President Barack Obama's $3.55 trillion budget, released on Thursday, retains his plan to cut climate-warming carbon dioxide emissions by auctioning off 100 percent of emission permits to industries.

Six in 10 U.S. residents -- more than 186 million people -- live in areas with dangerous levels of air pollution, the American Lung Association reported on Wednesday.

The air in many U.S. cities became dirtier last year, the association said in its annual "State of the Air" report.

Global warming activist Al Gore on Friday urged passage this year of a US law to slash greenhouse emissions, saying failure to pass legislation could cause the collapse of world climate negotiations.

In a vicious cycle made worse by humans, scientists now believe fires spur climate change, which in turn makes blazes bigger, more frequent and more damaging to the environment.

Alaskan Inuits, Australian aborigines and Pygmies from Cameroon have a message for a warming world: native traditions can be a potent weapon against climate change.

At a summit starting Monday in Anchorage, Alaska, some 400 indigenous people from 80 nations are gathering to hone this message in the hope that it can be a key part of international climate negotiations.

The recent decades-long drought that killed 100,000 people in Africa's Sahel may be a small foretaste of monstrous "megadroughts" that could grip the region as global climate change worsens, scientists reported on Thursday.