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The ability of NASA's Mars Reconnaissance Orbiter to continue charting the locations of these hidden glaciers and ice-filled valleys -- first confirmed by radar two years ago -- adds clues about how these deposits may have been left as remnants when regional ice sheets retreated. The subsurface ice deposits extend for hundreds of kilometers, or miles, in the rugged region called Deuteronilus Mensae, about halfway from the equator to the Martian north pole. Jeffrey Plaut of NASA's Jet Propulsion Laboratory, Pasadena, Calif., and colleagues prepared a map of the region's confirmed ice for presentation at this week's 41st Lunar and Planetary Science Conference near Houston. The Shallow Radar instrument on the orbiter has obtained more than 250 observations of the study area, which is about the size of California. "We have mapped the whole area with a high density of coverage," Plaut said. "These are not isolated features. In this area, the radar is detecting thick subsurface ice in many locations." The common locations are around the bases of mesas and scarps, and confined within valleys or craters. Plaut said, "The hypothesis is the whole area was covered with an ice sheet during a different climate period, and when the climate dried out, these deposits remained only where they had been covered by a layer of debris protecting the ice from the atmosphere."

By combining a hurricane model and coupled ocean-atmosphere general circulation model to investigate the early Pliocene, Emanuel, Brierley and co-author Alexey Fedorov observed how vertical ocean mixing by hurricanes near the equator caused shallow parcels of water to heat up and later resurface in the eastern equatorial Pacific as part of the ocean wind-driven circulation. The researchers conclude from this pattern that frequent hurricanes in the central Pacific likely strengthened the warm pool in the eastern equatorial Pacific, which in turn increased hurricane frequency — an interaction described by Emanuel as a “two-way feedback process.”�The researchers believe that in addition to creating more hurricanes, the intense hurricane activity likely created a permanent El Nino like state in which very warm water in the eastern Pacific near the equator extended to higher latitudes. The El Nino weather pattern, which is caused when warm water replaces cold water in the Pacific, can impact the global climate by intermittently altering atmospheric circulation, temperature and precipitation patterns.The research suggests that Earth’s climate system may have at least two states — the one we currently live in that has relatively few tropical cyclones and relatively cold water, including in the eastern part of the Pacific, and the one during the Pliocene that featured warm sea surface temperatures, permanent El Nino conditions and high tropical cyclone activity.Although the paper does not suggest a direct link with current climate models, Fedorov said it is possible that future global warming could cause Earth to transition into a different equilibrium state that has more hurricanes and permanent El Nino conditions. “So far, there is no evidence in our simulations that this transition is going to occur at least in the next century. However, it’s still possible that the condition can occur in the future.”�Whether our future world is characterized by a mean state that is more El Nino-like remains one of the most important unanswered questions in climate dynamics, according to Matt Huber, a professor in Purdue University’s Department of Earth and Atmospheric Sciences. The Pliocene was a warmer time than now with high carbon dioxide levels. The present study found that hurricanes influenced by weakened atmospheric circulation — possibly related to high levels of carbon dioxide — contributed to very warm temperatures in the Pacific Ocean, which in turn led to more frequent and intense hurricanes. The research indicates that Earth’s climate may have multiple states based on this feedback cycle, meaning that the climate could change qualitatively in response to the effects of global warming.

Opposition Republicans are using the delaying tactic at a record-setting pace. "The numbers are astonishing in this Congress," says Jim Riddlesperger, political science professor at Texas Christian University in Fort Worth. The filibuster, using seemingly endless debate to block legislative action, has become entrenched like a dandelion tap root in the midst of the shrill partisanship gripping Washington. But the filibuster is nothing new. Its use dates to the mists of Senate history, but until the civil rights era, it was rarely used.

As a matter of political philosophy, the concept of the filibuster arises from a deep-seated, historic concern among Americans that the minority not be steamrolled by the majority. It is a brake and protective device rooted in the same U.S. political sensibility that gave each state two senators regardless of population. The same impulse gave Americans the Electoral College in presidential contests — a structure from earliest U.S. history designed to give smaller population states greater influence in choosing the nation's leader. Given recent use of the filibuster by minority Republicans and the party's success in snarling the legislative process in this Congress, Democrats say the minority has gone way beyond just protecting its interests. The frequency of filibusters — plus threats to use them — are measured by the number of times the upper chamber votes on cloture. Such votes test the majority's ability to hold together 60 members to break a filibuster. In the 110th Congress of 2007-2008, with Republicans in the minority, there were a record 112 cloture votes. In the current session of Congress — the 111th — for all of 2009 and the first two months of 2010 the number already exceeds 40. The most the filibuster has been used when Democrats were in the minority was 58 times in the 106th Congress of 1999-2000.