Sowing a bitter crop: global reductions in available arable land

This brief states that arable land is being reduced and degraded around the world. The main causes for this are erosion and salination. By 2020, 30% of the world's arable land may be salinated, rising to as much as 50% by 2050. Other drivers include population growth, poverty, urbanisation, desertification and resource depleting subsistence strategies. Climate change is further aggravating the situation. The authors also assert that while technology offers the means to mitigate this by increasing yields, the reduction of arable land is likely to increase resource his and create political, social and economic pressures.

Summary of findings:

• less than half of the world’s land is suitable for agriculture, and the irrigated land area is falling. Soil erosion, salinisation, acidification and nutrient depletion contribute to declining land quality
  
• over the next 30-40 years, this trend is expected to continue, with more arable land becoming infertile, significantly reducing the scope for cultivation in many areas of the world. Compounding the loss of arable land is the degradation and depletion of topsoil over several decades, which has led to a decline in the quality of arable land and lower yields. The causes of this global problem range from water erosion to the overuse of pesticides
  
• the area of arable land per head of population is decreasing in all regions as populations grow. Between 1975 and 1995 the availability of cropland fell by approximately 25 per cent from 0.32 hectares per capita in 1975 to 0.24 hectares in 1995. [4] This has placed new pressures on resource-stressed regions and countries where population growth and environmental degradation collide
  
• climate change aggravates the situation further, leading to a higher frequency of flooding and droughts. As a result, agricultural yields may be under threat not only in tropical and sub-tropical regions, but also in temperate areas, particularly if temperatures rise by more than 1-2 degrees Celsius. 

(adapted from author)