Is it possible to combine modern tropical agriculture with environmental conservation? Brazilian agriculture offers encouraging examples that achieve high production together with adequate environmental protection ([ 1 ][1], [ 2 ][2]). However, these effective practices may soon lose ground to the conventional custom of resource overexploitation and environmental degradation. A revision to the Forest Act, the main Brazilian environmental legislation on private land, has just been submitted to Congress, and there is a strong chance that it will be approved. The proposed revision raises serious concerns in the Brazilian scientific community, which was largely ignored during its elaboration. The new rules will benefit sectors that depend on expanding frontiers by clear-cutting forests and savannas and will reduce mandatory restoration of native vegetation illegally cleared since 1965. If approved, CO2 emissions may increase substantially, instead of being reduced as was recently pledged in Copenhagen. Simple species-area relationship analyses also project the extinction of more than 100,000 species, a massive loss that will invalidate any commitment to biodiversity conservation. Proponents of the new law, with well-known ties to specific agribusiness groups, claim an alleged shortage of land for agricultural expansion, and accuse the current legislation of being overprotective of the environment in response to foreign interests fronted by green nongovernmental organizations. However, recent studies ([ 3 ][3]) show that, without further conversion of natural vegetation, crop production can be increased by converting suitable pastures to agriculture and intensifying livestock production on the remaining pasture. Brazil has a high potential for achieving sustainable development and thereby conserving its unique biological heritage. Although opposed by the Ministry of the Environment and most scientists, the combination of traditional politicians, opportunistic economic groups, and powerful landowners may be hard to resist. The situation is delicate and serious. Under the new Forest Act, Brazil risks suffering its worst environmental setback in half a century, with critical and irreversible consequences beyond its borders. 1. [↵][4] 1. D. Nepstad 2. et al ., Science 326, 1350 (2009). [OpenUrl][5][Abstract/FREE Full Text][6] 2. [↵][7] 1. C. R. Fonseca 2. et al ., Biol. Conserv. 142, 1209 (2009). [OpenUrl][8][CrossRef][9] 3. [↵][10] 1. G. Sparovek 2. et al ., Consideracoes sobre o Codigo Florestal brasileiro (“Luiz de Queiroz” College of Agriculture, University of Sao Paulo, Piracicaba, Brazil, 2010); [http://eco.ib.usp.br/lepac/codigo\_florestal/Sparovek\_etal_2010.pdf][11]. [1]: #ref-1 [2]: #ref-2 [3]: #ref-3 [4]: #xref-ref-1-1 View reference 1 in text [5]: {openurl}?query=rft.jtitle%253DScience%26rft.stitle%253DScience%26rft.issn%253D0036-8075%26rft.aulast%253DNepstad%26rft.auinit1%253DD.%26rft.volume%253D326%26rft.issue%253D5958%26rft.spage%253D1350%26rft.epage%253D1351%26rft.atitle%253DThe%2BEnd%2Bof%2BDeforestation%2Bin%2Bthe%2BBrazilian%2BAmazon%26rft_id%253Dinfo%253Adoi%252F10.1126%252Fscience.1182108%26rft_id%253Dinfo%253Apmid%252F19965742%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [6]: /lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6Mzoic2NpIjtzOjU6InJlc2lkIjtzOjEzOiIzMjYvNTk1OC8xMzUwIjtzOjQ6ImF0b20iO3M6MjQ6Ii9zY2kvMzI5LzU5ODkvMjc2LjIuYXRvbSI7fXM6ODoiZnJhZ21lbnQiO3M6MDoiIjt9 [7]: #xref-ref-2-1 View reference 2 in text [8]: {openurl}?query=rft.jtitle%253DBiol.%2BConserv.%26rft.volume%253D142%26rft.spage%253D1209%26rft_id%253Dinfo%253Adoi%252F10.1016%252Fj.biocon.2009.02.017%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [9]: /lookup/external-ref?access_num=10.1016/j.biocon.2009.02.017&link_type=DOI [10]: #xref-ref-3-1 View reference 3 in text [11]: http://eco.ib.usp.br/lepac/codigo_florestal/Sparovek_etal_2010.pdf