Students gathered in about 80 cities around the world yesterday to protest Citigroup’s role in funding environmentally destructive projects. At the company’s headquarters in New York City, demonstrators tossed the company’s signature red umbrellas and a replica of Earth into a coffin. They were objecting to projects like China’s Three Gorges Dam, an oil pipeline in Chad and Cameroon, and expansion of palm plantations in Indonesia — all of which they say have received Citigroup support. Rainforest Action Network, which organized the protests, used the occasion to launch an international boycott of Citigroup credit cards. A Citigroup spokesperson said that the company did not fund the Three Gorges Dam and that RAN was spreading false information.