Environment as a public good

The environment — clean air, a stable climate, biodiversity — is the largest public good of all: everyone benefits from it, nobody can be excluded, and one person's enjoyment does not reduce another's (until degradation sets in). That is precisely why markets mishandle it: polluters do not pay for the damage they spread, and conservers cannot charge the beneficiaries. Worked example: a factory gains 100 by dumping waste into a river, while downstream users lose 150 in health and fishing costs. Private profit says dump; social accounting says stop, since net social value is 100 - 150 = -50.