Estimating the Number of Civilizations - Assignment Example

In the class notes, we make use of the Drake equation as providing a statistical estimate of the number of civilizations that might exist in our Galaxy and are capable of communication. Recently, however, some scientists have argued that the Drake equation is an inaccurate description. This new theory is known as the "Rare Earth Theory" (by Ward and Brownlee).
Since 1961 when Drake came up with the drake equation as the tool for estimating the chances of civilizations in the Milky Way, it has been believed that there might be life on other planets. However, Ward and Brownlee have recently come up with the Rare Earth Theory that suggests otherwise. This theory suggests several arguments that portray the earth as a unique planet. Firstly, a planet needs to be big enough to sustain a healthy atmosphere, climatic conditions, and acceptable radiation levels. This is, however, not the case considering most planets and stars are far smaller or larger. Small planets and stars emit very large amounts of radiation and the large ones such as Jupiter are characterized by very high temperatures and pressure. Secondly, most planets are closer to either the sun or a host star which makes them very hot (Lallanilla, 2013). Thirdly, billions of stars in the galaxy make it difficult to decide which to look for life. Finally, the earth, unlike other planets, has a moon that stabilizes the orbit, next to Jupiter that protects it from frequent impacts, and water bodies that stabilize the climate on earth.

2. A dramatic new view of the geologic history of the Earth has arisen in the last few years. This view is quite controversial and is known as "Snowball Earth." Summarize what this theory is and what are some of the evidence for and against this hypothesis.
The Snowball Earth is a theory that posits the Earth could have entirely frozen about 650 million years ago. This could be explained to have resulted from events of very weak sun output and low CO2 output. The major evidence that shows the possibility of such a situation happening is the existence of organisms that can survive such conditions today. Additionally, the drop stone that is found at the bottom of sea beds all over the world could be a result of the ice age. However, there is evidence that suggests otherwise regarding the occurrence of an ice age (Lallanilla, 2013). This includes the chemical weathering activities and complex photosynthesized organisms dating back to the same period of the ice age.

3. Do some research on hydrothermal vents and their associated biological communities. Provide an argument that it is this environment that is most responsible for the existence of life on Earth.
The 1977 hydrothermal events and the biological community discovery, provide biologists a reason to research the possibility of hydrothermal vents being a source of life. They argue that a mix of hot and cold water in the vent results in the formation of organic compounds that combine and eventually create life. The water contains minerals, metals, and chemosynthetic bacteria that contribute to producing food for the biological communities. Once the bacteria accumulate on the vent, small animals such as amphipods come to feed than the larger ones that feed on both the bacteria and the smaller animals. The biologist also discovered that bacteria exist under the same conditions on the surface (Lallanilla, 2013).

4. Do some research on the rate at which Greenland is Melting and provide evidence that we are nearing a point of return where the ice sheet cannot recover.
The Greenland ice sheet refers to the enormous body of ice that covers about 80 percent of the Greenland surface (Lallanilla, 2013). The sheet for over 10 years has melted at an alarming rate above the expectations of the scientists. This is a result of sea warming, high land temperature, climatic change, and globalization. Till 2003 the meltdown has been limited but since then a significant mass loss has been recorded. Over the last decade, the melting rate has raised from 4.1 to 11.5 percent while the ice increased at the rate of only 1.2 percent. The Greenland melting, currently, contributes to 0.59 millimeters from 0.09 millimeters rise in sea level. At this rate, there are possibilities that by 2081the ocean levels will increase by 21 percent and more worrying by seven meters if allowed to completely melt.

5. Do some research on the warming in the arctic and the thawing of Arctic permafrost which releases Methane as part of the thawing process. Discuss whether or not you think we are now heading toward a climate catastrophe.

This would in turn affect the hydrology, infrastructure damages, as well as, habitat alteration. There are estimations that about 135 billion tonnes of methane may be released by 2100 and 415 billion tonnes by 2200. In my opinion, with the threat of global warming, the world may end up in a climatic crisis. Read More