Read 'N' Seed Third Quarter of "Under a Green Sky"

Main Topics
a main topic first discussed was that millions of years ago there is evidence that the Earth was at one time called a 'snowball Earth.' This was ended by a rapid rise in greenhouse gases that were probably volcanically produced. These gases were measure in parts per million, but even with such a small addition of these gases it was enough to completely change the temperature all around the World.  Greenhouse gases are believed to be the major culprit for causing climate shifts throughout Earth's history. When the World warms it affects the oceans circulation system.  Greenhouse extinctions were also explained.
Currently, the global temperature is around 15 degrees and 16 degrees celcius. Each time the carbon dioxide levels double the global temperature's increase by about 2 degrees celcius. According to this book, in just a century the Earth's temperature should be around 20 degrees celcius which would, "conceivably bring about the greatest mass death of humans in all of history."

Terminology

'snowball Earth': This was a possible time in Earth's history when the entire Earth became so cold that the oceans may have frozen from pole to pole.

Greenhouse extinction:Where low oxygenated bottom water is at depths were sunlight can hit it green sulfur bacteria start to grow and expand filling the low oxygenated water.  Living amoung other bacteria that produce large amouts of hydrogen sulfide, this gas rises into the atmosphere, breaking down the ozone layer and killing a lot of the plant and animal life. With an increase in ultraviolet radiation most of the phytoplankton are killed. With the heat of the planet rising and the high levels of hydrogen sulfide creates a mass extinction oin Earth.


Implications
It stated in the book that " the key to climate change seems to be both the level and the rate at which carbon dioxide rises into the atmosphere." Climate change is obviously something that is affecting us today. The scary thing about reading these chapters was that rises in carbon dioxide levels most likely played a huge role in extinctions from the past. Since our greenhouse gases have been rising today I think it is extremely important that we do something about now.
The last part of my main topics about temperature increase and carbon dioxide levels was shocking! If things keep going the way there going in just 100 years there could be a huge mass extinction. This is just goes to show that something NEEDS to be done and changes need to be made.

Carbon Dioxide Levels