Brazil has been cutting down large swaths of the Amazon rainforest for development,agriculture and the use of natural resources from the rainforest. However, the Amazon is widely regarded as the lungs of the earth. Keeping this in mind, what international laws bar or place limits on how Brazil can use the Amazon keeping in mind the Brazilian government has jurisdiction over Brazilian land.
There is an 1978 Amazon Cooperation Treaty but its wording on the matter is so vague and aspirational that it could hardly constitute any kind of firm commitment to concrete objectives:
“achieve also the preservation of the environment, and the conservation and rational utilization of the natural resources of those territories.”
It is basically a "framework agreement" that mainly obliged parties to maker further efforts towards
“operational agreements and understandings, as well as the pertinent legal instruments”.
As far as I can tell, not much came from that. On the other hand, in the context of climate change agreements, there was the
The Bali Action Plan encouraged actions to mitigate climate change, including “policy approaches and positive incentives on issues relating to reducing emissions from deforestation and forest degradation in developing countries” (Decision 1/CP13, Para. 1, b, iii). COP-13 adopted a specifi c decision on the issue of “Reducing Emissions from Deforestation in Developing Countries” (Decision 2/CP.13), inviting the parties to support ongoing efforts to reduce such emissions on a voluntary basis (Article 1) and, in particular, undertake “demonstration activities” (Article 3).
The United Nations’ Green Climate Fund (GCF) has accepted the first proposal for REDD+ results-based payouts from Brazil, effectively paying the country for reducing its deforestation rates in 2014 and 2015, as compared to the 1996-2010 average. In return for around 19 million tons of emissions reductions, the GCF has agreed to pay Brazil $96 million, which the country says it will use to launch a program called Floresta+ aimed at ecosystem restoration, the provision of environmental services, and strengthening the country’s REDD+ strategy.
There's also the Rio Declaration, which was probably signed by Brazil (as there are 175 signatories). It has broadly phrased principles such as:
States shall cooperate in a spirit of global partnership to conserve, protect and restore the health and integrity of the Earth's ecosystem. In view of the different contributions to global environmental degradation, States have common but differentiated responsibilities. The developed countries acknowledge the responsibility that they bear in the international pursuit of sustainable development in view of the pressures their societies place on the global environment and of the technologies and financial resources they command.
To achieve sustainable development and a higher quality of life for all people, States should reduce and eliminate unsustainable patterns of production and consumption and promote appropriate demographic policies.
States shall enact effective environmental legislation. Environmental standards, management objectives and priorities should reflect the environmental and developmental context to which they apply. Standards applied by some countries may be inappropriate and of unwarranted economic and social cost to other countries, in particular developing countries.
But these are probably interpretable enough that it's hard to take them as commitments to any concrete (i.e. numerical) objectives, although some UN sources interpret these as an obligation to do no environmental harm to other countries such as entailing a
responsibility to ensure that activities within their jurisdiction or control do not cause damage to the environment of other States or of areas beyond the limits of national jurisdiction.
There are however contrary opinions, e.g. commenting on similar language (regarding forests) in the Paris agreement:
Article 5 of the Paris Agreement sets the tone as it says that “parties should take action to conserve and enhance […] forests”. However, the drafting of this article may be insufficient to create direct responsibility on states (typically using ‘should’ and not ‘shall’), and it is rather broad and undetermined. It would require further elaboration from the tribunal to become fully operational.
This is quite apart from issues of venue and enforcement, e.g. whether Brazil (or any country) would agree to settle the matter in an international court, rather than e.g. being pressured by sanctions, which are usually easier to justify if some kind of violation of international norms/law is raised. (Sometimes the spectre of sanctions has been raised in re Brazil, e.g. by Biden as the "stick" counterpart to the "carrot" of payments for preserving forests.)
The environment as a global concern is relatively new unlike war or slavery. Thus existing legislation is thin on the ground. However, there are a number of proposals.
Ecocide has been proposed by a panel of 12 legal experts around the world as an international crime akin to genocude and crimes against humanity. The definition was unveiled in June this year. It defines this international crime as:
unlawful or wanton acts committed with knowledge that there is substantial likelihood of severe and either widespread or long term damage to the environment being caused by those acts.
The idea of such a law is not new. It was bought up originally by the Swedish Prime Minister Olof Palme at the 1972 UN Conference on the Human Environment. The term ecocide had already been used two years earlier by the bioethicist Arthur Galston in the Conferance on War and National Responsibility held in Washington. Ecocide was also considered and then dropped during the establishment of the ICC in 1998.
Also research by Essex & Sydney University published in The Review of European, Comparative International Environmental Law states that although legal frameworks have been established to safeguard the environment, in particular the Convention on Biological Diversity (CBD) and Reducing Emmissions from Deforestation and Forest Degradation (REDD), both under the auspices of the UN, they have not proved very effective.
In this opinion, they are agreed with by Luis Roberto Barroso, Justice at the Supreme Court of Brazil in an article published in Harvard's International Law Journal and titled, In Defense of the Amazon: The Role of the Law and Courts where he identifies key weaknesses in the legislative framework of Brazil. After all, international law, to be effective, has to be implemented at the national level and if the national legal framework is weak then this weakens the international law with weakened outcomes. One key proposal he suggests is a constitutional amendement to
prohibit the regularisation of public land invasions that favour land grabbers.
This should help strengthen the legal framework around CBD and REDD+ (this is an enhancement of REDD) and make it more effective in its aims.
Furthermore, the research referred to above states that human rights legislation may prove more effective in protecting the Amazon since:
campaigners would not need to submit information on more than one nation for it to be upheld. Courts would only need to judge that enviromental damage violated the rights of either certain individuals or tribal and indigenous peoples.