Ecological debt is a term used to describe an imbalance between a "fair share" of natural resources and the actual usage of those resources.
If a country or a person utilises more than this "fair share" of the earth's finite natural resources an ecological debt is created. This occurs when an individual or a community has a lifestyle that pushes an ecosystem beyond its ability to renew itself.
Global warming is probably the clearest example of an ecological debt. First World countries have become rich by burning up our finite inheritance of fossil fuel, which has triggered climate change. Bangladesh, the South Pacific Islands and sub Saharan Africa are set to suffer excessively from global warming.
(Stub only, adapted from the entry in Wikipedia) See http://www.deudaecologica.org/index.php?newlang=spanish