Long before the greenhouse effect was well known, Marx had much to say about the destruction of the environment. He argued that capitalism necessarily exploits human beings and the natural world simultaneously and sacrifices the interests of both on the altar of profit. In doing so, capitalism estranges human beings from nature, in a way that no other society has done before, laying the groundwork for the colossal environmental devastation we face today. Marxist philosophy has much to offer environmental activists of today, in both explaining the roots of the current crisis and pointing the way towards an environmentally sustainable world, free of exploitation and oppression.