Methane Emissions from Alaska Arctic Tundra in Response to Climatic Change PDF Download
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Author: Gerald P. Livingston
Publisher:
ISBN:
Category :
Languages : en
Pages : 6
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Book Description
In situ observations of methane emissions from the Alaska North Slope in 1987 and 1989 provide insight into the environmental interactions regulating methane emissions and into the local- and regional-scale response of the arctic tundra to interannual environmental variability. Inferences regarding climate change are based on in situ measurements of methane emissions, regional landscape characterizations derived from Landsat Multispectral Scanner satellite data, and projected regional scale emissions based on observed interannual temperature differences and simulated changes in the spatial distribution of methane emissions. Our results suggest that biogenic methane emissions from arctic tundra will be significantly perturbed by climatic change, leading to warmer summer soil temperatures and to vertical displacement of the regional water table. The effect of increased soil temperatures on methane emissions resulting from anaerobic decomposition in northern wetlands will be to both increase total emissions and to increase interannual and seasonal variability. The magnitude of these effects will be determined by those factors affecting the areal distribution of methane emission rates through regulation of the regional water table. At local scales, the observed 4.7 C increase in mid-summer soil temperatures between 1987 and 1989 resulted in a 3.2-fold increase in the rate of methane emissions from anaerobic soils.
Author: Gerald P. Livingston
Publisher:
ISBN:
Category :
Languages : en
Pages : 6
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Book Description
In situ observations of methane emissions from the Alaska North Slope in 1987 and 1989 provide insight into the environmental interactions regulating methane emissions and into the local- and regional-scale response of the arctic tundra to interannual environmental variability. Inferences regarding climate change are based on in situ measurements of methane emissions, regional landscape characterizations derived from Landsat Multispectral Scanner satellite data, and projected regional scale emissions based on observed interannual temperature differences and simulated changes in the spatial distribution of methane emissions. Our results suggest that biogenic methane emissions from arctic tundra will be significantly perturbed by climatic change, leading to warmer summer soil temperatures and to vertical displacement of the regional water table. The effect of increased soil temperatures on methane emissions resulting from anaerobic decomposition in northern wetlands will be to both increase total emissions and to increase interannual and seasonal variability. The magnitude of these effects will be determined by those factors affecting the areal distribution of methane emission rates through regulation of the regional water table. At local scales, the observed 4.7 C increase in mid-summer soil temperatures between 1987 and 1989 resulted in a 3.2-fold increase in the rate of methane emissions from anaerobic soils.
Author: Qianlai Zhuang
Publisher:
ISBN:
Category :
Languages : en
Pages : 10
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Book Description
We used a biogeochemistry model, the Terrestrial Ecosystem Model (TEM), to study the net methane (CH4) fluxes between Alaskan ecosystems and the atmosphere. We estimated that the current net emissions of CH4 (emissions minus consumption) from Alaskan soils are ~3 Tg CH4/yr. Wet tundra ecosystems are responsible for 75% of the region's net emissions, while dry tundra and upland boreal forests are responsible for 50% and 45% of total consumption over the region, respectively. In response to climate change over the 21st century, our simulations indicated that CH4 emissions from wet soils would be enhanced more than consumption by dry soils of tundra and boreal forests. As a consequence, we projected that net CH4 emissions will almost double by the end of the century in response to high-latitude warming and associated climate changes. When we placed these CH4 emissions in the context of the projected carbon budget (carbon dioxide [CO2] and CH4) for Alaska at the end of the 21st century, we estimated that Alaska will be a net source of greenhouse gases to the atmosphere of 69 Tg CO2 equivalents/yr, that is, a balance between net methane emissions of 131 Tg CO2 equivalents/yr and carbon sequestration of 17 Tg C/yr (62 Tg CO2 equivalents/yr).
Author: Donatella Zona
Publisher:
ISBN:
Category : Atmospheric carbon dioxide
Languages : en
Pages : 198
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Book Description
My research focuses on the patterns and controls of CO2 and CH4 fluxes in vegetated drained lake basins on the Arctic Coastal Plain in northern Alaska. These land features account for the majority of the landscape in the Arctic Coastal Plain, but have never been systematically investigated with respect to their impact on trace gas fluxes in the global carbon budget. In the first part of my research I focused on the impacts of water table change on CO2 and CH4 fluxes in a vegetated drained lake basin, where the water table was manipulated. I showed that the water table drop below the surface may not decrease CH4 emissions if a simultaneous increase in thaw depth increases the soil volume available for methanogenesis. On the other hand, an increase in water table above the surface could increase the diffusive resistance to CH4 release and decrease its emission. The impact of water table increase on CO2 was also surprising. Contrary to the common prediction, I demonstrated that increasing the water table level can increase CO2 injection into the atmosphere. This CO2 loss from the ecosystem is likely due to an increase in respiration, for the increase soil volume in the flood area, and decrease in light at the level of the photosynthetic organs. In the last part of my research, I study the carbon dynamics of a number of vegetated drained lake basins, which drained from 50 to 2000 years ago, in the Arctic Coastal Plain. I characterized 12 vegetated drained lake basins in terms of net ecosystem exchange (NEE), ecosystem respiration (ER) and gross primary production (GPP), and investigated the seasonal patterns and environmental controls on CO2 fluxes. The comparison of the seasonal CO2 fluxes in vegetated drained lake basins of different age allowed me to test the validity of the traditional view that net primary production decreases with ecosystem maturity . I showed that ecosystems thousands of years old (i.e. old vegetated drained lake basins are still a CO2 sink in the global carbon budget.
Author: Eduard A. Koster
Publisher:
ISBN:
Category : Climatic changes
Languages : en
Pages : 108
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Book Description
Author: Arctic Climate Impact Assessment
Publisher: Cambridge University Press
ISBN: 0521865093
Category : Science
Languages : en
Pages : 1053
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Book Description
The Arctic is now experiencing some of the most rapid and severe climate change on earth. Over the next 100 years, climate change is expected to accelerate, contributing to major physical, ecological, social, and economic changes, many of which have already begun. Changes in arctic climate will also affect the rest of the world through increased global warming and rising sea levels. Arctic Climate Impact Assessment was prepared by an international team of over 300 scientists, experts, and knowledgeable members of indigenous communities. The report has been thoroughly researched, is fully referenced, and provides the first comprehensive evaluation of arctic climate change, changes in ultraviolet radiation and their impacts for the region and for the world. It is illustrated in full color throughout. The results provided the scientific foundations for the ACIA synthesis report - Impacts of a Warming Arctic - published by Cambridge University Press in 2004.
Author: Hyojung Kwon
Publisher:
ISBN:
Category : Arctic regions
Languages : en
Pages : 360
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Book Description
Temporal and spatial variability in the Arctic introduces considerable uncertainty in estimations of the current carbon and energy budget and Arctic ecosystem response to climate change. Few representative measurements are available for land-surface parameterization of the Arctic tundra in regional and global climate models. Continuous measurements of net ecosystem CO 2 exchange (NEE), water vapor, and energy exchange using the eddy covariance technique were conducted in Alaskan wet sedge tundra and moist tussock tundra during the summer seasons (June 1--August 31) from 1999 to 2003 in order to quantify seasonal and spatial NEE, water vapor, and energy fluxes and to assess primary controlling factors which drive the change in the fluxes for the Arctic tundra ecosystems. At the wet sedge tundra, seasonal variation in energy balance was substantial, indicating ground heat flux (G) was significant during the snow-melt and post-snowmelt periods, whereas sensible heat flux (H) was dominant during the plant growth. During the measurement periods, H was the main energy component comprising 52% of net radiation (R n), followed by latent heat flux (LE) at 26% and G representing 8% of R n . The energy balance and evapotranspiration were strongly influenced by the maritime climate that brought cold, humid air to the site. Warmer and drier conditions prevailed for the moist tussock tundra compared with that of the wet sedge tundra. The wet sedge tundra was a sink for carbon of 46.4 to 70.0 gC m -2 season -1, while the moist tussock tundra either lost carbon of up to 60.8 gC m -2 season -1 or was in balance. The wet sedge tundra showed an acclimation (e.g., over days) to temperature, while the moist tussock tundra illustrated a strong temperature dependence. Warming and drying accentuated ecosystem respiration in the moist tussock tundra causing a net loss of carbon. The contrasting patterns of carbon balance at the two sites demonstrate that spatial variability can be more important in landscape NEE than intra- and inter-seasonal variability due to environmental factors with respect to NEE. Better characterization of spatial variability in NEE and associated environmental controls is required to improve current and future predictions of the Arctic terrestrial carbon balance.
Author: Mohammad Aslam Khan Khalil
Publisher: Springer Science & Business Media
ISBN: 3662041456
Category : Science
Languages : en
Pages : 370
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Book Description
Methane is an important greenhouse gas that can cause global warming. The present concentrations of methane are nearly three times higher than several hundred years ago. Today, more than 60% of the atmospheric methane comes from human activities, including rice agriculture, coal mining, natural gas usage, biomass burning, and raising of cattle. Methane affects the stratospheric ozone layer and the oxidizing capacity of the atmosphere, which in turn control the concentrations of many man-made and natural gases in the atmosphere. This book brings together our knowledge of the trends and the causes behind the increased levels of methane. Based on the scientific information on the sources and sinks, and the role of methane in global warming, strategies to limit emissions can be designed as part of a program to control future global warming.
Author:
Publisher:
ISBN:
Category : Power resources
Languages : en
Pages : 754
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Book Description
Author: M.A.K. Khalil
Publisher: Springer Science & Business Media
ISBN: 364284605X
Category : Science
Languages : en
Pages : 570
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Book Description
Methane plays many important roles in the earth's environment. It is a potent "greenhouse gas" that warms the earth; controls the oxidizing capacity of the atmosphere (OH) indirectly affecting the cycles and abundances of many atmospheric trace gases; provides water vapor to the stratosphere; scavenges chlorine atoms from the stratosphere, terminating the catalytic ozone destruction by chlorine atoms, including the chlorine released from the man-made chlorofluorocarbons; produces ozone, CO, and CO2 in the troposphere; and it is an index of life on earth and so is present in greater quantities during warm interglacial epochs and dwindles to low levels during the cold of ice ages. By all measures, methane is the second only to CO2 in causing future global warming. The book presents a comprehensive account of the current understanding of atmospheric methane, and it is an end point for summarizing more than a decade of intensive research on the global sources, sinks, concentrations, and environmental role of methane.
Author: John E. Hobbie
Publisher: Oxford University Press
ISBN: 0199860408
Category : Science
Languages : en
Pages : 354
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Book Description
The latest volume in the LTER series, this book presents the results and finding of the Long-Term Ecological Research site in the Alaskan Arctic, discussing Arctic ecology from a variety of perspectives and disciplines.
