“Ecological debt” is a term that was employed for the first time in 1992 during the Río de Janeiro Earth Summit, by María Luisa Robleto and Wilfredo Marcelo, both of the Chilean Ecology Policy Institute. It is also known as “climate debt” and refers to the larger consumption of natural resources than can be regenerated. In economic terms, this is spending more than we have.

But if we were to consider Earth as a large money-bank, not all of us spend the same. This is where the concept of ecological debt comes from, referring to the responsibility of industrialized countries due to the way they appropriate and control natural resources, as well as the planetary destruction caused by the North’s production and consumption models.

This debt run up by the more developed nations tends to consist of four pillars. The first, carbon debt, is the emission of an excessive proportion of polluting gases, mainly greenhouse effect gases, which overwhelm the absorption capacity of forests, soils and oceans. These emissions equally affect countries that are barely polluters at all, like those in Sub-Saharan Africa and South Asia, the poorest regions of the world. The consequences of this pollution in the Global South also result in reduced yields from basic food crops, greater flooding from rising sea levels, and fiercer droughts.

It’s impossible to determine how much industrialized countries should pay for their majority use of the oceans, forests and soils, which also neutralize and absorb their emissions. Or what the bill in economic terms is for the consequences of the four pillars mentioned above. No figure can even begin to get close to the true value of the entirety of such activities.

Since the colonial era – when this debt began to be accumulated – it has been impossible to assess and quantify each and every one of the activities in order to invoice for what’s owed. Much less their effects.Likewise, the relationships between ecosystems and distinct human societies are extremely complex and problematic, such that determining the consequences of environmental harm accurately is an impossible task.

Consider the following example: pollution spreads and accumulates throughout the food chain, where (often unpredictable) factors intervene to increase or (occasionally) reduce the risk. The time over which some consequences might need to manifest themselves also further complicates this hypothetical calculation. Cause and effect cannot always be deduced or shown empirically, and this is how our ability to quantify the harm is impaired. Add to this calculating the cost of human lives. How much is one worth?

For all these reasons, the ecological debt that could be compensated is, in any case, a minimal part of the whole. But efforts are increasing to argue economically that the external debt the Southern countries have with the North is more than offset by the ecological debt. Indicators are being used to estimate this effect, by comparing, for example, the tonnage of materials that enter and leave a specific country.

This is not a direct indicator of pollution (mercury contaminates more than iron, for example), but it does allow economies to be measured in the sense that the income obtained from the sale of a ton of exported goods might be equivalent, say, to the purchase of four tons of imported goods. Southern countries, suffering from poverty and external debt, often feel obliged to sell even more primary goods like fossil fuels, metals or minerals – which pollute much more than the wealth they bring - while Northern countries convert these goods into more expensive and cleaner products.

Yet ecological debt can be determined in terms of an ecological footprint, where data on the use of resources by a person, region or country is collected in relation to the regenerative capacity of the planet. This can be used to ensure that each one of us contributes, modestly but necessarily, so the money bank that is Earth escapes from the red. How? For example, by insulating homes (using less of both heating and air conditioning, the two activities that most depend on natural resources) or buying more efficient electro-domestic equipment. To these, we could add the practices of sustainable mobility (choosing to walk or cycle short trips, using public transport for longer journeys), consuming as responsibly as possible, consulting ecological labelling, and recycling and reducing (water and electricity). All because, at the end of the day, the future credit available to us will depend upon a money-bank called the planet.