6.7C - Forest Health
Climate change, resulting from the enhanced greenhouse effect, may increase the frequency of drought due to shifting climate belts, which may impact on the health of forests as carbon stores. (Amazonian drought events)
Like ocean acidification, the declining health of forests is also the outcome of the enhanced greenhouse effect and consequent climate change. The health of the world's forests as a carbon store is being challenged in three ways:
- by deforestation
- by the poleward shift of climatic belts
- by increasing drought
Amazon droughts
The Amazon rainforest acts as a giant climate regulator, pumping 20 billion tonnes of water into the atmosphere each day. This is 3 billion tonnes more than the River Amazon discharges into the Atlantic Ocean. The forest's uniform humidity lowers atmospheric pressure, allowing moisture from the Atlantic to reach almost across the continent. However, since 1990, a cycle of extreme drought and flooding has been observed. Droughts in 2005 and 2010 greatly degraded much of the forest already stressed by prolonged and large-scale deforestation.
In short, the diminishing health of the tropical rainforest means that it is:
In short, the diminishing health of the tropical rainforest means that it is:
- declining as a carbon store
- sequestering less carbon dioxide from the atmosphere, thereby exacerbating the greenhouse effect
- playing a diminished role in the hydrological cycle