Final answer:
The expansion of deserts into arable lands typically results in famine, as it diminishes the agricultural output by turning fertile lands into barren areas. This process, known as desertification, worsens environmental conditions like nutrient-poor soils and contributes to socio-economic issues like lower standards of living and reduced trade.
Step-by-step explanation:
When a desert expands into areas that were previously arable, the most likely impact is a famine. The expansion of deserts, a process also known as desertification, reduces the amount of productive land available for agriculture. Arable lands turn into barren, dry expanses that cannot support crops, thereby causing a significant drop in food production. This decrease in food availability can lead to famine, especially in regions that rely heavily on local agriculture for sustenance.
As desertification occurs, it can lead to several other environmental problems as well, such as pesticide resistance, increased salts in the soil, nutrient-poor soils, and blight. However, it can also have broader social and economic repercussions, exacerbating overpopulation issues in areas where competition for cropland is already high. On the contrary, in places like Russia, Australia, and North America, the competition for cropland is lower due to their larger expanses of agricultural land.
Desertification does not lead to overpopulation, higher standards of living, or increased trade, as might be inferred from others. In fact, it can contribute to the opposite, lowering standards of living due to the scarcity of food and water resources and reducing trade opportunities because of the decline in agricultural output.