What is the fine-grained topic of the following text: Andrew C. Revkin, in his excellent Dot Earth section of The New York Times, reported on the work of the artists, Nora Ligorano and Marshall Reese, who created an ice sculpture as part of the “People’s Climate March” held in Manhattan, Sept. 21, 2014. Only return the topic.
Artists creating an ice sculpture for the "People’s Climate March" in 2014.