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This week from AGU: Glacier health check, world ocean atlas, liquid brines on Mars

American Geophysical Union

  • From AGU's blogs: Health check reveals how glacier is declining due to warming climate

    Researchers from the British Geological Survey have taken the very first comprehensive health check of a rapidly melting glacier. Their latest study reveals that their icy patient, the Falljökull glacier in southeast Iceland, has been dramatically declining as it tries to adjust to recent changes in the climate.

    The new findings on Falljökull show unhealthy changes in the glacier's behavior and structure. Normal glacial patterns, growing in the winter and retreating in the summer, have been replaced by all year-round melting and rapid retreat of the margin of this Icelandic glacier, while its upper reaches continue to move forward. In fact, the retreat has increased so dramatically over the last five years that there has been complete detachment of the stagnant lower section, like a lizard losing its tail.

  • From this week's Eos: Higher-Resolution World Ocean Atlas to Aid Climate Studies

    The new, detailed atlas satisfies scientists' increasing need to model the ocean at spatial scales finer than one-degree resolution at the surface and at depth.

  • From AGU's journals: Cultivating salt-loving microbes on Mars

    Some scientists suspect that life on Earth began in cold salty waters around scorching hydrothermal vents deep beneath the ocean's surface. Scientists wonder whether similar conditions could exist on Mars. Indeed, they even wonder if liquid water, an essential ingredient for life, presently exists on Mars. The process by which salt absorbs water vapor from the atmosphere to create saline solutions on Earth would take much longer under the harsh, extremely cold and dry Martian conditions. However, observations do suggest evidence of brine flows near the Martian equator and even the formation of small pools of liquid brines in polar regions.

    One possible explanation is that brine could form in the short time period of the Martian day when conditions are most favorable. To test this, Fischer et al. conducted two sets of experiments using a 160 centimeter long cylindrical tube called the Michigan Mars Environmental Chamber, which can recreate the temperatures, humidity levels, and air pressures on Mars.

    First, the scientists tested whether salt would absorb water vapor from the air with 100% saturation, at a temperature of -50°C, and at an air pressure of 800 Pascals, about 100 times less than Earth's average air pressure at sea level. Second, they investigated at what temperature range salt, when placed in direct contact with water ice, would melt and form brine solutions.

    The scientists find that bulk amounts of salt cannot form solutions by absorbing water vapor from the air within the short period of the day when conditions are favorable but that salts in direct contact with water ice can melt and form liquid brines in these short periods. They conclude that liquid brines could form in the subsurface of Mars's equatorial regions where ice is present, as well as on the surface and shallow subsurface of Mars's polar regions during seasons when water ice, either in the form of snow or frost, is present on salty Martian soils. The results have important implications for the understanding of the habitability of Mars, the scientists state in their paper.


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