The Earth Planet is about 4.600 million years old (Ma). Life appears in the aquatic environment, almost 2.000 Ma after the formation of the Terrestrial Globe. For about another 2.000 Ma, many forms of life in the aquatic environment were differentiated, until living beings evolved and achieved adaptations to start occupying the uninhabited terrestrial environment (570-500 Ma).
Biodiversity has always been increasing, whether in the aquatic or terrestrial environment, despite periods of massive declines in biodiversity, until reaching its maximum value during the Cenozoic era, in the Tertiary, period in which Hominoids appear.
7-6 Ma ago there was not only climate change, but also relevant tectonic movements, originating the Rift Valley, with high mountains and vast plains, which resulted in a great diversity of habitats and, therefore, high biodiversity and a group of Apes, the Cercopithecines.
Then, the main groups of herbivorous animals of the African savannas appear, and the first representatives of Hominids appeared about 6 Ma ago in this African region.
That is, Hominids appear at a time of high biodiversity (Tertiary), in an area of large lacustrine surfaces (Lakes in the Rift Valley), therefore a lot of fresh water, and near tropical forests, ecosystems with extremely high biodiversity.
This is how, in this same area of the Rift Valley (Omo, Olduvai and Lake Turkana), fossils of the homo habilis (± 2 Ma). Where Olduvai Gorge is located, there was a large lake, into which several rivers flowed, flanked by riparian gallery forests (on the banks of the rivers), which provided fruits and other products, and large quantities of mammals, which served as food for these our ancestors.
Therefore, our species only survives as long as there is water, high biodiversity and forests, where the biggest producers of biomass are found, the huge tropical trees.
About 1,8-1,5 Ma appears the Homo erectus, nomad and hunter. With climate change from 1,5 Ma ago, the area of savannah increases and this nomadic hunter survives, migrating to the South and North, penetrating the Asian continent. There are about 1 Ma, according to some authors, the H. erectus evolves, appearing the H. neanderthalensis (± 120 thousand years) and the H. sapiens (± 100 thousand years), which came to coexist.
What is certain is that, throughout the dispersion across the Globe, we have always been felling forests for fuel (firewood), construction of houses and boats, production of furniture and utensils, as well as for other purposes.
An example of forest devastation with drastic results for human life is what happened on Easter Island. This island, Rapa Nui in the native language, located in the Pacific Ocean (East Polynesia) and which today belongs to Chile (3700 km off the west coast of this country) was covered by a subtropical forest before the arrival of Polynesians around 1600-1700 years (300-400 after Christ). This forest was completely devastated by the Rapanuios, which practically caused the extinction of this people.
Despite this knowledge, forests continue to be cut down at a truly mind-blowing and drastic rate. Currently, with powerful machines and sophisticated techniques, every 11 seconds an area of rainforest corresponding to the surface of a football pitch is cut down, that is, the equivalent of the area in England per year. Thus, just over 20% of the forest cover that existed after the last glaciation (Würm) remains on the Earth Globe, that is, after the beginning of the current period, the Holocene (Anthropogenic).
Figures from the Food and Agriculture Organization of the United Nations (FAO) reveal that, in the decade from 2000 to 2010, 13 million hectares/year of these tropical forests were cut down. For example, in Brazil, which is among the five countries with the largest area of forest, the loss reached 2,6 million hectares annually. Of the Brazilian “Atlantic Forest”, another subtropical forest ecosystem, less than 6% of what existed when the Portuguese discovered Brazil remains.
We know that forests, particularly equatorial ones (rain forest), due to the high plant biomass they produce, are ecosystems with extremely high biodiversity. We also know that it is in these forests, which are the largest producers of biomass (trees with more than 5.000 tons), a huge volume of carbon sequesters (plants), due to the amount of carbon dioxide (CO2) they use and immense ( plants) natural oxygen (O2) factories.
Large areas of pasture are needed for massive cattle raising, which has led to the clearing of huge areas of forests, particularly tropical ones.
In addition to having been another contribution to the increase in carbon dioxide (CO2) in the atmosphere due to the devastation of the tropical forest, the extremely high number of cattle is currently one of the greatest factors of atmospheric pollution, as each of these ruminants releases , daily, into the atmosphere about 50 liters of methane.
Forest devastation, particularly of the rain forest, and immense herds with innumerable heads of cattle, are currently one of the most relevant factors that contribute to climate change and, consequently, to Global Warming.
In addition to all this, in order to quickly obtain vast deforested areas for agricultural and agricultural fields, forested areas are annually set on fire in an uncontrolled and devastating manner, further increasing the volume of carbon dioxide (CO2) in the atmosphere.
Despite knowing this, the vast majority of the world population has no idea what is happening to the planet we live on and that it is nothing more than a tiny “island” in the Universe, which we have been deforesting, as well as it is also a huge “cage”, which we have been polluting for millennia (after the so-called “Industrial Revolution” we emitted 72.000 chemical products into the earth's atmosphere that did not exist there) and causing it to increase in temperature such that it will become uninhabitable for the human species.
Author Jorge Paiva is a botanist with internationally recognized work of merit.
He discovered several species of plants new to science. Some received his name.
He is a researcher at the Center for Functional Ecology at the University of Coimbra.
He was awarded the Grande Premio Ciência Viva Montepio 2014.
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