The Lost City Hydrothermal Field, an ultramafic-hosted system located 15 km west of the Mid-Atlantic Ridge, has experienced at least 30,000 years of hydrothermal activity. Previous studies have shown that its carbonate chimneys form by mixing of approximately 90 degrees C, pH 9-11 hydrothermal fluids and cold seawater. Flow of methane and hydrogen-rich hydrothermal fluids in the porous interior...

[1] The globally-averaged atmospheric methane abundance determined from an extensive network of surface air sampling sites was constant at 1751 ppb from 1999 through 2002. Assuming that the methane lifetime has been constant, this implies that during this 4-year period the global methane budget has been at steady state. We also observed a significant decrease in the difference between northern ...

Abstract Methane (CH 4 ) is the second most important naturally occurring greenhouse gas (GHG) after carbon dioxide (Myhre G et al 2013 Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to Fifth Assessment Report Intergovernmental Panel on (Cambridge: Cambridge University Press) pp 659–740). For both GHGs, present-day budget dominated by anthropogenic emissions (F...

The importance of methane emissions from pan-Arctic lakes in the global carbon cycle has been suggested by recent studies. These studies indicated that climate change influences this methane source mainly in twoways: thewarming of lake sediments and the evolution of thermokarst lakes. Few studies have been conducted to quantify the two impacts together in a unifiedmodeling framework. Herewe ada...

Titan’s thick atmosphere and volatile-rich surface cause it to respond to big impacts in a somewhat Earth-like manner. Here we construct a simple globallyaveraged model that tracks the flow of energy through the environment in the weeks, years, and millenia after a big comet strikes Titan. The model Titan is endowed with 1.4 bars of N2 and 0.07 bars of CH4, methane lakes, a water ice crust, and...

Lake Towuti is a tectonic basin, surrounded by ultramafic rocks. Lateritic soils form through weathering and deliver abundant iron (oxy)hydroxides but very little sulfate to the lake and its sediment. To characterize the sediment biogeochemistry, we collected cores at three sites with increasing water depth and decreasing bottom water oxygen concentrations. Microbial cell densities were highest...

The unprecedented challenges of creating Biosphere 2, the world's first laboratory for biospherics, the study of global ecology and long-term closed ecological system dynamics, led to breakthrough developments in many fields, and a deeper understanding of the opportunities and difficulties of material closure. This paper will review accomplishments and challenges, citing some of the key researc...