Brazilian President Dilma Rousseff announced on Tuesday at a joint White House news conference that Brazil sees the U.S. as a 'natural partner' and pledges to restore millions of acres of forests and expand renewable sources.Brazil's announcement stopped short of a commitment to bring deforestation down to zero, as many environmentalists had advocated. Still, the pledge offered some of the first signs of how Brazil intends to curb its emissions as part of the treaty. The vast majority of Brazil's greenhouse gas emissions come from destruction in the Amazon rainforest.As part of its plan, announced during Brazilian President Dilma Rousseff's visit to the White House, Brazil is vowing by 2030 to restore and reforest 12 million hectares an area roughly the size of England. The government is also pledging to "pursue policies aimed at eliminating illegal deforestation." Brazilian law allows landowners to legally cut 20 percent of trees in land, with some limitations.Speaking alongside Rousseff, President Barack Obama said the relationship the U.S. has with Brazil is a "cornerstone" of America's relations with Latin America. He added that the U.S. and Brazil are "natural partners" around the world.He said Rousseff's visit marks "one more step" and a "new more ambitious chapter" in relations between two of the world's largest economies.Brazil also plans to expand renewable sources other than hydropower to between 28 percent and 33 percent of its total energy mix by 2030. And in the electricity sector, the U.S. and Brazil jointly announced intentions to increase their share of renewable, non-hydropower sources to 20 percent by 2030. That will require tripling the amount of renewable energy on the U.S. electricity grid, while doubling it in Brazil, officials said."We believe that this is an ambitious target, but one that is actually achievable and will create new low-cost opportunities for the American economy," Deese said. "To achieve it, we're going to have to continue to hit our marks in implementing the regulations we've identified to date."Rich and poor countries alike have been putting forth their commitments, known as nationally determined contributions, to reduce emissions as part of the treaty, which world leaders hope to finalize later this year in Paris. The U.S. has already announced its full commitment to the climate treaty: a reduction of greenhouse gas emissions of up to 28 percent by 2025, compared to 2005 levels.But a key sticking point in the climate treaty has been whether developing nations like Brazil will be willing to make substantial contributions. Brazil and other developing countries have balked, arguing that industrialized nations that have polluted more historically bear more of the responsibility for curbing climate change.In another positive sign for the treaty's backers, China on Tuesday announced its highly anticipated contribution, pledging to reduce the intensity of its carbon emissions and to halt their growth by 2030. Officials said China would aim to reduce its emissions per unit of gross domestic product by 60-65 percent by 2030 from 2005 levels.Brazil still hasn't announced how much of an emissions cut it will pledge, but sought to use the reforestation announcement as an example of concrete steps the country can take to meet its eventual target. About 75 percent of Brazil's carbon dioxide emissions come from destruction of the Amazon, which acts as a giant absorber of carbon dioxide.Obama and Rousseff have been working to show they've moved beyond tensions sparked by the revelation nearly two years ago that the U.S. was spying on Rousseff. She canceled a planned state visit in response. Officials in both countries say neither leader is interested in rehashing the spying issues this week and instead want to focus on ways to deepen cooperation.