Final answer:
The IPCC AR4 projections indicate that regional soil moisture by 2100 will vary, with some areas experiencing an increase and others a decrease, influenced by changes in temperature and precipitation patterns.
Step-by-step explanation:
The IPCC AR4 multimodel climate projections suggest varied regional changes in soil moisture by 2100 AD. Due to an expected increase in global average temperatures, which will likely lead to more extreme meteorological conditions and changes in precipitation patterns, some regions may experience a decrease in soil moisture while others may see an increase. The intensity of precipitation events is projected to increase, especially in tropical and high-latitude regions, leading to overall increases in precipitation. However, increased evaporation rates under warmer temperatures can offset this, leading to decreased soil moisture in some areas.
Furthermore, the increased frequency and severity of storms and changing patterns of temperature and rainfall are expected to affect soil moisture levels. Areas anticipated to have an increase in precipitation include populous cities such as New York, Bogotá, and Manila, which will face specific challenges due to these climatic changes. By 2100, the rate of warming on land is projected to exceed that of oceans, with significant regional disparities in warming and precipitation changes.
Consequently, the availability of soil water will fluctuate, influencing plant growth, river flow, and water accessibility globally.