Though there is lots of background information about the theorys and viewpoints. There has been one main topic that has been talked about a lot so far. And then another that has been touched on.
The first being the K-T extinction. This took place inbetween the Cretaceous and Tertiary periods. This extinction caused a lot of controversy because a father and son scientific team from the University of Berkley named Alvarez published a paper saying that this extiniction was caused by a giant asteroid that hit the Earth caused huge environmental changes through out the whole world. Many critics didn't believe his theory and challenged it for a long time. They believe that it the extinction was caused by a long term climate change and extinctions happened over a course of a long time.
Alvarez explained his theory was like a domino effect. The first being that it wasn't just the impact itself that would have killed off so many species, it was a period of darkness that occured after the impact because of the large amount of debris in meteoric and Earth material that was blown into the atmosphere. This would kill much of the plant life on earth. Next, large amounts of sulfer was also in the atmosphere after the impact, that rained down as acid rain. Also, because so much sunlight would have been absorbed by atmosphereic dust particles the Earth cooled down to almost, or to, near freezing temperatures. Which before the impact the Earth had mostly tropical. With all of these drastic changes a mass extiniction was a definite possiblity.
Later, Peter Ward was able to vist a K-T boundary site, which are located all over the world. In his journey there he made a discovery that supported Alverez's theory. He found, tiny pieces of platinum and iridium- which is what stars and asteroids are made out of. Platunum and iridium were then discovered all over the world at other K-T boundary sites. By the 1990s very few people doubted Alvarez's theory. Were the asteroid supposedly hit was the Yucatan Peninsula of Mexico, the impact site being called the Chicxulub Crater. The other topic, was another boundary that was discovered that was first thought to be a time period when very little extinction took place. But it was discovered, through investigation of carbon and oxygen isotopes, that instead the shallow water of the oceans being more than the deeper water it was just the opposite. The water was being warmed from the bottom. Since the water was becoming more warm, there was less oxygen in the water many organisms living in the ocean started to die out fairly rapidly.
Implications
The topics so far affect society because the more we know about Earth's past the better we can prepare for the future. Actually many scientists in the book said that it is very possible that many of Earth's extinctions could have been caused my meteors, and that it could happen again. So far, not much has been mentioned about a rise in CO2 or global warming but many of the reviews of the book have said it's a big part of Under a Green Sky. So I think that implications that can affect society today are going to be addressed more later in the book.
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