Geology topics

P.A. Steudler

Publications and source records attributed to P.A. Steudler.

3 recordsLinked to original sources

USGS2007

Net emissions of CH4 and CO2 in Alaska: Implications for the region's greenhouse gas budget

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 CH 4/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 CH 4 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). ?? 2007 by the Ecological Society of America.

Ecological Applications↗

USGS2006

CO2 and CH4 exchanges between land ecosystems and the atmosphere in northern high latitudes over the 21st century

Terrestrial ecosystems of the northern high latitudes (above 50??N) exchange large amounts of CO2 and CH4 with the atmosphere each year. Here we use a process-based model to estimate the budget of CO 2 and CH4 of the region for current climate conditions and for future scenarios by considering effects of permafrost dynamics, CO 2 fertilization of photosynthesis and fire. We find that currently the region is a net source of carbon to the atmosphere at 276 Tg C yr -1. We project that throughout the 21st century, the region will most likely continue as a net source of carbon and the source will increase by up to 473 Tg C yr-1 by the end of the century compared to the current emissions. However our coupled carbon and climate model simulations show that these emissions will exert relatively small radiative forcing on global climate system compared to large amounts of anthropogenic emissions. Copyright 2006 by the American Geophysical Union.

Geophysical Research Letters↗

USGS2004

Methane fluxes between terrestrial ecosystems and the atmosphere at northern high latitudes during the past century: A retrospective analysis with a process-based biogeochemistry model

We develop and use a new version of the Terrestrial Ecosystem Model (TEM) to study how rates of methane (CH4) emissions and consumption in high-latitude soils of the Northern Hemisphere have changed over the past century in response to observed changes in the region's climate. We estimate that the net emissions of CH4 (emissions minus consumption) from these soils have increased by an average 0.08 Tg CH4 yr-1 during the twentieth century. Our estimate of the annual net emission rate at the end of the century for the region is 51 Tg CH4 yr-1. Russia, Canada, and Alaska are the major CH4 regional sources to the atmosphere, responsible for 64%, 11%, and 7% of these net emissions, respectively. Our simulations indicate that large interannual variability in net CH4 emissions occurred over the last century. Our analyses of the responses of net CH4 emissions to the past climate change suggest that future global warming will increase net CH4 emissions from the Pan-Arctic region. The higher net CH4 emissions may increase atmospheric CH 4 concentrations to provide a major positive feedback to the climate system. Copyright 2004 by the American Geophysical Union.

Global Biogeochemical Cycles↗