Science of Global Climate Modeling Confirmed By Discoveries on Mars
Scientific modeling methods that predicted climate change on Earth have been found to be accurate on Mars as well, according to a paper presented at an international planetary sciences conference Tuesday.
An international team of researchers from the Planetary Science Institute in Tucson, working with French colleagues, found that an unusual concentration of glacial features on Mars matches predictions made by global climate computerized models, in terms of both age and location.
PSI Senior Scientist William K. Hartmann led the team, which included Francois Forget (Universite Paris), who did the Martian climate modeling, and Veronique Ansan and Nicolas Mangold (Universite de Nantes) and Daniel Berman (PSI), all of whom analyzed spacecraft measurements regarding the glaciers."Some public figures imply that modeling of global climate change on Earth is 'junk science,' but if climate models can explain features observed on other planets, then the models must have at least some validity," said team leader Hartmann.
Hartmann presented the report, "Science of Global Climate Modeling: Confirmation from Discoveries on Mars," at the annual meeting of the Division for Planetary Sciences of the American Astronomical Society in Reno, Nev.The scientific team reached their conclusions by combining four different aspects of Martian geological mapping and Martian climate science in recent years.
They noted that the climate models, the presence of glaciers, the ages of the glacial surface layers, and radar confirmation of ice in the same general area all gave consistent results - that the glaciers formed in a specific region of Mars, due to unusual climate circumstances, just as indicated by the climate model.
The work has a long background. As early as 1993, astronomers analyzed the changing tilt of Mars's rotational axis and found that during high-tilt Martian episodes, the axis tilt can exceed 45 degrees. Under this extreme condition, the summer hemisphere is strongly tilted toward the Sun, and Mars's polar ice cap in that hemisphere evaporates, increasing water vapour in the Martian air, thus increasing the chances for snowfall in the dark, cold, winter hemisphere. The last such episodes happened on Mars 5 million to 20 million years ago.
By 2001-2006, various French and American researchers applied the global climate computer models to study this effect. The computer programs were originally developed for planet Earth to estimate climate effects, from hurricane paths to CO2 greenhouse warming.
Planetary scientists simply applied the Martian topography, atmosphere, and gravity, in order to run the computer calculations for Mars. The calculations indicated a strong concentration of winter snow and ice in a mid-latitude southern region of Mars, just east of a huge Martian impact basin named Hellas.
At the same time, the PSI scientists independently discovered an unusual concentration of glacial features in a 40-mile-wide crater named "Greg" centered in the same region. Their analysis showed that the surface layers of the glaciers formed at the same time as the predicted climate extremes, about 5 million to 20 million years ago.
"The bottom line is that the global climate models indicate that the last few intense deposits of ice occurred about 5 million to 15 million years ago, virtually centered on Greg crater, and that's just where the spacecraft data reveal glaciers whose surface layers date from that time," Hartmann said.
"If global climate models indicate specific concentration of ice-rich features where and when we actually see them on a distant planet, then climate modeling should not be sarcastically dismissed. Our results provide an important, teachable refutation of the attacks on climate science on our home planet."
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Article No.2
Climate Change May Alter Amphibian Evolution
— Most of the more than 6,000 species of frogs in the world lay their eggs in water. But many tropical frogs lay their eggs out of water. This behavior protects the eggs from aquatic predators, such as fish and tadpoles, but also increases their risk of drying out. Justin Touchon, post-doctoral fellow at the Smithsonian Tropical Research Institute, discovered that climate change in Panama may be altering frogs' course of evolution.
By analyzing long-term rainfall data collected by the Panama Canal Authority, Touchon discovered that rainfall patterns are changing just as climate-change models predict."Over the past four decades, rainfall has become more sporadic during the wet season," said Touchon. "The number of rainy days decreased, and the number of gaps between storms increased."
The eggs of the pantless treefrog, Dendropsophus ebraccatus, are extremely susceptible to drying. The embryos die within a day when there is no rain. Heavy rains trigger breeding, so as storms become sporadic, the chance of rain within a day of being laid decrease and so does egg survival.
As weather patterns have changed, the advantage of laying eggs out of water has decreased, not only for pantless tree frogs but potentially for many species. "Pantless tree frogs can switch between laying eggs in water or on leaves, so they may weather the changes we are seeing in rainfall better than other species that have lost the ability to lay eggs in water," said Touchon. "Being flexible in where they put their eggs gives them more options and allows them to make decisions in a given habitat that will increase the survival of their offspring."
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