The emissions gap refers to the difference between the projected greenhouse gas emissions trajectory based on currently planned climate change mitigation policies and the efficient emissions path required to achieve the 1.5-degree (or 2-degree) target agreed upon in the Paris Agreement under the United Nations Framework Convention on Climate Change. This disparity reflects the gap between what we intend to do for future generations (intergenerational altruism) and what we believe should be done for them (intergenerational equity). Resolving the emissions gap is crucial for achieving a carbon-neutral society. Addressing this challenge requires reinforcing intergenerational altruism and garnering significant support for the ethical foundation of intergenerational equity underlying the 1.5-degree target. Based on these concerns, this study introduces and examines various discussions in the social sciences, particularly in economics, regarding intergenerational altruism and intergenerational equity.