Feb 10, 2017 03:29 AM
Gas hydrate breakdown unlikely to cause massive greenhouse gas release
https://www.sciencedaily.com/releases/20...163835.htm
RELEASE: The breakdown of methane hydrates due to warming climate is unlikely to lead to massive amounts of methane being released to the atmosphere, according to a recent interpretive review of scientific literature performed by the U.S. Geological Survey and the University of Rochester.
Methane hydrate, which is also referred to as gas hydrate, is a naturally-occurring, ice-like form of methane and water that is stable within a narrow range of pressure and temperature conditions. These conditions are mostly found in undersea sediments at water depths greater than 1000 to 1650 ft and in and beneath permafrost (permanently frozen ground) at high latitudes. Methane hydrates are distinct from conventional natural gas, shale gas, and coalbed methane reservoirs and are not currently exploited for energy production, either in the United States or the rest of the world.
On a global scale, gas hydrate deposits store enormous amounts of methane at relatively shallow depths, making them particularly susceptible to the changes in temperature that accompany climate change. Methane itself is also a potent greenhouse gas, and some researchers have suggested that methane released by the breakdown of gas hydrate during past climate events may have exacerbated global warming.
The new review concludes that current warming of ocean waters is likely causing gas hydrate deposits to break down at some locations. However, not only are the annual emissions of methane to the ocean from degrading gas hydrates far smaller than greenhouse gas emissions to the atmosphere from human activities, but most of the methane released by gas hydrates never reaches the atmosphere. Instead, the methane often remains in the undersea sediments, dissolves in the ocean, or is converted to carbon dioxide by microbes in the sediments or water column.
The review pays particular attention to gas hydrates beneath the Arctic Ocean, where some studies have observed elevated rates of methane transfer between the ocean and the atmosphere. As noted by the authors, the methane being emitted to the atmosphere in the Arctic Ocean has not been directly traced to the breakdown of gas hydrate in response to recent climate change, nor as a consequence of longer-term warming since the end of the last Ice Age.
"Our review is the culmination of nearly a decade of original research by the USGS, my coauthor Professor John Kessler at the University of Rochester, and many other groups in the community," said USGS geophysicist Carolyn Ruppel, who is the paper's lead author and oversees the USGS Gas Hydrates Project. "After so many years spent determining where gas hydrates are breaking down and measuring methane flux at the sea-air interface, we suggest that conclusive evidence for release of hydrate-related methane to the atmosphere is lacking."
Professor Kessler explains that, "Even where we do see slightly elevated emissions of methane at the sea-air interface, our research shows that this methane is rarely attributable to gas hydrate degradation."
The review summarizes how much gas hydrate exists and where it occurs; identifies the technical challenges associated with determining whether atmospheric methane originates with gas hydrate breakdown; and examines the assumptions of the Intergovernmental Panels on Climate Change, which have typically attributed a small amount of annual atmospheric methane emissions to gas hydrate sources.
The review also systematically evaluates different environments to assess the susceptibility of gas hydrates at each location to warming climate and addresses the potential environmental impact of an accidental gas release associated with a hypothetical well producing methane from gas hydrate deposits.
Virginia Burkett, USGS Associate Director for Climate and Land Use Change, noted, "This review paper provides a truly comprehensive synthesis of the knowledge on the interaction of gas hydrates and climate during the contemporary period. The authors' sober, data-driven analyses and conclusions challenge the popular perception that warming climate will lead to a catastrophic release of methane to the atmosphere as a result of gas hydrate breakdown."
Current climate change models understate the problem, scientists argue
https://www.sciencedaily.com/releases/20...111626.htm
RELEASE: A new study on the relationship between people and the planet shows that climate change is only one of many inter-related threats to the Earth's capacity to support human life.
An international team of distinguished scientists, including five members of the National Academies, argues that there are critical components missing from current climate models that inform environmental, climate, and economic policies.
The article, published in the National Science Review, describes how the recent growth in resource use, land-use change, emissions, and pollution has made humanity the dominant driver of change in most of the Earth's natural systems, and how these changes, in turn, have important feedback effects on humans with costly and serious consequences.
The authors argue that current estimates of the impact of climate change do not connect human variables -- such as demographics, inequality, economic growth, and migration -- with planetary changes. This makes current models likely to miss important feedbacks in the real Earth-human system, especially those that may result in unexpected or counterintuitive outcomes.
Furthermore, the authors argue that some of the existing models are unreliable. The United Nations projections of a relatively stable population for the whole of the developed world depend, for instance, on dramatic, and highly unlikely, declines projected in a few key countries. Japan, for example, must decline by 34%, Germany by 31% and Russia by about 30% for the projected stability in total developed country population to be born out.12 In addition, countries often highlighted for their low birth rates, like Italy and Spain, are not projected to decline by even 1% for decades.
In this new research, the authors present extensive evidence of the need for a new type of model that incorporates the feedbacks that the Earth System has on humans, and propose a framework for future modeling that would serve as a more realistic guide for policymaking and sustainable development.
"Current models are likely to miss critical feedbacks in the combined Earth-Human system," said co-author Eugenia Kalnay, professor of Atmospheric and Oceanic Science at University of Maryland. "It would be like trying to predict El Niño with a sophisticated atmospheric model but with the Sea Surface Temperatures taken from external, independent projections by, for example, the United Nations. Without including the real feedbacks, predictions for coupled systems cannot work; the model can get away from reality very quickly."
https://www.sciencedaily.com/releases/20...163835.htm
RELEASE: The breakdown of methane hydrates due to warming climate is unlikely to lead to massive amounts of methane being released to the atmosphere, according to a recent interpretive review of scientific literature performed by the U.S. Geological Survey and the University of Rochester.
Methane hydrate, which is also referred to as gas hydrate, is a naturally-occurring, ice-like form of methane and water that is stable within a narrow range of pressure and temperature conditions. These conditions are mostly found in undersea sediments at water depths greater than 1000 to 1650 ft and in and beneath permafrost (permanently frozen ground) at high latitudes. Methane hydrates are distinct from conventional natural gas, shale gas, and coalbed methane reservoirs and are not currently exploited for energy production, either in the United States or the rest of the world.
On a global scale, gas hydrate deposits store enormous amounts of methane at relatively shallow depths, making them particularly susceptible to the changes in temperature that accompany climate change. Methane itself is also a potent greenhouse gas, and some researchers have suggested that methane released by the breakdown of gas hydrate during past climate events may have exacerbated global warming.
The new review concludes that current warming of ocean waters is likely causing gas hydrate deposits to break down at some locations. However, not only are the annual emissions of methane to the ocean from degrading gas hydrates far smaller than greenhouse gas emissions to the atmosphere from human activities, but most of the methane released by gas hydrates never reaches the atmosphere. Instead, the methane often remains in the undersea sediments, dissolves in the ocean, or is converted to carbon dioxide by microbes in the sediments or water column.
The review pays particular attention to gas hydrates beneath the Arctic Ocean, where some studies have observed elevated rates of methane transfer between the ocean and the atmosphere. As noted by the authors, the methane being emitted to the atmosphere in the Arctic Ocean has not been directly traced to the breakdown of gas hydrate in response to recent climate change, nor as a consequence of longer-term warming since the end of the last Ice Age.
"Our review is the culmination of nearly a decade of original research by the USGS, my coauthor Professor John Kessler at the University of Rochester, and many other groups in the community," said USGS geophysicist Carolyn Ruppel, who is the paper's lead author and oversees the USGS Gas Hydrates Project. "After so many years spent determining where gas hydrates are breaking down and measuring methane flux at the sea-air interface, we suggest that conclusive evidence for release of hydrate-related methane to the atmosphere is lacking."
Professor Kessler explains that, "Even where we do see slightly elevated emissions of methane at the sea-air interface, our research shows that this methane is rarely attributable to gas hydrate degradation."
The review summarizes how much gas hydrate exists and where it occurs; identifies the technical challenges associated with determining whether atmospheric methane originates with gas hydrate breakdown; and examines the assumptions of the Intergovernmental Panels on Climate Change, which have typically attributed a small amount of annual atmospheric methane emissions to gas hydrate sources.
The review also systematically evaluates different environments to assess the susceptibility of gas hydrates at each location to warming climate and addresses the potential environmental impact of an accidental gas release associated with a hypothetical well producing methane from gas hydrate deposits.
Virginia Burkett, USGS Associate Director for Climate and Land Use Change, noted, "This review paper provides a truly comprehensive synthesis of the knowledge on the interaction of gas hydrates and climate during the contemporary period. The authors' sober, data-driven analyses and conclusions challenge the popular perception that warming climate will lead to a catastrophic release of methane to the atmosphere as a result of gas hydrate breakdown."
Current climate change models understate the problem, scientists argue
https://www.sciencedaily.com/releases/20...111626.htm
RELEASE: A new study on the relationship between people and the planet shows that climate change is only one of many inter-related threats to the Earth's capacity to support human life.
An international team of distinguished scientists, including five members of the National Academies, argues that there are critical components missing from current climate models that inform environmental, climate, and economic policies.
The article, published in the National Science Review, describes how the recent growth in resource use, land-use change, emissions, and pollution has made humanity the dominant driver of change in most of the Earth's natural systems, and how these changes, in turn, have important feedback effects on humans with costly and serious consequences.
The authors argue that current estimates of the impact of climate change do not connect human variables -- such as demographics, inequality, economic growth, and migration -- with planetary changes. This makes current models likely to miss important feedbacks in the real Earth-human system, especially those that may result in unexpected or counterintuitive outcomes.
Furthermore, the authors argue that some of the existing models are unreliable. The United Nations projections of a relatively stable population for the whole of the developed world depend, for instance, on dramatic, and highly unlikely, declines projected in a few key countries. Japan, for example, must decline by 34%, Germany by 31% and Russia by about 30% for the projected stability in total developed country population to be born out.12 In addition, countries often highlighted for their low birth rates, like Italy and Spain, are not projected to decline by even 1% for decades.
In this new research, the authors present extensive evidence of the need for a new type of model that incorporates the feedbacks that the Earth System has on humans, and propose a framework for future modeling that would serve as a more realistic guide for policymaking and sustainable development.
"Current models are likely to miss critical feedbacks in the combined Earth-Human system," said co-author Eugenia Kalnay, professor of Atmospheric and Oceanic Science at University of Maryland. "It would be like trying to predict El Niño with a sophisticated atmospheric model but with the Sea Surface Temperatures taken from external, independent projections by, for example, the United Nations. Without including the real feedbacks, predictions for coupled systems cannot work; the model can get away from reality very quickly."
![[Image: 60300764.jpg]](https://cdn.meme.am/cache/instances/folder764/60300764.jpg)
