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Science for the Synod

Our founder, Dr. Thomas E. Lovejoy, along with Dr. Virgilio Viana and Dr. Emma Torres, drafted a background paper on the science of the impacts and consequences of deforestation and climate change in the Amazon rainforest, in advance of a 2019 meeting of the Synod of Bishops for the Pan-Amazon region at the Vatican in Rome.

Find the Brazilian Portuguese translation of the document here.

Find the Spanish translation of the document here.

Science for the Synod
by Thomas E. Lovejoy, Virgilio Viana and Emma Torres

September 2019


1.    The Amazon : A Unique Biodiversity, Hydrological System of Global, Regional and Country Significance

The Hydrological cycle

    In the 1970s Brazilian scientist Eneas Salati examined isotope ratios of oxygen in rainwater sampled from the Amazon estuary to the Peruvian border. The ratios demonstrated unequivocally that the Amazon generated about half the rain internally within the Amazon basin, recycling the moisture five or six times as the air mass moves from the Atlantic to the Andes.

    This was a paradigm shattering result. Previously it was considered incontrovertible that vegetation was simply the consequence of climate and had no influence on climate whatsoever.

     It works because of the complex structures of the Amazon rain forest itself. When moisture first arrives from the tropical Atlantic and falls as rain about 75% of the moisture returns to the westward moving air mass through evaporation off the complex structures of the forest as well as evapotranspiration of the vegetation. In deforested areas most of the moisture runs off and is not available to participate the hydrological cycle as it the air mass moves westward.

    That inevitably led some of us to wonder how much deforestation might cause the hydrological cycle to degrade to the point that there would be insufficient rainfall to support a rain forest (roughly 100 inches/year). In 2007 Gilvan Sampaio in association with Carlos Nobre and others tried to model where that point might be. A precise result was not possible but pinpointed somewhere in the vicinity of 40% deforestation. At that point insufficient moisture would reach the Eastern, Southern and Central Amazon to support rain forest and it would convert to savannah.

    Early climate models also projected Amazon dieback in the southern and Eastern parts. That did not stand up in some subsequent models but did make the point that climate change could affect the system.
More recently extensive use of fire has played a role. A frequent consequence of use of fire to burn felled forest or remove vegetation from pervious crop years shows clearly that fire affects the adjacent, drying it out and making it vulnerable to inroads by fire in subsequent years.

    At this point deforestation, extensive use of fire and climate change are interacting in a negative synergy which led Lovejoy and Nobre to conclude that the interaction has moved the tipping point closer to 20-25% deforestation. Indeed, they conclude that the unprecedented droughts of 2005, 2010, and 2015/16 are first flickering’s of the tipping point.

    The overall point to be derived from this is that the Amazon has to be managed as the system that it clearly is -- to avoid irreparable vegetation and biodiversity loss, to safeguard the enormous amount of carbon and biodiversity in those forests and the well-being of the people who live there and depend on the forest and its biology. The Amazon is also closely interwoven with the South American climate system so its survival is critical for that as well.

2.    The Amazon River system: From the Andes to the Atlantic Ocean

    When the air mass reaches the Andes and moves upward and cools almost all the moisture it is carrying condenses and falls as rain – in such quantity that it produces the 20% of the world’s river water that is the Amazon River system. During high water months of the year (which vary in time between the south and the north of the Amazon) the Amazon and its tributaries rise and flood surrounding forest for months at a time. The extent of these flooded forests is so great that together with the rivers themselves they constitute 20% of the Amazon basin.

    The annual flood cycle provides for a “pulse” agriculture practiced for millennia where crops are raised on the newly fertile sediment shore before the waters periodically reclaim them. There also are a number of important fish species which swim into the flooded forests which is their main source of sustenance annually. Those forests and fish need to be managed sustainably which local communities are very good at when given the autonomy to do so.

    Other important fish included large catfish species with life cycles that span the estuary to the headwaters.

    Poorly designed hydro-electric dams both block those migrations and impede the annual flow of sediments from the Andes which are important to agriculture. Run of the river dams have much less impact and could be considered at least somewhat sustainable infrastructure.

    Nonetheless, conventional infrastructure has led to a lot of unintended environmental destruction and impacts on indigenous peoples and other longer term residents of the Amazon. There needs to be a serious rethink of the development designs for the Amazon, including a fresh recognition of the value of rivers for transportation, pulse agriculture and fisheries.

3.    Biodiversity Superpower: Bio economy and engine for Sustainable Development

    The Amazon of course is the world’s greatest repository of terrestrial biodiversity (including its freshwater biodiversity. It has given the world rubber, cassava, chocolate (cacao), curare (used as a muscle relaxant in major abdominal surgery) and ACE inhibitors (which hundreds of millions of people around the world use to control their hypertension) and more.

    Each of the multiplicity of species represents a set of solutions to a set of biological problems – any one of which has the potential to change the biological sciences or be the source of a sustainable economy. Indigenous and local knowledge is always an obvious place to start.
There is a vast opportunity to harness modern science, local knowledge and entrepreneurial skills to developed forest resource based industries.

    This potential is recognized in its most recent vision by Carlos Nobre and discussions of a possible Amazon Business School. Bio economy

4.     Cultural Diversity

    We think it is fair to say that much of the way economics has been used has been neither thoughtful nor successful. We do not know of a truly thoughtful analysis that goes beyond the conventional to understand the value of the Amazon as a system in economic terms. Virtually no infrastructure project has ever gone beyond estimating the cost of construction, to look at maintenance, or estimated the socioeconomic costs of the ”gold rush mentality” that often follows, the enabling of drug trafficking, or the unanticipated refugee issues that take advantage of an already existed frontier road. What is the actual cost of the illegal goldmining activities which proliferate and rarely bring the miners anything more than ill health, social problems in return for no more than double their normal income?

    In contrast experiments in sustainable development are confined to a few communities, e.g., FAS’s Rio Negro Sustainable Development Reserve at Tumbiras or Alcoa’s efforts at the Juriti mine and community for long term sustainability.

    What might be a model for a sustainable Amazon city which, like Manaus, is composed mostly of economic activities that do not pillage natural resources (assembly plants in that case)?

    These are vital questions for the indigenous peoples and other long-term inhabitants of the Amazon.

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