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Researchers who gathered in San Francisco in December at the annual fall meeting of the American Geophysical Union heard the usual variety of talks treating everything from Earth's core to the tenuous wisps of solar particles far beyond Pluto. Earthquakes, the local California variety in particular, figured prominently, as did the currently popular subjects of ancient air trapped in amber and the deepening Antarctic ozone hole.
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December's annual fall meeting of the American Geophysical Union presented another opportunity for specialists in everything from air pollution to the origin of Earth to immerse themselves in their narrow disciplines as well as cross into related areas. Overlap between disciplines can be peripheral but interesting, as in the examples below. The amount of salt in surface water can influence ocean circulation and thus climate, and water passing from the crust through sediments into the ocean can help control the concentration and composition of seawater salts.
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At the annual meeting of the Geological Society of America in Boston during late October, Earth's crust came in for close scrutiny. One surprise was its age: Chemical and isotopic evidence suggested the crust formed soon after the planet did. Participants also discussed features of today's crust, including a horizontal slice beneath San Francisco and the possibility that a particular kind of crustal stretching, long envisioned, may not actually take place.
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With 6000 attendees and 4700 presentations, the annual fall meeting of the American Geophysical Union (AGU) in San Francisco last month was the biggest yet. And that made room for even more diversity than usual. Only the AGU could accommodate news of asteroid impacts and extinctions one-third of a billion years ago and a progress report on the first direct measurements of centimeter-scale ocean mixing, an ongoing study in the Atlantic.
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Searching for a common theme in a gathering as diverse as the spring meeting of the American Geophysical Union (AGU) in Baltimore last month might seem futile. But satellites, both natural and artificial, provided some of the meeting's high points. Researchers reported on the first science results from the Clementine spacecraft's 2-month sojourn orbiting the moon, the revealing color of the small moon that accompanies the asteroid lda, and the planned termination of the Magellan spacecraft orbiting Venus.
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Researchers attending the spring meeting of the American Geophysical Union held 18 to 21 May in Baltimore have grown familiar with doing geophysical studies by satellite. Here are three current examples discussed at the meeting: gauging the output of the sun, measuring crustal movement, and deciphering the mineral composition of surface rocks.
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Seismologists attending last month's meeting of the American Geophysical Union in San Francisco heard much about how the irregularities on faults control their behavior and thus the generation of earthquakes. The identification of small crucial areas of a fault, such as the strong spot where a rupture can begin or the fault jog where it can end, is proving a challenge, but it also offers one of the best hopes of understanding and predicting fault behavior.
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Geophysicists specializing in everything from atmospheric science to volcanology converged on Baltimore for the spring meeting of the American Geophysical Union held 18 to 21 May. The range of fare was huge, but here is a sampler: two high-energy phenomena-nuclear testing and the less frequent cratering by large impacts-and an imperceptibly slow process-the motion of the tectonic plates.
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Never one to take its middle name too literally, the American Geophysical Union indulged the interests of a range of extraterrestrial researchers at its spring meeting last month in Montreal. In a session on the big icy bodies of the outer solar system, attendees saw the first view of the face of Pluto. In another session, on dating small rock samples, listeners heard evidence that the moon might have been battered in its youth. And a session ostensibly devoted to Earth's mantle yielded news that some form of plate tectonics seems to be operating on Venus.
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A few years' perspective on the 1997-98 El Niño and a toughening of standards has dropped model forecast performance from spectacular to encouraging; some critics don't even give the models a passing grade. According to an analysis published in the September issue of the Bulletin of the American Meteorological Society, the sophisticated models did a poor job of predicting the 1997-98 El Niño's full course; in fact, they did no better than a rudimentary model that can run on a desktop. Others won't go that far but agree that the models' reputation needs to be taken down a notch or two.
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The climate treaty being hammered out this month at The Hague may be doomed to failure, as numerous observers say the United States simply won't ratify any treaty that requires such wrenching reductions in carbon emissions, and if the United States bails out, the protocol is in very deep trouble. Some policy analysts think that by tweaking the rules, the United States could eventually sign on, but if they are tweaked too much, other countries may balk. The key, some say, will be keeping the treaty going now and rethinking its controversial goals later.
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By publishing an alternative, and decidedly upbeat, scenario for how greenhouse warming might play out in the next half-century, the director of NASA's Goddard Institute for Space Studies in New York City hoped to open new prospects for attacking the problem. Instead, he got a lot of grief.
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According to the latest estimates by the U.S. Geological Survey, the world has 20% more oil awaiting discovery in yet-to-be-found fields than the USGS estimated 6 years ago. And a newly analyzed category--oil lurking in and around known fields--offers almost as much additional oil as in those undiscovered reservoirs. But even if the additional oil is really there, pessimists argue that it pushes back the global production peak--and the end of the era of cheap oil--by years, not decades.
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A U.S. national assessment, drawing on the best available climate model predictions, has concluded that the United States will indeed warm, affecting everything from the western snowpacks that supply California with water to New England's fall foliage. But on a more detailed level, the assessment often draws a blank. As much as policy-makers would like to know exactly what's in store for Americans, the rudimentary state of regional climate science will not soon allow it, and the results of this 3-year effort brought the point home.
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A wave of chatter about water and therefore possible life on Mars swept a paper at Science into headline news a week before its scheduled publication. The paper, on page 2330 of this issue, features high-resolution pictures of muddy-looking gullies on the sides of martian craters, suggesting the prospect of liquid water on, or at least near, the surface of the planet. But a number of skeptical planetary scientists are already coming up with alternative explanations for the rivulet-ridden piles of debris that exclude stores of liquid water and therefore readily accessible life.
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Last month, the Geological Society of America held their annual meeting here. Offerings included claims for the oldest known examples in a class: the oldest scrap of ocean crust, the oldest sample of Earth, and the oldest trace of life--which happens to come from Mars.
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This week an international team of astronomers announced the discovery of four new moons of Saturn, restoring the ringed planet to its status as commander of the largest retinue of satellites in the solar system. Their appearance should help researchers understand not just how the new moons were formed but also how the giant planets themselves came to be.
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For several years, ever-improving telescope technology has allowed astronomers to peer farther and farther beyond Neptune to discover a rapidly increasing number of bodies littering the outer reaches of the solar system. Now many researchers agree that an end is in sight, although some remain skeptical.
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Three researchers pondering what could be behind a roughly 1500-year cycle of warming and cooling are suggesting that it is a combination of two climate drivers, each too weak to have a large effect on its own. When a strictly periodic cycle teams up with just the right amount of thoroughly irregular noise, the combination could achieve "stochastic resonance" and set off the dramatic climate shifts of the last ice age--or the next, possibly human-triggered, Little Ice Age. No one is claiming the case is proven, but if true it will complicate predictions of future climate.
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On page 1338, a group of geophysicists suggests that the mysterious boundary between Earth's molten iron core and its rocky mantle most resembles an inverted sea floor, with liquid-iron-laced sediments collecting on the roof of the core. They argue that a slow, inverted rain of precipitates rising to the core-mantle boundary and settling into a kilometers-thick layer might explain a variety of observations, from a subtle nodding of Earth's axis to seismic speed zones at the boundary. Their story will be difficult to verify, however, because painting a portrait of the core-mantle boundary depends on very indirect geophysical evidence.