The Sixth Extinction: Chapter 8

     In Chapter 8, Kolbert goes to Peru to meet forest ecologist Miles Silman. She goes on to talk about global warming and how it’s dangerous for tropical life forms. She also talks about the different theories on tropical climates being helpful to biodiversity which are: 1) animals reproduce faster → more genetic mutations → more varieties of species; 2) tropical climates have low temperature fluctuation → different zones can only nurture life with very specific thermal tolerances; 3) they’re much older than other ecosystems and they've been able to accumulate great diversity over time. Silman takes Kolbert to the forest to explore different tree species and learns that he’s been recording the diversity of different tree plots. His student Kenneth Feeley found that the increasing temperatures of the Peruvian forests have driven plants/animals to higher altitudes at a rate of eight feet per year. For example, the Schefflera trees die off, and every year, their replacements grow at a higher altitude, showing the changing temperatures of the forests. Every species on the planet has evolved in some capacity to cope with changes in temperature. During the Pleistocene period of Earth’s history, the planet became significantly cooler. However, scientists predict that the average world temperature will increase at a faster rate than at any other time in the history of the Earth in the next century. Back in Peru, Silman shows Kolbert a tree species called Alzatea verticillata. Alzatea verticillata is one of the many species that hasn’t been able to migrate away from the rising temperatures. He then concludes the changes life forms will face in the next fifty years will be apocalyptic due to the changing temperatures.

     The theme that most resonated with this chapter is natural systems change over time and space. In the book it states, “For the last forty million years or so, the earth has been in a general cooling phase. It’s not entirely clear why this is so, but one theory is that the uplift of the Himalayas exposed vast expenses of rock  to chemical weathering, and this in turn led to a draw-down of carbon dioxide from the atmosphere. At the start of the Eocene, the world was so warm there was almost no ice on the planet. By around thirty-five million years ago, global temperatures had declined enough that glaciers began to form on Antarctica.” (Pg. 160) (R)  According to the book, there is nothing unusual about climate change because the world’s average temperature has changed many times in the past. However, Kolbert indicates that the speed at which the average temperature is rising is unknown to history. Due to this I think that many species won’t be to adapt to their new environments, reproduce, and survive climate change because there won’t be enough time. And because of this I predict that they’ll die out. (C) I can also connect to the recent news of the glaciers melting. In Alaska, it was reported that the glaciers were melting at a fast rate due to global warming. The glaciers in Alaska provide fresh water to many heavily populated areas of the globe and can also contribute to sea-level rise. However due to the warming of the climate and the Pacific, the rise of the sea levels are being impacted negatively.

By: Mousumi Dhar