Around the world, about Blank______ of earth's surface is threatened by desertification, or conversion of productive lands to desert.Multiple choice question.one-quarterone-tenthone-thirdone-half

The livelihoods of about 1 Blank______ people are threatened by desertification, or the conversion of productive lands to desert.Multiple choice question.hundred thousandmillionbillion

About 11 percent of the earth's land surface is used for Blank______.Multiple choice question.national parklandcommercial real estateurban developmentcrops

Forests and woodlands cover approximately Blank______ percent of the world's land surface.Multiple choice question.2102950

Building a few millimeters of soil can take anywhere from a few Blank______ (in healthy grasslands) to a few Blank______ (in a desert or tundra).Multiple choice question.days; monthsmonths; yearsyears; thousand yearsyears; million years

Deserts occur where Blank______.Multiple choice question.steady low-pressure systems occur year-roundprecipitation is rare and unpredictable with usually less than 30 cm of rain per yearthe daily temperature variations exceed 38οC during the winter monthsmore than half of an area is covered by sand