Threats of global warm­ing real, shouldn’t be ig­nored

Iran Daily - - Cultural Heritage & Environment -

Sci­en­tific re­search pub­lished in the past year has re­vealed some rel­a­tively new and po­ten­tially harm­ful ef­fects that may re­sult from the in­crease in at­mo­spheric car­bon diox­ide. An ar­ti­cle in a re­cent is­sue of Sci­ence News raises con­cerns that ris­ing car­bon diox­ide lev­els may steal some crop nu­tri­ents.

Ac­cord­ing to oze­mandai­ly­chron­i­, the mech­a­nism is not yet known. Sev­eral sta­ple crops were grown in out­door ex­per­i­ments on three con­ti­nents at ei­ther am­bi­ent or en­hanced car­bon diox­ide con­cen­tra­tions. Am­bi­ent lev­els ranged from 363-386 ppm and en­hanced lev­els ranged from 546-584 ppm. Moder­ate late cen­tury lev­els are ex­pected to be 580-720 ppm. In the tests, nu­tri­tional val­ues of zinc, iron, and pro­tein were re­duced 5-10 per­cent in wheat and rice, and in soy­beans zinc and iron were re­duced by five per­cent.

These ef­fects were not ob­served in sorghum and maize. De­creases in zinc con­cen­tra­tions in rice and wheat could cause zinc de­fi­ciency in an ad­di­tional 150-200 mil­lion peo­ple. Iron de­fi­cien­cies in grains and rice could also re­sult in higher ane­mia rates in In­dia and Al­ge­ria where this is al­ready a prob­lem. Re­duced pro­tein con­tent in wheat and rice could add an ad­di­tional 1.4 bil­lion peo­ple world­wide to be short of pro­tein by 2050. Graz­ing cat­tle also face a de­crease in nu­tri­tional value of their food. To­day there are 10.6 grams less pro­tein in ev­ery kilo­gram of plants that cat­tle eat com­pared to each kilo­gram they ate 22 years ago.


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