Human development patterns and economic activities have resulted in sustainability challenges of unprecedented scale and urgency, such as climate change and global biodiversity loss. This worrying development gives rise to the critical question of whether human-induced pressures now approach or exceed planet Earth’s environmental boundaries.

We conducted a study with the following aim:

To calculate the impact of the natural resources use by different generations in Portugal, identifying the legacy (or the burden) left to the next generations.

Portugal is above the environmental boundaries in all categories.

The key areas of concern are greenhouse gas emissions, waste production, water1 and air pollution, that are highly above the boundary, and/or with a pronounced growth rate.

1 Water pollution was calculated using the levels of phosphorus use (related with its usage in farming fertilizers).

Pre-Baby Boomers (1900 – 23)
Pre-Baby Boomers (1924 – 39)
Baby Boomers (1940 – 59)
Generation X (1960 – 83)
Generation Y (1984 – 99)
Generation Z (2000 – 19)

Elder generations have higher environmental impacts per capita than younger generations when concerning to Water Pollution and Pressure on Ecosystems.2.

2 The pressure on the ecosystems was calculated using the Human Appropriation of Net Primary Productivity (HANPP), that measures the amount of biomass harvested through agriculture and forestry, as well as biomass that is killed during harvest but not used, and biomass that is lost due to land use change.


In any case, all generations have been exceeding the ecological boundaries, and the economic growth is the main cause for this transgression3.

The only exception is Gen Z that, however, haven’t still reached the age where typically the level of consumption is higher (energy demand, water consumption, waste production, etc.)

3 For each generation it was analysed only part of their life cycle (Pre-baby boomers (I) – 55 years -…; Pre-baby boomers (II): 35-…; Baby boomers: 15-79; Gen X: 0-59; Gen Y: 0-39; Gen Z: 0-19), taking into account the available data, which results in a slight inflation in the elder generations.

Emission boundaries of past generations
Emission boundaries of present and future generations

To be sustainable, the present and future generations have a carbon emission budget 41% lower than what used to happen until the 90’s.

This happens because past generations exceeded the carbon emission boundaries.

Although elder generations4 have exceeded the boundaries in many indicators, they also have contributed to the implementation of policies that helped partly decoupling the environmental indicators from PIB.

These policies, implemented from the 90’s onwards, such as the introduction of natural gas, the investment in renewable sources of electricity, the energy efficiency measures, the policies promoting cleaner vehicles and fuels, and the policies on waste valorisation, reduced the environmental impacts of its own and of the younger generations.

4 Pre-baby boomers (born between 1900 and 1923 and between 1924 and 1939), Baby Boomers (born between 1940 and 1959) and Generation X (born between 1960 and 1983)

Study carried out by a team from Instituto Superior Técnico, and conducted by Tiago Domingos and Ricardo da Silva Vieira.