The end of the planet in 2100?
This is the rumor that has ignited the Web for several weeks: the ecosystems of the planet could experience a total collapse and irreversible by 2100. At the origin of this apocalyptic prophecy, not a sect of illuminated, a medium lacking publicity or the latest American blockbuster in vogue. No, the allegation comes from a study of the very serious journal Nature, a reference among scientific publications. The thesis ? The environment, under the effect of man-made degradation, could cross a point of no return before the end of the century.
In the Approaching a state-shift in Earth's biosphere, the authors, 22 researchers belonging to about fifteen international scientific institutions, warn about a loss of biodiversity faster and faster climate change.
According to the study, almost half of the climates we know today on the Earth may soon be gone. They would be thus replaced, on between 12% to 39% of the surface of the globe, by conditions which have never been known by living organisms. And this change would be brutal, preventing species and ecosystems from adapting to it.
The upheavals of the natural environments have always existed, recalls the study, whether on a local scale - at the level of basins or coral reefs for example -, regional - 5 500 years ago, the Sahara consisted of fertile meadows - or planetary. The Earth has experienced seven major crises: the Cambrian explosion, there are 540 million years, the five massive extinctions that have destroyed for some up to 90% of life on Earth and the passage of the last ice age in our time there is 12 000 years ago.
But while the Cambrian explosion and Holocene warming were triggered by natural disasters, changes in ocean composition and solar intensity, new pressures are now being exerted on ecosystems: 7 billions of human beings - and 9 billion in 2050.
"When the planet went from an ice age to the present one, interglacial, the most extreme biological changes occurred in just a thousand years. On the scale of the Earth, it is like passing from the baby's condition to adulthood in less than a year. The problem is, the planet is changing even faster today, "says Arne Moers, study co-author and professor in biodiversity at Simon Fraser University in Vancouver.
And the researcher continues: "The planet does not have the memory of its previous state. We are taking an enormous risk in modifying the Earth's radiative balance: suddenly tilting the climate system towards a new state of equilibrium in which ecosystems and our societies will be unable to adapt. [...] The next change could be extremely destructive for the planet. Once the critical threshold is passed, there will be no turning back. "
According to the study, this threshold corresponds to the use of 50% of terrestrial resources. Today, however, 43% of terrestrial ecosystems are already used to support men. One-third of the available freshwater is diverted for human use. Species extinction rates are at record highs throughout human evolution - from 10 to 100 times the natural extinction rate found by scientists over a period of 500 million years, while it could be 10 000 sooner. And CO2 emissions have increased by 35% since the pre-industrial era due to the burning of fossil fuels.
The evolution of land use over the centuries, as the world population increases:
"In view of these elements, we can say that a shift is very plausible during the next century", assures Anthony Barnosky, paleobiologist at the University of California at Berkeley. However, significant uncertainties remain: "The question is whether this global shift is inevitable and, if so, how soon will it take place."
A caution shared by many scientists who have read the study. For Brad Cardinal, a biologist at the University of Michigan, interviewed by the American magazine Wired, this research is convincing but not conclusive: "This is not the first time that a study of the kind has been published. Only time will allow us. whether these results hold true or not. " "We must be wary of the interpretation which is made of it in certain media, according to which the Earth may not reach the XXIIth century. The planet will not disappear for 4 billion years and it will remain habitable for a long time to come. the current degradations will affect our living conditions ", tempers for his part the climatologist Jean-Pascal van Ypersele, vice-president of the Intergovernmental Panel on Climate Change (IPCC) in an interview with the Belgian magazine Le Vif / L'Express.
Still, a truly change of lifestyle is necessary and urgent. The 22 scientists of the study propose to governments to undertake four immediate actions: drastically reduce the demographic pressure; to concentrate the populations on the areas already recording high densities in order to let the other territories try to find natural balances; adjust the living standards of the richest to those of the poorest; develop new technologies to produce and distribute new food resources without consuming more resources.
Audrey Garric
Source: http://ecologie.blog.lemonde.fr/2012/07 ... e-en-2100/
Ahmed, for once I understood you, and I agree with you.
The miracle would be an in-depth understanding of the reality of the situation and above all a lucidity sufficient to understand the intensity of our shunting. The action would then flow practically from itself ...
