September 16

As part of the United States National Hurricane Research Project on September 16, 1961, scientists dropped eight cylinders of silver iodide into the eyewall of Hurricane Esther. The seeding experiment unexpectedly reduced the storm's wind speed by approximately 10 percent, offering the first glimpse of potential hurricane modification. This success led to the formal launch of Project Stormfury, a long-term program aimed at mitigating hurricane intensity. Researchers over the next decade conducted multiple field tests in the Atlantic, refining cloud seeding techniques. While later studies cast doubt on the effectiveness of such interventions, Project Stormfury remained a landmark effort in weather control and atmospheric science history.

On September 16, 1987, representatives from more than 50 nations convened in Montreal to sign the Protocol on Substances that Deplete the Ozone Layer. The treaty aimed to phase out the production and use of chlorofluorocarbons (CFCs) and other chemicals harmful to the Earth's ozone layer. It established binding targets and timetables for gradual reductions, with adjustments based on emerging scientific data. The protocol entered into force in 1989 and has since been ratified by nearly all countries worldwide. It is credited with helping to stabilize and begin the recovery of the ozone layer by the mid-21st century. The success of the Montreal Protocol stands as a powerful example of global cooperation in tackling environmental challenges.