Geoengineering — the idea of intentionally modifying Earth’s climate or atmosphere — is often described as a modern concept. But the idea has actually been around for over a century. In the early 1900s, scientists and engineers began experimenting with ways to influence weather patterns. One of the earliest techniques was cloud seeding, which involves releasing particles into clouds to encourage rainfall or snowfall. Research into cloud seeding accelerated in the 1940s and 1950s. During the Cold War, governments also explored weather modification for strategic purposes. In the 1960s and early 1970s, the United States conducted a program known as Operation Popeye, which used cloud seeding to extend monsoon conditions over supply routes in Southeast Asia. The program later became public and raised significant ethical and political concerns. Because of these concerns, many countries later agreed to limits on hostile environmental modification through the Environmental Modification Convention, which prohibits the use of environmental modification techniques as weapons. Meanwhile, scientific research into climate systems continued. By the late 20th century, scientists began discussing much larger-scale ideas for influencing global climate. These proposals included reflecting sunlight away from Earth or removing carbon dioxide from the atmosphere. In 2006, atmospheric chemist Paul J. Crutzen helped bring the topic back into mainstream scientific discussion by suggesting that injecting particles into the upper atmosphere might temporarily reduce global temperatures. Since then, research into geoengineering has expanded significantly. Universities, research institutions, and policy groups now study potential approaches such as: • Solar radiation management (reflecting a small portion of sunlight) • Carbon dioxide removal (capturing carbon from the atmosphere) • Marine cloud brightening • Stratospheric aerosol research Today, geoengineering remains one of the most debated areas of climate science. Supporters argue that some techniques may help reduce climate risks. Critics warn about potential side effects, governance challenges, and the possibility of unintended consequences.