Papal encyclical on climate change: pope francis sent a letter to 1. 2 b catholics, angered us republicans called for end to tyrannical exploitation of nature framed environment as a moral social justice issue. G7 leaders pledge to eliminate fossil fuels by 2100. Tragedy of the commons: garrett hardin 1915-2003 individual interest vs collective interest, a (cid:858)(cid:272)o(cid:373)(cid:373)o(cid:374)s(cid:859) is (cid:271)ou(cid:374)d to (cid:271)e (cid:858)o(cid:448)e(cid:396)g(cid:396)azed(cid:859, picture a pasture open to all. It is to be expected that each herdsman will try to keep as many (cid:272)attle as possi(cid:271)le o(cid:374) the (cid:272)o(cid:373)(cid:373)o(cid:374)s(cid:859: adding one more animal: individual gains positive utility of one more animal. Neg utility of overgrazing shared (fraction of one) freedom in a common brings ruin to all: example: overfishing, water and air pollution, deforestation, almost any env issue. Assumes states prioritize conservation over economic gain fish do(cid:374)(cid:859)t sta(cid:455) i(cid:374) zo(cid:374)es, (cid:374)eithe(cid:396) does pollutio(cid:374) ships can overfish, discharge their toxic fuel right outside zone.