Poverty and environmental degradation are inter-related. They are, in fact, twins or possibly the two sides of the same coin.

Poverty generates environmental degradation while environmental degradation inevitably results in poverty. This was emphasised by Indira Gandhi, then Indian Prime Minister, way back in 1972 during her intervention at the United Nations Stockholm Conference on the Human Environment. It is also the underlying theme of Laudato Si, the eco-encyclical of Pope Francis, and a basic theme of the Bishops Synod for the Pan-Amazonian Region currently being held in Rome.

The Stockholm Conference was the United Nations first major conference on international environmental issues and marked the definite turning point in the development of international environmental politics.

Put simply, social and environmental policy are interlinked: it is what the Latin American roots of liberation theology describe as "the integral ecology".

In his memoirs, Maurice Strong, Secretary-General of the UN Stockholm Conference on the Human Environment, described Indira Gandhi's Stockholm speech as being the most memorable and influential speech of the entire conference. The theme - which she forcefully developed and communicated - was that "poverty is the greatest polluter". She eloquently emphasised: "...... how can we speak to those who live in villages and in slums about keeping the oceans, the rivers and the air clean, when their own lives are contaminated at the source?"

Everything is related. We humans are an integral part of the natural order: our health is the earth's health; our tears are the earth's tears.

Leonardo Boff, the Brazilian Franciscan Liberation Theologist, uses crystal clear language to describe this, even encapsulating it in the title of his 1995 seminal publication: Cry of the Earth, Cry of the Poor ( Grito da Terra, Grito dos Pobres) which is the essential backdrop for both Jorge Bergoglio's eco-encyclical as well as for the Amazonian Bishops' Synod currently under way.

Environmental degradation has a considerable impact on the quality of life of all of us except, that is, for the quality of life of the select few who pocket profits by appropriating for themselves advantages (economic or otherwise) and lumping the negative impacts on the rest.

Environmental degradation is an instrument of social injustice. Consequently, enhancing the protection of the environment is also essential to restore social justice. The Earth is our common home: together with the earth we have a common future and all the damage we cause comes back to us.

There are direct impacts, such as having to breathe contaminated air, drink polluted water, or eat fish and/or vegetables that contain various contaminants.

There are also the indirect impacts which take time to materialise. Climate change is a case in point. A slow build-up of carbon emissions over the centuries is currently close to a tipping point. We risk a catastrophic impact as a result of climate change: an increase in temperature and an accelerated melting of ice at the poles - in Greenland in particular - which would lead to a substantial rise in sea level.

The poor and the vulnerable will be those most affected. The vulnerable small island states in the Pacific are already experiencing these impacts. 'Climate refugees' are a new breed of immigrants, fleeing from the environmental impacts which they have to shoulder but to which they did not contribute.

The Earth continuously retaliates to restore a natural balance. It has no choice; it does not discriminate.

This is the result of greed - a myopic vision which takes every opportunity to cash in on short-term gains but is unable to understand the long-term impacts.

Nature is able to provide for the needs of everyone. It is, however, unable to sustain long-term greed. In our ecological community we need to interact not just with nature, our immediate environment, but more with the total environment. This can only be achieved if we take heed of the tears of the Earth.