- Há quem diga que a humanidade não tem capacidade de alterar o clima, o ambiente e a ecologia da Terra: A force of nature: our influential Anthropocene period - Comment is free.
"The best known global change is the rise in atmospheric carbon dioxide and resulting climatic changes. Some of the CO2 in the atmosphere dissolves into the oceans, making them more acid, which is degrading marine ecosystems. To put this in context, the oceans are more acidic today that they have been for at least 800 millenia. The atmospheric CO2 increase has also boosted plant growth in some places, changing the world's forests and grasslands. In short, the global cycling of carbon has been significantly altered.
The impacts of human activity on the other great global chemical cycles are similarly profound. To increase crop yields, more nitrogen is added to ecosystems through fertiliser use, than is added by all natural processes combined. But fertiliser run-off leads to 'dead-zones' of low-oxygen water that currently affect 245,000 sq km of the world's ocean.
Furthermore, scientists estimate that each year humans move more rock, sediment and soil than all natural processes , that at least three times as much fresh water is held in reservoirs than in rivers, and at least a third of all land has been appropriated for human use.
The heavy hand of humanity reaches into the living world too. Each year, we extract 7m tonnes of bushmeat from tropical forests, 95m tonnes of fish from the oceans, and raze 80,000 sq km of forest. The result: we are at the leading edge of the sixth mass extinction in Earth's history."
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