section_path: Environmental impact/Land and water issues
section_name: Land and water issues
paragraph_text: Land and water issues
  
  Land transformation, the use of land to yield goods and services, is the most substantial way humans alter the Earth's ecosystems, and is the driving force causing biodiversity loss. Estimates of the amount of land transformed by humans vary from 39 to 50%. It is estimated that 24% of land globally experiences land degradation, a long-term decline in ecosystem function and productivity, with cropland being disproportionately affected. Land management is the driving factor behind degradation; 1.5 billion people rely upon the degrading land. Degradation can be through deforestation, desertification, soil erosion, mineral depletion, acidification, or salinization. In 2021, the global agricultural land area was 4.79 billion hectares (ha), down 2 percent, or 0.09 billion ha compared with 2000. Between 2000 and 2021, roughly two-thirds of agricultural land were used for permanent meadows and pastures (3.21 billion ha in 2021), which declined by 5 percent (0.17 billion ha). One-third of the total agricultural land was cropland (1.58 billion ha in 2021), which increased by 6 percent (0.09 billion ha).
  
  Eutrophication, excessive nutrient enrichment in aquatic ecosystems resulting in algal blooms and anoxia, leads to fish kills, loss of biodiversity, and renders water unfit for drinking and other industrial uses. Excessive fertilization and manure application to cropland, as well as high livestock stocking densities cause nutrient (mainly nitrogen and phosphorus) runoff and leaching from agricultural land. These nutrients are major nonpoint pollutants contributing to eutrophication of aquatic ecosystems and pollution of groundwater, with harmful effects on human populations. Fertilizers also reduce terrestrial biodiversity by increasing competition for light, favoring those species that are able to benefit from the added nutrients.
  
  Agriculture simultaneously is facing growing freshwater demand and precipitation anomalies (droughts, floods, and extreme rainfall and weather events) on rainfed areas fields and grazing lands. Agriculture accounts for 70 percent of withdrawals of freshwater resources, and an estimated 41 percent of current global irrigation water use occurs at the expense of environmental flow requirements. It is long known that aquifers in areas as diverse as northern China, the Upper Ganges and the western US are being depleted, and new research extends these problems to aquifers in Iran, Mexico and Saudi Arabia. Increasing pressure is being placed on water resources by industry and urban areas, meaning that water scarcity is increasing and agriculture is facing the challenge of producing more food for the world's growing population with reduced water resources. While industrial withdrawals have declined in the past few decades and municipal withdrawals have increased only marginally since 2010, agricultural withdrawals have continued to grow at an ever faster pace. Agricultural water usage can also cause major environmental problems, including the destruction of natural wetlands, the spread of water-borne diseases, and land degradation through salinization and waterlogging, when irrigation is performed incorrectly.