Ch15_Mankind

Ch15_Mankind - Mankind at the Helm 1 Chapter Fifteen...

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Unformatted text preview: Mankind at the Helm 1 Chapter Fifteen Mankind at the Helm In the absence of “intelligent” life our planet would continue for billions of years along more or less the same course it has followed in the past. Our Sun has enough remaining hydrogen to burn smoothly for several billions of years. The heat produced by the radioactivity of our Earth’s mantle, although diminishing, will be adequate to drive the crustal plates for at least a few more billion years. However, we humans have changed the outlook for our planet. Although our F rst tool- bearing ancestors appeared some 2 million years ago, until about 10,000 years ago we competed on a more or less equal footing with our fellow inhabitants and we lived in harmony with the natural environment. Then we discovered agriculture which gave us a great competitive advantage over our fellow animals. In order to enhance our food supply, we learned to reroute the fl ow of water, to till the soils, to eliminate weeds and pests, and to domesticate animals. In so doing we began to tamper with natural cycles. Starting about 150 years ago, industrialization greatly accelerated this man-made modiF cation of our planet’s surface. It has led to the depletion of resources, a buildup of CO 2 in the atmosphere, acidiF cation of our soils, and the accumulation of poisonous compounds throughout the environment. ¡urther, our activities threaten the extinction of innumerable species of plants and animals. Even more recently we mastered the secrets of the atom. Our nuclear arsenals are now large enough to cripple civilization. The radioactive waste created by this enterprise scars the landscape. Terrorist organizations and rogue nations scheme to gain access to the plutonium produced in nuclear reactors. Thus, for better or worse, we are now at the helm. We have the power to modify climate, to designate the habitats of the remaining wildlife, to alter the chemistry of soil and water. We have even begun to tinker with the genetic make-up of many organisms and are at the brink of cloning even ourselves. Unfortunately, our activities are intervening at such an alarming pace that we are not in control. How much damage will be done before we are able to take the reins in a responsible manner? Introduction Is there any reason to believe that our planet’s hospitality toward life will someday change for the worse? In the absence of mankind the answer to this question would likely be no. Our Sun will burn steadily for several billion years before becoming depleted of its nuclear fuel. Hence, in all likelihood, climate will fl uctuate around a reasonably congenial mean as it has in the past. While these fl uctuations may now and then threaten vulnerable species, the advancement of life has not been stifl ed by climate. The Earth’s internal heat source – the decay of long-lived radionuclides – although slowly diminishing, will remain strong enough to drive the movement of the mantle’s convection cells for another billion or so years. Hence, the beauty of the landscape, the availability convection cells for another billion or so years....
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This note was uploaded on 02/08/2011 for the course EAS 1601 taught by Professor Lynch during the Spring '08 term at Georgia Tech.

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Ch15_Mankind - Mankind at the Helm 1 Chapter Fifteen...

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