Since coming into effect February 16, 2005, the Kyoto Protocol has cost the world about while the potential temperature saving by the year 2050 so far achieved by Kyoto is
(to get activity on the clock we had to go to billionths part of one degree, which obviously cannot be measured as a global mean) and yes, that really does represent about $100K per billionth of one degree allegedly "saved." Guess that means for the bargain price of just $100 trillion we could theoretically lower global mean temperature by about 1 °C.