Reflection on ecological literacy entered the international debate at the beginning of the 1990s and was part of the broader trend of the progressive emergence of sustainability thinking introduced in the previous decade under the auspices of the United Nations, which in 1983 established the World Commission on Environment and Development (WCED) (also known as the Brundtland Commission after the name of its president) with the mandate to seek answers to the growing negative ecological interdependence represented by environmental crises at global, regional and local level: Greenhouse effect, ozone depletion, acid rain, loss of biodiversity, soil erosion, desertification, deforestation, sea pollution, urban pollution, waste disposal, etc. .

The conclusions of the WCED published in 1987 with the report entitled Our Common Future (WCED 1987), propose to the attention of the whole world the concept of sustainable development as a strategic and universal approach to reconcile three fundamental dimensions of human progress that have for too long been considered separate and autonomous, if not conflicting: the economic dimension, as the ability to guarantee income, profit and work; the social dimension, as the ability to remove inequalities, promote social cohesion and improve the quality of life; the environmental dimension, as the ability to maintain the quality and reproducibility of natural resources, to enrich and enhance the historical, artistic and cultural heritage.

The report "Our Common Future" is the basis of Agenda 21 approved at the UN Conference on Environment and Development in Rio de Janeiro in 1992 and its Chapter 36 dedicated to education reconsidered within the vision of sustainable development (UNESCO, 1992). Following the adoption of Agenda 21 by major international and national organizations, UNESCO then changed its environmental education programme (1975-1995) to "Education for Sustainable Development" (UNESCO, 1997). As the concept of sustainable development influenced and reorganized the environmental education process, sustainable development itself was conceived as an educational educational field (e.g. Education for Sustainable Development, ESD) (Bonnett, 2002; Gonzalez-Gaudiano, 2005; Stevenson, 2006). (this text is taken from the introduction made by Anna and her team).

In the pedagogical field in 1969 the expression environmental education was introduced for the first time by the School of Natural Resources and Environment (SNRE) of the University of Michigan and in 1977 the "First World Intergovernmental Conference on Environmental Education" was held in Tbilisi, Georgia (USSR). The concluding statement states that the main purpose of environmental education is "to bring individuals and the community to know the complexity of the environment, both natural and human created, due to the interactivity of its biological, physical, social, economic and cultural aspects... to acquire the knowledge, values, behaviors and practical skills necessary to participate responsibly and effectively in prevention, environmental problem solving and environmental quality management" (Tiblissi Declaration).

Even ethical-philosophical reflection, starting from the fundamental and ultimate values on which all the actions of mankind are based, questions with more and more vigour the anthropocentric vision of life in search of a deeper and more correct relationship between man and the whole of creation. Over time, as a direct consequence of the socio-cultural and environmental evolution of our age of culture, other points of view that seek the overcoming of the man-nature contradiction have overlapped with the Western philosophical vision of man as the ruler of nature, proper to the industrialist production model based on the ideology of unlimited growth and the intensive use of energy. In this direction, the paradigm of complex thinking represents a scientific contribution to try to go beyond the alternative between anthropocentrism and biocentrism, since man and environment form a system of high intensity relationships. Every human being does not only benefit from nature, he is an integral part of it and belongs de facto and de jure to the natural world. Complex thinking urges us to consider the unity of the person with the environment without losing sight of its irreducible diversity and specificity (Mascia, 2014).

This new cultural and scientific climate characterised by criticism of the dominant development model is also, and not in a secondary way, the result of growing concerns about the deterioration of the natural environment. In the 1960s, and even more so in the following decade, due to the numerous nuclear tests and the reckless use of pesticides (DDT), it is beginning to be perceived that the effects of the release of radioactive substances and chemical syntheses into the environment have a global fallout that cannot be limited to the neighbouring areas concerned. The metabolisation of these new substances in plants, their uptake through aquifers in rivers and seas, their entry into the food chain to reach human homes in increasing concentrations,shows that any action on the natural environment gives rise to a non-linear and non-local response and triggers an unforeseen and difficult to predict pathway. We begin to understand the existence of ecological interdependence: the earth is a "global unique" constituted by the continuous interaction between living beings and the physical environment. The life of every organism is part of a large-scale process involving the metabolism of the entire planet (Commoner, 1972).

The growing awareness that human beings are not independent from nature, but are part of it - each person is, as Morin says, "100% culture and 100% nature" (Morin, 1990) - obliges human communities in their articulations to develop new knowledge that can make the human environment compatible with the natural environment and cultural evolution with natural evolution.

In this direction, during the 1990s and the first decade of the 21st century, there has been an acceleration of research, analysis and reflection in the direction of an understanding of sustainability through an increasingly precise capacity to collect and process a growing amount of environmental data, as well as an increasingly precise reading of the interrelationships between natural and social systems. It is in this period that we begin to talk about the science of sustainability as a natural evolution of complexity thinking, and which is defined by geologist Paul H. Reitan "the integration and application of the knowledge of the Earth system, obtained especially from holistic and historical sciences (such as geology, ecology, climatology, oceanography), harmonized with the knowledge of human interrelationships derived from the humanities and social sciences, aimed at assessing, mitigating and minimizing the consequences, both regionally and globally, of human impacts on the planetary system and societies" (Retain 2005).

The main place of elaboration of this new scientific paradigm is represented by the interaction between the four major international research programmes on global change: the International Geosphere Biosphere Programme (IGBP), the International Human Dimensions Programme on Global Environmental Change (IHDP), World Climate Research Programme (WCRP), World Programme on Biodiversity Science (Diversitas). The United Nations has relied on this international scientific coordination to carry out the Millennium Ecosystem Assessment (2005) , which represents the most authoritative and complete global report on the state of our planet's ecosystems. Among other things, this report introduces the concept of the so-called Ecosystem Service, which recognizes the fundamental role that natural processes (water cycle, climate regulation, photosynthesis, ...) play in promoting the well-being and quality of life of people and communities.

Other international research teams are part of the International Panel of Climate Change (IPCC), which monitors and validates scientific research on climate change and global warming, and in Europe the European Environment Agency, which has recently published a new assessment of the state of the environment on a continental level.

In the same direction are the studies on the ecological footprint of the Global Footprint Network and the "planetary borders" of the Stockholm Resilience Centre. The latter of 2009 analyzes the impact of global production and consumption patterns on the Earth system divided into 9 sub-systems (climate change, biosphere integrity, change in the biogeochemical cycle of nitrogen and phosphorus, ocean acidification, soil and water consumption, ozone depletion, aerosol diffusion in the atmosphere and chemical pollution) that represent boundaries to be respected to maintain the quality of life of people today and tomorrow within a "safe operating space for humanity". For four of these sub-systems - climate change, biosphere integrity, nitrogen cycle, land use - the safe operating space would have already been crossed with the risk of causing irreversible changes in the earth's ecosystem whose consequences for biophysical and social systems are still uncertain.

The emergence of a science of sustainability has accompanied and stimulated the progressive political, economic and cultural awareness of the need to promote an integrated approach to the different dimensions - economic, social and environmental - that determine the evolution and progress of societies. Scientific and technological research has made it possible to develop instruments capable of understanding with ever greater precision both the levels of environmental impact and the necessary actions to reduce the consumption of nature by human societies. The reference is to environmental indicators and in particular to the ecological footprint that calculates the weight of a community in terms of biologically productive territory. Other examples are the development of tools for eco-efficiency and measurement of nature consumption in industry, the development of environmental accounting systems for institutions and organisations in the broadest sense, measures for the progress of society and the overcoming of GDP as the only reading instrument for the wealth of a country and a community (Commission Stiglitz, Sen, Fitoussi on the Measurement of Economic Performance and Social Progress).

The most important milestone today is the Agenda 2030 approved by the United Nations in September 2015, which makes sustainability the paradigm of reference for people and the Planet for the 21st century, recognizing that in order to address the serious current problems (not only environmental) and take a virtuous path to renewed prosperity, it is necessary to rethink in depth the relationship with the natural environment and its resources, on which the entire set of human rights depends both intragenerational and intergenerational (Jackson 2015, Sachs, 2015).

Agenda 2030 contains 17 Sustainable Development Goals (SDGs) to be achieved by 2030, broken down into five main dimensions: people and communities, environment and natural resources, well-being and social quality, peace and security, partnership and global solidarity. These, interconnected and indivisible, are oriented towards the promotion of the dignity of the human being as a fundamental and universal right, which commits all segments of society to its full achievement, within a more balanced relationship with the natural environment. The SDGs are associated with 169 Targets, which on the one hand specify the content of each target and on the other represent a sort of operational guide to the development and definition of policies and strategies at national and international level.

Among the characteristics that make Agenda 2030 an innovative document are: its universality because the search for sustainability concerns all countries, both North and South; the search for solutions that take into account the territorial, economic, cultural characteristics of each country to be achieved through a broad process of involvement of local stakeholders; the integrated vision of the problems and solutions that must be activated to achieve sustainable development (Giovannini 2018).

In these few pages we have tried to describe, in a synthetic and certainly not exhaustive way, the socio-cultural context within which the reflection on ecological literacy introduced during the '90s of the last century by D.W Orr and F. Capra, as a contribution to face the great challenge of "building and cultivating sustainable communities" that needs to create a widespread competence that in the Earth Common House everything is connected, everything is related, everything is linked the same research of the common good comes to take on a new horizon intimately related with the need to deeply redefine the relationships between human beings and the natural environment and at the same time the relationships of solidarity between people and communities(Mascia, 2019).