Bazzaz and Fajer


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SCIENTIFIC AMERICAN REPRINTED WITH PERMISSION: Plant Life in a CO7-Rich World Even without considerations ofglobal warming, increasing atmospheric levels of carbon dioxide may greatly alter the structure and function of ecosystems. These changes will not necessarily benefit plants by Fakhri A. Bazzaz and Eric D. Fajer P iants are the green cornerstone of terrestrial life. The abundance and productivity of trees and @-as=, herbs, shaobs, mow weeds shape how ecosystems cirrulate gases and nutrients, deanse waterW?mild soils and provide sustenance for a variety of other lifeforms Any significant varih tion in the productivity and compo- sition of plant life would precipitate a cascade of dxmges affecting herbi- vores, carnivores omnivores alike. One such change may be mder way. Fuel combustion and deforestation are rapidly dtering the nature of the earrh's atmosphere. Perhaps the most impor- tant atmospheric campmm affmed by human activity is cabon dioxide (CO,). Since. dam of industrial age, the concentrations this gas have increased from 280 ro Js~ parts per miUion-the hghest level h the past 160,000 years for which a CO, record i FAKHRJ A BAZW and ERE D. Fm have studid veTious aqxtsoftheco~lp plex role of atmospheric carbon inecosy-BaazazfstBeKHfim- ken Professor of Scie at Harvard Uni- versity and for the past two decades has reseat&& how rlsfng CO, levels will al- ter plant life. He rrceived hij PILD. from uniwmity llllmJis in 1963. Fa@ recently completed Ms PhD. at Harm4 where he examiwd the Bnpact of high C& on plants hbiwrous in- sects: He is a postdoctoral marcher at the Center for Scieace and International Affairs at the john F. Kermedy School of GovemmeM. The awhors gratefully ac- knowledge the support of the U.S. De- ment of Energy. ELprinied with jzt'missi(m. Copyright can be found in ice core samples. Mea- swements at the Mauna Loa observa- tory in Hawaii have documented about a 20 percent increase in CO, lwels be- tween 1957 and the present. Although estimates vary, experts anticipate that global mnceno-aions of CO, will dou- ble by the middle to the end of the 2 1 st century. At first glance, elevated carbon diox- ide lwels might s&m an agricultural blessing. Initial studies suggested that a high CO, environment would enhance plant growth. This CO, fenilkation ef- fect, as it is called, wed to be particularly pronounced if plants have plentiful supplies of nutrients, light and water. The CO, fertikation effect also prom- ises to provide a buffer for concerns about glW warming. Plants growing larger in such environment could be counted on to draw more CO, from atmosphere. Tbus, lwd of this gmnbwe gas-which mps energy from the sun that reradiated as heat from the earth's surface-would be lower than expected. Indeed, the fed- zation has been considered in.
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This note was uploaded on 10/24/2011 for the course POLS POLS 333 taught by Professor Evans during the Winter '11 term at Cal Poly.

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