A lot of time and energy is spent in the movement talking about the human costs of war. There are casualties, both of military people and innocent bystanders (otherwise known as 'collateral damage').
However, the destruction war causes to the environment can be just as catastrophic. Agent Orange, an agent of chemical warfare used in the Vietnam War, destroyed the foliage over acres and acres of forest. Wildlife was also killed and maimed. Land mines are another hazard in countries such as Cambodia, where animals can end up tripping up mines, including endangered species.
As a result, many people who are involved in the peace movement are also involved in related causes such as the environment and animal rights. In Western Canada, in particular, the development of the tar sands is causing immeasurable environmental damage to surrounding communities, which is interfering with the ways of life there, particularly in Aboriginal communities.
Oil in Alberta does far more than fuel vehicles. Through a system of pipes, oil from this area is being shipped down to the United States and is being used by the military to fuel their machines. So clearly in this case there is a connection between the environment and war.
Peace activists do not have to become extreme tree huggers and throwing the rest of their limited time and energy into rallying for environmental causes. There are some activists who are indeed involved with multiple causes, but there are simple, everyday ways that one can reduce their carbon footprint and as a result, make some lifestyle changes that will impact both the environment and peace.