Do you think that war contributes to environmental change?
Yes, most definitely. But wars tend to be limited in geographic impact and so the environmental impact/change component tends to be confined to conflict areas.
Some examples: After World War II much of Europe was devastated, but the environment did bounce back within the following 50 years or so. Likewise, the atomic bombs dropped on Hiroshima and Nagasaki caused enormous death and destruction in these areas, but again, after 50 years or so the impact was reduced and the environment bounced back.
More disturbingly, in recent middle eastern conflicts, tanks and artillery often used uranium tipped shells and this radioactive waste will be around for hundreds if not thousands of years.
Wars also often destroy vast tracks of forests, which play a role in absorbing CO2 out of the atmosphere.