Final answer:
About 40 percent of Earth's land is used for agriculture, leading to significant deforestation, particularly in tropical regions. This land use accounts for the majority of freshwater consumption and contributes greatly to global greenhouse gas emissions. Intensive agriculture and pasturelands are also contributing to land degradation and water pollution.
Step-by-step explanation:
Humans have remarkably transformed the surface of the Earth to cater to agricultural demands. Agriculture occupies about 40 percent of Earth's ice-free land mass, creating a considerable impact on both land and aquatic ecosystems. Over the past 300 years, there has been a substantial growth from 2.7 to 15 million km² in cropland areas, primarily replacing forest habitats. Similarly, permanent pasturelands have expanded to approximately 34 million km². Although the net area for food production has remained nearly constant since the mid-20th century, the shift from temperate regions to tropical regions has led to a significant loss of forests and biodiversity.
These agricultural activities are not only reshaping the land but also exerting pressure on water resources. Agriculture accounts for approximately 70 percent of global freshwater use and significantly contributes to water pollution through livestock waste runoff. Besides, there is the challenge of land degradation, with about 10 percent of earth's vegetated surface being at least moderately degraded and 20 percent of the world's irrigated land seriously degraded in terms of crop production. The food production systems are also contributing to greenhouse gas emissions, estimated to be up to 30 percent of the global total, thereby exacerbating climate change.
With the world population surpassing 7 billion, the consequences of such extensive land use come to the forefront. It highlights the intricacies of maintaining ecosystem balances while sustaining an ever-increasing human population. The data shows that even though approximately half of the land in the US is dedicated to producing agricultural products, much of it is for non-food crops or indirectly consumed through livestock.