BALI, Indonesia - With much attention focused on the conference here, studies about warming-related catastrophes of the future are rolling out back to back.

Tuesday brought warnings that flooding could affect 150 million people and cause $35 trillion in damage worldwide. A study released yesterday predicted the demise of up to 30 percent of all land-based bird species by 2100. And then there's the Amazon rain forest.

The impact of climate change plus deforestation could wipe out or severely damage nearly 60 percent of it by 2030, making it impossible to keep global temperatures from reaching catastrophic levels, an environmental group said yesterday.

Several recent studies have suggested similar possibilities, but scientists say the size and complexity of the Amazon leaves many questions about its future open to debate.

"The importance of the Amazon forest for the globe's climate cannot be underplayed," said Daniel Nepstad, author of a new report by the World Wide Fund for Nature released at the U.N. climate change conference.

Besides its critical role in lowering world temperatures, the forest is such a big source of fresh water that it may influence ocean currents, he said. "And on top of that, it's a massive store of carbon."

Sprawling over 1.6 million square miles, the Amazon covers nearly 60 percent of Brazil. Largely unexplored, it contains one-fifth of the world's fresh water and 30 percent of all plant and animal species, many still undiscovered.

Large swaths of forest such as the Amazon are also valuable "carbon sinks," or absorbers of carbon dioxide. Deforestation pours carbon dioxide into the atmosphere and at the same time kills off carbon-absorbing vegetation.

The WWF said logging, livestock expansion and worsening drought were projected to rise in the coming years and could result in the clearing of 55 percent of the rain forest. If rainfall declines 10 percent in the Amazon, as predicted, an additional 4 percent could be wiped out.

Scientists say that if global temperatures rise more than 3.6 degrees above preindustrial levels, the risks to the environment and to people will be enormous. It is essentially the "tipping point" for catastrophic floods and droughts, rising sea levels and deadly diseases and heat waves.

"It will be very difficult to keep the temperatures at 3.6 degrees if we don't conserve the Amazon," said Nepstad, who is also a senior scientist at the Woods Hole Research Center in Massachusetts.

According to the WWF, deforestation in the Amazon could result in 56 billion to 97 billion tons of carbon dioxide being released into the atmosphere by 2030, roughly equal to two years of carbon emissions worldwide.

Earl Saxon, a climate-change expert with the World Conservation Union, said the report was consistent with "all the best science" on the issue.