19 January 2001 Vol 291 SCIENCE www.sciencemag.org POLIC Y F OR UM: ENVIRONMENT
The Future of the Brazilian Amazon*
William F. Laurance,* Mark A. Cochrane, Scott Bergen, Philip M. Fearnside, Patricia Delamônica, Christopher Barber, Sammya D 'Angelo, Tito Fernandes
M od els of de ve lopmen t in the Am azo n. Optimistic (top) a nd non op tim istic (bottom ) scenarios, sh owi ng pr edict ed fore st degr adation b y the year 2020.
(Black is deforested or heavily degraded, including savan n a s and othe r n on fo re sted a re a s . R e d is m o d e ra te ly d e g ra d ed, ye llow i s l ig h tl y d e g ra d e d , and g reen is pristine).
SCIENCE’S COMPASS • POLICY FORUM Pp. 438-439
T
he Brazilian Amazon contains about 40% of the world's remaining tropical rainforest and plays vital roles in maintaining biodiversity, regional hydrology and climate, and terrestrial carbon storage (1). It also has the world's highest absolute rate of forest destruction, currently averaging nearly 2 million hectares per year (2).This rapid pace of deforestation has several causes.
First, nonindigenous populations in the Brazilian Amazon have increased tenfold since the 1960s, from about 2 million to 20 million people, as a result of immigration from other areas of Brazil and high rates of intrinsic growth (3). Second, industrial logging and mining are growing dramatically in importance, and road networks are expanding that sharply increase access to forests for ranchers and colonists. Third, the spatial patterns of forest loss are changing; past deforestation has been concentrated along the densely populated eastern and southern margins of the basin, but new highways, roads, logging projects, and colonization are now penetrating deep into the heart of the basin.
Finally, human-ignited wildfires are becoming an increasingly important cause of forest loss, especially in logged or fragmented areas (4).
Growing concern over the rapid destruction of Amazonian forests has prompted a number of international and domestic initiatives to help promote conservation planning and sustainable development. The largest of these is the Pilot Program to Conserve the Brazilian Rainforest, which is attempting to channel $340 million from G-
W . F. La uran ce is a res earc h sc ientis t at the Sm iths onian Tropical Research Institute, Apartado 2072, Balboa, Panam á, and Bio logic al D yna m ics o f Fore st Fra gm en ts Project (BD FFP ), Na tional Institute for Amazonian Research ( IN P A ), C.P . 4 7 8, M an a us , A M 6 9 0 11 -9 7 0, Br az il . M . A . C ochra n e i s a r e s e ar c h sc i e ntis t at the B a sic S c ie nce an d Re m ote Se nsin g In itiativ e (BS RS I), M ichig an S tate University, East Lansing, MI 48823, USA. S. Bergen is a doctoral can did ate a t th e D e p ar tme nt o f F o r est Scien c e, Oregon State U niversity, Cor vallis, OR 97331, U SA . P . M . Fea r n si d e i s a re s e ar c h s c ie n ti st at th e IN P A E c o lo g y De par tm en t. P . D e l am ô n ic a is a s sist an t d ir ec tor of t h e B D F F P , C. B arbe r is a rese arch a ssoc iate at BS RS I, a n d S . D'A ng elo and T. Fernandes are BDFFP research assistants.
* T o w h o m c o rr e sp o n d e nc e s ho u ld b e a d d ress ed . E-m ail:
w f l@ i n p a .g o v .b r
7 nations (Germany, Britain, France, Italy, the United States, Canada, Japan, and the European Community) into land-use planning, extractive (5) and Amerindian reserves, ecological corridor systems, and capacity-building for local governments (6). There also are bilateral programs between the Brazilian and other governments, domestic governmental initiatives, and activities of private organizations. Collectively, these programs involve hundreds of millions of dollars and the energies of many dedicated individuals.
These efforts, however, pale in comparison to the scale of ongoing and planned development activities in the Amazon. Under the auspices of its
"Avança Brasil" (Advance Brazil) program (7), the Brazilian government is fast-tracking dozens of major infrastructure projects that will span large expanses of the basin--intended to accelerate economic development in the industrial agriculture, timber, and mining sectors of the economy.
Investments totaling about $40 billion over the years 2000-07 will be used for new highways, railroads, gas lines, hydroelectric projects, power lines, and river-channelization projects. The Amazonian road network is being greatly expanded and upgraded, with many unpaved sections being converted to paved, all-weather highways. Key environmental agencies, such as the Ministry of the Environment, are being largely excluded from the planning of these developments (6).
The effects of these massive projects and other development trends on Amazonian forests have not been assessed systematically (7). Therefore, we developed models to integrate current spatial data on deforestation, logging, mining, highways and roads, navigable rivers, vulnerability to wildfires, protected areas, and existing and planned infrastructure projects. We also assessed the past impacts of highways and roads on Amazonian forests, and then used these analyses to predict the pattern and pace of forest degradation over the next 20 years.
We generated two models with realistic but differing assumptions--termed the
"optimistic" and "nonoptimistic"
scenarios—for the future of the Brazilian Amazon. The models predict the spatial distribution of deforested or heavily degraded land, as well as moderately degraded, lightly degraded, and pristine forests (8). The principal differences between the models are that, under the optimistic scenario, degraded zones near highways, roads, and infrastructure projects are more localized and that protected and semi-protected areas near developments are less likely to be degraded (9).
Although the predictions of the two models differ substantially, both suggest that the Brazilian Amazon will be drastically altered by current development schemes and land-use trends over the next 20 years (see figure). Forest loss will be
19 January 2001 Vol 291 SCIENCE www.sciencemag.org greatest along the southern and eastern areas of the
basin, but there will also be extensive fragmentation and degradation of remaining forest blocks in the central and northern parts of the basin. Under the nonoptimistic scenario, few pristine areas will survive outside the western quarter of the region.
Models of development in the Amazon. Optimistic (top) and nonoptimistic (bottom) scenarios, showing predicted forest degradation by the year 2020. (Black is deforested or heavily degraded, including savannas and other nonforested areas.
Red is moderately degraded, yellow is lightly degraded, and green is pristine).
Policy Implications
Our models suggest that, under status quo conditions, current efforts to promote conservation planning in the Brazilian Amazon will be overwhelmed by prevailing destructive trends.
Although a combination of threatening factors is responsible, special attention should be focused on Avança Brasil, because it is a massive new initiative that will open vast areas of the Amazonian frontier to development activities. Moreover, this program is far more amenable to policy modification than are intrinsic problems such as rapid population growth, and its implications have been very poorly discussed and debated in Brazil.
To assess the likely impacts of Avança Brasil and other planned infrastructures on Amazonian forests, we reran our models but without the dozens of planned highways, waterways, and other projects.
For the optimistic and nonoptimistic scenarios, respectively, the predicted rate of deforestation drops by an amount ranging from 269,000 to 506,000 hectares per year, and the conversion of pristine or lightly degraded forest to moderately or heavily degraded lands slows by 1.53 to 2.37 million hectares per year. Forest fragmentation is also greatly reduced: under the nonoptimistic scenario, for example, the area retained in large (at least 100,000 km2) blocks of pristine to lightly degraded forest exceeds the earlier model by more than 36%
without these major new projects.
Avança Brasil typifies the current top-down planning process in the Amazon, in which megaprojects are proposed and approved long before the environmental costs and risks can be evaluated. Many projects (such as the BR-319 highway, the Urucu-Pôrto Velho pipeline, and the Araguaía-Tocantins waterway) will create corridors between densely populated areas and the remote Amazonian frontier. Such projects commonly initiate a process of spontaneous colonization, logging, mining, and land speculation that is almost impossible for governments to control (3-5). The results are often disastrous for forests.
Alternatives to Destructive Development There are, however, viable alternatives. The Amazon provides a diversity of valuable environmental services that could help sustain a moderate population indefinitely (10). The destruction of each hectare of forest, for example, causes a net release of nearly 200 metric tons of CO2-equivalent carbon (11). In the future, carbon-offset funds paid to developing countries are likely to become an important mechanism for promoting forest conservation (12). This is in addition to the benefits of intact forests for ameliorating floods, conserving soils, maintaining stable regional climates, preserving biodiversity, and supporting indigenous communities and ecotourism industries.
At present, however, Brazil's Ministry of Foreign Affairs opposes allowing carbon-offset funds to be linked to avoiding deforestation—a stance that alarms many Brazilian scientists and the Ministry for the Environment. In our view, this is an appalling mistake. As our study shows, the magnitude of projected forest destruction is tremendous, which means that substantial carbon credits could be gained if effective measures were taken to alter the course of development. For example, if the current wave of planned highways and infrastructure projects did not proceed, we estimate that the financial value of reduced carbon emissions alone would range from $0.52 to $1.96 billion per year (8).
There is a clear potential for such revenues to improve living standards for Amazonian communities. If translated into currency through the Kyoto Protocol, such funds could radically alter the economic logic that is currently driving rapid forest destruction (13).
Rather than rampant exploitation, an alternative and far superior model for Amazonian development is one in which agricultural land is used intensively rather than extensively—whereby high-value agroforestry and perennial crops are favored over fire-maintained cattle pastures and slash-and-burn farming plots (14). Such a model is very unlikely to develop, however, when land is cheap, destructive wildfires are common, and vast new frontiers are being continually opened for colonization. Again, this militates against the short-term thinking and aggressive development strategy embodied in Avança Brasil.
Conserving Amazonian forests will not be easy. If the world expects Brazil to follow a development path that differs from its current one—and from a path that most developed nations have followed in the past—then substantial costs will be involved.
The investment, however, would surely be worth it.
At stake is the fate of the greatest tropical rainforest on Earth.
References and Notes
1. R ec ent studies suggest that intact Am azo nian fores ts not only c o n tain a massive stock of carbon, but may also be a globally significant carbon si nk at present [J.
Grace e t a l. , S cienc e 270, 7 78 (1995); O . L. P hillips e t al., Sc ienc e 28 2, 43 9 (1 998 )].
2. Deforestation rates from 1995 to 1999 a ve rage d 1. 89 ± 0. 60 m i ll io n h ec ta r es p er year, n ot inc lud ing sm all (< 6. 25 h a) cl ea r in g s o r e x te n s iv e a re a s af fe c te d b y selective logg ing or s u rface fires [Deforestation Es timates for the Brazilian Am azon (Instituto Nacional d e Pesquisas Espaciais, São José dos Ca m po s, B razil, 200 0)].
3. G . G o o dm an, A . Ha ll, Eds ., The Futu re of A m azo nia : D es truction or S ustai nable D e ve lo pm e nt ? (M ac mi lla n , Lon do n, 19 90) .
4. W. F. Lau rance, Trend s Ecol. Evol. 13, 411 (19 98).
5. Extractive rese rves are inte n de d t o ma intain n a t ural e nvir onm ental serv ices wh ile allow ing sus taina ble harv ests of rubber latex, Brazil nuts, or other natural pro du cts [ P . M. Fearnside, BioScience 39, 387 (19 89)].
6. W . F. Lauranc e, P. M. F earnside , T re nds Ec ol. Evo l. 14, 457 (19 99) .
7. T he env ironm en tal cos ts of A van ça B rasil w e re first hi ghli ghted in a rep ort that pro jecte d the extent of deforestation caused by planned highway construction [D. C. Nepstad et al., Avança Brasil: Cenários Futuros p a ra a A m a zô n ia (I n st it u to d e P e sq u is a A m b ie n ta l d a Am azônia, Belém , Brazil, 2000)]. Our stud y is m o r e conservative in its p roje ctio n of highway impacts, b ei ng based on a n assessment of past deforestation along all existing highways, rather than o n ly fo ur that are located in are as th a t a re n o w h ea v il y d e fo r es te d . O ur s tu d y also inclu de s the im pac ts o f u n p a ve d r oa d s and of exis ting and plan ne d in frastru cture pro jects (e.g ., hydroelectric dams, power lines, gas lines, railroads), w h i c h also gen e ra te roa d ne t work s an d th e r eb y stron gly in fluen ce d efore statio n. Fin ally, o u r m od els distin gu ish a m ong m ultiple leve ls of fore st d egr adation, incorporate spatial data on pro te ct ed a n d s em iprotec ted areas, and inclu de ot h e r planne d proje cts (e.g ., X i ngu D am s be yon d B e lo M onte , Cui ab á-Santarém railway) that fall outside the Avança Bra sil pro gra m .
8. P ristine fores ts are thos e free fro m n onindi ge nou s use s.
9. For a detailed explanation of our m ode ls, inclu din g s u p p o r ti n g dat a, analysi s, a nd i n t e rp r e t a ti o n, sup plem entary m ateria l is available at Sc ie nc e On lin e at www .sciencem ag.org /cgi/con tent/full/291 /5503/438/
DC 1.
10. P. M . Fea rns ide , Eco l. Eco n. 21 , 53 (1 997 ).
11. ---, Clim . Ch ang e 46 , 115 (20 00) . 12. C. K rem en et al., S cien ce 2 88, 1 828 (20 00) . 13. P. M . Fea rns ide , Bio m ass Bio en erg y 16 , 171 (19 99) . 14. D . C . N e p st ad , A. G. Morei ra, A. A. Ale n c ar, Fla me s in
t he Rai n Forest: O rig ins, Imp acts, an d Alte rn atives to Am azo nian Fire s (W orld Ba nk, B rasília , Bra zil, 19 99) . 15. W e than k M . Ste ining er, R . M esq uita, E . Bru na, H . Vasco n celos, S. Laurance , and th re e ano n ym ou s r efer ees f or he lp fu l c o m m e n ts , t he N A S A -L B A p ro gra m , the A . W. M ellon Fou nd ation , the U .S . Agency for International D ev elopm e nt , the INP A Inte grate d Research Project, the Brazilian National Council for Sc ientific and Technological Resear ch (CN Pq), and th e Sm ithso nian Institu tion fo r sup po rt.
*This is not an original reprint. It was produced by Smithsonian Tropical Research Institute's Office of Information, for tempo rary purposes by [email protected]
