Glossary | Chesapeake Bay Program
Last Word Archive | New Scientist
A mass extinction began when humans left Africa and with ancestors of , but it accelerated when that founder group of behaviorally modern humans . They quickly drove the , as well as the and . Once the inhabitable continents were filled with that founder group’s descendants, , humans independently domesticated plants and animals. The mass extinction continued with the Domestication Revolution, but in less spectacular fashion, usually via habitat destruction. The increasing density of human populations became the primary factor in driving other species to extinction, which were often local extinctions. Ancient and particularly drove north-African megafauna to extinction, but there were few other notable mass extinctions until . When they did, the greatest proportional demographic catastrophes since the extinction of all other human species began. Those same three continents earlier robbed of their megafauna were quickly shorn of their human populations, who were and and in the Americas. In the midst of that unprecedented disaster for , . Although industrialization raised the human standard of living as never before, as the energy of hydrocarbon fuels was exploited on a large scale for the first time, it also enabled greater environmental devastation. Humanity has been turning forests into deserts since the first civilizations (, , , , , , , , , ), and the only reason it has not gotten worse during the industrial era, at least in industrialized, nations, is because hydrocarbons instead of wood were burned. The extinction of the , in the midst of , were indicative of the vast damage that industrialized peoples could inflict on Earth’s ecosystems. Industrialization also accelerated Europe’s conquest of the world. It conquered and subjugated and peoples, reducing them to effective slavery and further devastating the ecosystems.
Unit 8A Plants I - Biology Junction
Plants need trace amounts of iron to perform photosynthesis, but certain parts of the oceans lack it, and thus algae are scarce. Recent shipboard experiments have shown that when researchers dump iron particles into such areas, it can boost growth. The algae draw the greenhouse gas carbon dioxide from the air to help build their bodies, so fertilization on a large scale could, theoretically, reduce atmospheric CO2. Seafloor sediments show that during past ice ages, more iron-rich dust blew from chilly, barren landmasses into the oceans, apparently producing more algae in these areas and, presumably, a natural cooling effect. Some scientists believe that iron fertilization and a corresponding drop in CO2 is one reason why ice ages become icy and remain so.