In negotiations among nations on how to address climate change discussions of how much investment each country should contribute is always contentious because there is no simple clear answer. In class I introduced three different ways to quantify nation's contribution to climate change, listed below. a) Total current emissions: the amount of greenhouse gases being put out per nation in the present b) Per capita emissions: the total current emissions divided by the population of a nation, gives an average emissions per person alive today in that nation c) Cumulative per capita emissions: the cumulative greenhouse gas emissions from a nation over its entire history divided by its current population, gives an average cumulative emission per person alive today in that nation