By Gary Duffy
BBC News, Sao Paulo
President Lula says climate change is the world's most challenging issue
The Brazilian government has announced that it aims to achieve a reduction of at least 36% on its carbon emissions by the year 2020.
If it meets its pledge, greenhouse gas emissions would be near 1994 levels.
The proposal, which is not a binding target, was revealed in advance of the major UN summit on climate change to be held in Copenhagen in December.
Brazil hopes to put pressure on richer nations to declare their intentions and break the deadlock in the negotiations.
Details of the government's proposals were unveiled following a meeting involving President Luiz Inacio Lula da Silva and some of his senior ministers.
In common with other developing nations, Brazil is not setting a binding target for reducing carbon emissions, but is instead proposing to take voluntary action.
However with its promise to reduce the anticipated level of greenhouse gas emissions in 2020 by 36%-39%, South America's largest country hopes to encourage others.
Officials here regard the proposal as "ambitious" and a meaningful way to combat climate change.
Much of the proposed reduction is expected to be achieved by improved protection of the Amazon.
The government here announced this week that deforestation in the rainforest was its lowest level since monitoring first began 21 years ago.
Deforestation is blamed for more than half of Brazil's greenhouse gas emissions.
At the highest end of the proposed range of cuts, emissions would be reduced to nearly 1994 levels, but ministers say international and private sector help would be needed to reach this kind of objective.
A senior official involved in the preparations for Copenhagen said while some richer industrialised nations deserved praise for their efforts to combat climate change, as a group they had not been prepared to put their numbers on the table.
Brazil hopes it can play a leading role in securing an agreement in Copenhagen, and as part of that effort, President Lula will hold talks in Paris this weekend with his French counterpart Nicolas Sarkozy.