In the Amazon rainforest, there is a fine balance between efforts to prevent deforestation and the desire to clear the trees for agriculture. It says much about this tension that spikes in forest loss in Brazil earlier this year have been attributed to nothing more tangible than a perceived shift in where the country's politicians intend to draw the line between the two. After five years of stunning success in combating deforestation, the Brazilian authorities had started to ponder how to respond to the growing clamour from landowners and farmers in the region who were being prevented from clearing land to cash in on record prices for commodities such as soya and beef. That sense of a weakening political resolve to protect the rainforest was enough of an incentive for some to begin clearing it again.

Those wielding the chainsaws and driving the bulldozers may have judged the climate correctly: lobbying and political discussions have ultimately produced a controversial bill to change how the Amazon is protected in Brazil. Final voting on amendments to the forest code was due in the Brazilian parliament this month, but has been postponed until March. Supporters and critics of the legislation are gearing up for a final push, and both sides are putting pressure on President Dilma Rousseff, who has the power to veto sections of the bill, or the bill itself.

The proposed new forest code grants an effective amnesty to those who illegally deforested their land before 2008.

The proposed forest code would update regulations dating back to 1965 on how private landowners must preserve native forest. Under the existing rules, they must maintain forest on 80% of their land, and those who have cleared illegally must restore to that level. The proposed change would remove the 80% obligation from small landowners, and grant an effective amnesty to those who illegally deforested their land before 2008, removing the threat of legal sanctions and fines for those who agree to reforest.

The government has said that the legislation improved as it moved through the Senate, but there are certainly problems remaining with the proposals. The bill undermines the old code's base in ecology, in that it would loosen restrictions on cutting trees in areas around rivers and on steep hills — rules that are intended to protect river health and prevent soil that is normally protected by vegetation being washed into waterways. This is just bad policy.

Through its exemption for small landowners, the revised code will legalize massive new destruction of forest — about 220,000 square kilometres according to an analysis from researchers at the University of São Paulo — and there is reason for concern that the amnesty being granted could encourage further illegal deforestation, by giving landowners the impression that the government doesn't have what it takes to truly enforce the law. Furthermore, the requirements for reforestation by landowners who have broken the law are too weak. Scientists and environmentalists should continue to press for changes to the legislation in these and other areas. But they should also acknowledge that there are problems with the existing system — notably, that those landowners who have abided by the law have done so without reward, despite the promise of carbon payments down the road in exchange for the protection and stewardship of standing forest.

The Brazilian government maintains that it will meet its pledge to reduce deforestation by 80% by 2020, which was set by former president Luiz Inácio Lula da Silva at the Copenhagen climate conference in 2009, and that it is on target to do so.

Deforestation currently accounts for about 15% of global greenhouse-gas emissions, and some 75% of Brazil's. Meeting the pledge would be a massive achievement, and one that would allow Brazil to claim a place at the front of the global pack in terms of reducing carbon emissions and protecting biodiversity. But the government cannot get there on its own. It needs its policy to have broad support, or at least command respect, from people on the ground on all sides of the debate. And in this sense, the real danger isn't the new forest bill itself, but the sentiment of relaxed protection for the Amazon that seems to be behind it.