Which factors add to the greenhouse effect and are caused by human activities? check all that apply. a decrease in the amount of dust in the atmosphere a decrease in the amount of water on earth’s surface an increase in gases in the atmosphere that absorb heat an increase in surfaces that radiate energy into the atmosphere an increase in the amount of solar radiation that reflects into space

Amap of early human migration is shown. a flattened globe shows six continents: north america, south america, europe, africa, asia, and australia. purple lines and arrows show from where people originated and in which directions they migrated, starting in 18,000 bce. the lines start in central africa and from there, arrows point west toward northwestern africa, and east toward the middle east and asia. in the middle east, the line branches west into western europe and northeast into russia. the arrows also continue east into and throughout asia, including south into the southeast asian islands and australia. from north siberia, an arrow crosses into north america via the bering land bridge. from north america, the arrows move south into central and south america. © 2012 the exploration company based on this map, where are the oldest human civilizations? australia and africa africa and europe australia and asia asia and north america