In their original paper describing the “Biotic Pump” Theory¹, Makarieva and Gorshkov describe how the same large-scale processes that drive moist air inland may also transport dry air from inland deserts toward the ocean, desiccating vegetation in its path (see Figure 1). This is likely to occur when evaporation is stronger over the ocean than inland, as is the case in regions with little remaining coastal forest cover. These prevailing dry winds may thus help maintain arid climates in coastal areas, and even create deserts.

Whether through reduced precipitation recycling (PR), or the lack of a biotic pump effect, reduced forest cover appears to reinforce conditions that weaken the likelihood of precipitation. Evidence of this effect has manifested itself with changing land use in Kenya. More than 200,000 hectares (770 square miles) in the Mau Forest in western Kenya have been converted to agricultural land in the last 15 years. During this time, there has been a corresponding major reduction in regional rainfall. Investigation into new local temperature and weather patterns has provided insight into this relationship, indicating how strong an influence forests have on the regional climate.² There is likewise a growing body of evidence suggesting that deforestation leads to the observed precipitation declines in forested regions such as the Amazon.³ Additionally, the connection between reduced vegetation cover and the gradual onslaught of desertification is well documented in the scientific literature.^4,5,6,7