hypothesis may explain the rapid warmings and sawtooth pattern of the late Quaternary exhibited in the 100,000-year cycle, Bond cycles and individual Dansgaard-Oeschger (D-O) interstadials.
Substantial geological evidence suggests that the source of the rapid CH4 increases at glacial terminations and at the onset of D-O events in ice cores must have been from gas hydrates rather than continental wetlands. The major present day continental wetland systems did not form until well within the Holocene and therefore could not have contributed to the rapid methane increases that mark terminations during the late Quaternary.
Supporting evidence for this (clathrate gun hypothesis) includes: Extensive upper continental slope instability of the right timing to reflect clathrate dissociation; isotopic (C13) evidence for episodic CH4 release from gas hydrates during interstadials; intimate association between changes in CH4 and climate in ice cores; conspicuous overshoots in CH4 and climate warmings at some glacial terminations and at the onset of D-O events; and bottom water temperature oscillations associated with D-O cycles and glacial terminations on the continental margins.
This hypothesis, if correct, has major implications relative to mechanisms and timing of mass sediment transport on continental margins and in abyssal basins, the evolution of certain ocean floor features and topography, and the Quaternary history of atmospheric chemistry. Foremost however are implications relative to explaining a number of enigmatic problems of Quaternary climate behavior including triggering of rapid warming episodes.

For definitions (quaternary, Daansgard-Oeschger, Milankovitch, etc.) see the Global Change Dictionary: http://www.co2science.org/dictionary/define.php


Data repository
Data policy
What is happening in Monterey Bay today?
Central and Northern California Ocean Observing System
Chemical data
Ocean float data
Slough data
Mooring ISUS measurements
M1 ISUS CTD Data Display
Southern Ocean Data
Mooring data
M1 Mooring Summary Data
M1 Asimet
M1 Download Info
M1 EMeter
M1 Flourometer (CeNCOOS)
M1 GPS Location
Molecular and genomics data
ESP Web Portal
Seafloor mapping
Upper ocean data
Spatial Temporal Oceanographic Query System (STOQS) Data
Tide prediction
Image gallery
Video library
Previous seminars
David Packard Distinguished Lecturers
Research software
Video Annotation and Reference System
System Overview
Annotation Interface
Video Tape User Guide
Video File User Guide
Still Images User Guide
Annotation Glossary
Query Interface
Basic User Guide
Advanced User Guide
Query Glossary
VARS Publications
Oceanographic Decision Support System
MB-System seafloor mapping software
MB-System Documentation
MB-System Announcements
MB-System Announcements (Archive)
How to Download and Install MB-System
MB-System Discussion Lists
MB-System FAQ
Matlab scripts: Linear regressions
Introduction to Model I and Model II linear regressions
A brief history of Model II regression analysis
Index of downloadable files
Summary of modifications
Regression rules of thumb
Results for Model I and Model II regressions
Graphs of the Model I and Model II regressions
Which regression: Model I or Model II?
Matlab scripts: Oceanographic calculations
Matlab scripts: Sound velocity
Visual Basic for Excel: Oceanographic calculations
Educational resources
MBARI Summer Internship Program
Education and Research: Testing Hypotheses (EARTH)
EARTH workshops
2016—New Brunswick, NJ
2015—Newport, Oregon
2016 Satellite workshop—Pensacola, FL
2016 Satellite workshop—Beaufort, NC
EARTH resources
EARTH lesson plans
Lesson plans—published
Lesson plans—development
Lesson drafts—2015
Lesson drafts—2016 Pensacola
Center for Microbial Oceanography: Research and Education (C-MORE) Science Kits
Sample archive