The ghostly forests of dead trees along the Mid-Atlantic shores are one indicator of a changing climate. Rising sea levels, brought on, in part, by glacial melt, cause saltwater to move into forested areas where it hadn't reached before. The trees aren't able to drink in water with such high salt content and are starved of necessary nutrients.
In this process, gum bichromate, watercolor paints are sensitized to light by mixing them with chemicals. The mixture is then painted onto a sheet of paper, which is placed under a negative and exposed to light. This process can be repeated multiple times on the same image, using different colors.
See the story on NPR.org: