You are currently browsing the category archive for the 'climate' category.
Venus today is far too hot to sustain surface liquid water or any biology requiring it, but did Venusian life exist in the past? Nearly all remains of past life would have been destroyed by now, but it is plausable–and perhaps likely–that Venus once boasted Earth-like oceans. This possibility exists because the sun may not have been as bright in the past.
Models of stellar evolution predict that a star brightens by about 30% over it’s main sequence lifetime due to core contraction as the star fuses hydrogen into helium. The inference of warmer-than-present temperatures for the early Earth despite the reduction in solar luminosity is known as the faint young sun paradox (one of my research interests). Earth seems to have sustained both liquid water and life for nearly 4 billion years, continually maintaining habitable temperatures.
So what happened to Venus? Eventually the surface received enough energy to evaporate the oceans and enter a positive feedback known as a runaway greenhouse. Today, we see a cloudy world with sulfuric acid rain and a surface hot enough to melt lead. But 4 billion years ago life could have arisen in the Venusian oceans and perhaps even lasted long enough to develop intelligence.
I can imagine a Venusian scientist carefully working out models of stellar evolution–only to find that their parent star was slowly and steadily brightening! We look back in time and find a faint young sun paradox, but the Venusians would have a contemporary warming sun catastrophe! The greatest climate disaster in the history of our solar system may well have been when Venus entered its runaway greenhouse state to become uninhabitable.
Last day of AbSciCon tomorrow. The conference has been useful and thought provoking, though I have almost reached my saturation level for absorbing new information from fifteen minute talks. I present my talk on the climate of the Archean Earth (2.8 billion years ago) tomorrow morning. I also didn’t realize this until I arrived here, but apparently I have my name on four abstracts at the conference!
A Revised, Hazy Methane Greenhouse for the Archean Earth, J. Haqq-Misra, S. Domagal-Goldman, P. Kasting, J. Kasting
Synthesizing Archean Models and Data: A Self-Consistent Evolutionary History, S. Domagal-Goldman, J. Kasting, J. Haqq-Misra
Sustainability and the Fermi Paradox, J. Haqq-Misra
TPF-SETI, S. Domagal-Goldman, J. Haqq-Misra
Compared to the other conferences I’ve attended, it’s quite rewarding to feel like I’ve contributed something to the astrobiology community. More on the conference when I get back this weekend!
I took the trek to Punxsutawney, PA Friday night to witness the peculiar American tradition of seasonal forecasting by use of small, hibernating rodents. Phil, the groundhog of infamy, has been providing this service for upwards of a hundred years, thanks to a special elixir that grants him longevity. Though Phil paid our department a visit on Tuesday, for some reason a night-long excursion to see the groundhog in action seemed like a good idea.
The crowd stayed occupied between 2am and sunrise with a combination of classic rock and chants of “Phil! Phil! Phil!” Finally as the sky brightened, the full contingency of the Inner Circle took charge and produced Phil–the prognosticator of prognosticators–from a giant stump in the center of the stage. The senior member of the Inner Circle took Phil into his confidence where, using his special knowledge of groundhogese, he informed the crowd of 30,000 that Phil had seen his shadow and six more weeks of winter would follow.
Though Punxsutawney is touted as the “weather capital of the world”, the flurry of celebration seemed to have little concern for the actual prediction; people were more interested in groundhog veneration than the actual forecast. If deification can be attained by amassing followers, then Punxsutawney Phil is well on his way to godhood.
Though limited to the four elements of earth, air, fire, and water and lacking any experimental methods, some of Aristotle’s insights foreshadow the paradigm shifts brought on by the discovery of fossils and radioactive dating.
But these changes escape our observation because the whole natural process of the earth’s growth takes place by slow degrees and over periods of time which are vast compared to the length of our life, and whole peoples are destroyed and perish before they can record the process from beginning to end.
–Aristotle, Meteorologica XIV
Recent Comments