This paper explores why it is so hard for us to do what we morally ought to do to mitigate anthropogenic climate change by reducing our carbon dioxide, CO2, emissions. It distinguishes between two sources of this difficulty: (i) factors which make us underrate the harm that we individually cause when we perform our everyday CO2 emitting acts and, thus, the wrongness of these acts, and (ii) factors which make it difficult for us to cooperate to the extent necessary to mitigate effectively harmful climate change by reducing our everyday CO2 emitting acts. Under (i) are listed such factors as the temporal remoteness of climate harm, the fact that the causal connections between our acts and this harm are elusive, that countless agents together cause harm which is diffused widely over countless, anonymous victims, by acts routinely done. As regards (ii), a comparison with the problems of cooperation in the well-known tragedy of the commons is natural, but it is here argued that the problem of reducing our CO2 emissions is disanalogous in several respects which make it harder: the world’s nations differ enormously in respect of level of welfare, their record of past emissions, and the degree of exposure to climate harm; additionally, it is harder to survey compliance and apply sanctions to those who defect from agreements, in particular as future generations who have not consented to these agreements are involved. Together these factors make up a good case for saying that the problem of ameliorating anthropogenic climate change by reduction of our CO2 emissions is the hardest moral problem humanity is facing.
Key words: climate change, CO2 emissions, cooperation, the commons.
