A natural rainforest emits and absorbs vast quantities of carbon dioxide. On a global scale, long-term fluxes are approximately in balance, so that an undisturbed rainforest would have a small net impact on atmospheric carbon dioxide levels, though they may have other climatic effects (on cloud formation, for example, by recycling water vapour). No rainforest today can be considered to be undisturbed. Human induced deforestation plays a significant role in causing rainforests to release carbon dioxide, as do other factors, whether human-induced or natural, which result in tree death, such as burning and drought. Some climate models operating with interactive vegetation predict a large loss of Amazonian rainforest around 2050 due to drought, forest dieback and the subsequent release more carbon dioxide. Five million years from now, the Amazon rainforest may long since have dried and transformed itself into savannah, killing itself in the progress (changes such as this may happen even if all human deforestation activity ceases overnight). The descendants of our known animals may adapt to the dry savannah of the former Amazonian rainforest and thrive in the new, warmer temperatures.
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