NEFA BACKGROUND PAPER
This review was initiated in response to the question “How do forests affect rainfall?”. In the process of reviewing the available scientific literature it became apparent that there is now an overwhelming abundance of evidence that deforestation has had a profound impact on regional climates, including in southern and eastern Australia, and a growing effect on global climates. The answer is “profoundly”.
Deforestation accounts for as much as a third of total anthropogenic CO2 emissions since 1850 and thus is one of the principal contributors to global warming through the greenhouse effect. Though deforestation also has direct biogeophysical effects on rainfall, wind and temperature of similar amplitude, that in some cases is being mistakenly attributed to CO2 emissions, and in others may be masking the full impacts that CO2 emissions are having. It is the biogeophysical effects of deforestation that are the subject of this review.
Terrestrial climates evolved over hundreds of millions of years as vegetation colonised the land and created conditions more suitable for its own growth, modifying temperatures, conserving moisture and enhancing rainfall as it progressed inland. Human civilisations emerged within the climate created by the vegetation, modifying the vegetation to suit their purposes, sometimes with dire climatic consequences.
It is well known that climate influences vegetation, and while it has long been recognised by some that vegetation influences climate, we are still only beginning to understand the complexity and scale of the mechanisms involved.
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