Biodiversity is the variety of all living things on Earth (plants, animals, microorganisms), and how they fit together in the web of life, bringing oxygen, water, food and a great number of other material and cultural benefits for the human civilization. Biodiversity support the valuable Earth’s ecosystems and protect their survival. In the last decade scientific studies and global reports produced alarming news about the state of nature on Earth and its scientific data supporting the facts that biodiversity is under threat on a global scale.

In 2019 an intergovernmental panel of scientists said one million animal and plant species were now threatened with extinction. Also, a report in 2020 found global populations of mammals, birds, fish, amphibians and reptiles plunged by 68%, on average, between 1970 and 2016. How many living species exist on Earth? There are various estimates but the general consensus is that there are around 8.7 million species of plants, animals and microorganisms in existence. However, only around 1.2 million species have been identified and described so far, most of which are insects. Millions of other organisms remain unknown and research efforts are projecting an increase for the identification numbers in the near future.  However, much of the Earth’s biodiversity is in jeopardy due to anthropogenic activities like agriculture for food production and other activities that disturb ecosystems. Pollution, climate change, and population growth are all threats to biodiversity and have caused an unprecedented rise in the rate of species extinction.

The Convention of Biological Diversity (CBD) was signed by 150 countries at the 1992 Rio, Brazil, International Earth Summit, to promote sustainable development on Earth. It was conceived as a practical tool for translating the principles of Agenda 21 into reality which was adopted also in the United Nations Conference on Environment and Development 1992. This review provide a spherical presentation of the most important problems in the biodiversity crisis and the causes in the last century. At the same time the review gives a broad picture of the innovative environmental actions at national and international scale, to reduce the negative impact of agriculture, climate change and environmental pollution on the biodiversity of living species in megadiverse countries.