PLANETEARTHONLINE

Parts of the Amazon rainforest may face less serious droughts this century than previously feared, according to new research.

Aerial view of AmazonClimate models don’t yet quite capture some of the peculiar features of the geography of South America.

Scientists compared 19 global climate models with actual rainfall measurements for the region.

The team found that the models tended to underestimate current rainfall levels because the models don’t quite capture some of the peculiar features of the geography of South America. The models also ‘vary greatly in their projections of future climate change in Amazonia,’ according to the paper.

Some climate models have predicted that parts of the eastern Amazon will turn from rainforest to savannah this century. The new findings, with corrected rainfall patterns, suggest the region may move from year-long wet seasons to wet and dry seasons. This will result in a seasonal forest – not quite a rainforest, but, crucially, not savannah.

Western Amazonia could remain a rainforest, while the findings suggest north and south Amazonia may dry out.

The drier areas will become more susceptible to fires, which are rare at present, say the researchers in the US journal Proceedings of the National Academy of Sciences. Fire associated with deforestation, logging and fragmentation may trigger a transition of these seasonal forests to what is described as ‘fire-dominated, low biomass forests.’

Map of the AmazonThe Amazon is biologically the richest region on Earth, hosting a quarter of global species.

Tipping point

In 2008, the same journal published another paper entitled ‘Tipping elements in the Earth’s climate system.’ The paper listed Amazon rainforest dieback as one of nine policy-relevant tipping points that could happen this century. The paper warned that climate change may not be linear: as carbon dioxide levels gradually rise, the climate is some parts of the world may switch state more rapidly. The Amazon ranked eight on the list.

The new research suggests eastern Amazonia could escape this fate if deforestation and fires are controlled effectively. ‘Such intervention may be enough to navigate eastern Amazonia away from a possible ”tipping point,” beyond which extensive rainforest would become unsustainable,’ says the paper.

Lead author Professor Yadvinder Malhi from the University of Oxford says, ‘Active forest protection in the Amazon forest region can help the region adapt to climate change and minimise the risk of a dieback. This strategy will also contribute to the global effort to reduce greenhouse gas emissions.’

‘Even with sufficient funds and willpower, implementing biosphere management on such a scale will be a huge challenge. Brazil has recently announced an ambitious plan for slowing down Amazonian deforestation and deserves full international support. It will be critically important to understand the local and national social, political and economic context if this strategy is to succeed,’ he adds.

Rainfall predictions remain a major challenge for climate models, which is why reducing uncertainty is a key priority for the research community. In February, the Natural Environment Research Council launched the £10 million Changing Water Cycle programme.

The Amazon is biologically the richest region on Earth, hosting a quarter of global species.

The research was led by Oxford University in collaboration with the University of Edinburgh, Centre for Ecology & Hydrology, the University of Sheffield, and the Met Office Hadley Centre.

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