Tackling climate change presents an intergenerational dilemma: People must make sacrifices today, to benefit future generations. What causes people to feel an obligation to benefit future generations? Past research has suggested "intergenerational reciprocity" as a potential driver, but this research is quite domain specific, and it is unknown how well it applies to climate change. We explored a novel means of invoking a sense of intergenerational reciprocity: inducing reflection on the sacrifices made by previous generations. Our studies revealed that such reflection predicts and causes a heightened sense of moral obligation towards future generations, mediated by gratitude. However, there are also some downsides (e.g., feelings of unworthiness), and perceptions of obligation do not substantially affect pro-environmental attitudes or motivations. Thus, while reflecting on past generations' sacrifices can generate a sense of intergenerational obligation, it is limited in the extent to which it can increase pro-environmental concern.