"There are thresholds that humanity should not transgress if we intend to keep most of the Amazon forest," Carlos Nobre of Brazil’s National Center for Monitoring and Early Warning of Natural Disasters told environmentalresearchweb. "Today, the Amazon has warmed by about 1°C due to global warming, and total deforested area in the basin is about 20%. It seems that we are still operating in the safe space for the Amazon, but scenarios of future climate change and/or continued deforestation indicate that by 2050 the forest could be reduced by more than 50%."
To come up with the conclusions, Nobre and colleagues modelled the effects of tropical deforestation, climate change, increased forest fires and carbon dioxide fertilization. "Forests become moderately more resilient to climate change for higher levels of atmospheric carbon dioxide," said Nobre. "The other three anthropogenic drivers of change – namely deforestation, global warming, increased forest fires – are known to increase tropical forest vulnerability."
Some scenarios indicate that the south, southwest and southeast of the rainforest could become savanna, an ecosystem consisting of grassland and scattered trees. And Nobre and colleagues concluded that human-caused fires raise the chances of the Amazon forest changing state. As they write in PNAS, passing one or both of the tipping points for the Amazon would bring irreversible forest die-back and a tendency for drier seasonal forests or impoverished tropical savanna to prevail over 30–50% of the basin, especially in the south and east.
"Preserving the vitality of Amazonian ecosystems depends on two elements," said Nobre. "On one hand, it requires sustainable development policies for the Amazon to reduce deforestation rates to zero. That depends mostly on Amazonian countries' development policies. On the other hand, global warming cannot continue unchecked and that depends of the successful implementation of the Paris agreements. For that, the Amazonian countries do not play a significant role and decarbonization of the world's economy is mandatory."
Since 2005, deforestation rates in the Brazilian Amazon have decreased from almost 30,000 sq km a year to an average of around 6,000 sq km a year from 2011 to 2015. This drop is due to factors such as satellite monitoring, law enforcement, the soy moratorium, restrictions on access to credit for farms located in deforested areas, and expansion of protected areas and indigenous territory. But there’s pressure for additional deforestation from growing demand for agricultural commodities in emerging markets, weak institutions and large energy infrastructure projects.
"The present economic scenario continues to conspire against the Amazon by placing a higher premium on agricultural commodities such as soybeans, meat and tropical timber than on standing forests," writes the team in PNAS. "The long-term success of antideforestation policies must rest on firmer ground besides command and control measures to curb illegal deforestation."
Nobre believes that to lower the risk that the largest tropical forest on the planet will disappear, wiping out a harbour for 10–15% of the world's species, 15% of the freshwater inflow into the ocean, and tremendous ethnic and lingustic diversity, we need a "new development paradigm". This "Third Way" – as opposed to the First Way of maintaining large expanses of forest in conservation units or the Second Way intensification of agriculture on deforested land – calls for the introduction of "bioindustries all over the Amazon, tapping into the tremendous natural wealth from the sustainable use of the region's biodiversity".
The túngara frog, for example, creates long-lived foams and has inspired new energy generation and carbon sequestration technologies. The researchers reckon it’s feasible to develop biodiversity-based product value chains for global markets. "This new economy has the potential to become much larger than the present one that is based on the unsustainable use of natural resources in the Amazon," they write. "A number of biodiversity products from the Amazon, such as babassu (Attalea speciosa), cupuaçu (Theobroma grandiflorum), and the Brazil nut have already impacted the local economies, and there are plenty more to be discovered and commercialized."
In future, the team hopes, we’ll see tropical regions not only as sources of natural resources and biodiversity but also as "reserves of precious biological biomimetic knowledge that can fuel a new development model which can benefit both local/indigenous populations and the world at large".
Nobre and colleagues reported their findings in PNAS.