The release of aerosols since the Industrial Revolution may have shifted the tropical rainfall band over Central America southwards, suggests a study published online in Nature Geoscience.
Harriet Ridley and colleagues used the geochemistry of a stalagmite from Yok Balum Cave, Belize, to reconstruct rainfall intensity from AD 1550 to 2006. The authors identify a long-term drying trend over southern Belize beginning in the late 1800s, which coincides with an increase in aerosol emissions in the Northern Hemisphere following the Industrial Revolution. Other pronounced periods of drying in the record occurred immediately after large volcanic eruptions in the Northern Hemisphere, which also released large quantities of aerosols to the atmosphere.
In an accompanying News and Views, Jud Partin writes, “This change supports the hypothesis that the aerosol emissions reduced the rate of warming of the Northern Hemisphere relative to the Southern Hemisphere, causing a southward shift in [the band of tropical] rainfall.”