Hunting for New Habitats
|James Kasting: Finding a habitable planet
James Kasting, a geoscience professor at Penn State University and arguably the world´s leader in the study of habitable planets, offered some insights at the California Academy of Sciences in San Francisco.
His new book, How to Find a Habitable Planet, has recently been released and can be considered a primer on the search for other life. Other scientists, namely Peter Ward, author of The Medea Hypothesis (2009), have taken the viewpoint that life is rare in the universe because it is fundamentally harmful in its destabilizing affect on a planet´s climate (an argument hard to refute in today´s age of climate change).
Kasting, a Carl Sagan protege, has a more positive outlook that uses Earth as the prototype in the search for habitable planets. For the purposes of that search, he´s excited by planets that have liquid water on the surface, some semblance of plate tectonics (to cycle carbon), and occupies a "habitable zone" near its star (in relation to the sun, Earth, of course, qualifies while Mars and Venus do not). All those help give a planet an atmosphere, making life possible.
"If you follow climate at all — and it´s hard not to with climate change — you know that surface temperature depends on the greenhouse gas effect," Kasting said.
"Astronomers are finding lots of planets. They´re just not like ours," he said.
Although lots of research has shown some potential to further the science, Kasting pins his hopes on the Kepler Mission, which is hosted by NASA Ames in Mountain View. Launched in March 2009, the space observatory is monitoring the brightness of 145,000 stars near theNorthern Cross. If a planet passes in front of a star, the brightness of the star dims and by this measure the size and the proximity of the planet to the star can be determined.
So far, the results are encouraging. "They found more small planets than big ones in close proximity to stars," said Kasting. These Earth-sized planets are promising because they´re big enough to hold an atmosphere without being so big that they become a gas planet, like Jupiter. "The most important thing is having solid matter so you can have a surface for life," Kasting said.
Finding another habitable planet doesn´t mean we´ll embark on a Battlestar Galactic mission to transport ourselves to a newer, less screwed-up planet when the time comes. It´s prudent to still take care of Earth. But we may learn a bit more from other planets about why Earth supports life and how we, as the dominant life form, can keep it healthy.
Helping dying species find new habitats
Speaking of finding a habitable planet, the Sept. 24 journal Science has highlighted an interesting debate in the conservation community about recolonizing species that are going under because of climate change. The hope is that they can prevent species from going extinct by giving them a new home, one that is now habitable because of changing climate conditions.
Some 20-30 percent of the Earth´s species are at high risk of extinction if global temperatures exceed 2 degrees Celsius above pre-industrial levels, according to the Intergovernmental Panel on Climate Change.
These are questions that even the most seasoned of ecologists scratch their heads over. One the one hand, the article points out, moving a species may be the last hope of saving it from extinction. On the other, bringing it to a new place could open up a series of unknown consequences to the other species living there, similar to the destruction caused by other introduced species. Do you save one species and put the others at risk?
What´s clear is that there isn´t much time to make good decisions. Species are dying off at an alarming rate and ecological studies take much time and thought to generate satisfactory answers. Inaction by scientists could mean that citizens´ groups and agencies make decisions on their own.
"Assisted colonization," as it´s called, is a bit like geo-engineering. People are seeking a technological solution to the crisis because other solutions seem hopeless. But we surely don´t really know what we´re getting ourselves into, or whether we can pull it off.