Friday, October 29, 2010

Climate change and our understanding of habitability.

I was just checking out the astrobiology magazine website, and noticed that there is an entire blog dedicated t o Climate Change and Global Warming:

I initially thought this surprising because it didn't strike me as obvious that astrobiology and climate change would be related, but upon reading more, I learned that the process of watching climate change on Earth and noticing the effects, helps us to understand how climate and habitability relate. Understanding Earth's own climate is necessary to understanding what makes a planet habitable. Climate change makes us appreciate how influential climate is on habitability which is especially vital for the field of astrobiology because of the need to determine the importance of various habitability factors.

It is true that the knowledge gleaned from the study of climate change is most applicable to 'our' life form. Discovering the tipping points that govern whether a temperature is habitable for certain species is incredibly important for determining the habitability of our own planet for our life form, but how can this be extrapolated to other life forms? For one thing, all life will be dependent on climate and it is essentially impossible to imagine life will be adaptable to highly variable climates. Thus a stable climate over time may be crucial. The effects of climate change will be interesting to assess in our life time because of the short time frame in which climate is changing.

One notable thing that climate change has taught us is an appreciation for the interconnectedness of Earth. Timothy Herbert, of Brown University (!) recently wrote a paper on this and highlighted this interconnectedness: “What surprised us is that the tropics seemed to shiver when the polar latitudes get cold, and they warm up when the ice ages pass.” He suggests that the link between the oceans has to do with CO2 levels. The polar oceans absorb a lot of it and can draw down atmospheric levels by as much as 30 percent. This impacts the tropical oceans, which have a powerful influence over global climate conditions. Warm tropical oceans produce water vapor, which drives global rainfall patterns and is a potent greenhouse gas warmer.

Climate change also enhances the importance of relatively stable climate niches for the evolution of life. Such niches like deep sea vents, glaciers, and sub-surface environments are crucially removed from the fluctuating climate. This may be crucial for the ability of life to possibily originate in these niches, and to perhaps remain most primitive because of low levels of selection. Understanding where these niches are located and what makes them stable for life to evolve relatively un-disturbed may shed light on what features to look for in exoplanets to find life.

What are some other ways that climate change can help inform astrobiologists?

1 comment:

  1. That blog is really cool! There was definitely some research topics that I didn't even realize could be related to climate change in an astrobiological reference.
    Anyway, I looked up some other stuff on the relationship of Earth's climate to advances being made in astrobiology, and I found one article that I thought was particularly interesting. It was published in 2001, by some researchers at UC Santa Barbara. They found that the transient glaciation and other climatic variations during a period from about 20 to 25.5 million years ago correspond with variations in Earth's orbit known as Milankovitch cycles. These Milankovitch cycles are just cyclical variations in certain elements (eccentricity, obliquity, and precession) of Earth-Sun geometry that can cause major changes in the Earth's climate. The researchers discovered that around 23 million years ago there was a rare congruence of a low point in the Earth's eccentricity and a period of minimal variation in obliquity. The result of this rare congruence was a period of about 200,000 years when there was unusually low variability in the planet's climate, with reduced extremes of seasonal warmth and coldness. The Earth's orbit was nearly circular, so its distance from the Sun stayed about the same throughout the year. In addition, the tilt of Earth's axis, which gives rise to the seasons, varied less than usual.
    So, this is another way that climate change can help inform astrobiologists, but not as much in a way that utilizes current issues with climate change...