As its name suggests, ecological socialism is an ideology combining ecology and socialism. Critics have called it a “watermelon” — green on the outside and red on the inside — for adding typical socialist demands, such as “social justice,” to ecological concerns in an apparent attempt to advance socialist ideology by new means.
A good illustration of ecological socialism is An Ecosocialist Manifesto, published by Joel Kovel and Michael Lowy in 2001. Kovel was unsuccessful in his campaign to become the U.S. presidential candidate from the Green Party. Lowy is a member of the Trotskyist Fourth International. The Manifesto states that capitalism cannot resolve the ecological crisis and will be replaced by ecological socialism. They do not view ecological socialism as a branch of socialism, but rather as the new name of socialism in the new era.
In 2002, Kovel published a book titled The Enemy of Nature: The End of Capitalism or the End of the World? The book detailed the theory of ecological socialism, harshly criticized capitalism, and suggested a change to the current situation with radical new directions.
From Chapter 16: The Communism Behind Environmentalism