Imagine the government has imposed a $50-per-month tax on fossil fuels. Should that money be banked, gathering interest for future investment in climate adaptation? Or should it be spent immediately in developing countries hit hardest by climate change?

The matter came up for debate this month in the government class “Politics of the Environment and Climate Change.” One hand shot up immediately with a vote for spending the money later, since compounded interest adds to financial impact. Another student, more tentative, took the position of spending now, to benefit the greatest number of people — both existing humans and those still to be born.

This course is also available through Harvard Extension School.