This is nearly impossible to predict. The book authors are probably asking for an answer that says longer lives will lead to more pressure on natural resources and on societal resources in general, however this is debatable in a historic context. It is possible that increased lifespans, leading to increased population size and increase in the portion of the population needing additional care and services, will be an ecological strain due to resource consumption and the cascading impact of this on the environment. Social consequences would be related to and increased strain on social systems and the economy.
Work Step by Step
The way to the answer is to consider what would happen to resources if one straightlines longer lifetimes into more pressure on resources and on society as a whole due to an overall larger, older population. The improvements in our lives since the 1970's Green Revolution and associated phenomena extended life expectancy show that longer life could be be a win-win for us all. As another example, things like national parks only appeared after lifetimes rose and populations expanded-- people were too busy trying to survive to worry about such things before life got better and longer.