Half the Amazon rainforest will be lost within 20 years

Halfthe Amazon rainforest will be lost within 20 years

27 February 2008

Amazon — More than half the Amazon rainforest will be damaged or destroyedwithin 20 years if deforestation, forest fires, and climate trends continueapace, warns a study published in Philosophical Transactions of the RoyalSociety B.

Reviewing recent trends in economic, ecological and climatic processes inAmazonia, Daniel Nepstad and colleagues forecast that 55 percent of Amazonforests will be “cleared, logged, damaged by drought, or burned” inthe next 20 years. The damage will release 15-26 billion tons of carbon into theatmosphere, adding to a feedback cycle that will worsen both warming and forestdegradation in the region.

While the projections are bleak, the authors are hopeful that emerging trendscould reduce the likelihood of a near-term die-back. These include the growingconcern in commodity markets on the environmental performance of ranchers andfarmers; greater investment in fire control mechanisms among owners offire-sensitive investments; emergence of a carbon market for forest-basedoffsets; and the establishment of protected areas in regions where developmentis fast-expanding.

Trends driving the Amazon towards a near-term die-back

Macroeconomic trends are an increasingly important driver of deforestation inthe Amazon. The authors cite several developments that make converting Amazonforest for agricultural production more attractive, including the eradificationof foot-and-mouth disease from large swathes of the Amazon, opening foreignmarkets for Brazilian beef exports; risinginternational demand for agro-industrial commodities, triggering landscarcity in traditional growing regions like Europe and the United States;surging interest in biofuels, fed by record high oil prices; and agriculturalinnovation that has produced crops suitable for cultivation in the Amazon’sclimate. The authors note that Americansubsidies for corn ethanol production and Chinese meat consumption areindirectly contributing to Amazon deforestation and warn that though little oilpalm is presently cultivated in the region, muchof Amazonia is suitable for the plant, which is one of the world’shighest yielding biodiesel crops.

Soil suitability map for mechanized agriculture in the Pan-Amazon region. Restrictions include slope (more than 2%), inundation risk and poor soil (ultisols, hydromorphic soils, sands and lithosols). Map from Nepstad et al (2008). At the same time that globaldemand for agricultural commodities produced in the Amazon is growing, theregion is increasingly affected by drought (linked to climate change),fragmentation (tied to development) and forestfires (corresponding to both climate change and development) all ofwhich interact with one another to create positive feedback effects.

“Positive feedbacks among drought, forest fire and economic activities holdthe potential to degrade large areas of Amazon forest over the coming years,”write the authors. “Land-use activities of the Amazon contribute to forestsusceptibility to fire by providing ignition sources, by fragmenting the forest,and by thinning the forest through logging.

“Fires set to burn felled forests in preparation for crops or pasture, orto improve pasture forage, frequently escape beyond their intended boundariesinto neighbouring forests,” they continue. “Forest fire can thereforeincrease susceptibility to further burning in a positive feedback by killingtrees, opening the canopy and increasing solar penetration to the forest floor.”

Increasingfrequency of drought as a result of warmertemperatures in the tropical Atlantic are also having an effect on the vulnerabilityof the Amazon to fire. Climate models suggest that as temperatures continueto climb, incidence and severity of drought in the eastern and southern Amazonwill also increase. These regions are the areas that are seeing the mostpressure from development. Further, some research suggests that deforestationitself through the loss of transpiration can trigger a decline inrainfall.

2030 forecast for the Amazon

Analyzing the interacting trends, the authors lay out a scenario where more thanhalf the Amazon could be doomed by 2030.

A map of Amazonia 2030, showing drought-damaged, logged and cleared forests assuming the last 10 years of climate are repeated in the future. See text for further details. PPT, precipitation. Map from Nepstad et al (2008). “The economic, ecological and climatic systems of the Amazon may beinteracting to move the forests of this region towards a near-term tippingpoint,” they write. “In this scenario, the growing profitability ofdeforestation-dependent agriculture and cattle ranching provides an expandingfrontier of forest fragmentation and ignition sources that inhibits rainfall asforests are replaced by fields and pastures and as fires fill the late dryseason atmosphere with aerosols.”

“Forests damaged by drought, logging, fragmentation and previous fire burnrepeatedly as tall canopy tree species are gradually replaced by coppicing trees,grasses and other high-biomass plants. These local and regional processes areexacerbated when sea surface anomalies and extreme weather events cause severedrought episodes and the burning of vast forested landscapes. Global warmingreinforces these trends by elevating air temperatures, increasing dry seasonseverity and increasing the frequency of extreme weather events.”

Based on these trends, Nepstad and colleagues forecast that 31 percent of theAmazon rainforest will be deforested and 24 percent will be damaged by droughtor logging by the year 2030. They say a 10 percent drop in rainfall will resultin drought damage to an additional 4 percent of the forests. The impacts fromsuch degradation and deforestation will result in emissions of 15-26 Pg ofcarbon in less than three decades “without invoking the influence of globalwarming.” Worryingly, the authors note this scenario is a conservative one forest loss and emissions could be far worse.

Avoiding the Amazon tipping point

Still Nepstad and colleagues are hopeful that such a tipping point can beavoided. They say landowners in the Amazon especially those with firesensitive investments like orchards, intensive-cattle operations, and managedtimber harvesting are increasingly aware of damage wrought by burning andare avoiding the use of fire as a land management tool, reducing the incidenceof fires escaping into neighboring forest areas. Soy and beef producers are alsoresponding to new emphasis on environmental performance from commodity buyers soy growers in Mato Grosso are adhering to a moratorium on clearing ofrainforest for soy production, while cattleranchers are forming their own certification system for environmentalstandards. The Brazilian government has recently entered the fray by crackingdown on illicit commodity production in the Amazon, sending in troops andimplementing fines and threatening credit access to landowners for buying ortrading soy, beef, and other products produced on illegally deforested lands.

Nepstad and colleagues say that intensification of cattle production boosting head per hectare by a factor of 8 in some areas is reducing theneed to clear forest land for pasture. Finally the authors are optimistic thatnewly established protected areas can serve as a bulkhead against deforestationin especially vulnerable regions. They say carbon offsets under the REDDmechanism agreed toin principle at the December U.N. climate talks in Bali, Indonesia, canhelp finance forest conservation efforts as well as deliver benefits torural people and indigenous groups.

Daniel C. Nepstad, Claudia M. Stickler, Britaldo Soares- Filho and Frank Merry(2008). Interactionsamong Amazon land use, forests and climate: prospects for a near-term foresttipping point [FREE OPEN ACCESS]. Phil. Trans. R. Soc. B, DOI:10.1098/rstb.2007.0026

24. November 2017/by GFMCadmin